9S12XEP256 Stop mode power consumption

[luke_5817]

Dear Sir Or Madam,

I have a project that uses MC9S12XEP256. The system could goes to STOP mode. Based on the specification at STOP mode the MC9S12X power consumption is less than 100uA at 3.3V. However, the actual measurement is around 800uA in my system. I am pretty sure that all un-used serail interfaces, and I/Os are truned off. But few interrupts are still enabled that were used to wake up the system. The system runs at 96MHz clock.

Please help to point out where the problem is and how I can make the system to consume less power in STOP mode. Your help is really appreciated.

Best Regards,

--Luke

[GordonD]

Luke,

What package size of the XEP256 are you using? If you are using a package size smaller than the 144 LQFP, you must also configure any unbonded I/O as outputs. By default, like the bonded out I/O pins, these are inputs after reset. See Section 1.2.3, Detailed Signal Descriptions, of the MC9S12XE-Family Reference Manual , Rev. 1.23.

Regards,

Gordon

[kef]

Did you make unused pins not floating?

Did you disable pull up's that are pulling to different direction than the external circuit? Electrical characteristics state that Rpul/pdh = 25..50 kOhm. Thats 60-130uA @ 3.3V for each misconfigured pin.