Complete Bias and White LED Power Supplies

for Small TFT Displays

_______________________________________________________________________________________

7

PIN

NAME

FUNCTION

11

ONBIAS

charge pumps. Connect to GND to disable the charge pumps.

12

GND

Ground. Connect to PGND and the exposed pad directly under the IC.

13

COMP

sets the soft-start time.

14

CS

Current-Sense Feedback Input. Connect a resistor from CS to GND to set the LED current. For the

15

CTRL

LED Brightness Control Input. Connect CTRL to a 0.24V to 1.65V input to set the brightness of the

external LEDs. Hold CTRL below 100mV for more than 10.5ms, to shut down the LED driver. Drive CTRL

with a 200Hz to 200kHz unfiltered PWM dimming signal for DC LED current that is proportional to the

signal’s duty cycle.

16

OUT

17

LX

Inductor Connection. Connect to the switched side of the external inductor as well as the anode of the

external diode. LX is high impedance during shutdown.

18

PGND

Power Ground. Connect to GND and the exposed pad directly under the IC.

19

C1N

Main Charge-Pump Transfer Capacitor Negative Connection 1. Connect a 2.2µF capacitor between

C1N and C1P.

20

C2N

Main Charge-Pump Transfer Capacitor Negative Connection 2. Connect a 2.2µF capacitor between

C2N and C2P.

21

IN

Power-Supply Input. Connect to a 2.7V to 5.5V input supply. Bypass IN to GND with a 4.7µF capacitor.

22

C2P

Main Charge-Pump Transfer Capacitor Positive Connection 2. Connect a 2.2µF capacitor between

C2P and C2N.

23

C1P

Main Charge-Pump Transfer Capacitor Positive Connection 1. Connect a 2.2µF capacitor between

C1P and C1N.

24

—

EP

Exposed Paddle. Connect directly to a ground plane, GND, and PGND directly under the IC.

Pin Description (continued)