TLV9002: About the Vout vs slew rate.

Kengo.Y

Guru 10625 points

Part Number: TLV9002

Hi team.

I'd like to know about the Vout vs slew rate.

Our situation is when the output voltage is decrease and the slew rate decreases.

Sincerely.

Kengo.

over 4 years ago

0 Ron Michallick over 4 years ago

TI__Guru*** 145176 points

Kengo,

Slew rate is a function of input difference voltage (IN+ - IN-). Over 100 mV is needed for full slew rate. Lower value is less slew rate. This is true of all op amps. TLV9002 has input transistors for lower common mode voltage and another pair for upper common mode; they may not be matched. Slew rate should not change with output voltage.

Can you provide data demonstrating your observation?

0 Ron Michallick over 4 years ago in reply to Ron Michallick

TI__Guru*** 145176 points

Hello Kengo,

Do you need more help resolving the slew rate question?

0 Michael Steffes over 4 years ago in reply to Ron Michallick

Guru 48395 points

Also Kengo,

Designers are often confusing the output edge rate that might be linear vs a a true slew limited result.

Hard to tell for your case without a circuit and operating conditions, but a new approximation for a 2nd order output step developed the peak dV/dT is approximately =

2.85*Vstep*F-3dB.

So yes, the apparent peak dV/dT will go down with reducing step size. If it is not hitting the available slew rate, then it not really slew limited output, but linear - Again, this may not be your situation, but a possibility

That equation is #11 in this 1st of a two part article set where I was trying to sort this out for higher speed parts. But it has direct applicability to say active filter stages using any speed range part, It provides a simple screen for required slew rate in the various active filter designs.

https://www.edn.com/design/analog/4443250/What-is-op-amp-slew-rate-in-a-slew-enhanced-world--Part-1

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TLV9002: About the Vout vs slew rate.