ACE701

VER 1.2

4

LX leakage current

Vout=Vlx=6V

1.0

uA

CE “H” threshold voltage

0.6

0.9

V

CE “L” threshold voltage

0.3

0.6

V

Oscillator frequency

LX on “L” side Vout=Vout * 0.96

300

350

400

Khz

Oscillator duty cycle

Maxdty

On (Vlx “L”) side

70

75

80

%

Efficiency

η

85

%

Note :

1.

Diode: Schottky type, such as: 1N5817, 1N5819, 1N5822

2.

Inductor: 27uH(R<0.5Ω)

3.

Capacitor: 100uF (Tantalum type)

Typical Application Circuit

D 1N5819

Vin

Vout

L 27uH

LX

LX

OUT

Iout

Cin 47uF

ACE701

GND

Cout

Rload

100uF

Tan

Detailed Description

The ACE701 series are boost structure, voltage-type pulse-frequency modulation(PFM) step-up DC-DC

converter. Only three external components are necessary: an inductor, an output filter capacitor and a

schottky diode. And the converter’s low noise and low ripple output voltage can be adjusted from 2.5V to

5.0V, 0.1V step. By using the depletion technics, the quiescent current drawn from power source is lower

than 7uA. The high efficiency device consists of resistors for output voltage detection and trimming, a

start-up voltage circuit, an oscillator, a reference circuit, a PFM control circuit, a switch protection circuit

and a driver transistor.

The PFM control circuit is the core of the ACE701 IC. This block controls power switch on duty cycle to

stabilize output voltage by calculating results of other blocks which sense input voltage, output voltage,

output current and load conditions. In PFM modulation system, the frequency and pulse width is fixed.

The duty cycle is adjusted by skipping pulses, so that switch on-time is changed based on the conditions

such as input voltage, output current and load. The oscillate block inside ACE701 provides fixed

frequency and pulse width wave.

The reference circuit provides stable reference voltage to output stable output voltage. Because internal

trimming technology is used, The chip output change less than ±2%. At the same time，the problem of

temperature-drift coefficient of output voltage is considered in design, so temperature-drift coefficient of

output voltage is less than 100ppm/℃。