1.2A White LED Regulating Charge Pump for

Camera Flashes and Movie Lights

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5

Pin Description

PIN

NAME

FUNCTION

1

EN1

Control Logic Input (see Table 1)

2CP

CP to CN.

3CN

CP to CN.

4

EN2

Control Logic Input (see Table 1)

5

GND

Ground

6IN

Input Supply Voltage. Connect IN to a battery or supply voltage from 2.7V to 5.5V. Connect a 4.7µF

ceramic capacitor from IN to GND.

7CS

Current-Sense Input. Connect a current-sense resistor from OUT to CS to set the output current.

Connect the anodes of the LEDs to CS and the cathodes to GND.

8

OUT

Output. Connect a 10µF ceramic capacitor from OUT to GND. In shutdown, OUT is pulled to GND

with an internal 5k

Ω resistor.

—EP

Exposed Pad. Connect the exposed pad to GND directly under the IC.

Table 1. Enable, Dimming, Voltage Mode, and Overvoltage Protection

VOLTAGE MODE

OVP

EN1

EN2

DIMMING LEVEL

CS THRESHOLD

MAX1577Z

MAX1577Y

MAX1577Z

MAX1577Y

00

Shutdown

—

—

—

—

—

01

20% Current

60mV

5.10V

3.40V

5.30V

5.15V

10

33% Current

100mV

5.10V

4.60V

5.30V

5.17V

11

100% Current

300mV

5.10V

5.10V

5.30V

5.30V