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datashee t o product structure : silicon monolithic integrated circuit o this product has no designed prot ection against radioactive rays 1/27 tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 14 ? 001 optocoupler-less isolated flyback converter BD7F200HFN-LB bd7f200efj-lb general description this product guarantees long time supply availability in the industrial instrumentation market. bd7f200 is an optocoupler-less isolated flyback converter. an optocoupler or the tertiary winding feedback circuit which was needed to obtain a stable output voltage isolated by a transformer in the conventional application becomes unnecessary, thus, the number of parts is reduced drastically, producing a small-sized and high-reliability application isolated type power supply. furthermore, a highly by the use of the original adapted-type on-time control technology, it makes the external phase compensation parts become unnecessary, therefore a highly efficient isolated type power supply application can easily be produced. features ? guaranteed long time supply availability for industrial applications. ? no need for an optocoupler or a transformer tertiary winding. the output voltage can be set by two external resistors and the transformer turns ratio. ? uses original adapted type on-time control technology. high-speed load response is realized and external phase compensation parts are unnecessary. ? fixed switching frequency and low output ripple ? highly efficient light load mode available (pfm operation) ? shutdown / enable control ? built-in n-channel mosfet ? soft start function ? output load compensation function ? protection functions: vin under voltage lock-out (vin uvlo) over current protection (ocp) thermal shutdown protection (tsd) application ? industrial equipment isolated power supply key specifications ? supply voltage of operation: 8v to 40v ? sw terminal operating voltage: 50v (max) ? over current limit: 2.75a (typ) ? switching frequency: 400khz (typ) ? reference voltage accuracy: 1.5% (typ) ? quiescent current: 0a (typ) ? operating current: 2ma (typ) ? junction temperature of o peration: -40c to +125c packages w(typ) d(typ) h(max) hson8 2.90mm x 3.00mm x 0.60mm htsop-j8 4.90mm x 6.00mm x 1.00mm hson8 htsop-j8 downloaded from: http:///
2/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 typical application circuit pin configuration pin descriptions pin no. pin name function hson8 htsop-j8 1 1 agnd analog system gnd 2 2 sdx/en shutdown/enable control 3 3 comp load current compensation of the output voltage set up 4 4 ref output voltage setup 5 5 fb output voltage setup 6 6 pgnd power system gnd 7 7 sw switching output 8 8 vin power supply (top view) vin sw fb a g nd ref pgnd sdx/en comp 7 8 6 5 3 4 2 1 fb sw vin v out+ v out- sdx/encomp agnd ref pgnd v in BD7F200HFN-LB downloaded from: http:///
3/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 block diagram fb sw driver adaptive on-time controller vref soft start comparator vin internal regulator sdx/en loadcompensation vin uvlo pgnd comp ref agnd n-channel mosfet shutdown ocp tsd enable vref current monitor description of blocks 1. internal regulator this is the regulator block for internal circuits. also includes a reference voltage generating block (vref). this block is in the shutdown state when the sdx/en terminal is below 0.9v (typ). 2. vin uvlo this is the input low-voltage-protection block. if the power supply input voltage, v in , falls to below 6.2v (typ), it will be dete cted and this block will be in the protection state and the sw terminal becomes hi-z. when the power supply input voltage (v in ) rises to 6.9v (typ), it automatical ly recovers thorough the soft start. (hysteresis voltage: 0.7v (typ).) 3. soft start when the sdx/en terminal is in the enable state with more than 2.0v (typ), this block prevents inrush current and overshoot in the rising of the output voltage by making the reference voltage of the comparator block rise slowly from 0v to vref voltage. the default soft start time, t ss , is designed to be 6ms (typ) internally. the min off time is 750ns (typ) when the output voltage is below 50% of the set voltage. 4. comparator this is the block which compares the reference voltage vref with the ref terminal voltage which is the feedback voltage of the sw terminal voltage. since the feedback loop is structured by a comparator is established, it has excellent response to load fluctuation. 5. adaptive on-time controller this is the block corresponding to the orig inal adapted type on-time control technology. switching frequency is fixed at 400khz (typ) under pwm control when the load is stable. under on-time control, when the load varies, fast load response is enabled by changing the switching frequency. during light load, the highly efficient pfm will operate and the self-power dissipation is suppressed by decreasing the switching frequency. 6. driver this is the block which drives the built-in n-channel mosfet. downloaded from: http:///
4/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 description of blocks - continued 7. load compensation this is the block which compensates the output voltage regulati on by vf characteristic fluct uation of the secondary side output diode according to the load current. the current which flows into the built-in n-channel mosfet is monitored, and the current according to the compensation quantity and the time constant which are determined by the exte rnal resistor and the capacitor of the comp terminal is drawn from the ref terminal. the output voltage rises and is rect ified when feedback current which flows into the external resistor of the ref terminal decreases and the ref terminal voltage falls. 8. tsd this is the temperat ure protection block. if the chips junction temperature, tj, inside the ic is abov e 175c (typ), it will be detected and this block will be in the protection state and the sw terminal becomes hi-z. if tj falls to below 150c (typ), it will return automatically through soft start. 9. ocp this is the over-current protection block. if the peak current during the on-time of the built-in n-channel mosfet reaches 2. 