ac e7 40e 4 a , 18v high efficiency synchronous step - down converter ver 1. 1 1 d escription the ace 740 e is a wide input range, high - efficiency, dc - to - dc step - down switching regulator, capable of delivering up to 4 a of output current. current mode pwm control allows the use of small external components, such as ceramic input and outp ut caps, as well as small inductors, while still providing low output ripples. on top of the integrated internal synchronous rectifier that eliminates external schottky diode, ace 740e also employs a proprietary control scheme that switches the device into a power save mode during light load, thereby extending the range of high efficiency operation. therefore, ace 740e is a much superior solution in comparison to other competitions in terms of efficiency and cost. overall, ace 740e is a highly efficient and ro bust solution for dc - dc step - down applications that requires wide input ranges. ace 740e is available esop8 packages. . features ? wide input operating range from 4.5v to 18v ? high efficiency: up to 95% at light load ? capable of delivering 4 a ? no external schot tky diode needed ? inductor short circuit protection ? current mode control ? 0.923v reference for low output voltages ? logic control shutdown ? thermal shutdown and uvlo ? available in esop8 package application ? lcd tvs ? notebook computers ? fpga power supplies ? led dri vers absolute maximum ratings parameter value in voltage - 0.3v~20v sw, en voltage - 0.3v~vin+ 0.3 v bst voltage - 0.3v~sw+6v fb voltage - 0.3v ~6 v sw to ground current internally limited operating temperature range C 40c ~ 85c storage temperature range . ? 55c ~ 150c (note: exceeding these limits may damage the device. exposure to absolute maximum rating conditions for long periods may affect device reliability.)
ace7 40e 4a , 18v high efficiency synchronous step - down converter ver 1. 1 2 packaging type bst ss in en sw comp gnd fb esop8 ordering information ace7 40e xx + h esop - 8 description function 1 bst bootstrap pin. connect a 10nf capacitor from this pin to sw 2 in supply voltage. bypass with a 22f ceramic capacitor to gnd 3 sw inductor connection. connect an inductor between sw and the regulator output. 4 gnd ground 5 fb feedback input. connect an external resistor divider from the output to fb and gnd to set v out 6 comp regulator compensation. connect series rc network to gnd. 7 en enable pin for the ic. drive this pin to high to enable the part, low to disable. 8 ss soft start pin. connect a 0.1 uf capacitor from this pin to gnd im : esop - 8 pb - free halogen - free
ace7 40e 4a , 18v high efficiency synchronous step - down converter ver 1. 1 3 typical application 4a wide input step down synchronous converter electrical characteristics (vin=12v, t a =25 ) parameter test conditions min typ m ax unit input voltage range 4.2 18 v input uvlo rising, hysteresis=140mv 3.55 v input supply current v fb =1.0v 1.6 ma input shutdown current 6 ua fb feedback voltage 0.904 0.923 0.942 v fb input curren t 0.01 ua error amp transconductance 800 us switching frequency 340 khz high side switch on resistance l sw =200ma 90 p
low side switch on resistance l sw =200ma 85 p
high side switch current limit 5 a sw leakage current v in =12v,v sw =0 o r 12v, en= gnd 10 u a en input current 1 ua en input low voltage 0.5 ua en input high voltage 1.5 v thermal shutdown hysteresis=40c 150 c ace7 40 e
ace7 40e 4a , 18v high efficiency synchronous step - down converter ver 1. 1 4 typical performance characteristics (typical values are at ta = 25oc unless otherwise specified .)
ace7 40e 4a , 18v high efficiency synchronous step - down converter ver 1. 1 5 functional de sc riptions loop operation the ace7 40e is a wide input range, high - efficiency, dc - to - dc step - down switching regulator, capable of delivering up to 4 a of output current, integrated with a 90/85m synchronous mosfet pair, eliminating the need for external diode. it uses a pwm current - mode control scheme. an error amplifier integrates error between the fb signal and the internal reference voltage. the output of the integrator is then compared to the sum of a current - sense signal and the slope compensation ramp. this operation generates a pwm signal that modulates the duty cycle of the power mosfets to achieve regulation for output voltage. current limit there is a cycle - by - cycle curre nt limit on the high - side mosfet of 5 a (typ). when the current flowing out of sw exceeds this limit, the high - side mosfet turns off and the synchronous rectifier turns on. unlike the traditional method of current limiting by limiting the voltage at the comp ensation pin, which usually has large variation due to duty cycle variance, this type of peak current limiting scheme provides a relatively more accurate limit for output current, thereby lowering the requirements for system design. light load operation t raditionally, a fixed constant frequency pwm dc - dc regulator always switches even when the output load is small. when energy is shuffling back and forth through the power mosfets, power is lost due to the finite rdsons of the mosfets and parasitic capacita nces. at light load, this loss is prominent and efficiency is therefore very low. ace7 40e employs a proprietary control scheme that improves efficiency in this situation by enabling the device into a power save mode during light load, thereby extending the range of high efficiency operation.
ace7 40e 4a , 18v high efficiency synchronous step - down converter ver 1. 1 6 application information components selection v out (v) 1.2v 1.8v 2.5v 3.3v 5v 8v c out ( f) 22*2 22*2 22*2 22*2 22*2 22*2 l( h) 3.3 4.7 6.8 10 15 22
ace7 40e 4a , 18v high efficiency synchronous step - down converter ver 1. 1 7 packing information esop - 8 notes: all dimensions refer to jedec standard ms - 012 aa do not include mold f lash or protrusions.
ace7 40e 4a , 18v high efficiency synchronous step - down converter ver 1. 1 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 or effectiveness. ace technology co., ltd. http://www.ace - ele.com/
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