UC3838ADW MAGNETIC AMPLIFIER CONTROLLER

Magnetic Amplifier Controller

ABSOLUTE MAXIMUM RATINGS

Supply Voltage, VCC . . . . . . . . . . . 40V

Magnetic Amp. Source Voltage, VM .  . . . . . . . . . . . . . 40V

Reset Output Voltage, VR . . . . . . . . . . . . . .  . . . . . . –120V

Total Current Source Voltage, VM - VR . . . . . . . . . . –140V

Amplifier Input Range . . . . . . . . . . . . . .. –0.3V to VCC

Reset Input Current, IDR . . . . . . . . . . . . . . . . . . . . . . . . . –10mA Power Dissipation at TA = 25°C

Q, N, DP Package . . . .  .  . 2W

J, L Package. . . . . . . . .. . 1W

Power Dissipation at T (leads/case) = 25°C

Q, N, DP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5W

J, L Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2W Operating Temperature Range. . . . . . . . . . . . –55°C to +125°C Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C

Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . . 300°C

DESCRIPTION

The UC1838A family of magnetic amplifier controllers contains the circuitry to generate and amplify a low-level analog error signal along with a high voltage-compliant current source. This source will provide the reset current necessary to enable a magnetic amplifier to regulate and control a power supply output in the range of 2A to 20A.

By controlling the reset current to a magnetic amplifier, this device will define the amount of volt-seconds the magnetic amplifier will block before switching to the conducting state. Magnetic amplifiers are ideal for post-regulators for multiple-output power supplies where each output can be independently controlled with efficiencies up to 99%. With a square or pulse-width-modulated input voltage, a magnetic amplifier will block a portion of this input waveform, allowing just enough to pass to provide a regulated output. With the UC1838A, only the magnetic amplifier coil, three diodes, and an output L-C filter are necessary to implement a complete closed-loop regulator.

The UC1838A contains a precision 2.5V reference, two uncommitted high-gain op amps and a high-gain PNP-equivalent current source which can deliver up to 100mA of magnetic amplifier reset current and with –120 volt capability.

TYPICAL APPLICATION

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