AIC1553
Compact 500KHz PWM/PFM, Step-Down DC/DC
Converters


Analog Integrations Corporation 4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan DS-1553-P2 061402
TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw 1


null FEATURES
null Tiny 5-Lead SOT-23 package
null Uses Tiny Capacitors and Inductor
null High Frequency Operation: 500KHz
null High Output Current: 500mA
null Low RDS(ON) Internal Switch: 0.6Ω
null High Efficiency: Up to 90%
null Current Mode Operation for Excellent Line and
Load Transient Response
null Short-Circuit Protected
null Low Quiescent Current: 22µA
null Low Dropout Operation: 100% Duty Cycle
null Ultralow Shutdown Current: IQ < 1µA
null Peak Inductor Current Independent of Inductor
Value
null Low Output Voltages: Down to 0.75V

null APPLICATIONS
null Cellular Phones.
null PDAs and Handy-Terminals.
null CPU I/O Supplies.
null Cordless Phones.
null Notebook Chipset Supplies.
null Handheld Equipment
null DESCRIPTION
The AIC1553 is a step-down, current mode,
DC/DC converter. It operates from 2.5V to 5.5V
input voltage range and switches at 500KHz,
allowing the use of tiny, low cost capacitors and
inductors. The output voltage is adjustable from
0.75V to 5V. A built-in 0.6Ω switch allows up to
0.5A of output current at high efficiency.
The AIC1553 operates continuously to very low
load currents to provide low ripple at the
expense of light load efficiency. With no load,
the AIC1553 draws only 22µA. In shutdown
mode, it draws less than 1µA, making it ideal for
current sensitive applications.
The tiny 5-lead SOT-23 package makes it
easy to save the layout area.

null
TYPICAL APPLICATION CIRCUIT

SW
1
GND
2
VFB
3
VIN
5
SD
4
U1
AIC1553
V
IN

+
C1
10µF
L1 6.8µH
R2
560K
R1
240K
C2
47µF
C3
D1
SS12
C4
4.7µF
V
OUT
ON/OFF
2.5V
2.5V~5.5V
22pF

2.5V/500mA Step-Down Converter