# The maximum voltage that can be applied to the inputs of the comparator TLV1805Q1?

I'm creating a circuit with a comparator TLV1805-Q1.

Question: what maximum voltage can I apply to the comparator inputs and what is the maximum voltage difference between inverted and non-inverted inputs?

In the table, I found this:

I did not understand this wording.

Is it permissible for this comparator to supply 2.5 V to the inverted input and 5 V to the non-inverted (Also PWM 0-5V signal)? The voltage difference between the inputs reaches 2.5 V.

Circuit:

## 1 Answer

The inputs must remain (almost) within the supply rails.

It is permissible to supply 2.5V to one input if the positive supply rail is greater than or equal to 2.2V. If that supply rail can at any time be less than 2.2V (maybe the power rail has not yet come up to voltage) then you must include a series current-limiting resistor as described in note 2.

This is a common pitfall for young players where an input is supplied by a function generator or other separately supplied source, and the device can be destroyed as a result.

There is no limitation on the differential voltage, provided both inputs remain (almost) within the supply rails.

The above refers to what may cause damage to the device. As far as proper operation goes, this particular part is very accomodating, it will work provided the inputs are within 200mV of the supply range, so with +/-12V supply as long as both inputs are within the range of -12.2 to +12.2 it will function (it may also function with only one input outside the range, I didn't evaluate that condition).

To summarize, your circuit will work, but be careful about applying voltage to the inputs without power on the chip- if in doubt add a 2K series resistor to limit the current to 10mA maximum.

• thank you for the answer! I will install a resistor on the 5V line coming from the microcontroller. Do I need an additional resistor after the divider (5V -> 2.5V)? Or is the divider already limiting the current? – Delta Feb 14 at 9:43
• No necessity on the divider, it's equivalent to a 50K resistor. – Spehro Pefhany Feb 14 at 9:44
• Thank you for the help! – Delta Feb 15 at 11:16