high efficiency 1.5mhz, 1a synchronous step down regulator china resources powtech (shanghai) limited www.crpowtech.com page 1 PT1206_ds rev en_1.1 PT1206 general description the PT1206 is a high efficiency 1.5mhz synchronous step - down dc - dc regulator ic capable of delivering up to 1a current. the PT1206 operates over a wide input voltage rang e from 2.5v to 6v ; the main switch and the synchronous switch have been integrated with very low r ds (on) to minimize the conduction loss. low o utput voltage ripple s with small external inductor and capacitor size are achieved with 1.5mhz switching frequency. f eatures ? low r ds (on) for internal switches (top/bottom) 2 50m/200m ? 2.5 v~ 6 .0 v input voltage range ? 1.5mhz switching frequency minimizes the ? external components ? internal soft - start limits the inrush current ? 100% duty - cycle operation ? rohs c ompliant a pplications ? portable navigation device ? smart phone ? usb dongle ? set top box ? media player ordering information p ackage t emperature r ange ordering part number t ransport m edia m arking sot23 - 5 - 40 c to 85 c PT1206e23f tape and reel 3000 units 1206 typical application circuit i n g n d l x f b e n o n / o f f v i n c i n v o u t c o u t l r 1 r 2 c 1 ( o p t . ) p t 1 2 0 6
high efficiency 1.5mhz, 1a synchronous step down regulator china resources powtech (shanghai) limited www.crpowtech.com page 2 PT1206_ds rev en_1.1 PT1206 pin assignment sot23 - 5 pin descriptions p in s ymbol d escription 1 en enable control. pull high to turn on. do not float. 2 gnd ground pin 3 lx inductor pin. connect this pin to the switching node of inductor. 4 in input pin. decouple this pin to gnd pin with at least 1 f ceramic cap. 5 fb output feedback pin. connect this pin to the center point of the output resistor divider to program the output voltage: v out =0.6*(1+r1/r2). 1 2 0 6 1 3 2 5 4 e n l x g n d f b i n
high efficiency 1.5mhz, 1a synchronous step down regulator china resources powtech (shanghai) limited www.crpowtech.com page 3 PT1206_ds rev en_1.1 PT1206 absolute maximum ratings (note1) symbol parameter value unit v in supply input voltage 8.0 v v en enable voltage v in v v fb fb voltage 8.0 v ja package thermal resistance 250 c /w jc package thermal resistance 130 c /w t lead lead temperature 260 c t stg storage temperature - 65~150 c esd susceptibility human body mode 2000 v note 1: exceeding these ratings may cause damage to the device. recommended operating conditions (note 2) symbol parameter value unit v in supply input voltage 2.5 ~ 6 .0 v t j junction temperature range - 40 ~ 125 c t a ambient temperature range - 40 ~ 85 c note2 : the device is not guaranteed to function outside of i ts operating rating. functional block diagram o s c i l l a t o r c o n t r o l l o g i c b u f f e r a n d d e a d t i m e c o n t r o l l o g i c c u r r e n t s e n s i n g o v e r c u r r e n t c o m p a r a t o r r e v e r s e c u r r e n t d e t e c t o r p w m c o m p a r a t o r e r r o r a m p l i f i e r b a n d g a p r e f e r e n c e f b s o f t s t a r t u v l o e n a b l e e n i n g n d s l o p e c o m p l x 0 . 6 v + - + - + -
high efficiency 1.5mhz, 1a synchronous step down regulator china resources powtech (shanghai) limited www.crpowtech.com page 4 PT1206_ds rev en_1.1 PT1206 electrical characteristics (v in =5v, v out =2.5v, l=2.2h, c out =10f, t a =25 c , unless otherwise sp ecifi ed) symbol parameter test condition min typ max unit v in supply input voltage 2.5 - 6 .0 v i q quiescent c urrent i out = 0 a , v fb = 0.8 v - 2 3 0 - a i shdn shut down current en = 0 v - 0.1 1 .0 a %/v in output voltage line regulation v in = 2.5v to 6 .0 v - 0.08 - %/v %/i out output voltage load regulation i out = 200ma to 1a - 0.12 - %/a v fb fb reference volta ge v in = 2.5v to 6 .0 v 0.588 0.600 0.612 v i fb fb input current v fb = v in - 50 - 50 na r ds(on),p lx high side pmos on resistance - 250 - m ds(on),n lx low side nmos on resistance - 200 - m lim ,p lx high side pmos current limit - 1.5 - a v en en th reshold voltage 1.1 1.5 2.0 v v en en threshold voltage hysteresis - 0.2 - v v uvlo input under - voltage lockout threshold - - 2.4 v v uvlo under - voltage lockout threshold hysteresis - 0.2 - v f osc oscillator frequency i out = 200ma - 1.5 - mhz t on,m in minimum on time - 50 - ns d max maximum duty cycle - 100 - % t sd thermal shutdown threshold - 160 - c sd thermal shutdown threshold hysteresis - 30 - c
