I need to build a Potentiostat with CV, LSV, Amperometry functionalities. The applied potential ranges will be: ±10 mV, ±50 mV, ±100 mV, ±650 mV, ±3.276 V, ±6.553 V, ±10 V. Corresponding measured current range: ±10 pA to ±0.25 A. Can anyone please suggest whether LMP7721 is a suitable candidate for this purpose? What other components I need to look for? Any suggestion will be very helpful.
Hello Nibir,
I checked to see if TI has an application notes on potentiostat circuits and didn't find any. However, TI does offer the LMP91000 which is a configurable AFE potentiostat for low-power chemical sensing applications. You may want to have a look at this device before settling on a discrete circuit solution.
Should you prefer a discrete solution have a look at a Membrapor application note MEM1 that discusses electrochemical gas sensors. It provides a lot of good information about the gas sensors and provides basic sensor application circuits. We can certainly help you select the best performing op amps for your particular application.
www.membrapor.ch/.../Application_Note_MEM1.pdf
I am concerned that your applied potential ranges are quite high; +/-3.276 to +/-10 V. The LMP7721 is rated for a supply range of 1.8 to 5.5 V (+/-0.9 to +/-2.75 V) so it wouldn't be usable with the higher potential ranges. Also note that potentiostat sensors can appear as an extremely high capacitive load to the op amps in the circuit. That must be taken into consideration when designing the circuit to assure stability and correct circuit operation.
Regards, Thomas
Precision Amplifiers Applications Engineering
