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[FAQ] ADS7138: ADS7xx8 and ADS7xx8-Q1 product family input bias / leakage currents

Part Number: ADS7138
Other Parts Discussed in Thread: ADS7128

Hello,

I have an application with an unbuffered higher impedance source directly connected to the ADS7138 and ADS7128 devices.  What should I expect for the input bias current/ leakage currents into the pin?

  • Hello,

    The maximum input leakage current of the analog inputs when not converting is roughly 1uA across the full temperature range.  This current will be less at 25C, likely in the 10's of nA range. 

    The other, likely more significant effects on driving the device without a low impedance source will be the charge required during the acquisition period of the conversion process.  For more information there's a great video linked here about all of the effects and design considerations when driving these devices without an input buffer:  https://training.ti.com/ti-precision-labs-driving-sar-without-amplifiers