US3543140A - Constant potential output device having low temperature coefficient and overload protection - Google Patents

Constant potential output device having low temperature coefficient and overload protection Download PDF

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Publication number
US3543140A
US3543140A US706536A US3543140DA US3543140A US 3543140 A US3543140 A US 3543140A US 706536 A US706536 A US 706536A US 3543140D A US3543140D A US 3543140DA US 3543140 A US3543140 A US 3543140A
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Prior art keywords
transistor
resistor
constant
potential
output terminals
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Expired - Lifetime
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US706536A
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English (en)
Inventor
Friedrich Johann Krausser
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Emerson Electric Co
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Emerson Electric Co
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F3/00—Non-retroactive systems for regulating electric variables by using an uncontrolled element, or an uncontrolled combination of elements, such element or such combination having self-regulating properties
    • G05F3/02—Regulating voltage or current
    • G05F3/08—Regulating voltage or current wherein the variable is dc
    • G05F3/10—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics
    • G05F3/16—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices
    • G05F3/18—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices using Zener diodes

Definitions

  • This invention relates generally to a regulated power supply or voltage regulator circuit, and, more particularly, relates to a solid-state power supply which is immune to ambient temperature variations.
  • regulated power supplies or voltage regulator circuits must maintain, of necessity, a constant potential difference between their output terminals.
  • ambient temperature variations cause corresponding variations in the characteristics of the components, thereby producing voltage variations at the output terminals.
  • Such supplies are rendered unfit for their intended use.
  • temperature compensation circuits have been proposed to ameliorate this situation, such compensation circuits conventionally utilize a great many other components. Hence, such devices have been found to be uneconomic in terms of both cost and space.
  • an object of the present invention is to provide a regulated power supply which is independent of ambient temperature variations.
  • Another object of this invention is to provide a regulated power supply or voltage regulator circuit which is simple in construction and reliable in operation.
  • a further object and feature of the present invention resides in the novel details of construction which provide a regulated power supply of the type described which is economic to fabricate, and which occupies a relatively small volume.
  • a further disadvantage of solid-state devices is their susceptibility to burn out owing to overloads during even relatively small time intervals.
  • a further object of this invention is the provision of a regulated power supply which automatically turns off in the event of overload, as, for instance, when the output terminals are shorted.
  • a regulated power supply constructed in accordance with the present invention comprises a pair of input terminals adapted to be connected with a DC. source of potential, and a pair of output terminals adapted to be connected across a load.
  • a substantially constant voltage device having a first temperature coeflicient, and an impedance means having a temperature coefiicient equal in magnitude to said first temperature coefi'icient, but opposite in sense, are connected in series between the pair of output terminals.
  • a current regulating means is connected between said pairs of input and output terminals for supplying a constant current to said series circuit to maintain the potential between said pair of output terminals at a constant predetermined level. Ambient temperature changes cause equal and opposed voltage variations across the constant voltage device and the impedance means which cancel the effect of each other. Hence, the potential between the pair of output terminals remains at the predetermined level.
  • Supply 10 includes a pair of output terminals 12 and 14, which are adapted to be connected with a load (not shown).
  • a series circuit 17 comprising a back-biased Zener diode or constant voltage device 18, and a negative temperature coefficient impedance or resistor 20, such as a thermistor or the like.
  • Terminal 14 is further connected to ground by a lead 22.
  • a constant current source designated generally by the reference numeral 24 (shown enclosed by the dash lines) which supplies a constant current to series circuit 17.
  • the potential appearing between output terminals 12 and 14 will be equal to the sum of the potential drops across resistor 20 and diode 18. While the voltage drop across diode 18 is substantially independent of the current flowing therethrough in the Zener region, the voltage drop across resistor 20 is directly proportional to the current flowing through it. Hence, for a constant current flowing through series circuit 17, the potential drop across this circuit and, therefore, the potential between output terminals 12 and 14 similarly will be constant.
  • Zener diodes above a preselected voltage level have a positive temperature coefficient so that the voltage drop across such devices increases with a rise in temperature.
  • resistor 20 is selected to have a temperature coefficient which is equal in magnitude but opposite in sense to the temperature coefficient of Zener diode 18. Hence, the variations in the voltage drops across the respective elements 18 and cancel each other so that the potential between output terminals 12 and 14 remains at the preselected constant level.
  • Zener diode 18 has a temperature coefficient of +20 mv./ C. at the operating potential
