e - cmos corp. ( www.ecmos.com.tw ) page 1 of 8 4j07 n rev. f 001 38v synchronous buck converter with cc/cv ec 93 0 2 a pplication circuit general description ec93 02 is a wide input voltage, high efficiency active cc step - down dc/dc con verter that operates in either cv (constant output voltage) mode or cc (constant output current) mode. EC9302 provides up to 2.5a output current at 160khz switching frequency. current mode control provides fast transient response an d cycle - by - cycle current limit. an internal soft - start prevents inrush current at turn - o n, this device, available in an sop8l - ep(exposed pad) package, provides a very compact solution with minimal external components. features - wide 8v to 38v operating input range - integrated 140m power mosfet switches - output adjustable from vfb(1.0v) to 5.5v - up to 92% efficiency - internal soft - start. - stable with low esr ceramic output capacitors - fixed 160khz frequency - cycle - by - cycle over current protection - input under/ over voltage lockout EC9302
e - cmos corp. ( www.ecmos.com.tw ) page 2 of 8 4j07 n rev. f 001 38v synchronous buck converter with cc/cv ec 93 0 2 name description bs boot - strap pin. supply high side gate driver. decouple this pin to lx pin with 24ohm + 0.1uf ceramic cap. in power input pin. bypass in to gnd with a suitably large capacitor to eliminate noise on the input to the ic. sw power switching output. sw is the switching node that supplies power to the output. connect the output lc filter from sw to the output load. gnd ground. pad ground (connect to gnd). fb feedback input. fb senses the output voltage to regulate that v oltage. drive fb with a resistive voltage divider from the output voltage. comp compensation node. comp is used to compensate the regulation control loop. connect a series rc network from comp to gnd to compensate the regulation control loop. sen+ the cu rrent sense input (+) pin. sen - the current sense input ( - ) pin. p in assignment the package of ec93 02 is sop8l - ep(exposed pad); the pin assignment is given by:
e - cmos corp. ( www.ecmos.com.tw ) page 3 of 8 4j07 n rev. f 001 38v synchronous buck converter with cc/cv ec 93 0 2 ordering / m arking information EC9302nn xx x block diagram package type part number marking marking information sop 8l (exposed pad) EC9302nnmhr EC9302 lllll yyww 1. lll ll last five number of lot no. 2. yyww date code mh sop 8(exposed pad) r tape & reel
e - cmos corp. ( www.ecmos.com.tw ) page 4 of 8 4j07 n rev. f 001 38v synchronous buck converter with cc/cv ec 93 0 2 characteristics symbol rating unit supply voltage v in C 0.3 to +42 v switch node voltage v sw C 0.3 to v in + 0.3 v boost voltage v bs vsw C 0.3 to vsw + 6 v all other pins C 0.3 to +6 v lead temperature 260 c storage temperature C 65 to +150 c junction temperature t j 150 c output voltage v out vfb to 6 v ambient operating temperature C 40 to +85 c thermal resistance from junction to case jc 15 c/w thermal resistance from junction to a mbient ja 40 c/w absolute maximum ratings (at t a =25c) note: ja is measured with the pcb copper area of approximately 1 in 2 (multi - layer). that need connect to exposed p ad. electrical characteristics (v in = 12v, t a = +25c, unless otherwise noted.) characteristics symbol conditions min typ max units input voltage range 8 - 38 v quiescent current i ccq v fb = 1.05v - 1 1.5 ma feedback voltage v fb 8v v in 38v 0.9 8 1.00 1.02 v feedback overvoltage threshold ovp (fb) - 1.1x - v fb high - side switch on resistance (note) r ds(on)1 - 150 - m low - side switch on resistance (note) r ds(on)2 - 140 - m high - side switch leakage current v fb =1.05v, v sw = 0v - - 10 a up per switch current limit minimum duty cycle 2.9 3.5 - a lower switch current limit from drain to source - 0.9 - a oscillation frequency f osc1 - 160 - khz short circuit oscillation frequency f osc2 v fb =<0.5v - 60 - khz maximum duty cycle d max - 90 - %
e - cmos corp. ( www.ecmos.com.tw ) page 5 of 8 4j07 n rev. f 001 38v synchronous buck converter with cc/cv ec 93 0 2 minimum on time (note) t on(min) - 220 - ns sense voltage v sen (v sen+) - (v sen - ) 114 120 126 mv v in ovp turn - off voltage input voltage rising - 40 - v v in ovp hysteresis input voltage falling - 5 - v input under voltage lockout threshold uvlo v in rising 6.5 7.0 7.5 v input under voltage lockout threshold h ysteresis uvlo - hys - 800 - mv soft - start period - 3 - ms thermal shutdown t sd - 150 - c thermal shutdown hysterisis t sh - 30 - c note: guaranteed by design. function description the ec93 02 is a synchronous rectified, current - mode, step - d own regulator. it regulates input voltages from 8v to 38v down to an output voltage as low as v fb , and supplies up to 2.5a of load current. the ec93 02 uses current - mode control to regulate the output voltage. the output voltage is measured at fb through a resistive voltage divider and amplified through the internal tran conductance error amplifier. the converter uses internal n - channel mosfet switches to step - down the input voltage to the regulated output voltage. since the high side mosfet requires a gate voltage greater than the input voltage, a boost capacitor connected between sw and bs is needed to drive the high side gate. the boost capacitor is charged from the internal 5v rail when sw is low. when the ec93 02 fb pin exceeds 10% of the nominal regulati on voltage of v fb , the over voltage comparator is tripped and the comp pin is discharged to gnd, forcing the high - side switch off. a pplication i nformation setting the output voltage the output voltage is set using a resistive voltage divider from the o utput voltage to fb pin. the voltage divider divides the output voltage down to the feedback voltage by the ratio. thus the output voltage is: for example, vfb =1.00v for a 5.0v output voltage, r2 is 10k , and r1 is 40k. inductor selection the inductor is required to supply constant current to the output load while being driven by the switched input voltage. a larger value inductor will result in less ripple current that will result in lower output ripp le voltage. however, the larger value inductor will have a larger physical size, higher series resistance, and/or lower saturation current. a good rule for determining the inductance to use is to allow the peak - to - peak
e - cmos corp. ( www.ecmos.com.tw ) page 6 of 8 4j07 n rev. f 001 38v synchronous buck converter with cc/cv ec 93 0 2 vin <28v <35v inductor 47uh 33uh rsen 100m 50m 45m 40m iout 900ma 2000ma 2200ma 2500ma ripple current in the inductor to be approximately 30% of the maximum switch current limit. the choice of which style inductor to use mainly depends on the price vs. size requirements and any emi requirements. cc measurement (l=33uh) t ypical c haracteristics
e - cmos corp. ( www.ecmos.com.tw ) page 7 of 8 4j07 n rev. f 001 38v synchronous buck converter with cc/cv ec 93 0 2 power on : v in = 12v, v out = 5v, i load = 0a power on : v in = 12v, v out = 5v, i load = 2a cable on : v in = 12v, v out = 5v, i load = 2a power on : v in = 24v, v out = 5v, i load = 2a
e - cmos corp. ( www.ecmos.com.tw ) page 8 of 8 4j07 n rev. f 001 38v synchronous buck converter with cc/cv ec 93 0 2 p ackage o utlines
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