OPA2180: OPA2180 used as a Comparator

Steve Clauter

Part Number: OPA2180
Other Parts Discussed in Thread: TLV1805-Q1

Hello, I have a new design and would like to know if it is OK to use one of the OPA2180 Op Amps as a Comparator to drive a small MOSFET.

Thank you,

SteveC

over 5 years ago

0 Marek Lis over 5 years ago

TI__Guru 60610 points

OPA2180 includes back-to-back parasitic diodes between the input terminals that may turn on if the inputs are taken more than few hundred mV apart - this may cause erroneous tripping threshold voltage if OPA2180 is used as comparator.

0 Steve Clauter over 5 years ago in reply to Marek Lis

Prodigy 120 points

Thank you! I should have seen that, but I can put a resistor in series with the inputs so this won't be a problem.

0 Marek Lis over 5 years ago in reply to Steve Clauter

TI__Guru 60610 points

You need to place a large enough resistor to limit the max current to 10mA or less but this will still cause erroneous tripping threshold voltage by the voltage drop across the series input resistor unless the input transition signal is slow enough for the input current to stop flowing before comparator is tripped.

0 Paul Grohe over 5 years ago

TI__Guru 50016 points

Hello Steve,

FYI: We are now sampling the TLV1805-Q1 40V, R-R input and push-pull output comparator, that was specifically targeted to drive MOSFET gates (can drive high peak currents needed by the MOSFET gate capacitance).

The TLV1805-Q1 "Q1" version is sampling now, but the Commercial (non "Q1") version will be released in late December.

0 Steve Clauter over 5 years ago in reply to Paul Grohe

Prodigy 120 points

Hello Paul,

Thank you for the suggestion. The OP2180 application I have is a slow, but accurate, "Keyed-Autozero" circuit where we have a small MOSFET which does the "Keying". However we are always designing new test circuits since we design semiconductor test equipment.

I really appreciated the quick response on the forum as I have a design review on this design shortly.

Regards,

Steve

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OPA2180: OPA2180 used as a Comparator