12V/15V or Adjustable, High-Efficiency,

6

_______________________________________________________________________________________

LOAD–TRANSIENT RESPONSE

5µs/div

200mA

0mA

A

B

_____________________________Typical Operating Characteristics (continued)

LINE–TRANSIENT RESPONSE

5ms/div

6V

4V

A

B

NAME

FUNCTION

LBO

Low-battery output is an open-drain output that goes low when LBI is less than 1.5V.

Connect to V+ through a pull-up resistor. Leave LBO floating if not used.

LBI

Input to the internal low-battery comparator. Tie to GND or V+ if not used.

PIN

1

2

FB

Feedback input. For fixed-output bootstrapped operation, connect FB to GND. For

adjustable-output bootstrapped operation, connect a resistor divider between V+, FB and

GND. For non-bootstrapped operation, there is no fixed-output option. Connect a resistor

Modes section.

SHDN

Active-high TTL/CMOS logic-level input. In shutdown mode (SHDN = V+), the internal

switch is turned off and the output voltage equals V+ minus a diode drop (due to the DC

path from the input to the output). Tie to GND for normal operation.

REF

1.5V reference output that can source 100µA for external loads. Bypass with 0.1µF

or larger capacitor.

GND

Ground

3

4

LX

Drain of the internal N-channel FET. LX has an output resistance of 1

Ω and a peak current

limit of 1A.

V+

Power-supply input. In bootstrapped mode, V+ is also the output voltage sense input.

5

6

7

8

______________________________________________________________Pin Description