High Efficiency Charge Pump White LED Driver

A8435

3

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

(Top View)

Name Pin Number

Function*

C1–

13

Negative terminal of capacitor C1.

C1+

16

Positive terminal of capacitor C1.

C2–

15

Negative terminal of capacitor C2.

C2+

1

Positive terminal of capacitor C2.

CTRL

4

Brightness control scheme toggle. For 2-bit parallel or PWM dimming, leave open or tie to VIN

(see table 1). For single-wire serial input dimming, connect to GND (see figure 2).

EN1

3

When CTRL is open or HIGH: Enable and dimming control input 1 (see table 1).

When CTRL is grounded: single-wire enable and dimming control (see table 1 and figure 2).

(Do not leave unconnected.)

EN2

5

When CTRL is open or HIGH: Enable and dimming control input 2 (see table 1).

When CTRL is grounded: this pin disables shutdown. (Do not leave unconnected.)

EP

–

Exposed metal pad on bottom side. Connect this to ground plane for better thermal

performance.

GND

11

Ground.

ISET

6

Connect RSET resistor to ground to set desired constant current through LEDs.

LED1

8

Current sink for LED1. Connect to VIN or VOUT if not used for LED. (Do not leave unconnected.)

LED2

7

Current sink for LED2. Connect to VIN or VOUT if not used for LED. (Do not leave unconnected.)

LED3

10

Current sink for LED3. Always connect this pin to LED.

LED4

9

Current sink for LED4. Connect to VIN or VOUT if not used for LED. (Do not leave unconnected.)

NC

12

No Connection.

VIN

14

Power supply voltage input.

VOUT

2

Charge pump voltage source output for connection to the LED anodes.

* See Application Information section for cited figure and tables.

Terminal List Table

12

11

10

9

NC

GND

LED3

LED4

1

2

3

4

C2+

VOUT

EN1

EP

CTRL

Pin-out Diagram