LM12 Substitute

Donald Jones

Other Parts Discussed in Thread: LM675, OPA564, LM3886, OPA541, OPA549, OPA548

Looking for suggestions for a suitable replacement for the obsolete LM12 (LM12CLK).

Needs to be able to source/sink 5A (min), GBW 1MHz (min), min operating voltage +/-10V (or 20V)

Needs to be stable driving assorted LDO inputs at operating input voltages (3V to 20V) and input capacitance (1uF to 10uF) with normal output load current range (10mA to 3A), capable of drive fast voltage step (Vin+/-1V to Vin+/-2V) for line transient testing. DC gain will be low 2x or 5x, but not unity.

LM675 is probably not going to work due to the lower output current (3A) and bandwidth.

I am characterizing the OPA564 now, although the bandwidth is fine, the maximum output current (1.5A) is not adequate so there is extended rise/fall times to charge/discharge the input capacitance.

I have seen the datasheet for the APEX PA09, which looks promising, but at US$ 248 per unit (DigiKey) I'm going to keep looking around for awhile.

over 12 years ago

0 Paul Grohe over 12 years ago

TI__Guru 53266 points

Hello Donald,

The LM3886 is generally considered a replacement for the LM12, though it is NOT unity gain stable (gain of 10 min). The LM3875 is also an option. Pretty much any of the high power linear audio amps can be used as a replacement, but just watch the minimum gain requirements.

Regards,

0 Thomas Kuehl over 12 years ago

TI__Guru* 93105 points

Hi Donald,

Although not an exact replacement for the LM12, take a look at the OPA541 specifications. It will operate with +/-10 V supplies and is rated for 10 Amps peak output current. The ac performance appears to be in line with your requirements as well. The large load capacitance you mention can usually be dealt with using appropriate compensation. You can find the OPA541 data sheet here:

http://www.ti.com/product/opa541

If you don't quite need 10 A, the OPA549 at 8 Amps output is another amplifier to consider.

Regards, Thomas

PA - Linear Applications Engineering

0 Donald Jones over 12 years ago in reply to Thomas Kuehl

TI__Mastermind 22610 points

Paul, Thomas,

Thanks for your suggestions. Much appreciated.

0 Wankoye Oumou over 10 years ago

Prodigy 20 points

Hi Donald,

I'm working on project right now and I want to replace the obsolete LM12CLK. Do you find a way to replace it?!

0 Paul Grohe over 10 years ago in reply to Wankoye Oumou

TI__Guru 53266 points

Hello Wankoye,

Sadly, there is no direct replacement for the LM12. It was getting expensive to produce and customers were opting for other alternatives.

The LM12's DNA lives on in the LM3875 and LM3886 audio power amplifiers - which contains some of the LM12's concepts. Though, you will have the same issues since the LM3875 and LM3886 are not unity gain stable (min gain of 10).

As Thomas said, the OPA541 is the closest modern replacement - and also adds current limiting ability. Or the OPA548 for currents under 3A.

Regards,

0 Wankoye Oumou over 10 years ago in reply to Paul Grohe

Prodigy 20 points

Thank you Paul for the answers.

Regards,

Wankoye Oumou

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LM12 Substitute