How to reduce circuit current consumption

[paddy_p]

Hi,

I am using XTR 117 for two wire transmitter design. Please refer attached schematic.

Everything working fine except current consumption of the circuit. The total current consumed by circuit is around 7mA. Because of that I am not able to achieve the 4mA output.

I have implemented same schematic couple of months back and the results was good at that time. The current consumption was less than 3 mA.

The only difference is, earlier I have used DIP components for prototype and now used all SMD components.

Please have a look on schematic and bill of material and suggest what I need to do to reduce the current consumption of the circuit.

Thanks,

paddy

 

[KlausST]

Hi,

R8, R25 --> 10k
This is the most important.

Why did you parallel each three voltage references?
You don't need two positive and two negative references.
Place a C to those ref inputs (+) of the opamps for less noise and more stability.

Good luck

 

[Audioguru]

The ICs have a range of operating current. some will use a low current and some will use a higher current.
You can buy hundreds of ICs, measure their operating currents then use only the ones with low current.

 

[paddy_p]

Thanks for your prompt reply.

The excessive current consumption is due to capacitors C9 to C12 which are connected at the output of the op amp. Now removed that capacitors and the consumption is below 3 mA.

Thanks again for your help!!!!

Regards,
Paddy

 

[Audioguru]

The excessive current consumption is due to capacitors C9 to C12 which are connected at the output of the op amp. Now removed that capacitors and the consumption is below 3 mA.

These capacitors might cause the opamps to oscillate and should not be there.
Also, R15, R19, R23 and R32 at the outputs of the opamps to ground are not needed and draw extra current.