75a (typ), it will be detected and the n-channel mosfet is turned off. if output voltage goes to 50% or less of t he setting voltage, the peak detection curr ent of ocp will be controlled by 1.6a (typ).the min off time is 1.5 s (typ) when the ocp is operated under the co ndition where the output voltage is 50% of the set voltage. absolute maximum ratings (ta = 25 c) parameter symbol rating unit BD7F200HFN-LB bd7f200efj-lb vin input power voltage (note 1) v in 45 v sw terminal voltage v sw 60 v sdx/en terminal voltage v sdx/en v in v fb terminal voltage v fb v in -0.3v to v in v ref terminal voltage v ref 7 v comp terminal voltage v comp 7 v power dissipation pd 1.75 (note 2) 3.75 (note 3) w storage temperature range tstg -55 to +150 c maximum junction temperature tjmax 150 c (note 1) not to exceed power dissipation (pd). (note 2) reduced by 14.0mw/c for temperatures above 25c (when mounted on a one-layer glass-epoxy board with 70mm 70mm 1.6mm dimens ion, 65% copper foil density) (note 3) reduced by 30.0mw/c for temperatures above 25c (when mounted on four-layer glass-epoxy board with 70mm 70mm 1.6mm dimens ion.) caution: operating the ic over the absolute maximum ratings may damage the ic. the damage can either be a short circuit between pins or an open circuit between pins and the internal circuitry. therefore, it is import ant to consider circuit protection measures, such as adding a f use, in case the ic is operated over the absolute maximum ratings. recommended operating conditions parameter symbol limit unit min typ max vin input power voltage v in 8 24 40 v sw terminal voltage v sw - - 50 v junction temperature (note4) tj -40 - +125 c (note 4) life time is derated at juncti on temperature greater than 125c. downloaded from: http:///
5/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 electrical characteristics (unless otherwise specified ta = 25c, v in = 24v, and v sdx/en = 2.5v.) parameter symbol limit unit conditions min typ max power supply quiescent current i st - 0 10 a v sdx/en = 0v operating current i cc - 2 4 ma v sdx/en = 2.5v v ref = 2v (at pfm operation) uvlo detection voltage v uvlo 5.7 6.2 6.7 v v in falling uvlo hysteresis voltage v uvlo_hys 0.6 0.7 0.8 v sdx/en control shutdown voltage v sdx 0.3 0.9 1.5 v enable voltage v en 1.9 2.0 2.1 v v sdx/en rising enable hysteresis voltage v en_hys 0.15 0.2 0.25 v sdx/en input current i sdx/en - 0 1 a v sdx/en =2v reference voltage reference voltage v ref 0.768 0.78 0.792 v switch characteristics on-resistance r on - 0.5 - ? between sw - pgnd terminals over current limit i limit 2.2 2.75 3.3 a switching frequency f sw - 400 - khz at pwm operation (duty=40%) minimum on time t on_min - 350 - ns minimum off time t off_min - 300 - ns maximum off time t off_max - 20 - s soft start time t ss - 6 - ms 0v to (v ref 90%) downloaded from: http:///
6/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 typical performance curves 0 2 4 6 8 10 12 14 16 18 0 5 10 15 20 25 30 35 40 45 50 maximum output power [w] vin voltage [v] restriction by the current limit 2.2a (min) restriction by the sw terminal voltage 50v (max) maximum output power is restricted in general by a current limit and the maximum operating voltage of sw terminal. furthermore, it also changes with the characteristics of external parts (transformer, schottky barrier diode, snubber circuit, etc.). figure 1. maximum output power vs vin voltage downloaded from: http:///
7/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 typical performance curves figure 3. operating cu rrent vs vin voltage figure 2. quiescent current vs vin voltage 0 0.5 1 1.5 2 2.5 0 1 02 03 04 0 operating current [ma] vin voltage [v] ref=2vcomp=0v 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 1 02 03 04 0 quiescent current [ a] vin voltage [v] sdx/en=0v 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 sdx/en input current [ a] sdx/en voltage [v] figure 4. sdx/en input cu rrent vs sdx/en voltage 0 50 100 150 200 250 300 350 400 450 500 20 25 30 35 40 45 50 switching frequency [khz] duty [%] figure 5. switching frequency vs duty downloaded from: http:///
8/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 typical performance curves figure 9. load transient response (24v input, 5v output, with load compensation, and i out = 600ma <-> 2a) figure 6. efficiency vs load current (24v input, 5v output) 0 10 20 30 40 50 60 70 80 90 100 0 500 1000 1500 2000 efficiency [%] load current [ma] 4.5 4.55 4.6 4.65 4.7 4.75 4.8 4.85 4.9 4.95 5 -50 0 50 100 150 output voltage [v] ambient temperature [c] i out =2a no loadcompensation figure 7. output voltage vs load current (24v input, 5v output) 4.75 4.8 4.85 4.9 4.95 5 5.05 5.1 5.15 5.2 5.25 0 500 1000 1500 2000 output voltage [v] load current [ma] with ? load ? compensation r comp =12k no ? load compensation figure 8. output voltage vs ambient temperature (24v input, 5v output) i out : 1a/div v out : 500mv/div time: 1ms/div downloaded from: http:///
9/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 typical performance curves v in : 20v/div figure 10. start up wave forms(sdx/en control) (24v input, 5v outpu t, sdx/en=0v->2.5v) v in : 20v/div sdx/en: 2v / div v out : 2v / div sw: 20v/div figure 11. shutdown waveforms (sdx/en control) (24v input, 5v outpu t, sdx/en=2.5v->0v) time: 4ms/div v in : 20v / div sdx/en: 2v/div v out : 2v / div sw: 20v/div time: 4ms/div figure 13. shutdown waveforms(vin control) (24v input, 5v output, vin=24v->0v, r 1 =1m ? , r 2 =120k ? ) figure 12. start up wave forms(vin control) (24v input, 0v output, vin=0v->24v, r 1 =1m ? , r 2 =120k ? ) sdx/en: 2v/div v out : 2v/div sw: 20v/div v in : 20v / div sdx/en: 2v/div v out : 2v / div sw: 20v/div time: 4ms/div time: 4ms/div downloaded from: http:///
10/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 application examples exercise caution with the actual system since the characterist ic changes with the board layout and the types of external parts mounted, and etc. table1. recommended transformers part number size (w l h) [mm] l p [ h] n p : n s vendor target applications v in [v] v out [v] i out [a] cep1311d-2405051r-10 13.5 20.0 12.5 25 3 : 1 sumida electric 24 5 2 figure 14. 24v input, 5v output downloaded from: http:///
