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LT3466

Dual Full Function White LED Step-Up Converter with Built-In Schottky Diodes

Linear Technology 

LT3466

PI FU CTIO S (DD/TSSOP)

VOUT1 (Pin 1/Pin 3): Output of Converter 1. This pin is

connected to the cathode of the internal Schottky diode.

Connect an output capacitor from this pin to ground.

SW1 (Pin 2/Pin 4): Switch Pin for Converter 1. Connect the

inductor at this pin.

VIN (Pin 3/Pin 5): Input Supply Pin. Must be locally

bypassed with a 1µF, X5R or X7R type ceramic capacitor.

SW2 (Pin 4/Pin 6): Switch Pin for Converter 2. Connect the

inductor at this pin.

VOUT2 (Pin 5/Pin 7): Output of Converter 2. This pin is

connected to the cathode of the internal Schottky diode.

Connect an output capacitor from this pin to ground.

FB2 (Pin 6/Pin 10): Feedback Pin for Converter 2. The

nominal voltage at this pin is 200mV. Connect cathode of

the lowest LED and the feedback resisitor at this pin. The

LED current can be programmed by :

ILED2 ≈ (200mV/RFB2), when VCTRL2 > 1.6V

ILED2 ≈ (VCTRL2/5 • RFB2), when VCTRL2 < 1V

CTRL2 (Pin 7/Pin 11): Dimming and Shutdown Pin for

Converter 2. Connect this pin to ground to disable the

converter. As the pin voltage is ramped from 0V to 1.6V,

the LED current ramps from 0 to ILED2 (= 200mV/RFB2).

Any voltage above 1.6V does not affect the LED current.

RT (Pin 8/Pin 12): Timing Resistor to Program the Switch-

ing Frequency. The switching frequency can be pro-

grammed from 200KHz to 2MHz.

CTRL1 (Pin 9/Pin 14): Dimming and Shutdown Pin for

Converter 1. Connect this pin to ground to disable the

converter. As the pin voltage is ramped from 0V to 1.6V,

the LED current ramps from 0 to ILED1 (= 200mV/RFB1).

Any voltage above 1.6V does not affect the LED current.

FB1 (Pin 10/Pin 15): Feedback Pin for Converter 1. The

nominal voltage at this pin is 200mV. Connect cathode of

the lowest LED and the feedback resistor at this pin. The

LED current can be programmed by :

ILED1 ≈ (200mV/RFB1), when VCTRL1 > 1.6V

ILED1 ≈ (VCTRL1/5 • RFB1), when VCTRL1 < 1V

Exposed Pad (Pin 11/Pin 17): The Exposed Pad must be

soldered to the PCB system ground.

GND (NA/Pins 1, 8, 9, 16): These pins are internally fused

to the Exposed Pad (TSSOP package only). Connect these

GND pins and the Exposed Pad to the PCB system ground.

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