topic Re: MC13213 STOP3 Mode current requirements in 8-bit Microcontrollers

MC13213 STOP3 Mode current requirements

Kini — Fri, 22 Feb 2008 20:55:04 GMT

Hi,

I am using MC13213 chip for one of our projects. We are using STOP3 mode with RTI enabled internal clock for the MCU sleep functionality and we put modem in hibernate mode. I am putting all the unused pins as inputs with Pull Up enable. The operating voltage is 3.0V in this case.

Now, I measured the sleep current for the above sleep functionality and i found it is every time more than 400 micro amps and varies till 615 micro amps depending on the room temperature. But when i read through the data sheet MC1321xRM it shows that the combined current can not be more than say 2 micro amps.

So please suggest me how can i achive the current as low as say 10 micro amps during the sleep mode( as said STOP3 with modem hibernate).

Regards

Atul

Re: MC13213 STOP3 Mode current requirements

RickN — Tue, 26 Feb 2008 10:17:08 GMT

Hi Atul,

In general a particular MCU may have port pins that are included as part of the MCU but are not brought out to a physical pin on the part. These are called unbonded signals, and need to be addressed when you are in low power modes. Make sure that all unused Parallel Input/Output signals are set to a known state, such as output driven low. If you do not initialize all the ports on an MCU, then they typically default to inputs that are not pulled up (FLOATING INPUTS !!) I have seen these floating inputs consume ~150uA each in Stop modes on 9S08 MCUs.

Enough for theory. Initialize ALL your ports pins to outputs and set them low, unless you are using them for something specific. Figure 1-7 in the MC1321x Reference Manual v1.1 has a few clues for you listed as Notes 1 & 3. I would check to make sure PortF and PortG pins are set to outputs driven low, if possible.

Hopefully this will help clear up some of the current measurement problems. Also remove the BDM when testing. Measure Idd as close to the MCU as possible to ensure you are measuring the current going into the MC1321x only, and not peripheral components on your board. The LVI adder is 70uA, so you may want to disable it too.

Measuring current is the best way to make sure the MCU is operating in the correct Stop mode, keep going with section 6.3.2 of the MC1321x data sheet!!!!

Thanks,

Rick

Re: MC13213 STOP3 Mode current requirements

ImranChoudhary — Tue, 14 Apr 2009 20:23:01 GMT

Hi Rick,

I'm new to the MC13213, can you share some the code or how exactly the pins have to be driven low.

I'm using the Zigbee 2006 code base from beekit.

Thanks,

Imran