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RT7285C ? ds7285c-03 july 2014 www.richtek.com 1 ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. ordering information note : richtek products are : ? rohs compliant and compatible with the current require- ments of ipc/jedec j-std-020. ? suitable for use in snpb or pb-free soldering processes. 1.5a, 18v, 500khz acot tm synchronous step-down converter general description the RT7285C is a synchronous step-down converter with advanced constant on-time (acot tm ) mode control. the acot tm provides a very fast transient response with few external components. the low impedance internal mosfet supports high efficiency operation with wide input voltage range from 4.3v to 18v. the proprietary circuit of the RT7285C enables to support all ceramic capacitors. the output voltage can be adjusted between 0.6v and 8v. features ? ? ? ? ? 4.3v to 18v input voltage range ? ? ? ? ? 1.5a output current ? ? ? ? ? advanced constant on-time control ? ? ? ? ? fast transient response ? ? ? ? ? support all ceramic capacitors ? ? ? ? ? up to 95% efficiency ? ? ? ? ? 500khz switching frequency ? ? ? ? ? adjustable output voltage from 0.6v to 8v ? ? ? ? ? cycle-by-cycle current limit ? ? ? ? ? input under-voltage lockout ? ? ? ? ? hiccup mode under-voltage protection ? ? ? ? ? thermal shutdown ? ? ? ? ? rohs compliant and halogen free applications ? industrial and commercial low power systems ? computer peripherals ? lcd monitors and tvs ? green electronics/appliances ? point of load regulation for high-performance dsps, fpgas, and asics simplified application circuit package type e : sot-23-6 j6 : tsot-23-6 lead plating system g : green (halogen free and pb free) RT7285C pin configurations (top view) sot-23-6 / tsot-23-6 boot gnd fb sw vin en 4 23 5 6 marking information 0w= : product code dnn : date code 0b= : product code dnn : date code RT7285Cge RT7285Cgj6 vin en gnd boot fb sw v out v in RT7285C enable 0w=dnn 0b=dnn
RT7285C 2 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. functional pin description pin no. sot-23-6 tsot-23-6 pin name pin function 1 1 boot bootstrap supply for high-side gate driver. connect a 0.1 ? f ceramic capacitor between the boot and sw pins. 2 2 gnd power ground. 3 3 fb feedback voltage input. the pin is used to set the output voltage of the converter via a resistive divider. the converter regulates v fb to 0.6v 4 4 en enable control input. connect en to a logic-high voltage to enable the ic or to a logic-low voltage to disable. do not leave this high impedance input unconnected. 5 5 vin power input. the input voltage range is from 4.3v to 18v. must bypass with a suitable large ceramic capacitor at this pin. 6 6 sw switch node. connect to external l-c filter. function block diagram operation the RT7285C is a synchronous step-down converter with advanced constant on-time control mode. using the acot control mode can reduce the output capacitance and fast transient response. it can minimize the component size without additional external compensation network. current protection the inductor current is monitored via the internal switches cycle-by-cycle. once the output voltage drops under uv threshold, the RT7285C will enter hiccup mode. uvlo protection to protect the chip from operating at insufficient supply voltage, the uvlo is needed. when the input voltage of vin is lower than the uvlo falling threshold voltage, the device will be lockout. thermal shutdown when the junction temperature exceeds the otp threshold value, the ic will shut down the switching operation. once the junction temperature cools down and is lower than the otp lower threshold, the converter will autocratically resume switching. comparator vibias boot gnd sw pvcc en driver gnd sw control en uv & ov oc min off pvcc fb reg v ref v in vin on-time v in sw pvcc ugate lgate + - - ripple gen. sw
RT7285C 3 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. parameter symbol test conditions min typ max unit shutdown current i shdn v en = 0v -- -- 4 ? a quiescent current i q v en = 2v, v fb = 1v -- 0.5 -- ma switch-on resistance high-side r ds(on)_h v boot ? sw = 4.8v -- 230 -- m ? low-side r ds(on)_l v in = 5v -- 130 -- current limit i lim valley current 1.7 2.2 2.8 a oscillator frequency f sw -- 500 -- khz maximum duty cycle d max -- 90 -- % minimum on-time t on -- 60 -- ns feedback threshold voltage v fb 591 600 609 mv en input threshold logic-high v en_h 1.5 -- -- v logic-low v en_l -- -- 0.4 vin under-voltage lockout threshold v uvlo v in rising 3.55 3.9 4.25 v vin under-voltage lockout threshold hysteresis -- 340 -- mv electrical characteristics (v in = 12v, t a = 25 c, unless otherwise specified) absolute maximum ratings (note 1) ? vin to gnd ----------------------------------------------------------------------------------------------------- ? 