Excessive Power Consumption of AVR

[cksa]

I have a problem with my current ATMEGA48. It draws ~24mA (running off 4V) while doing nothing! I've even hooked it up on the breadboard with nothing connected other than the power supply rails. I've turned off most of the peripherals on the AVR by the PPR register and even sent the AVR to some sleep modes. They have reduced the power consumption by ~1mA (so it was drawing 25mA before). Clock speed is at 1Mhz (8Mhz internal resonator and CKDIV8).

I have no idea what is drawing so much current. I hooked up an ATMEGA32 similarly, and without turning off peripherals or shutting down, it is only drawing 5mA.

Also, I measured the impedance across the power supply rails of the AVR (AVCC and VCC hooked together), and whilst on the ATMEGA32, the impedance is in the megaohms, on the ATMEGA48, the impedance is around 187 ohms!!

Any ideas?

Thanks in advance,
Carson

[charliex]

bad chip?

[migsantiago]

Maybe one pin is burned and it is short circuiting internally the Vdd and Vss.

[saturation]

Its clearly out of spec in quiescent current so its busted.

The bigger question is why.

[xani]

My bet is static elecricity ;]

[jahonen]

All unused IO's configured as outputs and set appropriately (or if inputs, pulled up or down)? Floating CMOS-inputs tend to draw excessive currents.

Regards,
Janne