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2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 1 GR8837 features current mode control standby power below 100mw under-voltage lockout (uvlo) non-audible-noise green-mode control 65khz switching frequency internal leading-edge blanking internal slope compensation internal soft start gate output voltage clamp jitter and soft driving for reducing emi external ovp latch off mode external otp latch off mode over-load protection (olp)-auto recovery mode vcc ovp protection- latch mode 300ma driving capability application switching ac/dc adapter battery charger description the GR8837 is a highly-integrated, low startup current, current mode pwm controller with green-mode function. the integrated functions also include the leading-edge blanking of the current sensing, internal slope compensation, soft start olp, and ocp. besides, the rtl pin latch function by injecting a high over 3.5v to provide ovp latch off and low below 1v to provide otp latch off protection. these functions enable the power supply to easily meet even the strictest power requirements. the GR8837 improves the performance and reduces the cost of power supplies. it is with 8-pi n dip and 6-pin sot-26 package open frame smps ordering and marking information dip-8 sot-26 code 1 8 9 a b g h i j year 2008 2009 2010 2011 2016 2017 2018 2019 code 2 1 2 3 4 9 a b c month jan. feb. mar. apr. sep. oct. nov. dec. grenergy opto inc. reserves the right to make chang es to improve reliability or manufacture ability wi thout notice, and advise customers to obtain the latest version of re levant information to verify before placing orders. green-mode pwm controller with latch protection
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 2 GR8837 gnd comp rtl out vcc cs 12 3 4 5 6 pin configuration pin description pin no. name function 1 gnd ground pin 2 comp voltage feedback pin, by connecting a photo- coupler to control the duty cycle 3 rtl resistor trigger latch off which a high over 3.5v f or ovp latch off and a low below 1v for otp latch 4 cs current sense pin, connect to sense the mosfet current 5 vcc power supply pin 6 out the output driver for driving the external mo sfet absolute maximum ratings supply voltage vcc ------------------------------- --------------------------------------------------- ----------------------- 30v comp, rtl, cs ------------------------------------ --------------------------------------------------- ------------- -0.3 ~ 7v out ---------------------------------------------- --------------------------------------------------- ---------- -0.3 ~ vcc + 0.3v junction temperature ----------------------------- --------------------------------------------------- ----------------------- 150 operating ambient temperature -------------------- --------------------------------------------------- ------- -20 ~ 85 storage temperature range ------------------------ --------------------------------------------------- ------- -65 ~ 150 sot-26 package thermal resistance (junction to ambi ent) --------------------------------------------- ----- 250 /w power dissipation (sot-26, at ambient temperature = 85 ) ------------------------------------------------ 250mw power dissipation (dip-8, at ambient temperature = 85 ) ------------------------------------------------ --- 650mw lead temperature (all pb free packages, soldering, 10 sec) ------------------------------------------ -------- 260 esd voltage protection, human body model --------- --------------------------------------------------- -------------- 2kv esd voltage protection, machine model ------------ --------------------------------------------------- --------------- 200v
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 3 GR8837 block diagram
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 4 GR8837 electrical characteristics (vcc = 15.0v & t a = +25 , unless otherwise specified.) parameter pin min. typ. max. unit supply voltage startup current (vcc=uvlo on - 1v) 5 8 15 ua operating current (with 1nf load on out pin), vcomp = 0v 5 800 ua operating current (with 1nf load on out pin), vcomp = 2.5v 5 1 2 3 ma operating current (with 1nf load on out pin), prote ction tripped (olp, ovp) 5 0.4 0.7 1 ma uvlo(off) 5 5.8 6.8 7.8 v uvlo(on) 5 10.3 11.3 12.3 v ovp level on vcc pin-latch mode 5 27 28 29 v vcc level in latch mode (3meg start-up resistor) 5 6 v holding current at latch mode (vcc=5v) 20 ua latch mode release voltage 5 3.2 v voltage feedback short circuit current, vcomp = 0v 2 0.8 ma open loop voltage, comp pin open 2 4.4 5.5 v green-mode start voltage 2 1.5 v burst mode start voltage 2 0.85 v current sensing maximum input voltage, vcs(off)-auto recovery mode 4 0.80 0.85 0.9 v leading-edge blanking time 4 350 ns input impedance 4 1 m delay to output 4 100 ns oscillator frequency - 60 65 70 khz jitter frequency - + 6 % green mode frequency - 22 khz temp. stability (- 40c ~ 110c) - 5 % voltage stability (vcc = 11v~25v) - 3 % gate driver output output low level, vcc = 15v, io = 20ma 6 1 v output high level, vcc = 15v, io = 20ma 6 8 v rising time, load capacitance = 1000pf 6 200 ns falling time, load capacitance = 1000pf 6 80 ns vgate-clamp (vcc = 25v ) 6 12 13 v