0.3v to 20v ? sw to gnd ---------------------------------------------------------------------------------------------------- ? 0.3v to (v in + 0.3v) < 10ns ----------------------------------------------------------------------------------------------------------- ? 5v to 25v ? boot to gnd ------------------------------------------------------------------------------------------------- (v sw ? 0.3v) to (v sw + 6v) ? other pins ------------------------------------------------------------------------------------------------------ ? 0.3v to 6v ? power dissipation, p d @ t a = 25 c sot-23-6 / tsot-23-6 --------------------------------------------------------------------------------------- 0.625w ? package thermal resistance (note 2) sot-23-6 / tsot-23-6, ja --------------------------------------------------------------------------------- 160 c/w sot-23-6 / tsot-23-6, jc --------------------------------------------------------------------------------- 15 c/w ? lead temperature (soldering, 10 sec.) ------------------------------------------------------------------ 260 c ? junction temperature ---------------------------------------------------------------------------------------- 150 c ? storage temperature range ------------------------------------------------------------------------------- ? 65 c to 150 c ? esd susceptibility (note 3) hbm (human body model) --------------------------------------------------------------------------------- 2kv recommended operating conditions (note 4) ? supply input voltage, vin ---------------------------------------------------------------------------------- 4.3v to 18v ? junction temperature range ------------------------------------------------------------------------------- ? 40 c to 125 c ? ambient temperature range ------------------------------------------------------------------------------- ? 40 c to 85 c
RT7285C 4 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. note 1. stresses beyond those listed ? absolute maximum ratings ? may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions may affect device reliability. note 2. ja is measured at t a = 25 c on a high effective thermal conductivity four-layer test board per jedec 51-7. the case position of jc is on the top of the package. note 3. devices are esd sensitive. handling precaution is recommended. note 4. the device is not guaranteed to function outside its operating conditions. parameter symbol test conditions min typ max unit soft-start time t ss -- 800 -- ? s thermal shutdown threshold t sd -- 160 -- ? c thermal shutdown hysteresis ? t sd -- 20 -- ? c v out discharge resistance r dischg en = 0v, v out = 0.5v -- 50 100 ? uvp detect 70 75 80 output under-voltage trip threshold hysteresis -- 10 -- % output under-voltage delay time -- 250 -- ? s
RT7285C 5 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. typical application circuit v out (v) r1 (k ? ) r2 (k ? ) l ( h) c out ( f) c ff (pf) 5 110 15 10 22 39 3.3 115 25.5 6.8 22 33 2.5 25.5 8.06 4.7 22 nc 1.2 10 10 3.6 22 nc table 1. suggested component values vin en gnd boot fb sw 4 3 5 6 1 l 3.6h 100nf 22f r1 10k r2 10k v out 1.2v 10f v in 4.3v to 18v RT7285C c boot c in c out enable 2 c ff
RT7285C 6 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. typical operating characteristics referecnec voltage vs. input voltage 0.590 0.595 0.600 0.605 0.610 4.5 6.5 8.5 10.5 12.5 14.5 16.5 18.5 input voltage (v) referecnec voltage (v) v in = 4.5v to 18v, v out = 1.2v, i out = 0a switching frequency vs. input voltage 500 520 540 560 580 600 4681012141618 input voltage (v) switcing frequency (khz) 1 v out = 1.2v, i out = 0a output voltage vs. load current 1.190 1.194 1.198 1.202 1.206 1.210 1.214 1.218 1.222 1.226 1.230 0 0.3 0.6 0.9 1.2 1.5 load current (a) output voltage (v) v in = 4.5v to 18v, v out = 1.2v v in = 18v v in = 12v v in = 9v v in = 5v v in = 4.5v reference vs. temperature 0.590 0.595 0.600 0.605 0.610 -50-25 0 25 50 75100125 temperature (c) reference voltage (v) i out = 0a v in = 12v efficiency vs. load current 0 10 20 30 40 50 60 70 80 90 100 0 0.3 0.6 0.9 1.2 1.5 load current (a) efficiency (%) v out = 1.2v v in = 5v v in = 9v v in = 12v v in = 18v efficiency vs. load current 0 10 20 30 40 50 60 70 80 90 100 0 0.3 0.6 0.9 1.2 1.5 load current (a) efficiency (%) v out = 5v v in = 12v v in = 15v v in = 18v
