CAT3614 Datasheet, PDF (9/12 Pages) Catalyst Semiconductor – 4-Channel 1-Wire LED Driver in 3x3mm Package

Block Diagram
CAT3614
1 mF
C_1− C₁₊
1 mF
C_2− C₂₊
V_IN
C_IN
1 mF
EN/DIM
1x mode (LDO)
1.5x Charge Pump
V_OUT
Serial
Interface
1 MHz
Oscillator
Reference
Voltage
Current
Setting DAC
Mode Control
Registers
LED1
LED2
LED3
LED4
LED Channel
Current Regulators
GND
Figure 27. CAT3614 Functional Block Diagram
Basic Operation
At power−up, the CAT3614 starts operating in 1x mode
where the output will be approximately equal to the input
supply voltage (less any internal voltage losses). If the
output voltage is sufficient to regulate all LED currents the
device remains in 1x operating mode.
If the input voltage is insufficient or falls to a level where
the regulated currents cannot be maintained, the device
automatically switches (after a fixed delay of 400 ms) into
1.5x mode.
In 1.5x mode, the output is approximately equal to 1.5
times the input supply voltage (less any internal voltage
losses).
The above sequence is repeated each and every time the
chip is powered−up or is taken out of shutdown mode (via
EN/DIM pin).
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