ADG714 off resistance

Hi ADI Expert,

I had a project to use ADG714 and needs your support. There is ADG714 schematic as blow: I expected that high resistance Giga ohm between SW1~S4 when sets as opened, Unfortunately the real results not as I expected. The datasheet showed leakage currents 0.1nA at Drain and Source off, thus off resistance equal to Giga ohm.

DMM: BRYMEM BM-817 (3-4/5 Digi 5000 counts, Ohms range: 500K/5000K 0.1% accuracy)

ADG714 supplied voltage that Vdd is 3.3V,Vss is 0V.

Therefore I did more testing as blow:

When ADG714’s SW1~S4 sets to all open and R1 to R4 setup, The resistance few hundreds Kohm between TP1 and TP2.

If closed SW1,which DMM showed 200K ohm between TP1 and TP2.

If only setups R1 200K and R2 300Kohm and removed R3 and R4 in the PCB, then closed SW1, which DMM showed the resistance around 160Kohm, not 200Kohm.

ADG714 off isolation seems not huge Gohm as I expected. 

May I have your suggestion to verify this issue, thanks. 

Best regards. 

Ray.

  • +1
    •  Analog Employees 
    on Dec 23, 2020 4:56 PM 2 months ago

    Hi Ray,

    DMMs often have difficulty measuring large resistances accurately. 

    A better way to verify the off impedance of the mux would be put a DC voltage on the source of a closed channel and then measure the voltage that appears on the drain and then use ohms law to calculate the off resistance.

    Regards,

    Stephen