AT90S1200 rev.D errata sheet

Effect:

After power up the micro is not working. Only the XTAL is working. External reset can not change this state.
This state can only leaved by bringing VCC down to 0V.

Conditions:

This can occur, if VCC rising slow.

Explanation:

There is an application note from Atmel: AVR190
Look at page 3 section 3:
I have it tested with an AT90S1200 rev.D and its true. You must rise VCC in at least 100ms!
Otherwise the micro does absolute nothing !
Look at page 4:
In opposition to this, I found, that this time can not be increased with an external reset circuit.
Using of an external clock source have no influence too.

Work around:

• Use not the AT90S1200 rev.D.
• Use a cost expensive power supply with the desired power up timing
  (you must add power transistors, comparators, timers and watch,
  that no current from peripherals to the micro flow before power up).
• Use a micro with external reset circuit (e.g. AT89C2051 & MAX690)
• Use a micro with a right working internal power on reset (e.g. Dallas DS80C320).
• Wait for the AT90S2313 (it is planned to be avaiable on 1998).
  

Atmels answer:

See Application note AVR190.
The new AT90S2313 have solved this problem (because is not avaiable today).

Other affected devices:

AT90S8515 (reading in application note, not tested)

New:

I have tested a device AT90S1200 rev.F and this bug is no longer valid.
Be sure that you order AT90S1200 rev.F or later!

Author: Peter Dannegger

E-mail: danni@specs.de