CAT3603

Doc. No. 5017 Rev. C

8

Characteristics subject to change without notice

BLOCK DIAGRAM

Figure 2. CAT3603 Functional Block Diagram

BASIC OPERATION

At power-up, the CAT3603 starts operating in 1x mode

where the output will be approximately equal to the input

supply voltage (minus 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 falls to a level where the regulated

currents cannot be maintained, the device automa–

tically switches into 1.5x mode.

In 1.5x mode, the output is approximately equal to 1.5

times the input supply voltage (minus any internal

voltage losses), and high enough to achieve the

nominal LED current.

The above sequence is reinitialized every time the

chip is powered-up or is taken out of shutdown mode

(via EN pin).