33W Bridge Composite Amplifier

Two LM1875 ICs provide 33W of audio. IC4 is used as a phase inverter.

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Note: IC6 and IC2 must be heatsinked.

Low-Distortion Amplifier/Compressor

Designers can build a 15-dB compressor with a miniature lamp and a current-feedback amplifier. The circuit possesses extremely low distortion at frequencies above lamp's thermal time constant. This means that distortion is negligible from audio frequencies to beyond 10 MHz. There's also relatively little change in phase versus gain compared to other automatic gain-control circuits. Lastly, the circuit has many instrumentation, audio, and high-frequency applications as a result of its low distortion and small phase change.

The AD844 op amp is a perfect fit for this application because it's a current-feedback amplifier. Each stage of the circuit. U2. lamp, and feedback resistor compresses an ac signal by over 15dB (see the figure). Cascading a number of stages delivers higher compression ranges.

Op amp U1 operates as a unity-gain buffer to drive the input to the compressor. However. U1 is optional if a low-impedance signal source is used. The lamp's resistance will increase with temperature, which reduces the ration of resistor R3 to the resistance of the lamp. This ratio reduces the gain of U2. The lamp's cold resistance should be greater then the input resistance of U2 (more then 50 ohms) for proper operation. The lamp's resistance will change slightly for low input levels. Therefore, the ratio of R3 to the resistance of the lamp and the gain of U2 stays high.

ADUM2400: Quad-Channel Digital Isolators

FEATURES

Low power operation

5 V operation

    1.0 mA per channel maximum @ 0 Mbps to 2 Mbps

    3.5 mA per channel maximum @ 10 Mbps

    31 mA per channel maximum @ 90 Mbps

3 V operation

    0.7 mA per channel maximum @ 0 Mbps to 2 Mbps

    2.1 mA per channel maximum @ 10 Mbps

    20 mA per channel maximum @ 90 Mbps

Bidirectional communication

3 V/5 V level translation

High temperature operation: 105°C

High data rate: dc to 90 Mbps (NRZ)

Precise timing characteristics

     2 ns maximum pulse width distortion

     2 ns maximum channel-to-channel matching

High common-mode transient immunity: >25 kV/μs

Output enable function

16-lead SOIC wide body package version (RW-16)

16-lead SOIC wide body enhanced creepage version (RI-16)

Safety and regulatory approvals (RI-16 package)

    UL recognition: 5000 V rms for 1 minute per UL 1577

    CSA Component Acceptance Notice #5A

       IEC 60601-1: 250 V rms (reinforced)

         IEC 60950-1: 400 V rms (reinforced)

    VDE Certificate of Conformity

         DIN V VDE V 0884-10 (VDE V 0884-10):2006-12

         VIORM = 846 V peak

For further information please view it online: ADUM2400 (pdf | 24 pages)