CAT4134_08 Datasheet, PDF (7/13 Pages) Catalyst Semiconductor – 500mA Dual Channel Movie/Flash LED Driver

CAT4134
PIN DESCRIPTION
Pin #
1
2
3
4
5
6
7
8
9
10,11
12
Name
FLASH
EN
PGND
AGND
LED2
LED1
RFLASH
RSET
VIN
SW
OVP
Function
Logic input, set high to select the flash mode.
Enable control logic input (Active High).
Power ground reference.
Analog ground reference.
LED channel 2, connected to the LED cathode.*
LED channel 1, connected to the LED cathode.*
Resistor connection to set Flash mode LED current.
Resistor connection to set Movie mode LED current.
Power supply input.
Drain connection of low resistance power MOSFET.
Over Voltage Protection comparator input
* LED1 or LED2 pin should not be left floating.
PIN FUNCTION
VIN is the supply voltage input. The device is
compatible with supply voltages down to 2.8V and up to
4.2V. Internal under-voltage lockout (UVLO) circuitry
will automatically prevent the device from operating
whenever the supply falls below 1.9V. For operation up
to maximum rated loads a bypass ceramic capacitor of
10µF is recommended between the VIN and GND pins
near the device.
EN is the enable logic input (active high). When the pin
voltage is taken below 0.4V, the device enters
shutdown mode, drawing nearly zero current. At pin
voltages greater than 1.4V, the device is fully enabled.
FLASH is the logic input (active high) used to control
Flash mode operation. When the pin voltage is taken
above 1.4V, the device transitions from Movie mode to
Flash mode. When the pin voltage is taken back below
0.4V, the device returns back to Movie mode operation.
RSET, RFLASH pins allow to set the LED current
respectively in Movie and Flash mode. These pins,
regulated at 1.2V, must be connected to a pull-down
resistor tied to ground. The LED current is a function of
the resistor value.
GND is the ground reference for the driver. The pin
must be connected to the ground plane on the PCB.
SW pin is the drain terminal of the internal low
resistance power switch. The inductor and the Schottky
diode anode should be connected to the SW pin.
Traces going to the SW pin should be as short as
possible with minimum loop area. This pin contains
over-voltage circuitry which becomes active above 18V.
In the event of an “open-LED” fault condition, the
device will enter a low power mode and the SW pin will
be clamped to approximately 21V.
LED1, LED2 provide the internal regulated current for
each of the LED cathodes. These pins enter a high
impedance zero current state whenever the device is
placed in shutdown mode. In applications with only one
string of LEDs, the two LED pins should be tied
together. LED pins should not be left floating.
OVP is the overvoltage protection input pin. When the
pin voltage exceeds the 1.2V overvoltage threshold
(V_OVP), the driver stops switching. The output VOUT
then drops down. As soon as the OVP pin voltage falls
under the V_OVP threshold, the part starts switching
again.
TAB is the exposed pad underneath the package. For
best thermal performance, the tab should be soldered
to the PCB and connected to the ground plane.
© Catalyst Semiconductor, Inc.
7
Characteristics subject to change without notice.
Doc. No. MD-5021 Rev. B