LF357 equivelants

peter williams

Other Parts Discussed in Thread: OPA172, OPA1602

What is a suitable replacement for an LF357. I have tried an OPA 134 and this did not work- the +ve voltage rail was pulled from +15v to 1.2v-on pin 7.

What would be a more modern lower noise replacement for the LF357 for audio applications?

Why would the the +ve voltage rail be pulled down?

Thanks for your assistance

Peter

over 6 years ago

0 Paul Goedeke over 6 years ago

TI__Mastermind 30600 points

Hi Peter,

Can you share your schematic and explain a bit more about what you are trying to accomplish? Have you taken a look at our Audio portfolio? I'll refer your question over to that team for you to get more help.

www.ti.com/.../overview.html

A couple amps that might work from the general purpose portfolio with lower voltage noise than the LF357:
OPA172
OPA1602

Thanks,
Paul

0 peter williams over 6 years ago in reply to Paul Goedeke

Prodigy 45 points

Thanks Paul

I have attached the circuit. I am intrigued as to why the +ve voltage rail is pulled down. I will order both the OPA172 and OPA1602 to try

Regards

Peter

0 kai klaas69 over 6 years ago in reply to peter williams

Guru 140200 points

Hi Peter,

we cannot see the schematic.

Kai

0 peter williams over 6 years ago in reply to kai klaas69

Prodigy 45 points

I must be doing something dumb as I can not either attach or copy the schematic into this message.

I have tried the Cntrl +V ( on a mac Command +V) and cut and paste and attach- am I missing something?

hopefully this has worked

Peter

0 kai klaas69 over 6 years ago in reply to peter williams

Guru 140200 points

Hi Peter,

is anything connected to pin1 and pin 5 of LF357?

If the supply voltage at pin 7 drops to 1.2V then the zener diode supply voltage generation might fail. Can you measure the current flowing through the 2k7 current limiting resistor next to this zener? Can you do this also for the 2k7 resistor in the negative supply?

How about the voltage at pin 6 of LF357?

Kai

0 peter williams over 6 years ago in reply to kai klaas69

Prodigy 45 points

Hi Kai

there are no connections to pins 1 or 5of the LF 357, and pin 6 of the LF 367 has zero volts ( I will double check this)- I will measure the current on the 2k7 resistors for both +ve and -ve supply.

The 1.2v at pin 7 is only when I substitute an OPA 134 for the LF 357, which I was hoping to do to improve the noise floor.

Thanks

Peter

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LF357 equivelants