close

Вход

Забыли?

вход по аккаунту

?

Патент USA US3076140

код для вставки
i Jan. 29, 1963
R. P. FARNswoRTH ETAL
POWER SUPPLY CIRCUIT
Filed Sept. 29, 1958
„EnNM
3,076,135
ice
3,dlli,l35
¿Datenteel dan. 29, lgâêi
9
ad
independent of temperature and ageing of the amplifying
3,tl76,i35
Rohert i’. Farnsworth, Los Angeles, and Leonard Azar,
elements in the circuit.
It is a still further object of this invention to provide a
PGV/lili Sillery? Cil-mill?
fast acting power supply utilizing transistors which will
#Culver City, tïalil‘., assignors to Hughes Aircraft Corn
not only completely disconnect the source from the load
during an overload condition when operating at full rated
power but will return to supplying full rated power upon
removal of the overload condition.
This invention relates to power supplies and partic
Another object of this invention is to provide a tran
ularly to a direct-current power supply utilizing a fast 10 sistor power supply having a simplified overload protec
acting overload protection circuit.
tion circuit for protecting both the power supply and the
supplied circuitry, and which operates to disconnect the
ln the prior art, DC. (direct current) power supplies
power supply at a predetermined rated current independent
were used in connection with vacuum tubes and delivered
relatively high output voltages and could operate with
of changes of characteristics of the transistor due to age
pany, GCulver City, Cali, a corporation ot‘ Delaware
Filed Sept. 2.9, 1953, der. No. 765,693
1l Claims. (Qi. 323-22)
relatively high output impedances. However, with tran
sistor circuitry, power supplies may be required to supply
relatively low output voltages while supplying current of
15
ing and temperature.
The output impedance of the power
According to one feature of this invention, a power
supply receives unregulated direct current voltage from a
transformer and rectifier arrangement, and supplies it to
supply may be required to be less than l0"3 ohms. These
a load through a series connected regulating, or control,
25 amperes or more.
problems have been solved by utilizing power supplies 20 transistor which varies in static impedance in response to
with high power transistors for regulation and low for
ward resistance diodes for rectiiication.
“ìhe low output impedance from these power supplies
changes of its base current. A voltage comparator in~
cluding a i'lrst diilerential anipliñer and a voltage divider
both connected across the load, is utilized to control a
current signal in response to changes in the load voltage
that of protecting the power supply and the load against 25 or potential diiierence. A second differential ampliñer
has created new problems, the most formidable one being
short-circuits or accidental overloads.
During a short
circuit or accidental overload condition, destruction of. the
transistors and rectiiiers of the power supply as well as
is connected to the base of the control transistor and is
connected to the lirst differential amplifier for responding
to the changes of the current signal to maintain the con
stant load voltage. An overload control circuit is pro
destruction of the transistor circuitry being supplied with
power occurs at a fast rate. The time required for de 30 vided including a resistor connected from a terminal of
the control transistor and in series with the load to form
struction may be in the order of 100 microseconds under
a ñrst voltage divider and including a second voltage
severe conditions. Conventional fuses or mechanical dis
divider connected from the same terminal of the control
connections require 2G to 30 milliseconds to open, which
transistor to the other side oi the load. A signal~forming
operation is far too slow to protect transistors. Some elec
tronic disconnect circuitry of the prior art samples signal 35 transistor is connected between the ñrst and the second
voltage dividers so as to respond to a predetermined
current in a regulator loop and provide turmoil of the sup
polarity of potential dilierence indicating maximum rated
ply when the signal current reaches a preset value. The
load. The signal forming transistor is connected to
shunt out the current from the tirst differential amplilier in
stages of the supply, which gain is dependent upon ageing 40 response to the predetermined polarity which in turn
biases the regulating transistor out of conduction to etîec
and temperature oi the circuit elements, as well as upon
tively disconnect the source from the load. A leakage
supply voltages. Thus, the turn-oft current is variable
.shortcoming of this system is that the signal current is
related to the load current by the gain of one or more
path across the control transistor maintains this discon
nected condition by supplying a small current through the
45 first and second voltage dividers. When the overload con
load current.
dition is removed the potential difference between the
Also, some conventional power supplies having auto
lirst and second voltage dividers returns to a polarity to
matic turn-oit characteristics follow a turn-oit path which
bias the signal-forming transistor out oi conduction, thus
a though allowing them to turn on under full load añter
allowing the voltage comparator circuit to continue its
removal of a short circuit condition, will also allow them
regulating operation at any load up to maximum load.
to exceed maximum dissipations under partial short cir
The novel features of this invention, as well as the
cuit. Other conventional power supplies follow a path
invention itself, both as to its organization and method of
which allows them to turn completely off when an over
operation, will best be understood from the accompanying
load condition occurs under full load but requires partial
and changes under these conditions so as to not consis
tently disconnect the power supply at a ñxed maximum
removal of the full load to turn on after the overload or 55 description, taken in connection with the accompanying
drawings, in which:
short circuit condition has been corrected. rîhese turn
on and turn-od characteristics may result from the non
linearities of the system components. A system which
would provide tast operating overload protection, that
PIG. l is a schematic diagram of the power supply
circuit of this invention; and
FlG. 2 is a graph to illustrate the operation of the
