WS2812B Reducing Power Consumption.




Introduction: WS2812B Reducing Power Consumption.

The drivers on WS2812B addressable neopixels are drawing current even when the neopixels are off, set to color 0 (no neopixels elements lit).
Under 1 milliamp per pixel, but with lots of pixels this could add up. It's also not so much compared to the current when they're active but certainly a major concern for a battery powered device.

Step 1: WS2812B Reducing Power Consumption.

I use the circuit in my Rainbow Word Clock. It contains 168 neopixels and I measure 169 mA to the neopixels when they are all out. The neopixels are turned on by a radar sensor. As long as someone is around, the clock is on. Assuming that the clock is off 12 hours a day, total shutdown then saves: 5 (Volt power supply) * 169/1000 (Miliampere / 1000 = Ampere) * 12 (Number of hours per day) * 365 (Number of days in a year) = 3701 Watt hours. So on an annual basis 3.7 Kwh.

I agree, it's not much in itself, but many small ones make a big one.

The circuit is simple. The plus of the power supply is switched by a P-channel MosFet. I have put two MosFet parrelel to keep the ON resistance as low as possible due to loss of the MosFets. In normal use I measure 4.5 mili volts over the MosFets. The gate is controlled by an output from the Arduino via a 470 ohm resistor. If the output goes to low (0) digitally, the neopixels are on and at a high (1) they are off.

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    1 year ago on Step 1

    470 Kohm resistor betwen arduino pin and gate is a huge mistake. Voltage level on gate is to small. You can drive mosfet dirrectly in this circuit.
    But for protection if mosfet die to protect arduino pin you can use 270 ohm resistor.
    Resistor betwen gate and source is used for protection gate pull down only/ And usual it is about 1 - 10 Mohm


    Reply 1 year ago

    Thanks for the good comment.
    The value indicated in the schematic between arduino pin and gate should indeed not be 470 Kohm but 470 Ohm.