RT7285C 7 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. time (1 s/div) switching v out (20mv/div) i l (1a/div) v in = 12v, v out = 1.2v, i out = 1.5a v sw (10v/div) time (1 s/div) switching v in = 12v, v out = 1.2v, i out = 0.75a v out (20mv/div) i l (1a/div) v sw (10v/div) time (100 s/div) load transient response v out (20mv/div) i out (1a/div) v in = 12v, v out = 1.2v, i out = 0.75a to 1.5a switching frequency vs. temperature 450 470 490 510 530 550 570 590 610 630 650 -50 -25 0 25 50 75 100 125 temperature (c) switching frequency (khz) 1 v out = 1.2v v in = 6v v in = 12v v in = 18v v in = 4.5v current limit vs. temperature 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 -50 -25 0 25 50 75 100 125 temperature (c) current limit (a) v in = 6v v in = 12v v in = 18v time (100 s/div) load transient response v out (20mv/div) i out (1a/div) v in = 12v, v out = 1.2v, i out = 0a to 1.5a
RT7285C 8 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. v in (10v/div) v sw (10v/div) time (2.5ms/div) power off from vin v in = 12v, v out = 1.2v, i out = 1.5a v out (1v/div) i sw (1a/div) time (5ms/div) power off from en v in = 12v, v out = 1.2v, i out = 1.5a v out (1v/div) v en (2v/div) i sw (1a/div) v sw (10v/div) time (2.5ms/div) power on from vin v in = 12v, v out = 1.2v, i out = 1.5a v out (1v/div) v in (10v/div) i sw (1a/div) v sw (10v/div) time (2.5ms/div) power on from en v in = 12v, v out = 1.2v, i out = 1.5a v out (1v/div) v en (2v/div) i sw (1a/div) v sw (10v/div)
RT7285C 9 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. application information inductor selection selecting an inductor involves specifying its inductance and also its required peak current. the exact inductor value is generally flexible and is ultimately chosen to obtain the best mix of cost, physical size, and circuit efficiency. lower inductor values benefit from reduced size and cost and they can improve the circuit's transient response, but they increase the inductor ripple current and output voltage ripple and reduce the efficiency due to the resulting higher peak currents. conversely, higher inductor values increase efficiency, but the inductor will either be physically larger or have higher resistance since more turns of wire are required and transient response will be slower since more time is required to change current (up or down) in the inductor. a good compromise between size, efficiency, and transient response is to use a ripple current ( i l ) about 20% to 40% of the desired full output load current. calculate the approximate inductor value by selecting the input and output voltages, the switching frequency (f sw ), the maximum output current (i out(max) ) and estimating a i l as some percentage of that current. ? ? ?? ??? out in out in sw l vvv l = vf i once an inductor value is chosen, the ripple current ( i l ) is calculated to determine the required peak inductor current. ? ? ?? ? ?? ? ? ? ? out in out l in sw l l(peak) out(max) l l(vally) out(max) vvv i= vf l i i = i 2 i i = i 2 considering the typical operating circuit for 1.2v output at 1.5a and an input voltage of 12v, using an inductor ripple of 0.6a (40%), the calculated inductance value is : ?? 1.2 12 1.2 l = = 3.6 h 12 500khz 0.6 ?? ?? the ripple current was selected at 0.6a and, as long as we use the calculated 3.6 h inductance, that should be the actual ripple current amount. the ripple current and required peak current as below : ? ? l 1.2 12 1.2 i = = 0.6a 12 500khz 3.6 h ?? ? ?? l(peak) 0.6 and i = 1.5a = 1.8a 2 ? inductor saturation current should be chosen over ic's current limit. input capacitor selection the input filter capacitors are needed to smooth out the switched current drawn from the input power source and to reduce voltage ripple on the input. the actual capacitance value is less important than the rms current rating (and voltage rating, of course). the rms input ripple current (i rms ) is a function of the input voltage, output voltage, and load current : out in rms out(max) in out v v i = i 1 vv ?? ceramic capacitors are most often used because of their low cost, small size, high rms current ratings, and robust surge current capabilities. however, take care when these capacitors are used at the input of circuits supplied by a wall adapter or other supply connected through long, thin wires. current surges through the inductive wires can induce ringing at the RT7285C input which could potentially cause large, damaging voltage spikes at vin. if this phenomenon is observed, some bulk input capacitance may be required. ceramic capacitors (to meet the rms current requirement) can be placed in parallel with other types such as tantalum, electrolytic, or polymer (to reduce ringing and overshoot). choose capacitors rated at higher temperatures than required. several ceramic capacitors may be paralleled to meet the rms current, size, and height requirements of the application. the typical operating circuit use 10 f and one 0.1 f low esr ceramic capacitors on the input.
