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80W Power Amplifier based Single Power IC LM12 / LM12CL

80W Power Audio Amplifier with LM12 circuit

This is the schematic diagram of power audio amplifier using single power IC LM12 / LM12CL. The design is very simple. This power amplifier needs power supply with dual polarity output ( +, gnd, - ), don't exceed than 60V : (+30V) ; ground ; (-30V).

The LM12 is a power amplifier capable of driving ±25V at ±10A while operated at ±30V supplies (Vmax 60V). The monolithic IC can deliver 80W of sine wave power into a 4Ω load with 0.01% distortion. Power bandwidth is 60 kHz. Further, a peak dissipation capability of 800W allows it to handle reactive loads such as transducers, actuators or small motors without derating.

The IC delivers ±10A output current at any output voltage yet is completely protected against overloads, including shorts to the supplies. The dynamic safe-area protection is provided by instantaneous peak-temperature limiting within the power transistor array.

The turn-on characteristics are controlled by keeping the output open-circuited until the total supply voltage reaches 14V. The output is also opened as the case temperature exceeds 150°C or as the supply voltage approaches the BVCEO of the output transistors. The IC withstands overvoltages to 80V.

This monolithic op amp is compensated for unity-gain feedback, with a small-signal bandwidth of 700 kHz. Slew rate is 9V/μs, even as a follower. Distortion and capacitive-load stability rival that of the best designs using complementary output transistors. Further, the IC withstands large differential input voltages and is well behaved should the common-mode range be exceeded.

The LM12 establishes that monolithic ICs can deliver considerable output power without resorting to complex switching schemes. Devices can be paralleled or bridged for even greater output capability. Applications include operational power supplies, high-voltage regulators, high-quality audio amplifiers, tape-head positioners, x-y plotters or other servo-control systems.

PCB Layout:

80W Power Audio Amplifier with LM12 pcb layout

  • Input Protection
  • Controlled Turn On
  • Thermal Limiting
  • Overvoltage Shutdown
  • Output-Current Limiting
  • Dynamic Safe-Area Protection