Datasheet CAT4201 (ON Semiconductor) - 7

CAT4201 Table 6. PIN DESCRIPTION Pin Name Function
1 CTRL Analog dimming control and shutdown pin. 2 GND Ground reference. 3 RSET RSET pin. A resistor connected between the pin and ground sets the average LED current. 4 SW Interface to the inductor. 5 VBAT Supply voltage for the device.
Pin Function VBAT
is the supply input to the device. Typical current that the CTRL pin voltage be derived from the LED cathode conduction into this pin is less than 1 mA and voltage terminal. transients of up to 40 V can be applied. To ensure accurate
GND
is the ground reference pin. This pin should be LED current regulation, the VBAT voltage should be 3 V connected directly to the ground plane on the PCB. higher than the total forward voltage of the LED string. A
SW
pin is the drain terminal of the internal low resistance bypass capacitor of 4.7 mF or larger is recommended high−voltage power MOSFET. The inductor and the between VBAT and GND. Schottky diode anode should be connected to the SW pin.
CTRL
is the analog dimming and control input. An internal Voltages of up to 40 V can be safely handled on the SW pin. pull−down current of 20 mA allows the LEDs to shutdown Traces going to the SW pin should be as short as possible if CTRL is left floating. Voltages of up to 40 V can be safely with minimum loop area. The device can handle safely handled by the CTRL input pin. “open−LED” or “shorted−LED” fault conditions. When the CTRL voltage is less than 0.9 V (typ), the LEDs
RSET
pin is regulated at 1.2 V. A resistor connected will shutdown to zero current. When the CTRL voltage is between the RSET pin and ground sets the LED full−scale greater than about 2.6 V, full scale brightness is applied to the brightness current. The external resistance value and the LED output. At voltages of less than around 2.6 V, the LED CTRL pin voltage determine the LED current during analog current is progressively dimmed until shutdown. dimming. The RSET pin must not be left floating. The For lamp replacement applications, or applications where highest recommended resistor value between RSET and operation in dropout mode is expected, it is recommended ground is 90 kW.
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