ADM00939: 3.5A @ 37V, 6 ~ 20V in, LED Driver

The MIC3223 is a constant-current boost switching controller specifically designed to power a string of high-power LEDs. The MIC3223 has an input voltage range from 4.5V to 20V and is ideal for a variety of applications. The MIC3223 evaluation board is designed to accommodate for a VIN of 6V to 20V.

The MIC3223 evaluation board is set to operate as a boost converter, which requires the output voltage to be greater than the input voltage. It is important to have the series LED forward voltage drops be greater than the input voltage because when the converter is off the input is connected to the output through the inductor (L1) and diode (D1). VIN is effectively applied across the LEDs and will turn on if the series sum of their forward voltage drop is not greater than VIN. For 100% dimming duty-cycle, simply pull DIM IN to 5V.

Features:

• 4.5V to 20V supply voltage

• 200mV feedback voltage with an accuracy of ±5%

• Step-up output voltage (boost) conversion up to 37V

• 1MHz switching frequency

• 100mΩ/3.5A internal power FET switch

• LEDs can be dimmed using a PWM signal

• User settable LED current (through external resistor)

• Externally programmable soft-start

Protection features that include:

• Output over-voltage protection (OVP)

• Under-voltage lockout (UVLO)

• Over temperature protection

• Junction temperature range: -40°C to +125°C

• Available in an exposed pad 16-pin TSSOP package