CAT3612 Datasheet, PDF (11/13 Pages) Catalyst Semiconductor – Programmable 300mA Camera Flash LED Driver

CAT3612
Protection Mode
If an LED becomes open−circuit, the output voltage
VOUT is internally limited to about 5.5 V. This is to prevent
the output pin from exceeding its absolute maximum rating.
The driver enters a thermal shutdown mode as soon as the
die temperature exceeds about +165°C. When the device
temperature drops down by about 20°C, the device resumes
normal operation.
External Components
The driver requires a total of four external 1 mF ceramic
capacitors: two for decoupling input and output, and two for
the charge pump. Both capacitor types X5R and X7R are
recommended for the LED driver application. In the 1.5x
charge pump mode, the input current ripple is kept very low
by design, and an input bypass capacitor of 1 mF is sufficient.
In 1x mode, the device operating in linear mode does not
introduce switching noise back onto the supply.
Recommended Layout
In 1.5x charge pump mode, the driver switches internally
at a high frequency of 1 MHz. It is recommended to
minimize trace length to all four capacitors. A ground plane
should cover the area under the driver IC as well as the
bypass capacitors. Short connection to ground on capacitors
Cin and Cout can be implemented with the use of multiple
via. A copper area matching the TDFN exposed pad (GND)
must be connected to the ground plane underneath. The use
of multiple via improves the package heat dissipation.
Figure 29. Recommended Layout
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