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SD16_A of MSP430F2013
Posted: Thu Nov 27, 2008 12:40 am
by kuber
Hi to All,
Can you help me. We are working with msp430f2013 series on that am using SD16, but am facing one problem with that waht ever dig value am giving its not equal to or nearly equal to m input analog voltage. What may be the problem can help us?
Posted: Tue Mar 10, 2009 3:58 pm
by engrforever
Kuber,
I am having similar problems on an MSP430FE427 board, how did you resolve your issue?
Posted: Wed Mar 11, 2009 6:36 am
by gm
Kuber,
IIRC, the specs of the SD16 on the '2013 indicate that if you are within 20% of the rails, the linearity suffers. In other words, you can use only the middle 60% of the voltage range between -Vref and +Vref.
Also, are you using the recommended capacitors on the reference supplies?
HTH,
gm
Posted: Wed Mar 11, 2009 8:50 am
by engrforever
gm wrote:Kuber,
IIRC, the specs of the SD16 on the '2013 indicate that if you are within 20% of the rails, the linearity suffers. In other words, you can use only the middle 60% of the voltage range between -Vref and +Vref.
gm,
Wha tis IIRC? I was looking at the MSP430FE427 documentation and could not find anything similar.
Thank you for your time!
Posted: Wed Mar 11, 2009 9:49 am
by gm
I looked at the specs on the '427 and there is a note regarding the range at the bottom of page 28 of the current data sheet:
2. The analog input range depends on the reference voltage applied to VREF. If VREF is sourced externally, the full-scale range
is defined by VFSR+ = +(VREF/2)/GAIN and VFSR− = −(VREF/2)/GAIN. The analog input range should not exceed 80% of
VFSR+ or VFSR−.
I mentioned this to a TI Rep at one of the MSP430 meetings and he said it was due to the protection diodes on the inputs.
gm
P.S. - IIRC means "If I recall correctly"