Hi, Sir
How detect the high voltage in ADS1100 Differential Mode?The inquiry as below description：1. Input Voltage：-15~15V2. Just only using the resistor.3. No OP AMP4. Resolution：1mV
Look forward to your kindly reply as soon as possible.Thanks and have a nice dayAndy Lu
Hi Andy,
What is the source of the +/-15V input to the ADS1100? Is it coming from a differential output sensor or is it single ended? To due this using only resistors, you'd have to divide down your 30V signal and then level shift it to a suitable range for the ADC. The ADS1100 cannot take negative voltage inputs, so assuming you are running the part at 5V, you would have to get your +/-15V into the range of 0-5.
Regards,
Tom
Hi, Tom
Thanks for your kindly reply.The signal is the Personal Computer Power.So, the signal should be single-end source.
The ADS1100 can be take negative voltage inputs when the ADS1100 is differential mode.I use the resistor 20K and 10K to divide the voltage.But the attenuation ratio is not accurate.In the normal status, The voltage outputs is +/-5V when the signal inputs is +/-15V.In actual test, The voltage outputs is +/-5V when the signal inputs is +/-24V.
Andy Lu
Andy,
Even though the input may be designated as +/-, this does not mean that you can measure below ground. The input does measure differentially with one input relative to the other, but the actual signal must be within the range of the supply used to power the ADS1100. If you power the ADS1100 with +5V to VDD, then you can measure 5V at the input. If ground is placed at VIN- and +5V at VIN+, you will measure +5V. If +5V is connected to VIN-, and ground is connected to VIN+, then you will measure -5V. So you are measuring one input (+) relative to the other (-). If the + input is higher potential than the - input the result will be positive. If the + input is lower potential than the - input the result will be negative.
You will damage the device is you try to measure a voltage below ground by more that 300mV as it exceeds the Absolute Maximum Input Specifications. At this point the ESD protection diodes will conduct, and the excessive current will damage the device.
Best regards,
Bob B