TL331B-Q1: Internal resistance

Alexander Mills

Prodigy 10 points

Part Number: TL331B-Q1

Tool/software:

Hi, does anyone know what the internal resistance of the TL331B-Q1 comparator is?

Thanks!

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 325440 points

What exactly do you mean with "internal resistance"?

The inputs are the bases of PNP transistors. You could compute the slope of the input bias current curves (see figures 5-8…5-10), but the input bias current specification itself is usually more useful when designing a circuit.

0 Alexander Mills over 1 year ago in reply to Clemens Ladisch

Prodigy 10 points

I'm using some high precision resistors to provide a reference voltage to 'IN+', and wanted to know if the resistance between IN+ and ground is high enough that it won't affect my reference voltage?

0 Clemens Ladisch over 1 year ago in reply to Alexander Mills

Guru 325440 points

The input bias current flows through one of your two resistors. You can compute the error from that.

0 Paul Grohe over 1 year ago in reply to Alexander Mills

TI__Guru 68376 points

As Clemens said, there is about 3-4uA current flowing OUT of the input pins towards ground. That is more useful to know than any parallel "resistance" to calculate error. Normally that current should not be an issue, but if you are using large resistors in the 100k-1M range, then that current can make a difference. See the input bias current graphs in figures 5-7 to 5-10.

Amplifiers

Amplifiers forum

TL331B-Q1: Internal resistance