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Hello,
I am using Analog Devices ADuC836 micro-controller. As per my application total current consumption of all module of micro-controller must not exceed 2.5 mA. I am using inbuilt 16 bi Delta Sigma ADC, 12 bit DAC, external refernce (2.5V) for ADC, Clock frequency approx. 3MHz.
I've gone through the datasheet, but didn't found anything how to lower power consumption... Uunused pins should be connected thus (pullup / pulldown / floating / configure as input or out put).....
Can anyone point me to an application note or other info that could help? If I don't find any more info I'll simply connect the unused pins to ground...
Thanks.
I don't know your device - but I would say, turn off all unnecessary clocks, peripherals, etc.
Thanks for prompt response.
But what to do with unused port pins...(pullup/pulldown/floating)?
It is generally a good practice to prevent pins from floating, but I don't think it has anything to do with power consumption.
Do you mean state (pull up/down or floating) of port pin doesn't effect the power consumption?
I don't think the state matters. If you drive a LED via a pin, you can expect impact on power consumption.
I am not driving LED or ... with port pins. Micro Controller i used has 52 pins, out of them approx. 15 pins are unused. Question is that, WHAT TO DO WITH UNUSED PINS to reduce power consumption ???
"Question is that, WHAT TO DO WITH UNUSED PINS to reduce power consumption ???"
Depends what purpose the individual pins have and what the can be configured to be.
If they can be configured as an open collector output, then that would normally be best.
If they are only usable as inputs, then you might need to put a high value pull up resistor on.
Then, as Tamir suggested, if a pin is connected to an unused on-chip peripheral then that on-chip peripheral should be switched off.
The answer is - Go through each in turn, find out what it can do and select the lowest power option.
Just set signals as inputs with internal pull-down or pull-up to keep the signals in known state.
If you ground them, you'll get a fight if your program happens to set them as outputs and try to drive them high. And if grounded on the outside, you can't use them as debug pins and use a scope or other device to check timings etc.
To minimize power consumption: traditional port pins (Quasi-bidirectional) should be left in the reset state (high) non-traditional port pins should if possible be configured open collector and written low if not possible port pins should be configured Quasi-bidirectional and left in the reset state (high)
also, have you considered sleep mode
Erik