RT7285C 10 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. output capacitor selection the RT7285C is optimized for ceramic output capacitors and best performance will be obtained using them. the total output capacitance value is usually determined by the desired output voltage ripple level and transient response requirements for sag (undershoot on positive load steps) and soar (overshoot on negative load steps). output ripple output ripple at the switching frequency is caused by the inductor current ripple and its effect on the output capacitor's esr and stored charge. these two ripple components are called esr ripple and capacitive ripple. since ceramic capacitors have extremely low esr and relatively little capacitance, both components are similar in amplitude and both should be considered if ripple is critical. ? ripple ripple(esr) ripple(c) v = v v ?? ripple(esr) l esr v = ir ? ?? l ripple(c) out sw i v = 8c f output transient undershoot and overshoot in addition to voltage ripple at the switching frequency, the output capacitor and its esr also affect the voltage sag (undershoot) and soar (overshoot) when the load steps up and down abruptly. the acot transient response is very quick and output transients are usually small. however, the combination of small ceramic output capacitors (with little capacitance), low output voltages (with little stored charge in the output capacitors), and low duty cycle applications (which require high inductance to get reasonable ripple currents with high input voltages) increases the size of voltage variations in response to very quick load changes. typically, load changes occur slowly with respect to the ic's 500khz switching frequency. for the typical operating circuit for 1.2v output and an inductor ripple of 0.46a, with 1 x 22 f output capacitance each with about 5m esr including pcb trace resistance, the output voltage ripple components are : ripple(esr) v = 0.46a 5m = 2.3mv ?? ripple(c) 0.46a v = = 5.227mv 822 f500khz ?? ripple v = 2.3mv 5.227mv = 7.527mv ? but some modern digital loads can exhibit nearly instantaneous load changes and the following section shows how to calculate the worst-case voltage swings in response to very fast load steps. the output voltage transient undershoot and overshoot each have two components : the voltage steps caused by the output capacitor's esr, and the voltage sag and soar due to the finite output capacitance and the inductor current slew rate. use the following formulas to check if the esr is low enough (typically not a problem with ceramic capacitors) and the output capacitance is large enough to prevent excessive sag and soar on very fast load step edges, with the chosen inductor value. the amplitude of the esr step up or down is a function of the load step and the esr of the output capacitor : v esr _step = i out x r esr the amplitude of the capacitive sag is a function of the load step, the output capacitor value, the inductor value,the input-to-output voltage differential, and the maximum duty cycle. the maximum duty cycle during a fast transient is a function of the on-time and the minimum off-time since the acot tm control scheme will ramp the current using on-times spaced apart with minimum off-times, which is as fast as allowed. calculate the approximate on-time (neglecting parasitics) and maximum duty cycle for a given input and output voltage as : ?? out on on max in sw on off(min) vt t = and d = vf t t the actual on-time will be slightly longer as the ic compensates for voltage drops in the circuit, but we can neglect both of these since the on-time increase compensates for the voltage losses. calculate the output voltage sag as : ?? 2 out sag out in(min) max out l(i ) v = 2c v d v ?? ?? ?? the amplitude of the capacitive soar is a function of the load step, the output capacitor value, the inductor value and the output voltage : 2 out soar out out l(i ) v = 2c v ?? ??
