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Andy Neil
02/25/12 04:59
Read: 493 times

#186189 - Datasheet
Responding to: Jesus Calvino-fraga's previous message
It would be helpful to provide a link to the Datasheet.

It's listed here:
Direct link:

In the AT89LP428/828 Datasheet, Atmel said:
6.3 Internal RC Oscillator
The AT89LP428/828 has an Internal RC oscillator (IRC) tuned to 8.0 MHz ±1.0% at 5.0V and 25°C ... The frequency of the oscillator may be adjusted within limits by changing the RC Calibration Byte stored at byte 64 of the User Signature Array. This location may be updated using the IAP interface (location 00C0H in SIG space) or by an external device programmer (UROW location 0040H). See “User Signature and Analog Configuration” on page 122.

So it should be 8.0 MHz ±1.0% at 5.0V and 25°C - if you're not getting that, under those conditions, you should contact your supplier, or FAE, or whatever.

Are you sure you haven't adjusted the calibration?

In the AT89LP428/828 Datasheet, Atmel said:
Table 23-7. Analog Configuration Definitions

Description: The RC Calibration Byte controls the frequency of the internal RC oscillator ... A copy of the factory-set calibration value is stored at location 0008H of the Atmel Signature.

Have you checked that the "current" calibration setting matches the factory-set calibration value...?

List of 5 messages in thread
at89lp828 RC oscillator frequency      Jesus Calvino-Fraga      02/25/12 00:11      
   "about" 8 MHz      Andy Neil      02/25/12 02:04      
   Datasheet      Andy Neil      02/25/12 04:59      
   sounds to me like      Erik Malund      02/25/12 07:27      
      forgot to update the datasheets      Andy Neil      02/25/12 07:59      

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