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r ev . 1.8 i w1690 p age 1 f ebr ua r y 3, 2012 1.0 features ? primary-side feedback eliminates opto-isolators and simplifes design ? direct drive of bjt switching device ? multi-mode operation for highest overall effciency ? built-in cable drop compensation ? v ery tight output voltage regulation ? no external compensation components required ? complies with cec/ep a no load power consumption and average effciency regulations ? built-in output constant-current control with primary-side feedback ? low start-up current (10 a typical) ? built-in soft start ? built-in short circuit protection and output overvoltage protection ? optional ac line under/overvoltage protection ? fixed switching frequency: 45 khz, 65 khz or 75 khz ? dynamic base current control ? pfm operation at light load ? built-in current sense resistor short protection figure 2.0.1 iw1690 typical application circuit 2.0 description the iw1690 is a high performance ac/dc power supply controller which uses digital control technology to build peak current mode pwm fyback power supplies. the device directly drives a bjt switching device and provides high effciency along with a number of key built-in protection features while minimizing the external component count, simplifying emi design and lowering the total bill of material cost. the iw1690 removes the need for secondary feedback circuitry while achieving excellent line and load regulation. it also eliminates the need for loop compensation components while maintaining stability over all operating conditions. pulse-by-pulse waveform analysis allows for a loop response that is much faster than traditional solutions, resulting in improved dynamic load response. the built-in power limit function enables optimized transformer design in universal off-line applications and allows for a wide input voltage range. the ultra-low start-up power and operating current at light load ensure that the iw1690 is ideal for applications targeting the newest regulatory standards for average effciency and standby power. 3.0 applications ? low power ac/dc adapter/chargers for cell phones, pdas, digital still cameras ? low power ac/dc adapter/chargers to replace rcc implementations l n + v out gnd + u1 iw1690 v sense v in r in v cc output i sense 1 2 3 8 7 6 4 5 i bc gnd iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 2 f ebr ua r y 3, 2012 iw1690 v sense v in r in i bc v cc output i sense gnd 1 2 3 8 7 6 4 5 4.0 pinout description pin # name type pin description 1 v sense analog input auxiliary voltage sense (used for primary regulation and zvs). 2 v in analog input rectifed ac line voltage sense. 3 r in analog input sense line input voltage. 4 i bc analog input adjust maximum base current. 5 gnd ground ground. 6 i sense analog input primary current sense. used for cycle-by-cycle peak current control and limit. 7 output output base drive for bjt. 8 v cc power input power supply for control logic and voltage sense for power-on reset circuitry . iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 3 f ebr ua r y 3, 2012 parameter symbol value units dc supply voltage range (pin 8, i cc = 20ma max) v cc -0.3 to 18 v continuous dc supply current at v cc pin i cc 20 ma peak dc supply current at v cc pin i ccpk 120 ma low voltage output (pin 7) -0.3 to 4.0 v v sense input (pin 1) -0.6 to 4.0 v v in input (pin 2) -0.3 to 18.0 v low voltage analog input (pins 3, 4 and 6) -0.3 to 4.0 v power dissipation at t a 25c p d 526 mw maximum junction temperature t j max 125 c storage temperature t stg C65 to 150 c lead temperature during ir refow for 15 seconds t lead 260 c thermal resistance junction-to-ambient ja 160 c/w esd rating per jedec jesd22-a114 (hbm) 2,000 v latch-up test per jedec 78 100 ma 5.0 absolute maximum ratings absolute maximum ratings are the parameteic values or ranges which can cause permanent damage if exceeded. for maximum safe operating conditions, refer to electrical characteristics in section 6.0. v cc = 12 v, -40c t a 85c, unless otherwise specifed (note 1) 6.0 electrical characteristics parameter symbol test conditions min typ max unit v in section (pin 2) start-up voltage low threshold v inst(lo) t a = 25c, positive edge 332 370 407 mv start-up voltage high threshold v inst(hi) t a = 25c, positive edge 1.755 1.950 2.145 v start-up current i in(st) v cc = 10 v 8 15 a shutdown low voltage threshold v uvdc t a = 25c, negative edge 203 225 248 mv shutdown high voltage threshold v ovdc t a = 25c, positive edge 1.791 1.990 2.189 v v sense section (pin 1) input leakage current i vsense v sense = 2 v 1 a nominal voltage threshold v sense(nom) t a =25c, negative edge 1.522 1.538 1.553 v output ovp threshold v sense(max) t a =25c, negative edge 1.667 1.700 1.734 v iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 4 f ebr ua r y 3, 2012 notes: note 1. adjust v cc above the start-up threshold before setting at 12 v. note 2. these parameters are not 100% tested, guaranteed by design and characterization. v