RT7285C 11 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. feed-forward capacitor (c ff ) the RT7285C is optimized for ceramic output capacitors and for low duty cycle applications. however for high-output voltages, with high feedback attenuation, the circuit's response becomes over-damped and transient response can be slowed. in high-output voltage circuits (v out > 3.3v) transient response is improved by adding a small ? feed- forward ? capacitor (c ff ) across the upper fb divider resistor (figure 1), to increase the circuit's q and reduce damping to speed up the transient response without affecting the steady-state stability of the circuit. choose a suitable capacitor value that following below step. ? get the bw the quickest method to do transient response form no load to full load. confirm the damping frequency. the damping frequency is bw. figure 1. c ff capacitor setting ? c ff can be calculated base on below equation : ff 1 c 2 3.1412 r1 bw 0.8 ? ???? enable operation (en) for automatic start-up the en pin can be connected to v in , through a 100k resistor. its large hysteresis band makes en useful for simple delay and timing circuits. en can be externally pulled to v in by adding a resistor- capacitor delay (r en and c en in figure 2). calculate the delay time using en's internal threshold where switching operation begins (1.4v, typical). an external mosfet can be added to implement digital control of en when no system voltage above 2v is available (figure 3). in this case, a 100k pull-up resistor, r en , is connected between vin and the en pin. mosfet q1 will be under logic control to pull down the en pin. to prevent enabling circuit when vin is smaller than the vout target value or some other desired voltage level, a resistive voltage divider can be placed between the input voltage and ground and connected to en to create an additional input under voltage lockout threshold (figure 4). figure 4. resistor divider for lockout threshold setting figure 2. external timing control figure 3. digital enable control circuit RT7285C en gnd v in r en c en en RT7285C en gnd 100k v in r en q1 enable RT7285C en gnd v in r en1 r en2 RT7285C gnd fb r1 r2 v out c ff internal soft-start (ss) the RT7285C soft-start uses an internal soft-start time 800 s. following below equation to get the minimum capacitance range in order to avoid uv occur. out out lim cv0.61.2 t (i load current) 0.8 t 800 s ??? ? ?? ? bw
RT7285C 12 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. output voltage setting set the desired output voltage using a resistive divider from the output to ground with the midpoint connected to fb. the output voltage is set according to the following equation : v out = 0.6 x (1 + r1 / r2) figure 5. output voltage setting RT7285C gnd fb r1 r2 v out for output voltage accuracy, use divider resistors with 1% or better tolerance. external boot bootstrap diode when the input voltage is lower than 5.5v it is recommended to add an external bootstrap diode between vin (or vinr) and the boot pin to improve enhancement of the internal mosfet switch and improve efficiency. the bootstrap diode can be a low cost one such as 1n4148 or bat54. external boot capacitor series resistance the internal power mosfet switch gate driver is optimized to turn the switch on fast enough for low power loss and good efficiency, but also slow enough to reduce emi. switch turn-on is when most emi occurs since vsw rises rapidly. during switch turn-off, sw is discharged relatively slowly by the inductor current during the deadtime between high-side and low-side switch on-times. in some cases it is desirable to reduce emi further, at the expense of some additional power dissipation. the switch ?? ? out r2 (v 0.6) r1 0.6 place the fb resistors within 5mm of the fb pin. choose r2 between 10k and 100k to minimize power consumption without excessive noise pick-up and calculate r1 as follows : sw boot 5v 0.1f RT7285C over-temperature protection the RT7285C features an over-temperature protection (otp) circuitry to prevent from overheating due to excessive power dissipation. the otp will shut down switching operation when junction temperature exceeds 160 c. once the junction temperature cools down by approximately 20 c, the converter will resume operation. to maintain continuous operation, the maximum junction temperature should be lower than 125 c. under-voltage protection hiccup mode the RT7285C provides hiccup mode under-voltage protection (uvp). when the vfb voltage drops below 0.4v, the uvp function will be triggered to shut down switching operation. if the uvp condition remains for a period, the RT7285C will retry automatically. when the uvp condition is removed, the converter will resume operation. the uvp is disabled during soft-start period. figure 6. external bootstrap diode turn-on can be slowed by placing a small (<47 ) resistance between boot and the external bootstrap capacitor. this will slow the high-side switch turn-on and vsw's rise. to remove the resistor from the capacitor charging path (avoiding poor enhancement due to undercharging the boot capacitor), use the external diode shown in figure 6 to charge the boot capacitor and place the resistance between boot and the capacitor/diode connection.
