LM2901AV: LM2901AVQPWR

Ramgopal Divakar

Part Number: LM2901AV
Other Parts Discussed in Thread: LM2901, LM2901B, LM339

Hello,

In the circuit below, I am unable to use D86 which was designed for reverse protecting pin 11 of U67. However under normal mode, because of the high leakage resistance of D86 we had to take it out. I have a 4.99K resistor. Does the IC have internal schottkey diodes for protecting itself?

LM2901AVQPWR

10 months ago

0 Paul Grohe 10 months ago

TI__Guru 53696 points

Hello Ramgoplal,

In short - no.

The LM2901 does NOT have a dedicated input protection structure. The new LM2901B does have a ESD diode, which helps, but you should NOT apply a negative voltage to the inputs. If negative voltages are expected as part of normal operation then external protection Must be provided,.

Please see the LM339 family application note, section 3.8:

Application Design Guidelines for LM339, LM393, TL331 Family Comparators

0 Clemens Ladisch 10 months ago

Guru 280970 points

If you can put a resistor between the diode and pin 11, then most of the clamping current will go through the external diode, and a silicon diode (like the BZX84) will be enough for protection against negative voltages.

0 Ramgopal Divakar 10 months ago in reply to Clemens Ladisch

Expert 1165 points

Thank you,

but the forward drop of the BCX84 > 0.3. Will that be okay?

0 Chi Nguyen1 10 months ago in reply to Ramgopal Divakar

TI__Genius 11701 points

Ramgoplal,

if the forward voltage is still too large, you could add a resistor divider network after the diode to divide the voltage down to be within 0.3V.

Amplifiers

Amplifiers forum

LM2901AV: LM2901AVQPWR