AD5941
Recommended for New Designs
The AD5940 and AD5941 are high precision, low power analog front ends (AFEs) designed for portable applications that require high precision, electrochemical...
Datasheet
AD5941 on Analog.com
AD8694
Production
The AD8691, AD8692, and AD8694 are low cost, single, dual, and quad rail-to-rail output, single-supply amplifiers featuring low offset and input voltages...
Datasheet
AD8694 on Analog.com
Hi, I'm using the CN0510 to measure a single 18650 lithium battery.
For some purpose, I need to amplify the sense current to 2A maximum from the Darlington pair of CN0510.
The schematic of CN0510 is here:
After I replace the emitter resister which is named R21 in the schematic, and the value is 62Ohm, into 4.8Ohm,
the current flow out from the battery increase from 23.835mA(mean) and 11.062mA(peak-peak) to 269.86mA(mean) and 133.81mA(peak-peak).
This is the same as circuit simulation.
The actual waveform is like below, and the channel configuration is in the picture,
R21=61Ohm waveform
R21=4.8Ohm waveform
It seems good but after I open the terminal such as Putty, the result from CN0510 gets strange.
When I use 62Ohm as R21, the impedance of measurement is like the lithium battery impedance theory as below:
But after the 4.8Ohm resistor installed, the result is distortion:
I'm wondering if the current is too large so the input stage of AD5941 gets over the range.
So I measured the AIN2 pin and AIN3 pin after AD8694, the voltage is like below:
CH1: AIN2
CH2: AIN3
Is this value over the range of the AD5941 input stage?
Or there is something I missed, so I can get the right value of EIS of lithium battery?
Thanks for your apply, hope you have a nice day 
Hi, thanks for your reply.
I want to know is there any information about the voltage threshold of AIN2 and AIN3?
Is the datasheet mentions it?
I try to increase the current into 2A by replacing R21 with 0.6Ohm, and the AIN2 and AIN3 pin voltage seem like below:
As you can see, the instrument amplifier amplifies the battery voltage (or RCAL voltage when the device is in the calibrating process).
Those two signals had already been distorted (or saturate?), so I know the measurement result is not acceptable.
But in the previous post, the waveform of AIN2 and AIN3 haven't been distorted, they still are sine waves, but the measurement results are not correct, too.
I need to know the voltage threshold to design the ratio of the instrument amplifier to match my large disturbance current.
Is there any information?
P.s: I had already check out the HSTIA chapter of the datasheet, but I can't understand is there any relationship between High-Speed TIA and ADC?