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 5 GR8837 olp section olp trip level, vcomp (olp) - 3.5 v olp delay time - 60 ms pwm section maximum duty cycle - 70 75 80 % rtl section over voltage protection threshold voltage 3 3.2 3.5 3.8 v ovp debounce time 3 100 us over temperature protection threshold voltage 3 0.9 5 1 1.05 v otp debounce time 3 100 us output current from rtl pin 3 75 80 85 ua rtl pin voltage when floating 3 1.8 2.4 3.0 v
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 6 GR8837 typical performance characteristics
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 7 GR8837
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 8 GR8837 application information start-up current the typical start-up current is around 8ua. very lo w start-up current allows the pwm controller to increase the value of start-up resistor and then reduce the power dissipation on it. uvlo (under voltage lockout) a hysteresis uvlo comparator is implemented in GR8837, then the turn-on and turn-off thresholds level are fixed at 11.3v and 6.8v respectively. thi s hysteresis shown in fig.9 ensures that the start-up capacitor will be adequate to supply the chip durin g start-up. the GR8837 is designed to meet the standby power below 100mw. so the start-up resistor can be used as several mega ohms to reduce the power loss. due to the low uvlo on level, so the turn-on delay time will also never greater than the general pwm ic. fig.9 soft start during initial power on, the GR8837 provides 16ms soft start function. it effectively suppresses the start up peak current to reduce the power mosfet drain voltage especially at high line. oscillator the maximum duty-cycle of internal oscillator is limited to 75% for avoiding the transformer saturation. the frequency of the oscillator is fixe d to 65khz by internal setting. green-mode operation when the load decreases to an extent, the frequency of the controller will decrease so as to reduce the system power consumption. the minimum frequency is about 22 khz, which is outside the audio range . leb (leading-edge blanking) each time the power mosfet is switched on, a turn-on spike will inevitably occur at the sense resistor. to avoid fault trigger, a 350ns leading-e dge blanking time is built in. conventional rc filterin g can therefore be omitted. during this blanking period, the current-limit comparator is disabled an d can not switch off the gate driver. internal slope compensation a built-in slope compensation circuit is constructe d in GR8837. when the switch is on, a ramp voltage is added to the sensed voltage across the cs pin, which helps to stabilize the system and prevent the sub-harmonic oscillations . olp (over load protection) the GR8837 has over load protection function. an internal circuit detects the load level, when the l oad is larger than a threshold level and the condition lasts more than 60ms, the gate output will keep on low level. then vcc decreases below uvlo off level, the controller resets again. fig.10 shows th e waveform of the olp operation. fig. 10
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 9 GR8837 ovp (over voltage protection) on vcc to prevent power mosfet from being damaged, the GR8837 is implemented an ovp function on vcc. when the vcc voltage is higher than the ovp threshold voltage, the output gate driver circuit w ill be shut down immediately to stop the switching of power mosfet. the vcc pin ovp function is a latch type protection. GR8837 is working in latch mode as shown in fig. 11. fig. 11 gate clamp/soft driving driver is clamped to 13v by an internal clamping circuit. a totem pole gate driver is fine tuned to meet both emi and efficiency requirement in low power application. an internal pull low circuit is activa ted after pretty low v dd to prevent external mosfet from accidentally turning on during uvlo. vcc mode operation in order to avoid the output voltage shut down by load changing from full to no load, the GR8837 is built-in the vcc mode function. when the load from full changes to no load, the output voltage will overshoot and pull low the comp pin by feedback loop. thus the duty will disappear and no power delivers to the secondary. if there is without any mechanism to prevent this situation, the vcc pin voltage will down to uvlo off and the ic will re-st art again. in the GR8837, before the vcc is down to uvlo off, it will force the out pin outputs the specified duty to pull the vcc higher than uvlo off . the operation is shown in fig.12. vcc uvlo(off) t t load t out switching vcc mode(on) vcc mode(off) full load vcc mode burst mode fig. 12 the vcc mode function is used to prevent the output re-start again when load changes. so never let the system operate on the vcc mode at no load. the system should operate on burst mode, otherwise the input power maybe become larger. rtl pin latch off mode fig. 13 the typical application for rtl pin is shown in fig . 13. the zener diode is setting as external ovp protection and the ntc thermal resistor is setting as external otp protection. in the rtl pin, there are two comparators for latch-off mode protection. whil e the voltage on this pin is higher than 3.5v or lowe r
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 10 GR8837 than 1.0v, the GR8837 will shut down after the de-bounce time 100us. and the GR8837 will never auto recovery, unless the vcc pin voltage is down to reset level as same as shown in fig. 11.
