The Adafruit Constant Current Boost Converter for LEDs drives series or parallel LEDs up to 40V/400mA from a 3–5V input. Features include DIP-switch current control, PWM dimming, short-circuit protection, and efficient constant current output—ideal for nOOds, filaments, and backlights.
The Adafruit Constant Current Boost Converter for LEDs makes driving LEDs easy, whether they're in series or parallel - with a chip that can generate up to 40V and 400mA from 3~5V input. Unlike most of our booster chips that generate a fixed voltage (like 5V or 12V), the TPS61169increases the voltage until a set current is being drawn. That makes it excellent for LEDs, which are specified in current, not voltage. Perfect for use with ourLED nOOdsand filaments, where sometimes you need up to 12V or 24V, at 200mA or so. Also excellent when you have a bunch of 3V LEDs in series, so they add up to a high voltage, but only at 25mA or 50mA.
We've used the TPS61169in our boards with LED backlights: it's pretty common to see 5 to 7 white LEDs in series, and a 30mA current requirement. We like this chip because it has a 1.2A internal switch and automatic over-voltage protection in case the output is disconnected. You can also dim the LEDs via the PWM input pin. It's quiet, efficient, and fairly cool, with 90% efficiency. Since it's constant current, it's not good when you need a fixed and stable voltage output like 5V -for those cases, use our everyday boosters.
Note that you can get up to 40V and up to 400mA, but not at the same time. To figure out the approximate power output you can achieve, use the formula: Iout = (Vin * 1.2A * 0.9 efficiency) / Vout. So, for example, with 5V input, and approx. 12V output you can get 450mA out (the board is limited to 400mA on the switches). For a 24V nOOd, you can get about 225mA out. The current is selectable via mini DIP switches; the default is 25mA, and each switch adds 25mA/50mA/100mA/200mA for a total of 400mA.
You get one fully assembled breakout with a TPS61169 and required passive components, and a small bit of header. Give 3 to 5V DC on the IN and Ground pins or terminal block. Connect your LEDs on the output port, and you're instantly in business! Note if the output is shorted or opened, you may need to power cycle the chip to get it out of safe-shutdown mode.
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