CAT4134 Datasheet, PDF (7/12 Pages) Catalyst Semiconductor – 500mA Dual Channel Movie/Flash LED Driver

CAT4134
Table 4. PIN DESCRIPTION
Pin #
Name
Function
1
FLASH
Logic input, set high to select the flash mode.
2
EN
Enable control logic input (Active High).
3
PGND
Power ground reference.
4
AGND
Analog ground reference.
5
LED2
LED channel 2, connected to the LED cathode.*
6
LED1
LED channel 1, connected to the LED cathode.*
7
RFLASH
Resistor connection to set Flash mode LED current.
8
RSET
Resistor connection to set Movie mode LED current.
9
VIN
Power supply input.
10, 11
SW
Drain connection of low resistance power MOSFET.
12
OVP
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 2.8 V and up to 4.2 V. Internal
under-voltage lockout (UVLO) circuitry will automatically
prevent the device from operating whenever the supply falls
below 1.9 V. For operation up to maximum rated loads a
bypass ceramic capacitor of 10 mF 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 0.4 V, the device enters shutdown
mode, drawing nearly zero current. At pin voltages greater
than 1.4 V, 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 1.4 V,
the device transitions from Movie mode to Flash mode.
When the pin voltage is taken back below 0.4 V, 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 1.2 V, 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 18 V. 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 21 V.
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 1.2 V 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.
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