ADA4099-1 MULTIOUTPUT CURRENT SENSE

Hi Nicola,

I do not think that you can add anymore PMOS because in doing so, you will change the current on the output of the ADA4099-1 and therefore will also change the response of VOUT (different V/A value).

What you can explore is to (1) utilize the VOUT of the application circuit and use it as the input to another circuit that will adjust the sensitivity, or (2) use a current mirror circuit but on the low side replacing the 1kohm resistor (see simplified circuit below). If you do (2) then you have to ensure that the effective resistance (Reff) on the low side is still 1kohm to maintain the 1V/A sensitivity at VOUT.  



Hope it helps.

Best Regards,
Sham

Hi Nicola,

I do not think that you can add anymore PMOS because in doing so, you will change the current on the output of the ADA4099-1 and therefore will also change the response of VOUT (different V/A value).

What you can explore is to (1) utilize the VOUT of the application circuit and use it as the input to another circuit that will adjust the sensitivity, or (2) use a current mirror circuit but on the low side replacing the 1kohm resistor (see simplified circuit below). If you do (2) then you have to ensure that the effective resistance (Reff) on the low side is still 1kohm to maintain the 1V/A sensitivity at VOUT.  



Hope it helps.

Best Regards,
Sham

Thanks for the information. Another question

What about the Common mode of the ADA4099? The application show a 70V bus voltage and 5v supply voltage for the opamp. How the opamp can survive to a such high voltage on its inputs?

Thanks

Hi Nicola,

The input protection is detailed on page 21 of the datasheet.

"The ADA4099-1 and ADA4099-2 op amps do not have clamping diodes between the inputs and can be differentially overdriven up to 80 V without damage, inducing parametric shifts, or drawing appreciable input current."

Best Regards,
Sham

Perfect. Thanks very much