1

This errata is applicable to the following devices:

• AT89S8252

• AT89LS8252

•AT89S53

• AT89LS53

with the following markings and needs to be used in conjunction with the correspond-

ing device datasheets.

Regarding the in-system programming procedure, ATMEL currently recommends the

following ISP waveforms for implementing the ISP programming algorithm in the

AT89S-series devices:

These waveforms should be used in addition to the serial downloading waveforms

shown in the respective device datasheets.

AT89S8252

24XX

XXXX

AT89LS8252

12XX

XXXX

AT89S53

24XX

XXXX

AT89LS53

12XX

XXXX

RST

(>2 machine cycles)

A (<1/2 machine cycle)

(>1 machine cycle)

SCK

7

6

GND

This glitch MAY occur in certain systems because when RST

goes high, port 1 pins will be driven with a strong pullup for

one clock cycle; if the glitch does occur, it can be interpreted

incorrectly as the first SCK pulse of a serial data stream.

So the falling edge of RST at point A is necessary to

“clean-up” the internal state machine.

should be powered up and stable PRIOR to the waveforms below)

CC

(V

Microcontrollers

AT89S8252

AT89LS8252

AT89S53

AT89LS53

Errata Sheet

Rev. 1486A–10/99