cc = 12 v, -40c t a 85c, unless otherwise specifed (note 1) parameter symbol test conditions min typ max unit output section (pin 7) output low level on-resistance r ds(on)lo i sink = 5 ma 3 6.0 w output switching frequency f s -02/-03/-08/-09 suffxes p load > 15% of maximum 45 khz -00/-05 suffxes p load > 15% of maximum 65 khz i sense section (pin 6) overcurrent limit threshold v ocp 1.2 v cc limit threshold v cc-th 1.1 v input leakage current i isense i sense = 1 v 1.6 2.5 a r in section (pin 3) input leakage current i rin r in = 1 v 10 a i bc section (pin 4) i bc pin voltage v ibc r bc = 100 kw 1 v v cc section (pin 8) maximum operating voltage v cc(max) 16 v start-up threshold v cc(st) v cc rising 11 12 13.2 v undervoltage lockout threshold v cc(uvl) v cc falling 5.0 5.5 6.1 v quiescent current i ccq r bc = 100 kw, no i b current 2.5 6.0 ma 6.0 electrical characteristics iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 5 f ebr ua r y 3, 2012 7.0 typical performance characteristics 2.004 2.002 2.000 1.998 1.996 internal reference voltage (v) ambient temperature (c) -50 -25 0 25 50 75 100 v cc = 12 v figure 7.0.4 internal reference vs. temperature 100 80 60 40 20 0 i out (ma) r bc (k?) 40 60 80 100 k bc = 10 k bc = 31 figure 7.0.5 i out vs. r bc 48 47 46 45 44 43 42 switching frequency (khz) ambient temperature (c) -50 -25 0 25 50 75 100 v cc = 12 v figure 7.0.1 switching frequency vs. temperature -01/-02/-03/-08 suffxes 69 67 65 63 61 switching frequency (khz) ambient temperature (c) -50 -25 0 25 50 75 100 v cc = 12 v figure 7.0.2 switching frequency vs. temperature -00/-05 suffxes 12.2 12.1 12.0 11.9 11.8 v cc start-up threshold (v) ambient temperature (c) -50 -25 0 25 50 75 100 figure 7.0.3 start-up vs. temperature iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 6 f ebr ua r y 3, 2012 figure 8.0.1 iw1690 functional block diagram 8.0 functional block diagram the iw1690 is a digital controller which uses a new, proprietary primary-side control technology to eliminate the opto-isolated feedback and secondary regulation circuits required in traditional designs. this results in a low-cost solution for low power ac/dc adapters. the core pwm processor uses fxed-frequency discontinuous conduction mode (dcm) operation at higher power levels and switches to variable frequency operation at light loads to maximize effciency. furthermore, iwatts digital control technology enables fast dynamic response, tight output regulation, and full featured circuit protection with primary-side control. referring to the block diagram in figure 8.0.1, the digital logic control block generates the switching on-time and off-time information based on the line voltage and the output voltage feedback signal and provides commands to dynamically control the bjt base current. the system loop is automatically compensated internally by a digital error amplifer. adequate system phase margin and gain margin are guaranteed by design and no external analog components are required for loop compensation. the iw1690 uses an advanced digital control algorithm to reduce system design time and improve reliability. 9.0 theory of operation furthermore, accurate secondary constant-current operation is achieved without the need for any secondary-side sense and control circuits. the iw1690 uses pwm mode control at higher output power levels and switches to pfm mode at light load to minimize power dissipation to meet the blue angel specifcation. additional built-in protection features include overvoltage protection (ovp), output short circuit protection (scp) and soft-start, ac low line brown out, overcurrent protection, single pin fault protection and isense fault protection. iwatts digital control scheme is specifcally designed to address the challenges and trade-offs of power conversion design. this innovative technology is ideal for balancing new regulatory requirements for green mode operation with more practical design considerations such as lowest possible cost, smallest size and high performance output control. ? + v in gnd enable v cc 1 v 5 v sense v fb v vms v ipk output i sense 6 1.2 v 0.2 v ~ 1.1 v v in_a 0.2 v ~ 2.0 v i peak adc v ocp ? dac ? + 1 2 r in 3 8 i bc digital logic control signal conditioning 7 enable 4 start-up iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 7 f ebr ua r y 3, 2012 9.1 pin detail pin 1 C v sense sense signal input from auxiliary winding. this provides the secondary voltage feedback used for output regulation. pin 2 C v in sense signal input representing the rectifed line voltage. v in is used for line regulation. the input line voltage is scaled using a resistor network. it also provides input undervoltage and overvoltage protection. this pin also provides the supply current to the ic during start-up. pin 3 C r in sense line input voltage. connect this pin to gnd with the r in resistor. pin 4 C i bc adjusts the maximum base current for the bjt drive. pin 5 C gnd ground. pin 6 C i sense primary current sense. used for cycle-cycle peak