AIC1577
External NMOS Step-Down PWM Controller



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FEATURES
null N-Channel MOSFET Drive
null Operating Input Voltage from 4.5V to 24V
null Wide Ouput Range : 0.8V to 20V
null ±1.5% 0.8V Reference
null Low Dropout Operation : 95% Duty Cycle
null 500KHz Fixed Constant Frequency
null Low Standby Current, I
Q
Typically 720µA
null Logic-Control Micropower Shutdown
null Output Overvoltage Protection
null Internal Diode for Bootstrapped Gate Drive
null Current Mode Operation for Excellent Line and
Load Transient Response
null Available in an 8-Lead SO and MSOP Package


APPLICATIONS
null LCD Monitor
null Palmtop Computers, PDAs
null Wireless Modems
null On-Card Switching Regulators
null DC Power Distribution Systems
DESCRIPTION
The AIC1577 is a current mode switching
regulator controller that drives external N-
channel power MOSFET using a fixed fre-
quency architecure. It uses external divider to
adjust output voltage from 0.8V to 20V with
excellent line and load regulation. A maximum
high duty cycle limit of 95% provides low
dropout operation which extends operating
time in battery-operated systems.
Switching frequency up to 500KHz are
achievable thus allowing smaller sized filter
components. The operating current level is
user-programmable via an external current
sense resistor. It also provide output overvolt-
age protection under fault conditions.
A multifunction pin (I
TH
/RUN) allows external
compensation for optimum load step re-
sponse plus shutdown. Soft start can also be
implemented with this pin to properly se-
quence supplies. Package available are in
SOP8 and MSOP8 for SMD.

Analog Integrations Corporation Si-Soft Research Center DS-1577P-02 010405
3A1, No.1, Li-Hsin Rd. I , Science Park , Hsinchu 300, Taiwan , R.O.C.
TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw 1