  • a resistor 20 is selected having a temperature coeflicient of 20 mv./ C. at the particular value of current. If the ambient temperature rises 1 C., the voltage drop across diode 18 rises 20 mv., and the voltage drop across resistor 20 decreases 20 mv.
  • the total change in potential across series circuit 17 and, therefore, appearing between output terminals 12 and 14, owing to temperature variations is zero.
  • regulated power supply 10 maintains a constant potential between the output terminals which is substantially immune to temperature variations.
  • Constant current source 24 includes a pair of input terminals 26 and 28 between which is connected a D.C. source of potential 30. Terminal 28 is connected to ground. Moreover, D.C. source 30 may comprise a battery or a rectified A.C. source of potential, or the like. Also connected between input terminals 26 and 28 and output terminals 12 and 14 is a current regulating circuit, designated generally by the reference numeral 32, which regulates the current flowing therethrough to supply the constant current to series circuit 17 and a load which may be connected between terminals 12 and 14.
  • the current regulating circuit 32 includes a serially connected PNP transistor or variable impedance 34 having an emitter or input electrode, a collector or output electrode, and a base or control electrode.
  • the emitter electrode of transistor 34 is connected to terminal 26 through a resistor 36 by a lead 38.
  • the collector electrode of transistor 34 is connected to output terminal 12 by a lead 40.
  • Connected to transistor 34 is a negative feedback network 42 which maintains the current flowing through the collector electrode of transistor 34 at a constant value.
  • the network 42 includes an NPN transistor or variable impedance 44 having electrodes similar to transistor 34.
  • the base electrode of transistor 44 is connected to lead 40 by a lead 46.
  • the collector electrode of transistor 44 is connected to the base electrode of transistor 34 and input terminal 26, through a resistor 48, by a lead 50.
  • the emitter electrode of transistor 44 is connected to ground through serially connected resistors 52 and 54.
  • Resistor 54 is shown connected between a pair of output terminals 56 and 58 since resistor 54 may comprise any load which requires a constant potential thereacross. In other words, a constant potential will appear across any impedance connected between terminals 56 and 58.
  • a resistor 60 is connected between the emitter and collector electrodes of transistor 44 for reasons which will become apparent from a consideration of the operation of the circuit.
  • D.C. source 30 comprises an A.C. rectified source, it may be desirable to provide an additional degree of filtering. Accordingly, a capacitor 62 is connected in parallel with resistor 48, and a capacitor 64 is connected across resistor 54, to short A.C. hum signals to ground.
  • the current flowing through the collector electrode of transistor 44 is equal to the sum of the base current of resistor 34 and the current flowing through resistor 48. Since this base current is negligible compared to the current flowing through resistor 48, it can be assumed that transistor 44 maintains the current through resistor 48 at a constant value. Hence, the voltage drop across resistor 48 is maintained at a constant level.
  • resistor 48 is connected in parallel with the series circuit of resistor 36 and the base-emitter junction of transistor 34.
  • the voltage drop across this series circuit similarly is maintained at the constant level, thereby to maintain the current flowing in the emittercollector path of transistor 34 at a constant magnitude.
  • the current flowing through lead 40 i.e., the collector electrode of transistor 34 is maintained at the constant level noted above.
  • constant current source 24 automatically protects transistors 34 and 44 against overloads. For example, if a short circuit occurs between terminals 12 and 14, the current through series circuit 17 will decrease. Hence, the potential at the base electrode of transistor 44 similarly will decrease, thereby decreasing the current in the emitter-collector path of that transistor. As a result, the potential across resistor 48 will decrease, thereby causing the current flowing through the emitter-collector path of transistor 34 to drop. This action will continue until transistors 34 and 44 are driven into cut-off, thereby preventing damage to the transistors.
  • transistor 44 will not conduct initially.
  • resistor 60 is included to cause a voltage drop to exist between the emitter and collector electrodes of transistor 44, to initiate conduction.
  • transistors of opposite or complementary conductivities may be used for the respective transistors disclosed, with appropriate changes in the biasing arrangements.
  • a regulated power supply comprising first and second lnput terminals adapted to be connected to a D.C. source of potential, first and second output terminals adapted to be connected with a load, a substantially constant voltage device having a first temperature coeflicient, impedance means having a temperature coefficient equal in magnitude to said first temperature coeflicient and opposite in sense, lead means for connecting said voltage device and said impedance means in a series circuit between said first and second output terminals, and current regulating means connected between said first and second input and output terminals for supplying a constant current to said series circuit to maintain the potential between said first and second output terminals at a constant predetermined level, said current regulating means including a first transistor having an emitter, a collector and a base electrode, a first resistor, lead means for connecting said first resistor between said first input terminal and the emitter electrode of said first transistor, lead means for connecting the collector electrode of said first transistor to said first output terminal, and feedback means connected between the collector and base electrodes of said first transistor for maintaining

