Author Topic: Is there a resistor value limit ?  (Read 10849 times)

Arnulfo Gonzalez

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Is there a resistor value limit ?
« on: June 09, 2003, 11:32:13 AM »
I am planning to read current (transducer output is 0 to +/- 1mA) with ADC input 1. According to ohm?s law i need a 2.5 K resistor to get 5 Volts. Is there a limit on the value of the resistor to connect in parallel with ADC1 ? ???
« Last Edit: December 31, 1969, 04:00:00 PM by 1076562000 »

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Re: Is there a resistor value limit ?
« Reply #1 on: June 11, 2003, 07:47:58 PM »
If you connect a higher resistor the voltage will become higher (up to the limit of the voltage of the current power supply). However, the ADC input employ series resistors and diode clamp to clamp the input voltage to no more than 0.7V + AVcc. So the maximum voltage that the ADC input will see is about 5.7V. That will drive the ADC to saturation and the value read will be 4092.
« Last Edit: December 31, 1969, 04:00:00 PM by 1076562000 »
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