AIC1578
High-Efficiency, Step-Down DC/DC Converter
FEATURES
•
4V to 20V Input Voltage Operation.
•
High Efficiency (up to 95%).
•
Low Quiescent Current at 90µA.
•
Pulse-Skipping and Pulse-Frequency Modulation.
•
Inputs-Uncommitted Current Sense Comparator.
•
Duty Cycle Adjustable.
•
90KHz to 280KHz Oscillator Frequency.
•
Power-Saving Shutdown Mode (8µA Typical).
•
Push-Pull Driver Output.
DESCRIPTION
The AIC1578 is a high performance step-down
DC/DC converter, designed to drive an external
P-channel MOSFET to generate programmable
output voltages. Two main schemes of Pulse-
Skipping and Pulse-Frequency Modulation are
employed to maintain low quiescent current and
high conversion efficiency under wide ranges of
input voltage and loading condition. The
AIC1578 delivers 10mA to 2A of output current
with 87%~93% efficiency at V
IN
=9V, V
OUT
=5V
condition. A current sense comparator with both
inverting and non-inverting input uncommitted is
included to provide the crucial function of either
current limit protection or constant output current
control. When the AIC1578 is used in a high-side
current sensing step-down constant current
source, the efficiency is typically greater than
90%. Duty cycle can be adjusted to greater than
90% by connecting a resistor from DUTY pin to
V
IN
. Quiescent current is about 90µA and can be
reduced to 8µA in shutdown mode. Switching
frequency being in around 90KHz to 280KHz
range, small size switching components are ideal
for battery powered portable equipment.
APPLICATIONS
•
Notebook 5V/3.3V Main Power
•
Step-Down DC/DC Converter Module.
•
Constant Current Source for Battery Chargers.
TYPICAL APPLICATION CIRCUIT
V
IN
IRF9Z34
Q1
* L1
33µH
D1
1N5820
C3
220µF
+
C4
10µF
**RS
+
D2
100µF
+
0.1µF
C2
R
DUTY
R2 1M
1M
Control
*Sumida MPP CORE
VIN
DUTY
SHDN
FB
AIC1578
**Charge current=57mV/RS
CS+
CS -
DRI
GND
Battery
C1
Constant Current Source for Battery Charger
ORDERING INFORMATION
AIC1578 XX
PACKAGE TYPE
N: PLASTIC DIP
S: SMALL OUTLINE
TEMPERATURE RANGE
C: 0°C~+70°C
1N5820
ORDER NUMBER
AIC1578CN
(PLASTIC DIP)
PIN CONFIGURATION
TOP VIEW
VIN
DUTY
1
2
3
4
8 CS+
7 CS-
6 DRI
5 GND
AIC1578CS
(PLASTIC SO)
SHDN
FB
Analog Integrations Corporation
DS-1578-02
Dec 27, 00
4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
1
AIC [ ANALOG INTERGRATIONS CORPORATION ]