RT7285C 13 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. thermal considerations for continuous operation, do not exceed absolute maximum junction temperature. the maximum power dissipation depends on the thermal resistance of the ic package, pcb layout, rate of surrounding airflow, and difference between junction and ambient temperature. the maximum power dissipation can be calculated by the following formula : p d(max) = (t j(max) ? t a ) / ja where t j(max) is the maximum junction temperature, t a is the ambient temperature, and ja is the junction to ambient thermal resistance. for recommended operating condition specifications, the maximum junction temperature is 125 c. the junction to ambient thermal resistance, ja , is layout dependent. for sot-23-6 / tsot-23-6 package, the thermal resistance, ja , is 160 c/w on a standard four-layer thermal test board. the maximum power dissipation at t a = 25 c can be calculated by the following formula : p d(max) = (125 c ? 25 c) / (160 c/w) = 0.625w for sot-23-6 / tsot-23-6 package the maximum power dissipation depends on the operating ambient temperature for fixed t j(max) and thermal resistance, ja . the derating curve in figure 7 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. figure 7. derating curve of maximum power dissipation layout considerations for best performance of the RT7285C, the following layout guidelines must be strictly followed. ? input capacitor must be placed as close to the ic as possible. ? sw should be connected to inductor by wide and short trace. keep sensitive components away from this trace. 0.0 0.4 0.8 1.2 1.6 2.0 0 25 50 75 100 125 ambient temperature (c) maximum power dissipation (w) 1 four-layer pcb figure 8. pcb layout guide boot gnd fb sw vin en 4 2 3 5 6 sw v out r1 r2 v in c in c in c s* r s* r en c out c out sw should be connected to inductor by wide and short trace. keep sensitive components away from this trace. suggestion layout trace wider for thermal. keep sensitive components away from this trace. suggestion layout trace wider for thermal. suggestion layout trace wider for thermal. the feedback components must be connected as close to the device as possible. the r en component must be connected to v in . suggestion layout trace wider for thermal. input capacitor must be placed as close to the ic as possible. suggestion layout trace wider for thermal. v out gnd
RT7285C 14 ds7285c-03 july 2014 www.richtek.com ? copyright 2014 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. outline dimension a a1 e b b d c h l sot-23-6 surface mount package dimensions in millimeters dimensions in inches symbol min max min max a 0.889 1.295 0.031 0.051 a1 0.000 0.152 0.000 0.006 b 1.397 1.803 0.055 0.071 b 0.250 0.560 0.010 0.022 c 2.591 2.997 0.102 0.118 d 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 h 0.080 0.254 0.003 0.010 l 0.300 0.610 0.012 0.024
RT7285C 15 ds7285c-03 july 2014 www.richtek.com richtek technology corporation 14f, no. 8, tai yuen 1 st street, chupei city hsinchu, taiwan, r.o.c. tel: (8863)5526789 richtek products are sold by description only. richtek reserves the right to change the circuitry and/or specifications without notice at any time. customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a richtek product. information furnish ed by richtek is believed to be accurate and reliable. however, no responsibility is assumed by richtek or its subsidiaries for its use; nor for any infringeme nts of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of r ichtek or its subsidiaries. tsot-23-6 surface mount package dimensions in millimeters dimensions in inches symbol min max min max a 0.700 1.000 0.028 0.039 a1 0.000 0.100 0.000 0.004 b 1.397 1.803 0.055 0.071 b 0.300 0.559 0.012 0.022 c 2.591 3.000 0.102 0.118 d 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 h 0.080 0.254 0.003 0.010 l 0.300 0.610 0.012 0.024 a a1 e b b d c h l

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