11/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 application information 1. outline operation this product is an isolated type flyback converter without an optocoupler. an optocoupler or a transformers tertiary winding feedback circuit which was needed to obtain a stable output voltage isolated by a transformer in the conventional application becomes unnecessary, thus, the number of parts is reduced drastically, producing a small-sized and high-reliability application isolated type power supply. furthermore, a highly efficient isolated type power supply application can easily be produc ed the use of the original adapted-type on-time control technology which eliminat es the need for external phase compensation parts. the off time is determined by comparing the reference voltage in side the ic with the information which was obtained by the feedback of the secondary output volt age through primary flyback voltage. adapted-type on time control, (1) switching frequency is fixed at 400khz (typ ) for pwm operation when the load stabilizes. (2) during load current fluctuation, t he on-time control will operate and the swit ching frequency will change, thus a high-speed load response is obtained. (3) during light load, high efficiency is obtained because the switching frequency decreases. 2. timing chart (1)start-up/shut-down output voltage gradually turns on through the soft start fu nction when sdx/en terminal rises to above 2.0v(typ) (enable state) .when sdx/en terminal falls below 1.8v (typ), output voltage turn s off (disable state). (note 1) in the control system of this ic, it has to be oper ated where duty is below 50%. when turning on/off the ic, control the sdx/en terminal as enable/ disable under the condition where v in fulfills below equation. ?? ][ v f out s p in v v n n v ? ? ? where: v in is the vin input power voltage n p is the number of turns in the transformer primary side n s is the number of turns in the transformer secondary side v out is the output voltage v f is the forward voltage of the out put diode in the secondary side if sdx/en terminal is connected to vin terminal, duty could be more than 50% and unexpected output voltage might occur when turning on/off. please refer to 8. enable voltage on page 15 of the application information for the enable control with vin terminal. figure 15. start-up/shut-down timing chart downloaded from: http:///
12/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 (2) vin under voltage lock-out (vin uvlo) when the input voltage (v in ) falls below 6.2v (typ), it will be detected, followed by sw terminal becomes hi-z then output turns off. when the input voltage (v in ) rises to above 6.9v (typ), it automatic ally recovers thorough the soft start. (hysteresis voltage: 0.7v (typ)) (3) thermal shutdown protection (tsd) when the internal chip (junction) temperature exceeds tj= 175c (typ) ,it will be detected, followed by sw terminal becomes hi-z, then output turns off. when tj decreases below 150c (typ), it automatically recovers through the soft start. note that the thermal shutdown circuit is designed to shut down the ic from thermal runaway under abnormal circumstances with the temperature exceeding tjmax = 150 c. it is not designed to protect or guar antee the application set. please refrain from using this function as a prot ection design of the application set. (4) over current protection (ocp) when the peak current reaches 2.75a (typ ) during the built-in n-channel mosfet is on, it will be detected, followed sw terminal becomes hi-z, then n-channel mosfet turns off. it is detected per switching cycle, and output voltage decreases as on duty is limited. figure 17. tsd timing chart figure 16. vin uvlo timing chart figure 18. ocp timing chart v in v out sw vin uvlo on vin uvlo off 6.2v 6.9v tss v out 0.9 0v downloaded from: http:///
13/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 3 output voltage sw terminal voltage is higher than input voltage (v in ) when the built-in n-channel mosfet is off. this primary flyback voltage (the gap between sw terminal voltage and v in ) contains the information of the secondary output voltage. sw terminal voltage can be calculated as follows: ?? ][ v es r i v v n n v v s f out s p in s w ? ? ? ? ? ? where: v sw is the sw terminal voltage i s is the transformer current in the secondary side esr is the total impedance in the secondary side (transformer wirewound resistance of the secondary side, pcb impedance, and etc.) this primary flyback voltage is converted to the current i rfb by rfb resistor. as fb terminal voltage almost equals to vin voltage due to the differential circuit of vin, i rfb can be expressed by following equation: f b f b s w rf b r v v i ? ? ?? ][ a f b s f out s p r es r i v v n n ? ? ? ? ? where: i rfb is the fb input current v fb is the fb terminal voltage r fb is the external resistance between the fb-sw terminals ref terminal voltage can be expressed as follows since i rfb flows into r ref resister. ?? ][ v es r i v v n n r r v s f out s p f b ref ref ? ? ? ? ? ? where: v ref is the ref terminal voltage r ref is the external resistance between the refCagnd terminals (the ic is designed on the assumption that this value is 3.9k ? .) the ref terminal voltage is input into the comparator and compared with the ic internal reference voltage (0.78v(typ)). since the loop gain of the whole system is high, the ref terminal voltage can be eq ual to the reference voltage in the ic. therefore, the output voltage v out and the ref terminal voltage v ref are as follows: ][ v es r i v v n n r r v s f ref p s ref f b out ? ? ? ? ? ? that is, the output voltage v out can be set by the primary and secondary side turns ratio of the transformer, and the ratio of the resistances r fb and r ref . v f and esr cause an output voltage error. the feedback resistor r fb can be expressed as follows from the relative quation with v out : ?? ][ ? es r i v v n n v r r s f out s p ref ref f b ? ? ? ? ? ? figure 19. control block diagram v in <60v <50v v sw time ?? es r i v v n n s f ou t s p ? ? ? figure 20. primary flyback voltage = primary flyback voltage downloaded from: http:///
