Timeline for Battery Voltage Sensing Circuit (Voltage divider, buffer)
Current License: CC BY-SA 3.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 24, 2014 at 13:28 | comment | added | Andy aka | @emfields I know what was asked. My suggestion of 15 volt is to hint to him to be sure that 13 volts is the highest voltage. For an arduino I believe 10k is the highest recommended source impedance. | |
| Jun 24, 2014 at 11:40 | comment | added | EM Fields | @Andy: The OP asked for 5V out with 13V in, and for that he'd need a divider with 8K on top for 5K on the bottom. The problem with running that junction into the ADC circuitry is that the 5K will appear in parallel with the ADC stuff, changing the divider ratio and lowering the input voltage to the ADC, creating an error. Finally, with the divider output sitting at around 5V and a unity-gain buffer powered by 13V, there'd be no need for the opamp to have RR inputs or outputs, the input being well within the common-mode range of most opamps, and the output not even close to the rails. | |
| Jun 23, 2014 at 21:31 | comment | added | Andy aka | @sherrellbc because of the sample and hold capacitor and the multiplexer. | |
| Jun 23, 2014 at 20:06 | comment | added | sherrellbc | I've never read of that 10k output resistance (of the circuit being measured) on an ADC before; why is this constraint imposed on the ADC input? Does it have to do with the ADC input resistance and the measured circuits output resistance forming some sort of a divider? | |
| Jun 23, 2014 at 19:52 | history | answered | Andy aka | CC BY-SA 3.0 |