RT8560

5

DS8560-01 April 2011

www.richtek.com

Pin Number

Pin Name

Pin Function

1, 2, 3, 19, 20,

21 (Exposed Pad)

GND

and connected to GND for maximum power dissipation.

4, 5

SW

PWM boost converter switch node.

6

VCC2

Bipolar power switch base current supply. Typical beta of the power NPN

switch is approximately 70. VCC2 can be connected either to VCC1 or to a

separate lower voltage, as low as 3V, for better system efficiency and/or

heat concern. A good bypass is necessary.

7

VCC1

Power supply of the chip. For good bypass, a low ESR capacitor is required.

8

RISET

A resistor or a current from DAC on this pin programs the full LED current.

9

ACTL

Analog/Digital dimming control. When using analog dimming,

LED

ACT L

ISET

5.36k

I

= 20mA

for V

1.2V.

R

×≥

10

DCTL

By adding a 0.1uF filtering capacitor on ACTL pin, the PWM dimming signal

on DCTL pin will be averaged out and converted into analog dimming signal

on ACTL pin.

11

EN

Chip enable pin, when low chip is in shutdown mode.

12

OVP

higher than 2.5V.

13

SS

Soft start pin, a capacitor of at least 10nF is required for soft start.

14

VC

PWM boost converter loop compensation node.

18, 17, 16, 15

LED1, LED2,

LED3, LED4

Channel 1 to Channel 4 LED current sink. Leave the pin unconnected if not

used.

Functional Pin Description