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  • Author Author: scottiebabe
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E14 Op-amp Kit - First Power Up

scottiebabe

I am happy to report both Renesas op-amps made it safe and sound onto a breadboard. Additionally, I am even more thrilled that the 61 MHz bandwidth op-amp doesn’t breakout into oscillation when used in a breadboard.

Both op-amps I received in my op-amp-a-palooza kit are modern surface mount devices. Fortunately, I have a bag of little breakout boards on hand. So, the first step in experimenting with these op-amps was to mount them onto an SMD to DIP breakout board.

image (ISL28291 in an SOIC-8 package)

image (ISL28213 in an MSOP-8 package)

On the underside of the breakout board, I added a 10 uF 16V MLCC bypass capacitor for my best chance of success using these amplifiers on a breadboard.

image

I didn't take a photo, but I also added a 30 AWG mod wire from the capacitor to the appropriate power pin.

I then wired up the two op-amps on my breadboard as unity gain buffers. I used my MP750668 function generator as a signal source. 

 image

image

Renesas ISL28213

A nice little general purpose CMOS input op-amp with the following bannerline specifications:

image

Small signal step response of the op-amp shows minimal overshoot (good phase margin):

image

Also, the small signal step response shows good agreement with the spice model provided on Renesas’s website.

image

The large signal step response and slew rate:

image

Renesas ISL28291

Is a nice little precision, low noise, modestly fast op-amp with the following high level specifications:

image

Here is the small signal step response (not bad for a circuit on a breadboard):

image

The spice model of the ISL28291 look reasonable similar to what I measured on a breadboard, I think that is a win!

image

image

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Summary

Both Renesas op-amps are unity-gain stable:

  • In a breadboard
  • With a 10x scope probe on the output (~20 pF)
  • With a 1x scope probe on the output (~120 pF)
  • Modest feedback resistance of 100 kOhms

The noise seen in the scope shots are the results of a rats nest of hookup wires and probes and not the op-amps themselves.

The ISL28291 is a fast op-amp, but not too fast for its own good Slight smile.

Parents

  • Good update.

    Takes me back a few decades when we were learning about Op Amps in collage.

  • in reply to DAB

    I dared not share too loudly..............when I first graduated school, my first enginnering job was as an industrial controls field engineer. The older electronics controls racks were pages of wire wrapped backplanes filled with relay cards and discrete component op amp cards.  Op Amps in school wasnt proper preparation for the nightmare of dealing with constantly drifting offsets and gains. Linear time ramps were op amps too.

  • in reply to robogary

    Op-amps were barely mentioned when I was in school. Our profs were big on transistors and considered use of op-amps to be cheating, just like they considered use of calculators to be cheating. However, I've been on a pretty deep dive into op-amps ever since then. I'm doing a couple of op-amp projects right now but unfortunately they use quad op-amps (because one of them needs at least 16 op--amps), so these projects wouldn't qualify for the Op-Amp-a Palooza.

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  • in reply to robogary

    Op-amps were barely mentioned when I was in school. Our profs were big on transistors and considered use of op-amps to be cheating, just like they considered use of calculators to be cheating. However, I've been on a pretty deep dive into op-amps ever since then. I'm doing a couple of op-amp projects right now but unfortunately they use quad op-amps (because one of them needs at least 16 op--amps), so these projects wouldn't qualify for the Op-Amp-a Palooza.

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