Other Parts Discussed in Thread: LM293
Hi,
my customer is using LM239 with single 12V supply. There will be inevitable -6.25V pulse(less than 50ms) at the negative input IN-, IN+ is always 3.4V.
They observed that -6.25V pulse is clamped to -0.6V at IN- pin, and in the datasheet the absolute maximum input at Vin- is -0.3V to 36V.
The question is:
1. what internal circuit clamps IN- to -0.6V?
2. Is it possible that they use an external diode that clamps Vin- above -0.3V? What kind of diode is recommended?
3. If it's not possible to clamp Vin- through external diode. Are there any suggestion to handle the -6.25V pulse at IN-?
If we use dual supply, the output low will be the same level as the negative supply, for example -12V, it's not acceptable for the subsequent circuit.