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WIDE RANGE VOLTAGE REGULATOR

IP.com Disclosure Number: IPCOM000005462D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2001-Oct-10
Document File: 2 page(s) / 85K

Publishing Venue

Motorola

Related People

Robert W. Deutsch: AUTHOR

Abstract

The voltage regulator maintains a high quality of Voltage regulation over a wide range of load and temperature conditions with an input to output voltage differential (Vin-Vout) as small as 0.5 volts or less. When designed to have a 5.0 volt output voltage (Vout) and to provide a load current of up to 1.0 ampere over a temperature range of - 40 to + 85 degrees C, output regulation can be kept within + 5 percent.

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WIDE RANGE VOLTAGE REGULATOR By Robert W. Deutsch

   The voltage regulator maintains a high quality of Voltage regulation over a wide range of load and temperature conditions with an input to output voltage differential (Vin-Vout) as small as 0.5 volts or less. When designed to have a 5.0 volt output voltage (Vout) and to provide a load current of up to 1.0 ampere over a temperature range of - 40 to + 85 degrees C, output regulation can be kept within + 5 percent.

   The voltage reference 21 for the regulator is a combined voltage reference and error amplifier having an output at its cathode terminal capable of sinking up to 150 milliamperes. The error amplifier in reference Zl compares an output voltage feedback signal from voltage sensing and dividing resistors R4 and R5, at its reference input terminal, to an internal 2.5 volt voltage reference to determine the amount Of current to sink at its cathode terminal. This, of course, adjusts the bias voltage to the base terminal of transistor Q2 to maintain the desired output voltage Vout level. This device is commercially available under part number TL4311.

   A current amplifier is formed by the transistors Ql and Q2 and develops a gain which is proportional to the product of the individual current gains of the transistors. The voltage gain of the amplifier is ap- proximately equal to (R2 + R3)/R3. Thus, when R2 is equivalent to R3 in resistive value, the voltage gain is fixed at approximately 2. For a voltage regulator designed with a 5.0 volt output, the voltage at the cathode of the voltage reference Zl will be slightly greater than 3 volts and will show very little voltage change for all values of load current.

   The series pass transistor Ql is pref...