High-Efficiency LCD Boost

with True Shutdown

_______________________________________________________________________________________

5

PIN

NAME

FUNCTION

FB

(MAX8570/

MAX8571/

MAX8574)

Feedback for setting the output voltage. Connect FB to the center of a resistor voltage-divider from the

output to GND to set positive output voltages.

1

OUT

(MAX8572/

MAX8573/

MAX8575)

Output. The output voltage is preset to 15V. Connect a 1µF ceramic capacitor from OUT to GND. In

shutdown, OUT is pulled to GND by an internal 7.5M

Ω resistor.

2

GND

Ground

3

SHDN

Shutdown Input. A logic low at

SHDN places the part in low-power shutdown mode. Pull SHDN high or

4LXInductor Switching Connection

5SW

Isolation Switch Output. Internally connected to the drain of a p-channel MOSFET used to isolate the

output from the input during shutdown. Connect a 4.7µF ceramic capacitor from SW to GND. If true

shutdown is not required, SW can be left open with the input supply connected directly to the inductor.

Pin Description

LOAD TRANSIENT

MAX8570/71/73/74/75 toc15

100µs/div

100mV/div

(AC-COUPLED)

5mA/div

0

STARTUP AND SHUTDOWN WAVEFORMS

MAX8570/71/73/74/75 toc16

400µs/div

5V/div

10V/div

200mA/div

1.8Ω LOAD

0

0

BOOST SOFT-START

SW TURN-ON

Typical Operating Characteristics (continued)