Hello,
We are experiencing unusual current draws in a circuit containing 3 ADA4898-1. Two of those are configured as unity gain buffers and one is a differential to single ended converter. The power supply is ±15 V for all the op-amps in question and the DC loads to ground are 2.4 kOhm for one of the two unity gain buffers, open circuit for the other and 400 Ohm for the converter.
If the current in the positive supply is not limited to a safe value of 250 mA, one of the two unity gain buffers gets damaged. We didn't find any parasitic oscillation in any part of the circuit. The problem appears even when the inputs are all 0 V with no AC signal applied.
With the current limited supply, we start observing fluctuations in the rails after 20 minutes of operation. No component on the board exceeds 50°C at this point. From now on the power supply keeps decreasing the voltage in the current limited state until reaching 7V after 40 minutes and then drops to 0 abruptly.
While the supply keeps dropping, if we apply a small AC signal, we see that the 3 op-amps are still providing the correct output. If we cool any of the three devices, the supply voltage increases again momentarily, letting us think the problem is thermal-related.
Can someone help us with this issue please?
Regards.
Sergio