high efficiency 1.5mhz, 1a synchronous step down regulator china resources powtech (shanghai) limited www.crpowtech.com page 5 PT1206_ds rev en_1.1 PT1206 operation description PT1206 is a synchronous buck regulator ic that integrates the pwm control, top and bottom switches on the same die to minimize the switching transition loss and conduction loss. with ultra low r ds ( on ) power switches and proprietary pwm control, this regulator ic can achieve the highest efficiency and the highest switch f requency simultaneously to minimize the external inductor and capacitor size, and thus achieving the minimum solution footprint. the internal softstart time is about 1ms. application information output voltage programming choose r1 and r2 to program the p roper output voltage. to minimize the power consumption under light loads, it is desirable to choose large resistance values for both r1 and r2. a value of between 100k and 1m is highly recommended for both resistors. if r2=120k is chosen, then r1 can b e calculated to be: input c apacitor selection with the maximum load current at 2 a, the maximum ripple current through input capacitor is about 0.6a - rms. a typical x7r or better grade ceramic capacitor with 6v rating and greater tha n 4.7f capacitance can handle this ripple current well. in order t o minimi ze the potential noise problem , this ceramic capacitor need to be placed really close to the in and gnd pins. care should be taken to minimize the loop area formed by cin, and in/gn d pins. output c apacitor selection the output capacitor is selected to handle the output ripple noise requirements. both steady state ripple and transient requirements must be taken into consideration when selecting this capacitor. for the best performanc e, it is recommended to use x7r or better grade ceramic capacitor with 6v rating and greater than 10 f capacitance. i nductor selection there are several considerations in choosing this inductor. 1) choose the inductance to provide the desired ripple curre nt. it is suggested to choose the ripple current to be about 40% of the maximum output current. the inductance is calculated as: w here fsw is the switching frequency and i out , max is the maximum load current. the PT1206 re gulator ic is quite tolerant to different ripple current amplitude. consequently, the final selection of inductance can be slightly off with the calculat ed value without significantly impact to the performance. 2) the saturation current rating of the inductor must b e selected to be greater than the peak inductor current under full load conditions. 3) the dcr of the inductor and the core loss at the switching frequency must be low enough to achieve the target efficiency requirement. it is desir able to choose an inductor with dcr<50m to achieve a good overall efficiency. layout design the layout design of PT1206 regulator is relatively simple. for the best efficiency and minimum noise ? ? 6 . 0 6 . 0 2 1 r v r out ? ? ? ? ? % 40 , , / 1 ? ? ? ? ? max out sw max in out out i f v v v l ? ? l f v v v i i sw max in out out max out min sat ? ? ? ? ? ? 2 / 1 , , ,
high efficiency 1.5mhz, 1a synchronous step down regulator china resources powtech (shanghai) limited www.crpowtech.com page 6 PT1206_ds rev en_1.1 PT1206 problems, we should place the following components close to the ic: cin, l, r1 and r2. 1) it is desirable to maximize the pcb copper area connecting to gnd pin to achieve the best thermal and noise performance. if the b udget allowed, a ground plane is highly desirable. 2) cin must be close to p in in and gnd. the lo op area formed by cin and gnd must be minimized. 3) the pcb copper area associated with lx pin must be minimized to avoid the potential noise problem. 4) the components r1 , r2, and the trace connecting to the fb pin must not be adjacent to the lx net on th e pcb layout to avoid the noise problem. 5) if the system chip interfacing with the en pin has a high impedance state at shutdown mode and the in pin is connected directly to a power source such as a li - i on battery, it is desirable to add a pull down 1m r esistor between the en and gnd pins t o prevent the noise from false triggering a turn on t o the regulator at shutdown mode. load transient considerations the PT1206 regulator ic integrates the compensation components to achieve good stability and fast tra nsient responses. in some applications, adding a 22pf ceramic cap in parallel with r1 may further speed up the load transient responses and is recommended for applications with large load transient step requirements.
high efficiency 1.5mhz, 1a synchronous step down regulator china resources powtech (shanghai) limited www.crpowtech.com page 7 PT1206_ds rev en_1.1 PT1206 typical performance characteristics efficiency vs load current efficiency vs load current efficiency vs load current normal operation load transient startup
high efficiency 1.5mhz, 1a synchronous step down regulator china resources powtech (shanghai) limited www.crpowtech.com page 8 PT1206_ds rev en_1.1 PT1206 shutdown
high efficiency 1.5mhz, 1a synchronous step down regulator china resources powtech (shanghai) limited www.crpowtech.com page 9 PT1206_ds rev en_1.1 PT1206 package information symbol millimeters inches min max min max a - 1.450 - 0.057 a1 0 0.150 0 0.006 a2 0.900 1.300 0.035 0.051 b 0.300 0.500 0.012 0.020 c 0.080 0.220 0.003 0.009 d 2.820 3.020 0.111 0.119 e 1.500 1.700 0.059 0.067 e1 2.600 2.950 0.102 0.116 e 0.950typ 0.037typ e1 1.80 0 2.000 0.071 0.079 l 0.600ref 0.024ref l1 0.300 0.600 0.012 0.024 0 8 0 8 d b e e 1 e 1 e l 1 0 . 2 l c a a 2 a 1
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