ace 722 2 a step - down dc - dc converter ver 1. 6 1 d escription ACE722 is a current mode pwm step - down dc - dc converter, which has an internal 2 a p ower switch. it has the wide input voltage range of 3.6v to 20v, so it can suit for regulating a wide variety of power source. ACE722 make of a pwm control circu it, a reference voltage unit, an error amplifier, a protection circuit , chip enable circuit, and under voltage lockout circuit. a low ripple, high efficiency step - down dc - dc converter can be easily composed of this ic with only several external components, or an inductor, a diode and capacitors. output voltage can be adjusted with external resistors. ACE722 has the cycle - by - cycle current limit circuit; current limiting provides protection against shorted output. the low current (<5ua) shutdown provides comp lete output disconnect, enabling easy power management in battery powered systems. features ? range of input voltage: 3.6v~20v ? built - i n 90m powe r mosfet ? <5ua shutdown current ? oscillation frequency: 500khz ? high efficiency: 90% ? 2.5a peak current limit cycle by cycle ? operating temperature range: - 40 ~85 ? demo board available application ? power source for hand - held communication equipment, cam eras video instruments such as vcrs, camcorders. ? power source for battery - powered equipment ? power sou rce for household electrical appliance absolute maximum ratings p arameter m ax u nit s upply v oltage 23 v sw pin voltage 25 v ce pin voltage - 0.3v to vin +0.3v v fb pin voltage - 0.3v to 6v v operating ambient temperature range - 40 o c to 85 o c o c storage temperature - 65 o c to 150 o c o c thermal resistance: ja 150 o c /w
ace 722 2 a step - down dc - dc c onverter ver1.6 2 packaging type sop - 8 1 8 2 7 3 6 4 5 pin description ace 722 xx + h block diagram sop - 8 description function 1 nc not connected 2 vin power supply pin 3 sw switching node: pwm output connection to inductor 4 gnd ground pin 5 fb pin for feedback voltage 6 nc not connected 7 ce chip enable pin (a ctive with pb - free halogen - free
ace 722 2 a step - down dc - dc c onverter ver1.6 3 electrical characteristics (test conditions: t a =25 , v in =12v, unless otherwise noted .) parameter symbol conditions min typ max units under voltage lockout v uvlo 3.35 3.6 v feedback voltage v fb 1.225 1.25 1.275 v fb pin bias current i fb v fb =1.25v 150 600 na supply current i q v fb =1.3v, v ce =vin 2 m a quiescent current in shutdown v ce =0v 2 5 ua reference line regulation v fb / v v in =5v to 20v 0.08 %/v feedback voltage temperature coefficient v fb / t - 40 Q topt Q 85 100 ppm/ oscillator frequency f osc _max v fb =1.1vvfb 500 khz frequency shift threshold on fb pin f oscth f sw =200k 0.44 v max duty cycle d mx 97 % switch current limit i limit 2.5 a static p - channel mosfer on state resistance r ds_on 90* m switch leakage current i sw 1 ua ce h input current i ceh v ce =3v 6.7 15 ua c e l input current i cel v ce =0v 0.03 0.1 ua ce h input voltage v ceh v in =12v 1.8 v ce l input voltage v cel v in =12v 0.4 v typical application
ace 722 2 a step - down dc - dc c onverter ver1.6 4 demo board bom no. reference type specification note 1 c1 capacitor mlcc 10uf; smd 0805 2 c2 capacitor mlcc 10uf; smd 0805 3 d1 diode ss34; 40v, 3a; smd, shielding 4 l1 inductor 10 uh; 3a; smd; shielding 5 ic1 ic ACE722; smd sop - 8 6 r1 resistor smd 0805; 30 k; 1% 7 r2 resistor smd 0805; 10 k; 1% layout conside ration ? careful pcb layout is critical to achieving low switching losses and clean, stable operation. the switching power stage requires particular attention. if possible, mount all the power components on one side of the board, with their ground terminals as close to one another as possible. ? keep the high - current paths short, especially the distance between cin and the vin (gnd) terminals. it is essential for stable, jitter - free operation, showing as the following figure. the esr of cin should be smalle r enough and the capacitance of cin should be large enough for filtering the switching noise across power path, a 10uf ceramic capacitor is recommended. ? keep the trace connecting to sw terminal wide enough for heat dissipation, if possible, it is bette r to place some vias connected to the bottom copper for enhancement. ? route high - speed switching nodes, for example sw terminal, away from sensitive analog trace (eg. fb terminal).
ace 722 2 a step - down dc - dc c onverter ver1.6 5 demo board measurement efficiency vs. load curr ent (vout=5v) load regulation (vout=5v) load current (ma) load current (ma) ce pin bias current vs. ce pin voltage feedback voltage vs. supply voltage c e pin voltage (v) supply voltage (v) quiesent current vs. supply voltage supply current vs. supply voltage (vce=0v) (vfb=1.3v, vce=vin) supply voltage (v) supply voltage (v)
ace 722 2 a step - down dc - dc c onverter ver1.6 6 frequency vs. temperature feedback voltage vs. temperature temperature t empe r a t u r e t r a n s i e n t l o a d i n g r e s p o n s e
ace 722 2 a step - down dc - dc c onverter ver1.6 7 packing informat ion sop - 8
ace 722 2 a step - down dc - dc c onverter ver1.6 8 notes ace does not assume any responsibility for use as critical components in life support devices or systems without the express written approval of the president and general counsel of ace electronics co., ltd. as sued herein: 1. life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and shoes failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. a critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety o r effectiveness. ace technology co., ltd. http://www.ace - ele.com/
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