TLV9004: Slew Rate and temp dependency for small signal values and comparator application

As shown in figure 7-12, the output cannot reach the rails when there is load. What is your load?

Prince

Thanks for your post. The team will provide a response when we return from holiday break on Tuesday.

What you have described does sound odd and unexpected. Clemens’s question about loading would be good to know but I’m thinking your minimum differential input (overdrive in comparator terminology) is the likely cause. 

I’m assuming that you are using a spare channel on your quad amplifier as the comparator and not intentially using all the channels that way. In general using a spare channel as a general purpose comparator is reasonable but your min overdrive input has me concerned.

Chuck

Clemens

thanks for your continued support. 

Clemens Ladisch thanks for your response, i am operating at room temp and my load current is <1mA; attached the opamp output for your reference

Please include the inputs in the oscilloscope trace.

Opamps like the TLV9004 are optimized to precisely reach a specific output voltage, even at the cost of lower speed. Consider using a comparator instead.

Both opamps used as comparators and actual comparators work better with hysteresis.

from Datasheet slew Rate is 2V/uS, this speed is good enough for me does this slew rate has other influencing factors ?

Price,

Slew rate of 2V/us needs over 350mV of input signal at the op amp's input pins. The original question was flagged as [FAQ] Why does the slew rate in my application not match the op amp’s data sheet?

From that I would expect 0.015V/us is slew rate in the application here. 3% of 0.5V/us

Ron Michallick thanks for your response,

"Slew rate of 2V/us needs over 350mV of input signal at the op amp's input pins" is it mentioned on the datasheet ? if it is mentioned through a different parameter or terminology, can you please help in finding the which parameter is it ? 

"3% of 0.5V/uS" on what basis this 3% was taken and what the reason the slew rate was stepped down to 0.5V/uS

-Prince. A

Prince,

Slew rate and over load recovery time. Is based on large signal behavior. It has been this way since the beginning of op amps. The reason is simple, for large signals it really doesn't matter how large because this is where the rate and time is fixed. Below some signal level point it is no longer fixed.

Where does 350mV, 0.5V/us, and 3% come from? From here: [APP] Ramping Up on Slew Rate and original FAQ here: [FAQ] Why does the slew rate in my application not match the op amp’s data sheet? I recommend reading one of these. 

Because slew rate is 0.015V/us versus 2V/us (1:133) then over load recovery could be (133:1) up to 113 us versus 0.85 us.