OPA1688: Quiescent current

Hello, 

You are correct that the Iq specification is per channel. For this reason you would see 4mA max for the quiescent current alone on a dual device. This assumes that the device is unloaded and no excess current is flowing through the feedback path or to a load. Any additional current could be coming from driving a load on the output of the amplifier. If you share your circuit schematic and voltage potentials we can help determine if the excess current is coming from a load. 

Best Regards, 
Chris Featherstone

Hi Chris,

Thanks for your reply! Please find the schematic of OPA1688 attached for your reference.

Hello, 

Do you now how much output current you are driving into the load? Has this output current been accounted for in the total Iq? Have you checked the output to ensure there is no oscillation and the op amp is not unstable?

Best Regards, 
Chris Featherstone

Hi Chris，

The output load of the OPA1688 was disconnected, and the measured current of the OPA1688 is 5.9mA.

Hello, 

Our op amps are production tested meaning that when they leave the factory they are within spec. A few common issues that increase quiescent current are

1. Output loading
2. Instability
3. Damaged part that has experienced electrical overstress.

Is the op amp oscillating? Have you monitored the output with an oscilloscope? Have you simulated your circuit inside of Tina Ti using our methods for checking for phase margin which are outlined in our video training series Texas Instruments Precision Labs?

TIPL: https://www.ti.com/video/series/precision-labs/ti-precision-labs-op-amps.html

Free Tina Ti Download: https://www.ti.com/tool/TINA-TI

Tina Ti File for OPA1688:

5344.OPA1688.tsc

Best Regards, 
Chris Featherstone