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Nonlinear Science (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Continuous-Control Power Sources That Use Transistors (AREA)
  • Control Of Electrical Variables (AREA)
  • Amplifiers (AREA)
US706536A 1968-02-19 1968-02-19 Constant potential output device having low temperature coefficient and overload protection Expired - Lifetime US3543140A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US70653668A 1968-02-19 1968-02-19

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US3543140A true US3543140A (en) 1970-11-24

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US (1) US3543140A (sv)
DE (1) DE1908261A1 (sv)
FR (1) FR2002192A1 (sv)
GB (1) GB1234503A (sv)
NL (1) NL6902559A (sv)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4218730A (en) * 1977-11-09 1980-08-19 Hitachi, Ltd. Transistor switching apparatus for use in the control of a D.C. load
US4638397A (en) * 1984-12-21 1987-01-20 Xerox Corporation Self-biased scorotron and control therefor
US20080180082A1 (en) * 2007-01-29 2008-07-31 Inventec Corporation Power regulator with constant voltage output
CN108933517A (zh) * 2018-09-06 2018-12-04 广州金升阳科技有限公司 开关变换器的输出电压反馈电路及温度补偿电路

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2832035A (en) * 1956-06-14 1958-04-22 Avco Mfg Corp Transistor voltage or current regulator
US3069617A (en) * 1958-08-01 1962-12-18 Motorola Inc Voltage regulated power supply
US3094654A (en) * 1958-02-27 1963-06-18 North American Aviation Inc Balanced current series transistor regulator
US3293540A (en) * 1964-04-08 1966-12-20 Photovolt Corp Temperature compensated circuit arrangements
US3300710A (en) * 1963-01-23 1967-01-24 Dalton L Knauss Voltage reference circuit with low incremental impedance and low temperature coefficient
US3419789A (en) * 1966-04-09 1968-12-31 Forbro Design Corp High precision dc voltage regulator

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2832035A (en) * 1956-06-14 1958-04-22 Avco Mfg Corp Transistor voltage or current regulator
US3094654A (en) * 1958-02-27 1963-06-18 North American Aviation Inc Balanced current series transistor regulator
US3069617A (en) * 1958-08-01 1962-12-18 Motorola Inc Voltage regulated power supply
US3300710A (en) * 1963-01-23 1967-01-24 Dalton L Knauss Voltage reference circuit with low incremental impedance and low temperature coefficient
US3293540A (en) * 1964-04-08 1966-12-20 Photovolt Corp Temperature compensated circuit arrangements
US3419789A (en) * 1966-04-09 1968-12-31 Forbro Design Corp High precision dc voltage regulator

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4218730A (en) * 1977-11-09 1980-08-19 Hitachi, Ltd. Transistor switching apparatus for use in the control of a D.C. load
US4638397A (en) * 1984-12-21 1987-01-20 Xerox Corporation Self-biased scorotron and control therefor
US20080180082A1 (en) * 2007-01-29 2008-07-31 Inventec Corporation Power regulator with constant voltage output
US7579813B2 (en) * 2007-01-29 2009-08-25 Inventec Corporation Power regulator having a voltage regulator module and having a voltage buffer module to provide a constant voltage output
CN108933517A (zh) * 2018-09-06 2018-12-04 广州金升阳科技有限公司 开关变换器的输出电压反馈电路及温度补偿电路

Also Published As

Publication number Publication date
DE1908261A1 (de) 1969-09-11
FR2002192A1 (sv) 1969-10-17
NL6902559A (sv) 1969-08-21
GB1234503A (sv) 1971-06-03

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