W-6137 Datasheet, PDF (8/16 Pages) Copal Electronics – CMOS Boost Converter

W-6137
Pin Description
VIN is the supply input for the internal logic. The device is
compatible with supply voltages down to 2.2 V and up to
5.5 V. A small bypass ceramic capacitor of 1 F is
recommended between the VIN and GND pins near the
device. The underïvoltage lockout (UVLO) circuitry will
place the device into an idle mode (not switching) whenever
the supply falls below 1.9 V.
SHDN is the shutdown logic input. When the pin voltage is
taken below 0.4 V, the device immediately enters shutdown
mode, drawing nearly zero current. At voltages greater than
1.5 V, the device becomes fully enabled and operational.
GND is the ground reference pin. This pin should be
connected directly 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 24 V. In the event of an “OpenïLed” fault
condition, the device will enter a low power mode and the
SW pin will be clamped to approximately 30 V.
FB feedback pin is regulated at 0.3 V. A resistor connected
between the FB pin and ground sets the LED current
according to the formula:
0.3 V
I_LED
R1
The lower LED cathode is connected to the FB pin.
Table 4. PIN DESCRIPTIONS
Pin #
Name
Function
1
SW
Switch pin. This is the drain of the internal power switch.
2
GND
Ground pin. Connect the pin to the ground plane.
3
FB
Feedback pin. Connect to the last LED cathode.
4
SHDN
Shutdown pin (Logic Low). Set high to enable the driver.
5
VIN
Power Supply input.
8