14/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 4 transformer (1) turns ratio turns ration is the parameter which determines the output voltage, maximum output voltage, duty and sw terminal voltage.the duty of a flyback converter ca n be expressed by the following equation: ?? ?? f ou t s p i n f out s p v v n n v v v n n duty ? ? ? ? ? ? feedback voltage is monitored by the sw terminal and duty needs to be below 50% for the stable control. the minimum duty will be 20% due to the limitation of the min on time and the turns ratio needs to fulfill below conditions: f out in s p f out in v v v n n v v v ? ? ? ? ? (2) primary side inductance flyback converter has the secondary pole from the primar y inductance and the secondary output capacitor. therefore, for operational stability, selection of the primary side in ductance value is important. in addition, as the primary inductance influences the maximum load, please follow below conditions: ?? ][ _ _ _ h s w out_ma x f ou t i n p ma x ou t ma x ou t i n mi n limi t i n f i v v v duty l i v v duty i duty t v ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? where: l p is primary side inductance t is switching output cycle is efficiency i limit_min is minimum over current limit i out_max is maximum load current f sw is switching frequency (3) leakage inductance transformer leakage inductance causes sw terminal ringing when the built-in n-channel mosfet turns off. a snubber circuit is recommended in order to avoid the peak voltage of the ringing from exceeding the absolute maximum rating (60v). furthermo re, after a voltage spike occurs, ringing is also caused. in order to prevent erroneous detection of the secondary output voltage, the ringing must be converged within 250ns (typ). when the built-in n-channel mosfet turns on, reverse spike voltage in the output diode is generated. note that this spike voltage must not e xceed the diode rating voltage. (4) winding resistance either primary or secondary winding resistance will re duce overall power efficiency. moreover, secondary winding resistance lowers the output voltage. therefore, a transformer with smalle r winding resistance is recommended. (5) saturation current the current in the primary transformer will not be transferred to the secondary if the core is saturated due to the exceeded current. when the core is saturated, the inductanc e value decreases and the current drastically increases. the current in the transformer should no t exceed its rated saturation current. downloaded from: http:///
15/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 5 output capacitor selecting the secondary side output capacitor value is important for a stable operation. please select the value which fulfils below condition. ][ . f s p p out duty n n l c ? ?? ? ? ?? ? ? ? ? ? ? ? where: c out is output capacitor in addition, as secondary side output vo ltage rises through soft start time (t ss ), please consider below equation when choosing an output capacitor. over current protection operates due to the inrush current especially when the capacitance value is extremely large, thus, start-up failure might occur. ?? ][ _ _ f out max out s p min limit ss out v i dut y n n i t c ? ? ? ? ? ? ? ? ? ? ?? ? ? ?? ? ? ? ? ? where: t ss is soft start time 6 input capacitor use ceramic capacitor for the input capacitor and place the i nput capacitor as close as possible to vin terminal. please refer to the pcb layout design guidelines on page 19 for t he design as malfunctions might occur due to the layout pattern or the position of the capacitor. as for the capacitance value of the input capacitor, the rippl e voltage of vin terminal needs to be below 4% of the input voltage. and, make sure that ripple voltage is suppressed when load changes or start up. 7 output diode since the forward voltage v f of the output diode becomes an error factor in the output voltage, a schottky barrier diode of small v f is recommended. when selecting a diode, note that forward current must not exceed the rated values. and, when the built-in n-channel mosfet is on, the output diode or reverse voltage v r decrease is expressed by the following equation: ][ v out p s i n r v n n v v ? ? ? furthermore, ringing occurs to the reverse voltage v r when built-in n-channel mosfet turns on. please prevent the peak voltage from exceeding the rated value of the output diode. 8 enable voltage this ic is shut downed when sdx/en voltage is below 0.9v (typ). if the voltage becomes above 2.0v (typ) when sdx/en terminal voltage is rising, ic goes to enable state and starts up. (hysteresis voltage: 0.2v (typ)) enable control with vin terminal is done by di viding the vin terminal and gnd terminal with r 1 and r 2 resistors connecting to sdx/en terminal, as shown in figure 25. the enable voltage when v in is rising can be set with the following equation: ?? ][ v vin_enable r r r .v v ? ? ? disable voltage when v in is falling can be set with the following equation: ?? ][ v e vin_disab l r r r .v v ? ? ? since the control system of this ic needs to operate with 50% duty or less, set disable voltage which fulfils the following equation: ?? ][ v f ou t s p e vin_disab l v v n n v ? ? ? please note that the clamping element inside the ic will turn on and the inflow current occurs if the sdx/en terminal voltage rises above 5v. figure .21 enable control with vin terminal downloaded from: http:///
