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| CAT3604_08 Datasheet, PDF (4/12 Pages) Catalyst Semiconductor – 4-Channel Regulated Charge Pump White LED Driver | |||
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CAT3604
BLOCK DIAGRAM
1µF
1µF
C1-
C1+ C2-
C2+
Battery
VIN
3V to 4.2V
VIN
CIN
1µF
EN
RSET
24kâ¦
RSET
CTR0
CTR1
CTR2
1x mode (LDO)
1.5x Charge Pump
VOUT
1MHz
Oscillator
1.2V Ref
Current
Setting
LED
Output
Select
Mode Control
GND
LED1
LED2
LED3
LED4
4 Current
Sink Regulators
Figure 1. CAT3604 Functional Block Diagram
COUT
1µF
20mA
BASIC OPERATION
At power-up, the CAT3604 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. The
1.5x charge pump will boost the output voltage
accordingly to achieve the nominal LED current.
The operating mode 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 control
pins (CTR0, CTR1, CTR2) does not reconfigure the
mode of operation.
Doc. No. MD-5008 Rev. J
4
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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