Trevor Wilson wrote:
> On 4/09/2022 5:06 am, Phil Hobbs wrote:
>> Trevor Wilson wrote:
>>> I am servicing a power amplifier which uses a dual, 8 pin DIP OP amp.
>>> Unfortunately, the rail Volts on the OP amp (LF353) is +/- 22 Volts.
>>> I am familiar with this particular amplifier and OP amp failure is
>>> quite a frequent thing. I need a suggested replacement. I am quite
>>> happy to use single OP amps, or SOICs, as I can employ a Brown Dog
>>> carrier to adapt to the existing layout. Ideally, a bit more
>>> performance over the LF353 would be nice.
>>> And no, it is not possible to drop the rail Voltages. They must
>>> remain at +/-22 Volts.
>> What's the required output swing? A baby board with one or two zeners
>> in the supply leads (plus a 100 nF-ish bypass between them) is pretty
>> easy, at least if you get these things in a lot.
> **I need maximum output Voltage swing. Hence the designer (now deceased)
> chose a +/- 22 Volt supply. Hence the need for higher Voltage OP amps.
Sure, but typically not everything in a circuit needs to swing the full
supply range. You're losing at least a couple of V_BEs on each end
now--in fact the LF353 datasheet minimum output swing is +-3 V from the
rails (+-12 on +-15 supplies) even at light loads.
There are nice things in the 40V range such as the MC34072, which
typically swings +14 to -14.7 off +-15 if fairly lightly loaded. It's
also a lot quieter than the LF353, not that you probably care much in a