16/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 9 minimum load current to achieve a stable output voltage, the built-in n-channel mosfet s enses and feeds back information on the output voltage on the secondary side (which was isolated by the transformer) by using the sw terminal voltage on the primary side (during off time). meaning, t he output will not be regulated in any case unl ess the built-in n-channel mosfet is in the switching operation. during light load, the switching operation uses minimum on-time. the output voltage may rise when there is a small load current since it will supply the least amount of energy to the secondary side output. therefore, it is necessary to add a dummy resistor etc. to the output in order to secure minimum load current. the required minimum load current (i out_min ) can be expressed by: ][ a ? ? ? ? ? ? ? ? ? ? ? out p in out_mi n v l v . i 10 switching frequency changing point during light load, high efficiency is achieved by changi ng the switching frequency according to the load current. the load current equation where the switching frequency begins to fall from the fixed 400khz (typ) is expressed following equation: ?? ][ 2 _ _ 400 2 1 a ?? ?? ? ?? ?? ? ? ? ? ? ? out p min on in fsw out v l t v khz i where t on_min is the minimum on time figure 22. switching frequency vs load current image downloaded from: http:///
17/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 11 load compensation the relational expression of v out shows that v f and esr are the factors leading to poor load regulation. for an application which these factors cause the problem, an ideal load regula tion can be obtained using load compensation function. load compensation mechanism is explained below. in the applic ation wherein output voltage accuracy in particular is not required, load compensation function can be cance lled by short-circuiting the comp terminal to gnd. v out voltage drop is compensated corresponding to the av erage current of the primary transformer current i p. since i p and i s have a relationship as indicated in the following eq uation, the load compensation value is determined by assuming i s from i p and then adjusted by using external cr of the comp terminal. the current of k ? i p is injected to the comp terminal from the current monitor bloc k in the figure. 23 and then converted to v comp through r comp resistor externally attached to comp terminal. k here is the compression magnification and indicated as 1/50k. the upper limit of v comp operating voltage is limited in the internal circuit. set r comp below 0.5v. ][ a s p s p i n n i ? ? . v r i k v com p p com p ? ? ? ? steep changes in i comp may make the operation of the loop unstable. therefore, c comp is needed to stabilize v comp . recommended values of c comp are from 0.01f to 0.1f. by the addition of c comp , v comp becomes: p_av e com p com p i r k v ? ? ? ][ v t t i i r k on p_ma x p_min com p ? ? ? ? ? ][ v k v i com p com p ? where: i p_ave = average transformer primary side current r comp = external resistance for i comp adjustment t on = on-time of built-in n-channel mosfet how to decide the amount of load compensation and i comp setup by adjustment of r comp is explained next. the feedback current which originally flows into r ref is partially lost by i comp due to the load compensation function. as a result, in order to compensate this, the h level of v sw increases and recovers t he dropped output voltage. figure 23. load compensation functional block diagram figure 24. monitor of the amount of load compensation (continuous mode) downloaded from: http:///
18/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 while the load compensation function is not operating, v out , as described previously, will now be: ][ v es r i v v n n r r v s_ave f ref p s ref f b out ? ? ? ? ? ? where: i s_ave is the average transformer secondary side current when i comp occurs, the load compensation function operates and v out becomes the following equation. the voltage v out increases by i comp . ][ v es r i v r i r v n n v s_ave f f b com p ref ref p s ou t ? ? ? ? ? ? ? es r i r i r n n k i r k s_av e v f s_av e f b p s av e p com p ? ? ? ? ? ? ? ? _ in order to remove v f and esr by using i comp , the following equation is needed. es r i v r n n i s_ave f f b p s com p ? ? ? ? ? next, linearity approximation of the change of v f to i s is carried out by r vf , and r comp which adjusts i comp from the expression mentioned earlier is calculated. es r i r i r n n k i r k s_av e vf s_av e f b p s p_av e com p ? ? ? ? ? ? ? ? es r r r n n k r k vf f b p s com p ? ? ? ? ?? ? ? ?? ? ? ? ][ s p f b vf com p n n r k es r r k r ? ?? ? ? ?? ? ? ? ? ? ? although the setting of the theoretical value of r comp was shown, r vf , esr, and r fb are dependent on the environment, such as used parts and the mounting board. therefore, when determining the actual value of r comp , monitor v out in the used load current range and adjust r comp accordingly. figure 25. load compensation image downloaded from: http:///
19/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 pcb layout design guidelines the dotted line is the image of the wiring in another layer. figure 26. application circuit block diagram pcb layout greatly affects the stable oper ation of the ic. depending on the layout, the specs of the ic might not be secured or ic might not operate correctly. please take the following points into consideration when designing the pcb layout. 1. place input ceramic capacitors c in1 and c in2 as close as possible to vin terminal on the same pcb surface with ic. 2. shorten the thick line as short as possible with wide width pattern. 3. place r ref as close as possible to ref terminal. 4. place r fb as close as possible to fb terminal. 5. place transformer t 1 close to sw terminal and make the current loop indicated as an arrow (primary side) short. in addition, make the pattern of the sw node as thick and short as possible. 6. place output diode d 2 close to sw terminal and make the current loop indicated as an arrow (secondary side) short. 7. in case of multilayer board, do not place gnd layer or v out- node pattern in the internal layer that is just below the sw node pattern and d 2 anode pattern. 8. r comp and c comp are for load compensation function. short the comp terminal to the gnd when the load compensation function is not used. 9. connect the exposed die pad to the gnd plane. 10. please note that temperature of the ic increase as bd7f200 has higher output power than bd7f100. downloaded from: http:///
20/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 reference layout pattern top layer middle layer bottom layer r fb r 3 c in1 d 1 c 1 c in2 c comp r comp r ref r 2 r 1 t 1 d 2 r dummy c out z 1 downloaded from: http:///
