amc1304 resistor divider for measured voltage

yelsing torres

Other Parts Discussed in Thread: AMC1304M25, AMC1304M05, TIDA-00209

hi all

I need measure dc voltage from array of solar panels. this voltage is Vmin= 75V and Vmax=125V. I will use the amc1304M25 for this work.

I have read the application note SBAA215, saying that lower shunt resistor, lower offset and gain error. why in the reference design place a big resistor increasing gain error above of 10% ?. is for currents issues?, or why issue?

I plan to use a shunt resistor of 100 ohms and series resistor of 50K. this values are ok?

over 8 years ago

0 Tom Hendrick over 8 years ago

TI__Guru**** 168485 points

Hi Yelsing,

Can you tell me where the AMC1304M25 schematic above is coming from? The smaller you make the shunt resistor, the lower the gain errors will be. The application note you mentioned (SBAA215) is actually for the AMC1304M05 version, so the errors are a little worst because of the lower input voltage range. For the AMC1304M25, please take a look at app note SBAA214 - using a 100 ohm shunt, you may have ~1% error.

0 yelsing torres over 8 years ago in reply to Tom Hendrick

Intellectual 340 points

I take the schematic from ti design TIDA-00209. Is necessary divide resistor with values of megas, against increase gain error?
regards

0 Tom Hendrick over 8 years ago in reply to yelsing torres

TI__Guru**** 168485 points

Hi Yelsing,

I'm looking for the detail on how they calculated the error in TIDA-00209. There is no need for 'megas' on the resistor divider, the error is based on the bias current and shunt resistor size.

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amc1304 resistor divider for measured voltage