current control limit. pin 7 C output base drive for the external power bjt switch. pin 8 C v cc power supply for the controller during normal operation. the controller will start up when v cc reaches 12 v (typical) and will shut-down when the v cc voltage is 5.5 v (typical). a decoupling capacitor should be connected between the v cc pin and gnd. 9.2 start-up prior to start-up the v in pin charges up the v cc capacitor through the diode between v in and v cc . when v cc is fully charged to a voltage higher than the start- up threshold v cc(st) , the enable signal becomes active to enable the control logic, the enable switch turns on, and the analog-to-digital converter begins to sense the input voltage. once the voltage on the v in pin is above v inst(lo) but below v inst(hi) , the iw1690 commences soft start function. an adaptive soft-start control algorithm is applied at startup state, during which the initial output pulses will be small and gradually get larger until the full pulse width is achieved. the peak current is limited cycle by cycle by ipeak comparator. if at any time the v cc voltage drops below v cc(uvl) threshold then all the digital logic is fully reset. at this time enable switches off so that the v cc capacitor can be charged up again towards the start-up threshold. v cc v cc(st) enable start-up sequencing v in figure 9.2.1 start-up sequencing diagram 9.3 understanding primary feedback figure 9.3.1 illustrates a simplifed fyback converter. when the switch q1 conducts during t on (t) , the current i g (t) is directly drawn from rectifed sinusoid v g (t) . the energy e g (t) is stored in the magnetizing inductance l m . the rectifying diode d1 is reverse biased and the load current i o is supplied by the secondary capacitor c o . when q1 turns off, d1 conducts and the stored energy e g (t) is delivered to the output. iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 8 f ebr ua r y 3, 2012 + v in (t) t s (t) i o v o d1 q1 n:1 v aux c o v g (t) i g (t) + ? i in (t) i d (t) figure 9.3.1 simplifed flyback converter in order to tightly regulate the output voltage, the information about the output voltage and load current needs to be accurately sensed. in the dcm fyback converter, this information can be read via the auxiliary winding or the primary magnetizing inductance (l m ). during the q 1 on-time, the load current is supplied from the output flter capacitor c o . the voltage across l m is v g (t) , assuming the voltage dropped across q 1 is zero. the current in q 1 ramps up linearly at a rate of: () () gg m di t v t dt l (9.1) at the end of on-time, the current has ramped up to: _ () () g on g peak m vt t it l (9.2) this current represents a stored energy of: 2 _ () 2 m g g peak l e it (9.3) when q 1 turns off at t o , i g (t) in l m forces a reversal of polarities on all windings. ignoring the communication-time caused by the leakage inductance l k at the instant of turn-off t o , the primary current transfers to the secondary at a peak amplitude of: _ () () p d g peak s n it i t n (9.4) assuming the secondary winding is master, the auxiliary winding is slave. v aux 0v v aux = -v in x n aux n p v aux = v o x n aux n s figure 9.3.2 auxiliary voltage waveforms the auxiliary voltage is given by: () aux aux o s n v vv n (9.5) and refects the output voltage as shown in figure 9.3.2. the voltage at the load differs from the secondary voltage by a diode drop and ir losses. the diode drop is a function of current, as are ir losses. thus, if the secondary voltage is always read at a constant secondary current, the difference between the output voltage and the secondary voltage will be a fxed v . furthermore, if the voltage can be read when the secondary current is small, v will also be small. with the iw1690, v can be ignored. the real-time waveform analyzer in the iw1690 reads this information cycle by cycle. the part then generates a feedback voltage v fb . the v fb signal precisely represents the output voltage under most conditions and is used to regulate the output voltage. 9.4 constant voltage operation after soft-start has been completed, the digital control block measures the output conditions. it determines output power levels and adjusts the control system to a light load or a heavy load. if this is in the normal range, the device operates in the constant voltage(cv) mode, and changes the pulse width (ton), and off time (toff) in order to meet the output voltage regulation requirements. during this mode the pwm switching frequency is either 45 khz or 65khz, depending on which product option is being used. if no voltage is detected on v sense it is assumed that the auxiliary winding of the transformer is either open or shorted and the iw1690 shuts down. iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 9 f ebr ua r y 3, 2012 9.5 constant current operation the constant current mode (cc mode) is useful in battery charging applications. during this mode of operation the iw1690 will regulate the output current at a constant maximum