21/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 i/o equivalent circuits 2. sdx/en 3. comp 4. ref, 5. fb 7. sw sdx/en agnd 1m ? (typ) downloaded from: http:///
22/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 operational notes 1. reverse connection of power supply connecting the power supply in reverse polarity can damage the ic. take precautions against reverse polarity when connecting the power supply, such as mounting an external diode between the power supply and the ics power supply pins. 2. power supply lines design the pcb layout pattern to provide low impedance supply lines. furthermore, connect a capacitor to ground at all power supply pins. consider the effect of temperature and aging on the c apacitance value when using electrolytic capacitors. 3. ground voltage ensure that no pins are at a voltage below that of t he ground pin at any time, even during transient condition. 4. ground wiring pattern when using both small-signal and large-current ground traces, the two ground traces should be routed separately but connected to a single ground at the refer ence point of the application board to av oid fluctuations in the small-signal ground caused by large currents. also ensure that the ground trac es of external components do not cause variations on the ground voltage. the ground lines must be as s hort and thick as possible to reduce line impedance. 5. thermal consideration should by any chance the power dissipation rating be exceed ed the rise in temperature of the chip may result in deterioration of the properties of the ch ip. in case of exceeding this absolute maximum rating, increase the board size and copper area to prevent exceeding the pd rating. 6. recommended operating conditions these conditions represent a range within which the expect ed characteristics of the ic can be approximately obtained. the electrical characteristics are guaranteed under the conditions of each parameter. 7. inrush current when power is first supplied to the ic, it is possible that the internal logic may be unstable and inrush current may flow instantaneously due to the internal powering sequence and delays, especially if the ic has more than one power supply. therefore, give special consideration to power c oupling capacitance, power wiring, width of ground wiring, and routing of connections. 8. operation under strong electromagnetic field operating the ic in the presence of a strong electromagnetic field may cause the ic to malfunction. 9. testing on application boards when testing the ic on an application board, connecting a capacitor directly to a low-impedance output pin may subject the ic to stress. always discharge capacitors completely after each process or step. the ics power supply should always be turned off completely before connecting or removing it from the test setup during the inspection process. to prevent damage fr om static discharge, ground the ic during as sembly and use similar precautions during transport and storage. 10. inter-pin short and mounting errors ensure that the direction and position are correct when mounting the ic on the pc b. incorrect mounting may result in damaging the ic. avoid nearby pins being shorted to each ot her especially to ground, power supply and output pin. inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment) and unintentional solder bridge deposited in between pins during assembly to name a few. 11. unused input pins input pins of an ic are often connec ted to the gate of a mos transistor. the gate has extremely high impedance and extremely low capacitance. if left unconnec ted, the electric field from the out side can easily charge it. the small charge acquired in this way is enough to produce a signifi cant effect on the conduction through the transistor and cause unexpected operation of the ic. so unless otherwise specified, unused input pins should be connected to the power supply or ground line. downloaded from: http:///
23/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 operational notes C continued 12. regarding the input pin of the ic this monolithic ic contains p+ isolat ion and p substrate layers between adj acent elements in order to keep them isolated. p-n junctions are formed at the intersection of the p layers with the n layers of other elements, creating a parasitic diode or transistor. for example (refer to figure below): when gnd > pin a and gnd > pin b, the p-n j unction operates as a parasitic diode. when gnd > pin b, the p-n junction o perates as a parasitic transistor. parasitic diodes inevitably occur in t he structure of the ic. the operation of parasitic diodes can result in mutual interference among circuits, operational faults, or physical damage. therefore, conditions that cause these diodes to operate, such as applying a voltage lower than the gnd voltage to an input pin (and thus to the p substrate) should be avoided. figure 27. example of monolithic ic structure 13. ceramic capacitor when using a ceramic capacitor, determine the dielectric constant considering the change of capacitance with temperature and the decrease in nominal capacitance due to dc bias and others. 14. area of safe operation (aso) operate the ic such that the output voltage, output current, and power dissipation are all within the area of safe operation (aso). 15. thermal shutdown circuit (tsd) this ic has a built-in thermal shutdown circuit that prevents heat damage to t he ic. normal operation should always be within the ics power dissipation rating. if however th e rating is exceeded for a continued period, the junction temperature (tj) will rise which will activate the tsd circui t that will turn off all output pins. when the tj falls below the tsd threshold, the circuits are autom atically restored to normal operation. note that the tsd circuit operates in a situation that exceeds the absolut e maximum ratings and therefore, under no circumstances, should the tsd circuit be used in a set desi gn or for any purpose other t han protecting the ic from heat damage. 16. over current protection circuit (ocp) this ic incorporates an integrated over current protection circuit that is acti vated when the load is shorted. this protection circuit is effective in preventing damage due to sudden and unexpected incidents. however, the ic should not be used in applications characterized by continuous operation or transit ioning of the protection circuit. downloaded from: http:///
