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Thread: reliability and current draw from 3.6 @240mhz?

  1. #1
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    reliability and current draw from 3.6 @240mhz?

    Hey, does anyone know the current draw from changing the clock speed from stock to 240? I need really fast calculations but there is a ton of stuff attached to the arduino so im trying to be a little bit more consious about the power draw. Im running it off of a L7805 and its getting toasty, when the relays are on. I'm adding a heatsink so hopefully that will help.

  2. #2
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    Quote Originally Posted by slythy View Post
    Hey, does anyone know the current draw from changing the clock speed from stock to 240? I need really fast calculations but there is a ton of stuff attached to the arduino so im trying to be a little bit more consious about the power draw. Im running it off of a L7805 and its getting toasty, when the relays are on. I'm adding a heatsink so hopefully that will help.
    did some tests three years ago - temp are ir spot meter looking at top center of cpu while air around board is slowly heated

    at 240 mhz current was 92 ma and ok until top of chip 90 deg c
    at 256 mhz current was 99 ma and ok until top of chip 70 deg c

    i concluded that i would limit clock in outdoor summer in sun in white box to 180
    same but in shade or with sun screen 240, and indoor 256 seems ok even in
    small metal box w just very small heatsink on part

  3. #3
    Senior Member PaulStoffregen's Avatar
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    For a very quick test, I programmed a Teensy 3.6 with an empty Arduino sketch 4 times, and then measured the reading on my BK Precision 1474 lab bench power supply for each. Here's the results.

    Code:
    120 MHz         48 mA
    180 MHz         73 mA
    240 MHz         93 mA
    256 MHz         98 mA
    These measurements are approximate, probably within 2mA. Current may vary somewhat between boards, and may change with temperature.

    Using certain peripherals, like the 2nd USB port, will probably increase power consumption. The orange LED was off, but you can expect it to add about 3mA if you drive pin 13 high.

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