The TLC272 is a dual op-amp, I note the TLC270 is a single channel and looks like a differing 'beast' looking at the data sheet, I'm after a single version of the TLC272, looks like I'm gonna have to try it or use the dual op-amp leaving one side un-used..... something I don't really like doing.

I've tried searching without any luck, anyone know if there's an alternative, this is only for audio pre-amp running from 9V single ended, thought I'd ask here first. I've tried the usual op-amps but can't seem to get the TLC271 performance.

Thanks, Dave

 

The TLC271 family is not all that great for an audio application.
It has a very slow Slew-Rate, so don't expect any high frequency performance in a high-Gain application.

You would get more useful suggestions if You would provide a detailed explanation
of exactly what You are trying to accomplish, and the type of performance that You expect.
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It only needs 0.137V/us for a 20kHz 0dBm signal, so slew-rate is hardly a problem, but noise certainly is.

 

The TLV910x series is a newer opamp and a drop in replacement with better performance according to TI for the TLC272.
The TLV9101 is a single opamp.

 

Hi, thanks for the reply.
Well, certainly not hi-tech or super hi-quality, just a normal audio pre-amp to boost a 70mV signal up to say about 1V or so, this is for a 9V single ended supply. I tried TL0's and 741 chips, the TLC272 sounded ideal and just right.... rightly or wrongly I put it down to the low single ended supply voltage, I tried both modes inverted and non-inverted.

Just that I found it odd I can't seem to find a single version. Dave

 

Just that I found it odd I can't seem to find a single version. Dave

TLC271 by TI’s usual numbering convention.
https://www.ti.com/product/TLC271

 

It has a very slow Slew-Rate, so don't expect any high frequency performance in a high-Gain application.

A nit, but the slew-rate is not significantly affected by the closed-loop gain.

 

In any case, an OP275 would be a much better choice.
Available in SMD or PDIP Packages.
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Sorted.... I used a LF351, that did the trick. Thanks all for your replies, the numbering seems to be all over the place these days, a TLC271 *may* have done, just that I hadn't any to try.

I used 3 off 33K for biasing for pin 3 and input to pin 3, for feedback from pin 6 to pin 3. select for required gain, I used a 4u7 decoupling cap for the mid-voltage split, those values worked for me so I just left it at that. I used a 22pF across the feedback resistor to stop oscillation.

Dave

 

one channel unused, grounding the unused inputs and tying the output to prevent oscillation is a good practice.

Tying the output to what?
Normally the output is left open..

 

Tying the output to what?
Normally the output is left open..

You're right that it's typically left open however, leaving the input floating can cause instability or unwanted oscillations.
To properly terminate an unused op-amp, connect the inverting input (-) to the output and then connect the non-inverting input (+) to ground. This configuration will create a unity-gain buffer that stabilizes the op-amp without causing any oscillations.

For split-supply systems you can connect the non-inverting input (+) to the virtual ground (0V reference) and then connect the inverting input (-) directly to the output. This also results in a stable unity-gain configuration.

In most cases, tying the inputs this way ensures the op-amp remains inactive without causing interference in your circuit. Leaving the output itself open is fine as long as the inputs are properly terminated to prevent oscillations.

 

Some other alternatives would be:

1. OPA172: This is a precision op-amp that provides low noise and high output drive capabilities (75 mA). It works pretty well in single-supply applications making it ideal for your 9V supply. The OPA172 can deliver excellent performance for audio pre-amps with clean sound and low distortion, making it one of the best alternatives to the TLC271.
2. TL071CD: This is a JFET-input single op-amp with low input bias current, high input impedance, and low noise making it another excellent choice for audio pre-amp circuits. It’s widely used in audio equipment for its low noise and good sound quality. It would perform similarly to the TLC271 and might even give better audio performance.
3. OPA171: A general-purpose op-amp that can work well in audio applications, though it might not match the TLC271 in terms of noise performance. It’s reliable, but the OPA172 or TL071CD would be better suited for high-quality audio.
4. TLV2371: A low-power, single-channel op-amp that’s also a potential candidate, though not as optimized for audio as the OPA172 or TL071CD. This might be useful for portable or battery-powered applications, but its noise performance might not be ideal for high-fidelity audio.

If you do decide to use the TLC272 (dual op-amp) and leave one channel unused, grounding the unused inputs and tying the output to prevent oscillation is a good practice.

Super helpful for a project i'm working on right now, thanks for being so thorough!