'Stop 2' mode current draw question 56F8300E/56F832X

BitBangerB — Fri, 08 Feb 2008 17:33:29 GMT

I am using a 56F8322 simply as a peripheral device in my design. There is little more connected to it than a signal source at the A/D and a the result of processing output using a PWM. Upon testing the STOP mode (with A/D and PWM modules disabled), my system is drawing about 90 mA. If I power-down the DSC, the rest of my system draws about 20 mA. The 56F appears to be drawing over 60 mA in STOP mode. I have thought of one bug that might be causing it that I will investigate tomorrow.

Still, I really don't know what to expect for current draw in this mode. The data sheet suggests 5 mA per power supply pin. Is that right? Looking at the same chart and interpreting it as 'current per supply pin' suggests that this thing could draw half an AMP. That is wrong. Running full throttle this part never draws more than about 160 mA.

I am not using the GPIO to source or sink anything. All unused GPIO is set to drive outputs to 0 if uninitialized. It dawned on me that I have one that should have been initialized as an input, but is an output at 0V in contention with another part trying to drive a 1. Somehow, I don't think this is the problem. Even if it is, what can I expect this part to draw in STOP mode with ADC and PWM explicitly off and no other peripherals used.

Is it 5 mA per power pin (4 Vss @ 5 mA), or total part at 5 mA? Input from anyone else who has experimented with the STOP mode and knows what to expect would be appreciated.

- B

Re: 'Stop 2' mode current draw question 56F8300E/56F832X

BitBangerB — Sat, 09 Feb 2008 04:55:14 GMT

I fixed my contention problem and saw a huge difference. Total current consumption in Stop 2 mode went from 87 mA down to 33 mA with about 12 mA attributable to the 56F8322. I can live with this, but I am still unsure if it is what I should be seeing.

- B

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'Stop 2' mode current draw question 56F8300E/56F832X

Re: 'Stop 2' mode current draw question 56F8300E/56F832X