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 11 GR8837 typical application circuit 10u/50v c6 68u/400v c1 gbu206 db1 pr1007 d2 bav103 d4 1r / 1206 r14 51k / 1206 r2 2200pf / 1206 c2 20a100v d1 470u/25v c7 t2a/250v f1 1000pf / 1206 cs1 100r r7 10nf c9 470u/25v c8 10r / 1206 r17 cy1 431 u3 100r r22 27k r27 0.1uf c10 107k r23 51k / 1206 r3 500k / 1206 r6 pc817 u2a pc817 u2b 0.1uf cx1 1r / 1206 r15 22r / 1206 rs1 500k / 1206 r5 10r / 1206 r1 nc mov1 short ntc1 l n l1 t1a t1b comp 2 out 6 cs 4 vcc 5 gnd 1 rtl 3 GR8837 u1 75r / 1206 r4 6n60c q1 10k r12 10r r8 0r r18 10nf ct nc r9 nc c3 l2 + - 12v/3.0a 100pf c4 0.1uf c5 1k r16 20v dz1 100k ntc2
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 12 GR8837 package information sot-26 sot-26 millimeters inches symbol min. max. min. max. a 1.45 0.057 a1 0.00 0.15 0.000 0.006 a2 0.90 1.30 0.035 0.051 b 0.30 0.50 0.012 0.020 c 0.08 0.22 0.003 0.009 d 2.70 3.10 0.106 0.122 e 2.60 3.00 0.102 0.118 e1 1.40 1.80 0.055 0.071 e 0.95 bsc 0.037 bsc e1 1.90 bsc 0.075 bsc l 0.30 0.60 0.012 0.024 0 o 8 o 0 o 8 o note: 1. followed from jedec to-178 ab. 2. dimension d and e1 do not include mold flas h, protrusions or gate burrs. mold flash, protrusio ns or gate burrs shall not exceed 10 mil per side
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 13 GR8837 package information dip-8 dip-8 millimeters inches symbol min. max. min. max. a 5.33 0.210 a1 0.38 0.015 a2 2.92 4.95 0.115 0.195 b 0.36 0.56 0.014 0.022 b2 1.14 1.78 0.045 0.070 c 0.20 0.35 0.008 0.014 d 9.01 10.16 0.355 0.400 d1 0.13 0.005 e 7.62 8.26 0.300 0.325 e1 6.10 7.11 0.240 0.280 e 2.54 bsc 0.100 bsc ea 7.62 bsc 0.300 bsc eb 10.92 0.430 l 2.92 3.81 0.115 0.150 note: 1. followed from jedec ms-001 ba. 2. dimension d, d1 and e1 do not include mold flash or protrusions. mold flash or protrusions sha ll not exceed 10 mil.
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 14 GR8837 carrier tape & reel dimensions sot-26 application a h t1 c d d w e1 f 178.0 2.00 50 min. 8.4+2.00 -0.00 13.0+0.50 -0.20 1.5 min. 20.2 min. 8.0 0.30 1.75 0.10 3.5 0.05 p0 p1 p2 d0 d1 t a0 b0 k0 sot-26 4.0 0.10 4.0 0.10 2.0 0.05 1.5+0.10 -0.00 1.0 min. 0.6+0.00 -0.40 3.20 0.20 3.10 0.20 1.50 0.20 (mm) application carrier width cover tape width devices per reel sot -26 8 5.3 3000
2011.06 ver.1.0.copyright grenergy opto, inc. www.g renergy-ic.com 15 GR8837 tape and specification reel sot 26 ___________________________________________________ ___________________ grenergy opto, inc. reserves the right to make corre ctions, modifications, enhancements, improvements, and other changes to its products and services at any time and to dis continue any product or service without notice. cust omers should obtain the latest relevant information before placing orders a nd should verify that such information is current a nd complete. direction of feed

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