level regardless of the output voltage drop, while avoiding continuous conduction mode. to achieve this regulation the iw1690 senses the load current indirectly through the primary current. the primary current is detected by the i sense pin through a resistor from the bjt emitter to ground. output voltage output current i out(cc) v nom cv mode cc mode figure 9.6.1 power envelope 9.6 pfm mode at light load the iw1690 normally operates in a fxed frequency pwm mode when i out is greater than approximately 10% of the specifed maximum load current. as the output load i out is reduced, the on-time t on is decreased. at the moment that the load current drops below 10% of nominal, the controller transitions to pulse frequency modulation (pfm) mode. thereafter, the on-time will be modulated by the line voltage and the off-time is modulated by the load current. the device automatically returns to pwm mode when the load current increases. 9.7 variable frequency operation at each of the switching cycles, the falling edge of v sense will be checked. if the falling edge of v sense is not detected, the off-time will be extended until the falling edge of v sense is detected. the maximum switching period is seen at 75 s. when the switching period reaches 75 s, the iw1690 immediately shuts off. this avoids operating at continuous conduction mode. 9.8 internal loop compensation the iw1690 incorporates an internal digital error amplifer with no requirement for external loop compensation. for a typical power supply design, the loop stability is guaranteed to provide at least 45 degrees of phase margin and C20db of gain margin. 9.9 voltage protection functions the iw1690 includes functions that protect against input line undervoltage and overvoltage (uv/ov) and the output overvoltage (ovp). the input voltage is monitored by the v in pin and the output voltage is monitored by the v sense pin. if the voltage at these pins exceed their undervoltage or overvoltage thresholds the iw1690 shuts down immediately. however, the ic remains biased which discharges the v cc supply. once v cc drops below the uvlo threshold, the controller resets itself and then initiates a new soft-start cycle. the controller continues attempting start-up until the fault condition is removed. 9.10 pcl, oc and srs protection peak-current limit (pcl), over-current protection (ocp) and sense-resistor short protection (srsp) are features built-in to the iw1690. with the i sense pin the iw1690 is able to monitor the primary peak current. this allows for cycle by cycle peak current control and limit. when the primary peak current multiplied by the i sense sense resistor is greater than 1.2 v an over current (ocp) is detected and the ic will immediately turn off the base drive until the next cycle. the ocp is not a latched shutdown. the base drive will send out switching pulse in the next cycle, and the switching pulse will continue if the ocp threshold is not reached; or, the switching pulse will shut down again if the ocp threshold is still reached. if the i sense sense resistor is shorted there is a potential danger of the over current condition not being detected. thus the ic is designed to detect this sense-resistor-short fault after the start up, and shutdown immediately. similar to the ovp shutdown, the v cc will be discharged since the ic remains biased. once v cc drops below the uvlo threshold, the controller resets itself and then initiates a new soft-start cycle. the controller continues attempting start-up, but does not fully start-up until the fault condition is removed. iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 10 f ebr ua r y 3, 2012 9.11 cable drop compensation the iw1690 incorporates an innovative method to compensate for any ir drop in the secondary circuitry including cable and cable connector. a 5 w ac adapter with 5 v dc output has 6% deviation at 1 a load current due to the drop across the dc cable without cable compensation. the iw1690 cancels this error by providing a voltage offset to the feedback signal based on the amount of load current detected. to calculate the amount of cable compensation needed, take the resistance of the cable and connector and multiplyby the maximum output current. 9.12 dynamic base current control one important feature of the iw1690 is that it directly drives a bjt switching device with dynamic base current control to optimize performance. the reference bjt base current is adjusted by connecting an external r bc resistor from i bc to gnd, which generates a constant current source with a value of: _ 1 bc ref bc v i r = (9.6) i bc_ref is multiplied by 100 times inside the ic and is then used to control the base current for the bjt drive, i b_out , which is the output i b current at the output pin. the i b_out is dynamically controlled according to the power supply load change, as: __ 100 b out bc ref bc ii k = (9.7) where k bc is dynamically changed by the digital control block: the heavier the load is, the higher k bc becomes. the minimum k bc is