Thursday, August 4, 2016

Seriously optimizing power consumption on a STM8F103F3P6 "minimum system board"

You know, these things, they're all over EBay

Anyway, when running off 3.3v (not using the USB connector) and putting them into the lowest power mode I could find (ACTIVE-HALT using the AWU to wake it up once a second) I was still seeing several milliamps power consumption; was expecting a hundred microamps or thereabouts;

To achieve this;
a) (Obviously) Remove the "PWR" led (or take off the resistor on the underside) to save a few mA
b) Remove the 3.3v regulator(!!) this was the main problem; was leaking about 2.2mA when back-powered with 3.3v

Down to about 178uA now (with internal main voltage regulator (MVR) on) running off internal LSI clock, which is nicely just under the datasheet's quoted 200uA.

With the MVR off in halt and the flash powered down (and again waiting up with AWU at 1hz to do practically nothing), i.e.
FLASH_SetLowPowerMode(FLASH_LPMODE_POWERDOWN);
CLK_SlowActiveHaltWakeUpCmd(ENABLE);

we're down to 38uA!!! Sweeeet!



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