AP1601

STEP-UP DC/DC CONVERTER

AP1601 Rev. 5

3 of 12

SEPTEMBER 2009

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Pin Descriptions

Pin Name

Description

FB

Use a resistor network to set the output voltage from +2.0V to +5.5V.

LBI

Low-Battery Comparator Input. Internally set to trip at +1.30V.

LBO

Open-Drain Low-Battery Comparator Output. Connect LBO to OUT through a 100k

Ω resistor.

REF

1.2V Reference Voltage. Bypass with a 0.1

μF capacitor.

OUT

Power Output. OUT provides bootstrap power to the IC.

LX

N-Channel and P-Channel Power MOSFET Drain

GND

Ground

SHDN

shutdown mode. Connect to OUT for normal operation.

CLSEL

Current-Limit Select Input. CLSEL = OUT sets the current limit to 0.8A. CLSEL = GND sets the

current limit to 0.4A.

BATT

Battery Input and Damping Switch Connection. If damping switch is unused, leave BATT

unconnected.

Functional Block Diagram

S

Q

R

F/F

TRIG

One-Shot

Q

One-Shot

Q

TRIG

Maximum

On-Time

One-Shot

Error

Amplifier

Current-Limit

Amplifier

Low-Battery

Comparator

Reference

Zero

Crossing

Amplifier

Minimum

Off-Time

One-Shot

LBO

LBI

Damping

Switch

OUT

LX

GND

BATT

FB

REF

0.1uF

22uH

R1

200

R5

R6

0.1uF

47uF

47uF

SHDN

CLSEL

V

OUT

R2

100k

V

IN

R3

R4

P

N

V

IN

EN

Ω