limited to 10, and the maximum k bc is limited to 31. therefore, the maximum i b_out is set by (1v/ r bc )*100*31. the range of r bc is 40 k? to 100 k?. choosing different r bc can adjust the maximum i b_out for different bjts and/or different power levels. the minimum and maximum i b_out are given by table 9.12.1. k bc r bc = 40 kw r bc = 100 kw units i bc_ref i b_out i bc_ref i b_out minimum 10 0.025 25 0.01 10 ma maximum 31 0.025 77.5 0.01 31 ma deo iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 11 f ebr ua r y 3, 2012 10.0 physical dimensions figure 10.0.1. physical dimensions, 8-lead soic package compliant to jedec standard ms12f controlling dimensions are in inches; millimeter dimensions are for reference only this product is rohs compliant and halide free. soldering temperature resistance: [a] package is ipc/jedec std 020d moisture sensitivity level 1 [b] package exceeds jedec std no. 22-a111 for solder immersion resistance; package can withstand 10 s immersion < 270?c dimension d does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.15 mm per end. dimension e1 does not include interlead flash or protrusion. interlead flash or protrusion shall not exceed 0.25 mm per side. the package top may be smaller than the package bottom. dimensions d and e1 are determined at the outermost extremes of the plastic bocy exclusive of mold flash, tie bar burrs, gate burrs and interlead flash, but including any mismatch between the top and bottom of the plastic body. 8-lead small outline (soic) package coplanarity 0.10 (0.004) 8 5 4 1 seating plane a1 e h b d e a a2 c l h x 45 inches symbol millimeters min 0.0040 a1 max min max 0.010 0.10 0.25 0.053a 0.069 1.35 1.75 0.014b 0.019 0.35 0.49 0.007c 0.010 0.19 0.25 0.189d 0.197 4.80 5.00 0.150e 0.157 3.80 4.00 0.050 bsc e 1.27 bsc 0.228h 0.244 5.80 6.20 0.10h 0.020 0.25 0.50 0.016l 0.049 0.4 1.25 0 8 0.049 a2 0.059 1.25 1.50 iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 12 f ebr ua r y 3, 2012 11.0 ordering information part number options package description IW1690-00 f sw = 65 khz, cable comp = 0 mv soic-8 tape & reel 2 iw1690-02 f sw = 45 khz, cable comp = 150 mv, no ovdc 1 soic-8 tape & reel 2 iw1690-03 f sw = 45 khz, cable comp = 412 mv, no ovdc 1 soic-8 tape & reel 2 iw1690-05 f sw = 65 khz, cable comp = 337 mv soic-8 tape & reel 2 iw1690-07 f sw = 75 khz, cable comp = 0 mv soic-8 tape & reel 2 iw1690-08 f sw = 45 khz, cable comp = 337 mv soic-8 tape & reel 2 iw1690-09 f sw = 45 khz, cable comp = 0 mv, no ovdc 1 soic-8 tape & reel 2 note 1: no input over-voltage shutdown. note 2: product is provided on 13 reels, 2,500 per reel. minimum ordering quantity is 2,500. this product is rohs compliant and halide free. iw1690 low-power off-line digital pwm controller not recommended for new designs
r ev . 1.8 i w1690 p age 13 f ebr ua r y 3, 2012 iwatt inc. is a fabless semiconductor company that develops intelligent power management ics for computer, communication, and consumer markets. the companys patented pulsetrain ? technology, the industrys frst truly digital approach to power system regulation, is revolutionizing power supply design. trademark information ? 2012 iwatt, inc. all rights reserved. iwatt, ez-emi , and pulsetrain are trademarks of iwatt, inc. all other trademarks and registered trademarks are the property of their respective companies. contact information web: https://www.iwatt.com e-mail: info@iwatt.com phone: 408-374-4200 fax: 408-341-0455 iwatt inc. 675 campbell technology parkway, suite 150 campbell, ca 95008 disclaimer iwatt reserves the right to make changes to its products and to discontinue products without notice. the applications information, schematic diagrams, and other reference information included herein is provided as a design aid only and are therefore provided as-is. iwatt makes no warranties with respect to this information and disclaims any implied warranties of merchantability or non-infringement of third-party intellectual property rights. iwatt cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an iwatt product. no circuit patent licenses are implied. certain applications using semiconductor products may involve potential risks of death, personal injury, or severe property or environmental damage (critical applications). iwatt semiconductor products are not designed, intended, authorized, or warranted to be suitable for use in life - support applications, devices or systems, or other critical applications. inclusion of iwatt products in critical applications is understood to be fully at the risk of the customer. questions concerning potential risk applications should be directed to iwatt, inc. iwatt semiconductors are typically used in power supplies in which high voltages are present during operation. high-voltage safety precautions should be observed in design and operation to minimize the chance of injury . about iwatt iw1690 low-power off-line digital pwm controller not recommended for new designs

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