Tool/software:
Dear Texas Instruments Team,
I have been using the LM101AH in one of my circuit designs, and unfortunately, it failed during operation under load after running for several hours. I will attach the schematic and connection details for your review.
Could you kindly analyze the circuit and provide your feedback or any recommendations for improvement? Your expertise and guidance would be greatly appreciated.
Thank you in advance for your support.
Hi Gangula,
Could you kindly analyze the circuit and provide your feedback or any recommendations for improvement?
I converted your schematic to the simulation using LM301A op amp, which is similar to LM101A-N. The op amp is configured as comparator. I do not know where the part is failed, but I can see that you can make some improvement.
1. You should have limited the input current somewhat to either Vin+ and Vin- nodes, though the abs. max. current rating is not specified.
2. The input common mode ranges are from +15V/-13V for ±15V supply rails, your configuration is up to 27Vdc at the each pin. So this is considered as EIPD conditions.
LM301 Comparator Simulation 05292025.TSC
Please let me where the part is failed - you may be able to figure it out by comparing the input conductivity in Resistance or diode mode. My guess is that your input may be shorted or open. So failed short is likely the scenario.
Here is the comparator reference, may be you should also check for the hysteresis behavior of the circuit.
https://www.ti.com/lit/an/sboa219b/sboa219b.pdf?ts=1748500524453
If you have other questions, please let me know.
Best,
Raymond
Hi Gangula,
This circuit will works perfectly in static conditions, when it connected to a generator (27V)
I do not know what does the statement means. You'd need to provide better description what is going on during operation. In a static state, it may be working ok, but not during operational or transient states.
This reference voltage sets to 2.4V ( current of ~32A), when it increased the reverse current of 32A , the op-amp state changes and the contactor (K1) will be open to break the battery and the 27V path.
I inserted 1kohm at input to limit the input current to the comparator (may need to be higher). Please tell me the following.
1. What are the voltage readings across Vin+ and Vin- in static, operational and transient state.
2. Is this generator detection circuit? Is there inductive load at the input of the comparator? If input has inductive load or inductive element, where Ldi/dt transient event during K1 On/Off could cause huge voltage surge/spike that damage the input of comparator.
This circuit will works perfectly in static conditions, when it connected to a generator (27V) and the battery the op-amp LM101AH failed twice after ~ 40hrs (On & OFF 15 times) run. We observed that the op-amp input sensitivity failed.
If the op amp's input has inductive load and current is as high as 32A, then Ldi/dt events may be the root cause of the damage input. You need to find a way to clamp the voltage spike and protect LM101AH. This is also considered as EIPD events. Please tell me more about the load and transient conditions.
Best,
Raymond
