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LME49710 and Neoelec in Niagara Falls
LME49710 and Neoelec in Niagara Falls
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Old 6th September 2019, 03:47 PM   #1
keilau is offline keilau  United States
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Default LME49710 and Neoelec in Niagara Falls

I just ordered a bunch of LME49710 from Neoelec in NIAGARA FALLS, NY. How reputable are they as an electronic supplier. They told me that their LME49710 were from TI directly and are leftover from an old project.

What is the best way to test slew rate of these LME49710? Or the easiest way. I have a 100KHz signal generator and a 100MHz oscilloscope.

I got my LME49720 from DigiKey, but I cannot find any established distribution who has the LME49710.
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Old 7th September 2019, 11:45 PM   #2
Monte McGuire is offline Monte McGuire
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LME49710 and Neoelec in Niagara Falls
To test slew rate, I'd wire up a follower on a proto-board, power the chip with 15V and drive the chip wired as a follower with a nice square wave, about 1-2V peak to peak. Look at the slope of the output and there you go - slew rate on display.

The only thing that could go wrong is that a modern arbitrary waveform generator might give you a DAC synthesized square wave with a sinx/x shaped rise time, and not an actual sharp edge. So, it all depends on your generator. But, a follower is the ideal circuit to torture an amplifier with in order to test for slew rate.
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Old 8th September 2019, 04:26 AM   #3
keilau is offline keilau  United States
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Any suggestion on a "good" waveform generator affordable for hobbyist use? What frequency to use for adequately test 20V/microsec?
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Old 8th September 2019, 07:04 AM   #4
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by Monte McGuire View Post
To test slew rate, I'd wire up a follower on a proto-board, power the chip with 15V and drive the chip wired as a follower with a nice square wave, about 1-2V peak to peak. Look at the slope of the output and there you go - slew rate on display.

The only thing that could go wrong is that a modern arbitrary waveform generator might give you a DAC synthesized square wave with a sinx/x shaped rise time, and not an actual sharp edge. So, it all depends on your generator. But, a follower is the ideal circuit to torture an amplifier with in order to test for slew rate.
Slew rate is a large signal spec. If you want to test it that way (and there's nothing wrong with it) do it with say 20V pk-pk signal. Slew rate goes up with signal level, for a given frequency, slew rate with 20V is 10x the slew rate at 2V. It may pass at 2V but fail at 20V.

Jan
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Old 11th September 2019, 12:26 PM   #5
Mark Tillotson is offline Mark Tillotson
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Any CMOS logic chip will produce a razor-sharp square wave, just feed through a coupling cap to your opamp circuit. Typical rise and fall times are 1 to 5ns. So something like a microcontroller output, comparator output, 555 oscillator fed through a 75HC14 schmitt trigger...
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