24/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 ordering information b d 7 f 2 0 0 h f n - l b t r part number package hfn:hson8 efj:htsop-j8 product class lb: for industrial applications packing, forming specification tr: embossed tape and reel (hson8) e2: embossed tape and reel (htsop-j8) marking diagrams line up package orderable part number hson8 BD7F200HFN-LBtr htsop-j8 bd7f200efj-lbe2 hson8 (top view) 200 part number marking lot number 1pin mark d7f htsop-j8(top view) d7f200 part number marking lot number 1pin mark downloaded from: http:///
25/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 physical dimension, tape and reel information package name hson8 direction of feed reel ? order quantity needs to be multiple of the minimum quantity. embossed carrier tape tapequantity direction of feed the direction is the 1pin of product is at the upper right when you hold reel on the left hand and you pull out the tape on the right hand 3000pcs tr () 1pin downloaded from: http:///
26/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 physical dimension, tape and reel information package name htsop-j8 ? order quantity needs to be multiple of the minimum quantity. embossed carrier tape tapequantity direction of feed the direction is the 1pin of product is at the upper left when you hold reel on the left hand and you pull out the tape on the right hand 2500pcs e2 () direction of feed reel 1pin downloaded from: http:///
27/27 datasheet d a t a s h e e t BD7F200HFN-LB bd7f200efj-lb tsz02201-0j1j0az01220-1-2 ? 2016 rohm co., ltd. all rights reserved. 24.mar.2016 rev.002 www.rohm.com tsz22111 ? 15 ? 001 revision history date revision changes 10.mar.2016 001 new production 24.mar.2016 002 add bd7f200efj-lb(htsop-j8 package) downloaded from: http:///
notice-paa-e rev.003 ? 201 5 rohm co., ltd. all rights reserved. notice precaution on using rohm products 1. if you intend to use our products in devices requiring extreme ly high reliability (such as medical equipment (note 1) , aircraft/spacecraft, nuclear power controllers, etc.) and whose malfunction or failure may cause loss of human life , bodily injury or serious damage to property ( specific applications ), please consult with the rohm sales representative in advance. unless otherwise agreed in writin g by rohm in advance, rohm shall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of any rohm s products for specific applications. (note1) medical equipment classification of the specific applic ations japan usa eu china class class class b class class ? class 2. rohm designs and manufactures its products subject to stri ct quality control system. however, semiconductor products can fail or malfunction at a certain rate. please be sure to implement, at your own responsibilities, adeq uate safety measures including but not limited to fail-safe desig n against the physical injury, damage to any property, whic h a failure or malfunction of our products may cause. the followi ng are examples of safety measures: [a] installation of protection circuits or other protective devic es to improve system safety [b] installation of redundant circuits to reduce the impact of single or multiple circuit failure 3. our products are no t designed under any special or extraordinary environments or conditions, as exemplified below . accordingly, rohm shall not be in any way responsible or liable for any damages, expenses or losses arising from the use of any rohms products under any special or extraordinary environments or conditions. if you intend to use our products under any special or extraordinary environments or c onditions (as exemplified below), your independent verification and confirmation of product performance, reliabil ity, etc, prior to use, must be necessary: [a] use of our products in any types of liquid, including water, oils, chemicals, and organi c solvents [b] use of our products outdoors or in places where the products are exposed to direct sunlight or dust [c] use of our products in places where the products are e xposed to sea wind or corrosive gases, including cl 2 , h 2 s, nh 3 , so 2 , and no 2 [d] use of our products in places where the products are exposed t o static electricity or electromagnetic waves [e] use of our products in proximity to heat-producing component s, plastic cords, or other flammable items [f] sealing or coating our products with resin or other coating materials [g] use of our products without cleaning residue of flux (even if you use no-clean type fluxes, cleaning residue of flux is recommended); or washing our products by using water or water-soluble cleaning agents for cleaning residue after soldering [h] use of the products in places subject to dew condensation 4. the products are not subject to radiation-proof design. 5. please verify and confirm characteristics of the final or mou nted products in using the products. 6 . in particular, if a transient load (a large amount of load appl ied in a short period of time, such as pulse. is applied, confirmation of performance characteristics after on-board mou nting is strongly recommended. avoid applying power exceeding normal rated power; exceeding the power rating u nder steady-state loading condition may negatively affec t product performance and reliability. 7. de -rate power dissipation depending on ambient temperature. wh en used in sealed area, confirm that it is the use in the range that does not exceed the maximum junction temperature. 8 . confirm that operation temperature is within the specified range desc ribed in the product specification. 9 . rohm shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in this document. precaution for mounting / circuit board design 1. when a highly active halogenous (chlorine, bromine, etc .) flux is used, the residue of flux may negatively affect prod uct performance and reliability. 2. in principle, the reflow soldering method must be used on a surface-mount products, the flow soldering method mus t be used on a through hole mount products. i f the flow soldering method is preferred on a surface-mount p roducts, please consult with th e rohm representative in advance. for details, please refer to rohm mounting specification downloaded from: http:///
