cat3649 ON Semiconductor, cat3649 Datasheet - Page 4

• Manufacturer Part Number: cat3649
• Description: Cat3649 6-channel Quad-mode Led Driver With 32 Dimming Levels & Pwm
• Manufacturer: ON Semiconductor

Basic Operation
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.
the regulated currents cannot be maintained, the device
automatically switches into 1.33x mode. In 1.33x mode, the
output voltage is approximately equal to 1.33 times the input
supply voltage (less any internal voltage losses).
At power−up, the CAT3649 starts operating in 1x mode
If the input voltage is insufficient or falls to a level where
Figure 3. Functional Block Diagram
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driver enters the 2x mode. In 1.5x mode, the output voltage
is approximately equal to 1.5 times the input supply voltage.
While in 2x mode, the output is approximately equal to 2
times the input supply voltage.
drive all LED currents in 1x mode, it will change
automatically back to 1x mode. This only applies for
changing back to the 1x mode. The difference between the
input voltage when exiting 1x mode and returning to 1x
mode is called the 1x mode transition hysteresis (V
is about 300 mV.
This sequence repeats in the 1.33x and 1.5x mode until the
If the device detects a sufficient input voltage is present to
HYS
) and