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9S08QG8 bandgap giving unexpected readings

Question asked by Tony Papadimitriou on Dec 13, 2007
Latest reply on Dec 14, 2007 by Tony Papadimitriou
Hi all,

I have this issue with a QG8 (actually I tried with several).  While it measures 3.287V on the chip between Vdd/Vss, reading the bandgap channel (27)  with 10-bit A/D gives 200 (decimal).  If I understand how the bandgap works, this indicates an operating voltage of 6.138 assuming typical 1.2V bandgap (Vdd=1023*1.2/ADBG)

Shouldn't I be getting a bandgap reading of about 375?

TIA


Message Edited by tonyp on 2007-12-13 02:54 PM

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