notice-paa-e rev.003 ? 201 5 rohm co., ltd. all rights reserved. precautions regarding application examples and external circuits 1. if change is made to the constant of an external circuit, p lease allow a sufficient margin considering variations o f the characteristics of the products and external components, inc luding transient characteristics, as well as static characteristics. 2. you agree that application notes, reference designs, and a ssociated data and information contain ed in this document are presented only as guidance for products use. therefore, i n case you use such information, you are solely responsible for it and you must exercise your own independ ent verification and judgment in the use of such information contained in this document. rohm shall not be in any way respon sible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of such informat ion. precaution for electrostatic this product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. please take p roper caution in your manufacturing process and storage so t hat voltage exceeding the products maximum rating will not be applied to products. please take special care under dry co ndition (e.g. grounding of human body / equipment / solder iro n, isolation from charged objects, setting of ionizer, friction prevention and temperature / humidity control). precaution for storage / transportation 1. product performance and soldered connections may deteriorate if the products are stored in the places where: [a] the products are exposed to sea winds or corrosive gases, in cluding cl2, h2s, nh3, so2, and no2 [b] the temperature or humidity exceeds those recommended by rohm [c] the products are exposed to direct sunshine or condensation [d] the products are exposed to high electrostatic 2. even under rohm recommended storage condition, solderabil ity of products out of recommended storage time period may be degraded. it is strongly recommended to confirm so lderability before using products of which storage time is exceeding the recommended storage time period. 3. store / transport cartons in the correct direction, which is indi cated on a carton with a symbol. otherwise bent leads may occur due to excessive stress applied when dropping of a carton. 4. use products within the specified time after opening a humi dity barrier bag. baking is required before using products of which storage time is exceeding the recommended storage tim e period. precaution for product label a two-dimensional barcode printed on rohm products label is f or rohm s internal use only. precaution for disposition when disposing products please dispose them properly usi ng an authorized industry waste company. precaution for foreign exchange and foreign trade act since concerned goods might be fallen under listed items of export control prescribed by foreign exchange and foreign trade act, please consult with rohm in case of export. precaution regarding intellectual property rights 1. all information and data including but not limited to appl ication example contained in this document is for reference only. rohm does not warrant that foregoing information or data will not infringe any intellectual property rights or any other rights of any third party regarding such information or data. 2. rohm shall not have any obligations where the claims, a ctions or demands arising from the combination of the products with other articles such as components, circuits, systems or ex ternal equipment (including software). 3. no license, expressly or implied, is granted hereby under any inte llectual property rights or other rights of rohm or any third parties with respect to the products or the information contai ned in this document. provided, however, that rohm will not assert its intellectual property rights or other rights a gainst you or your customers to the extent necessary to manufacture or sell products containing the products, subject to th e terms and conditions herein. other precaution 1. this document may not be reprinted or reproduced, in whole or in p art, without prior written consent of rohm. 2. the products may not be disassembled, converted, modified , reproduced or otherwise changed without prior written consent of rohm. 3. in no event shall you use in any way whatsoever the pr oducts and the related technical information contained in the products or this document for any military purposes, includi ng but not limited to, the development of mass-destruction weapons. 4. the proper names of companies or products described in this document are trademarks or registered trademarks of rohm, its affiliated companies or third parties. downloaded from: http:///
datasheet datasheet notice ? we rev.001 ? 2015 rohm co., ltd. all rights reserved. general precaution 1. before you use our pro ducts, you are requested to care fully read this document and fully understand its contents. rohm shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny rohms products against warning, caution or note contained in this document. 2. all information contained in this docume nt is current as of the issuing date and subj ec t to change without any prior notice. before purchasing or using rohms products, please confirm the la test information with a rohm sale s representative. 3. the information contained in this doc ument is provi ded on an as is basis and rohm does not warrant that all information contained in this document is accurate an d/or error-free. rohm shall not be in an y way responsible or liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccur acy or errors of or concerning such information. downloaded from: http:///

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