LM387 equivalent?

[Leon Heller]

The LM387 single-supply low-noise op-amp has been obsolete for some years.
I'd like to try a circuit out that uses it, and was thinking of using the TI
OPA2350 instead. They are rather expensive, though. Has anyome got any other
suggestions?

Leon

 

[Winfield Hill]

Leon Heller wrote...

The LM387 single-supply low-noise op-amp has been obsolete for some
years. I'd like to try a circuit out that uses it, and was thinking
of using the TI OPA2350 instead. They are rather expensive, though.
Has anyome got any other suggestions?

THe LM387 features low noise (7nV at 1kHz, vs 13nV for the opa350),
a nice wide bandwidth (15MHz vs 38MHz) and a respectable slew rate
(5V/us vs 22V/us). In this comparison, the opa350 family looks OK,
except it's somewhat noisier than the LM387, as is to be expected,
with its small-area-MOSFET input stage (Cin = 6.5pF). For example,
at 40Hz the opa2350 sports 100nV/rt-Hz vs 12nV for the LM387. The
low operating voltage of the opa2350 is also a severe disadvantage,
because it means very low output-voltage capability. :>( Another
issue to consider for preamp ICs is their cable-driving ability.

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)

 

[Leon Heller]

Leon Heller wrote...

THe LM387 features low noise (7nV at 1kHz, vs 13nV for the opa350),
a nice wide bandwidth (15MHz vs 38MHz) and a respectable slew rate
(5V/us vs 22V/us). In this comparison, the opa350 family looks OK,
except it's somewhat noisier than the LM387, as is to be expected,
with its small-area-MOSFET input stage (Cin = 6.5pF). For example,
at 40Hz the opa2350 sports 100nV/rt-Hz vs 12nV for the LM387. The
low operating voltage of the opa2350 is also a severe disadvantage,
because it means very low output-voltage capability. :>( Another
issue to consider for preamp ICs is their cable-driving ability.

Thanks, Win.

I've actually managed to find a couple of LM387N, at 9 GBP each, in stock at
one of my suppliers, so I've ordered one. It's for a low-noise direct
conversion radio pre-amp. I'll get it working with that and then modify the
circuit and try it with something more modern. They also had lots of
LM387AN, at 18 GBP. Lower noise, but I think I'll give it a miss at that
price.

Leon