CAT3614HV2-T2 Datasheet, PDF (9/13 Pages) ON Semiconductor – 4-Channel 1-Wire LED Driver in 3 x 3mm Package

BLOCK DIAGRAM
1µF
C_1-
C₁₊
1µF
C_2- C₂₊
CAT3614
V_IN
C_IN
1µF
EN/DIM
1x mode (LDO)
1.5x Charge Pump
V_OUT
1MHz
Oscillator
Mode Control
Reference
Voltage
Current
Setting DAC
Serial
Interface
Registers
GND
LED1
LED2
LED3
LED4
LED Channel
Current Regulators
Figure 2. 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 400µs) 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).
© 2008 SCILLC. All rights reserved.
9
Characteristics subject to change without notice
Doc. No. MD-5035, Rev. C