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| MCP3425 input voltage range |
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| madwolfe:
I'm having difficulties understanding the input voltage range for the MCP3425. I'm needing to measure a 0->3.3v range. From the datasheet (description at top): --- Quote ---The on-board precision 2.048V reference voltage enables an input range of ±2.048V differentially (Δ voltage = 4.096V) --- End quote --- But also from the datasheet: --- Quote --- The differential input voltage should not exceed an absolute of (VREF/PGA) for accurate measurement, where VREF is the internal reference voltage (2.048V) and PGA is the PGA gain setting. The converter output code will saturate if the input range exceeds (VREF/PGA). --- End quote --- Where PGA is the gain (which would = 1). I feel like it should be capable of measuring the voltage correctly, or would a voltage divider be necessary? (As the output is calibrated, the accuracy of the voltage divider wouldn't be important but the stability would be, so this could be an option). Thanks |
| madwolfe:
And of course, I forgot the link to the datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/22072b.pdf |
| SiliconWizard:
As the internal reference is 2.048V and the internal PGA min gain is 1, there is no way you can measure a 0-3.3V input range without attenuating it first... You can safely apply an input up to VDD but the ADC will saturate at 2.048V. A quick suggestion would be to use an LTC2453 instead (similar specs and price). |
| madwolfe:
Brilliant, thanks for that. The LTC2453 looks like it will be good, and better than using a voltage divider. |
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