CAT3606

Doc. No. MD-5009 Rev. C

4

Characteristics subject to change without notice

BLOCK DIAGRAM

Figure 2. CAT3606 Functional Block Diagram

BASIC OPERATION

At power-up, the CAT3606 starts operation in 1x

mode. If it is able to drive the programmed LED

current, it continues in 1x mode. If the battery voltage

drops to a level where the LED current cannot be met,

the driver automatically switches into 1.5x mode, to

boost the output voltage high enough to achieve the

nominal LED current.

The above sequence is reinitialized each and every

time the chip is powered up or is taken out of

shutdown mode (via EN pin). The use of the Main and

Sub display enable pins (ENM

¯¯¯ or ENS

¯¯¯ ) does not affect

the mode of operation.

VIN

Battery

3V to 4.2V

1µF

CIN

Current

Setting

1.2V Ref

1MHz

Oscillator

Mode Control

1x mode (LDO)

1.5x Charge Pump

EN

RSET

ENM

LED1

LED2

LED3

LED4

LED5

LED6

LED Output

Select

6 Current

Sink Regulators

VOUT

20mA

C1-

C1+ C2-

C2+

1µF

1µF

1µF

24kΩ

GND

Sub

Main

ENS