"Real" Vcc range for AT90S1200-12 ???

Go To Last Post
6 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hello Folks,

this weekend I succeded in building myself a Fuse-Bit-Programmer for the AT90S1200. I have only seriell programmer hardware (which works fine for me) so I was not able to set the fuse bits in the 1200 which can only be set in parallel mode. Anyway, I used a second AVR and built myself a board with a socket where I can put the 1200 in and set the RCEN bit so that it runs on the internal RC oscillator. (Atmel Folks: The description of the parallel fuse-bit-setting in the data sheet is correct but not easy understand. A bit more explaining would have saved some of my weekends sparetime.)

My 1200's are usually used for simple PLL programming jobs in amateur radio equipment so timing is not critical.

But lets get to the point: From my vendor I can only get 1200-12 that have a guaranteed speed of 12MHz and a Vcc range of 4-6 Volts. Since it runs on the 1MHz internal clock I assume that I can use lower voltages as well since the 1200-4 works down to 2.7Volts. My guess is that the chip is the same but the 1200-12 has passed a 12MHz check. Since you need the higher voltage for the higher speed I assume Atmel simply rates them for 4-6 Volts if they guarantee the 12MHz.

The idea is to use the 1200-12 in battery powered devices with 3 cells, i.e. at supply voltages of 3.3 - 4.5 Volts without a voltage regulator.

Does anyone know if the chip is the same? If not what is the difference? Any commends from a practical point of view (do you think it will work at lower voltages)?

Have fun everyone,
Herbert

admin's test signature
 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi Herbert,

The bottom line is: The device hasn't been tested for anything but what's stated. Thus, if you operate your device out of spec, you liberate Atmel of all our responsibilities concerning the correct operation of the MCU. And what would be the fun in that? ;)

As some of you may have noticed, the test limits have been narrowed throughout the years, especially on the AT90S1200. This is due to more rigorous QA.

Best regards,

Morten, AVR tech. support, Atmel FAE

admin's test signature
 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Well, maybe there is the need now for a avr based "tester" that can run the chip at a programmable clock speed and voltage, and do something to it every so often to see if it is ok at that voltage/clock or not.

I'm sure we could all come up with our own specs for the testing, but it would be nice to hear what the chips must endure at atmel exactly to get various ratings

admin's test signature
 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

hi

in a past preoject im have the same question\trouble

im find tha for some unknot reasont old version of -12pc

dont like low volatage at all it beging to operate radomly

but new chip like 98 end up work verry well end in dont

have any return

but in strongly sujest to use the corect chip

but due tu lead time if you ave choise of lost a costomer

or use -12 chip .........

marc lalonde
alphatronic

MLalonde C.I.D
IPC Certified PCB Designer
WWW.Alphatronique.COM

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi all,

For specifics, I must ask you to address the QR department, as I haven't got these data.

Best regards,

Morten, AVR tech. support, Atmel FAE

admin's test signature
 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I suspect that the higher speed/voltage AVRs have ALREADY flunked the test for lower speed/voltage. I say this because the LOWER speed/voltage devices sell for slightly MORE money (at least in small quantities). This is sorta like the resistor game. (Don't look for any 5% resistors in your pile of 10% resistors, because the 5% dudes have already been culled after testing.)
Nick

admin's test signature