I have selected a TS922 op-amp to use in a voltage follower configuration. The specs for the TS922 in summary are:
- Rail-to-rail input and output
- Low noise: 9 nV/√Hz
- Low distortion
- High output current: 80 mA (able to drive 32 Ω loads)
- High-speed: 4 MHz, 1 V/μs
- Operating from 2.7 to 12 V
- Low input offset voltage: 900 μV max.
- Latch-up immunity
The voltage follower configuration is:
Supply voltage is 5 V.
To test I am using a simple 10 kΩ pot arrangement (range supply voltage to GND) to apply a voltage to the input (pin 3) with a voltmeter measuring the output on pin 1.
My issue is that the TS922 output latches up to 4.7 V if the input voltage rises above 3.6 V. If the input voltage is less than 3.6 V the TS922 behaves as a voltage follower.
To try to identify why this is happening I have tried:
- placing a light load (2 kΩ resistor) from pin 1 to ground - no effect
- grounding the inputs to the other dual amp in case there was some interaction - no effect.
Is there something I am missing? Otherwise I suspect the markings on this device don't match what is inside.
I would also appreciate any advice on other op-amps which are close to the TS922. The most important specs are:
- single supply 5 V.
- rail to rail input/output.
- high output current capability > 50 mA.
I know I can search for devices, but I am hoping someone has experience with a device that works well.