circuit of FIG. l.
would provide overload protection at a fixed maximum 60
Referring iirst to FIG. l, a schematic circuit diagram
load current independent oi the gain of the circuit ele
is shown of the power supply circuit including the over
ments, and which would turn both completely oli and
load protection arrangement of this invention. The power
completely on when a short circuit condition occurs and
supply of this invention receives unregulated voltage,
is removed at full load, would have wide use, especially
which may be -32 volts, from an unregulated voltage
with transistor circuitry.
lt is, therefore, an object of this invention to provide a
power supply which rapidly disconnects from its load upon
the occurrence ot a short circuit or an overload condition.
it is a further object of this invention to provide a
transistor power supply which turns ott under an overload
condition and turns on upon removal of the overload
condition at a consistent maximum load current value,
65 source 2@ comprising a transformer and alternating cur
rent voltage source 22 connected to a terminal 2S which
may be at ground potential and a rectitler 2d connected
to the transformer and voltage source 22. rihe unregulat
ed voltage source Ztl supplies power through a regulating
transistor 26 of a regulating element circuit 32. to a load
34, which may include a resistor RL, and is connected
to the terminal 25 through a ground lead lith. The regu
3,076,135
3
4
lating element circuit 32 also includes a driver transistor
128 which is connected to the lead 84 and has a collector
130 which is connected to the lead 9@ at a junction 132.
Thus, it can be seen that current passes into the junction
132 either from the transistor 12t- or from the transistor
64 of the current amplifier circuit 66. The lead 103 is
also connected to the base ‘le of the regulating transistor
26 by'way of a biasing resistor 136 which acts to pass
leakage current from the base 44 to maintain the regulat
38. The regulating transistor 26 which may be of the
PNP type has a base 46, an emitter 42 and a collector 4t),
and the driver transistor 318 which may be of the NPN
type has a base Sti, an emitter 4S, and a collector 46.
The collector ‘ttl of the regulating transistor 26 is con
nected to the rectifier 24 and the base de of the regulating
transistor 26 is connected to the collector ¿i6 of the driver
transistor 33. The emitter d8 of the driver transistor 33
ing transistor 26 biased when in its nonconducting state,
is connected to the collector ¿itl of the regulating transistor 10 as will be explained subsequently.
26 to provide a return path for current from the base 44
The voltage comparator circuit 96 includes transistors
of the regulating transistor 26, as will be explained sub
138 and 146y arranged as a second differential amplifier
sequently. A leakage resistor 54 is connected between the
circuit. The transistors 1355 and 146 may be of the PNP
collector d@ and the emitter ¿t2 of the regulating transistor
type. The transistor 138 has a base 14€), an emitter 162,
26 and, as will be explained hereinafter, passes a current
to maintain the circuit disconnected during an overload
and a collector 144, and the transistor 166 has a base
condition.
The base 56 of the driver transistor 38 is connected
to a current-amplifier circuit 6d which utilizes a differen
tial amplifier ior controlling the current passed into the 20
base Sil of the driver transistor 38. The diiferential
amplifier includes a transistor 64 and a transistor 66 both
of which may be of the PNP type. The transistor 64 has
a base 66, an emitter 7d, and a collector 72, and the
transistor 66 has a base 74, an emitter 76, and a collector 25
'76. The collector 72 of the transistor 64 is connected
to the base 5t! of the transistor 36 and the collector 7S
of the transistor 66 is connected to the collector 46 of the
regulating transistor 26. A biasing resistor Si) is con
nected between the collector ’72 of the transistor 64 and 30
the collector 78 of the transistor 66 to provide a leakage
current path from the base Sil of the transistor 38 when
the transistor 38 is biased out of conduction, as will be
explained subsequently. The emitters 70 and 76 of the
transistors 64 and 66 are connected by way of a current
limiting resistor 32 to a lead 84.
The lead 3d is con
ected to a terminal 88 which may be connected to a -|-l5
voltage unregulated source (not shown), which provides "î
a bias for maintaining operation of the circuit during an
overload condition. The base 68 of the transistor 64 is
connected to a lead 99 and the base ’74 of the transistor
66 is connected to a lead 92 through which leads, control
current passes, as will be explained subsequently. Thus,
the current ampliiier circuit 66 is connected for control
ling the regulating element circuit 32.
The current ampliñer circuit 6i) is controlled by an
146, and emitter 156, and a collector 152. The collector
144 of the transistor 138 is connected to the lead 162 by
way of a biasing resistor 156 and the collector 152 of the
transistor 146 is connected to the lead 102 by way of a
biasing resistor 158. The emitters 142 and 150 of the
transistors 138 and 146 are connected to ground lead 108
by way of a current limiting resistor 159. The base 148
of the transistor 146 is connected to a lead 162 by way of
an impedance-matching resistor 16d. The lead 162 is
connected to the ground lead 106 by way of a resistor
166 and is connected to the cathode of a diode 168, which
may be a Zener type diode. The anode of the diode 168
is connected to the lead 102 to provide a potential to the
base 14S of the transistor 146 which follows the variation
ot' the load potential on the lead 102. It is to be noted
that the resistor 164 is utilized to match the impedance
out of the base 14S of the transistor 146 to the impedance
out of the base 1d@ of the transistor 136.
The base 146 of the transistor 13S is connected by a
variable tap 172 to a resistor 174, one end of which is
connected to the lead 102 by way of a resistor 176 and
the other end of which is connected to ground lead 168
by way of a resistor 178. The resistors 174, 176, and
178 thus are a voltage divider of the potential diñerence
-acrossthe load 34 for dividing out a potential to control
the conduction of the transistor 138. The collector 144
of the transistor 138 is connected to the lead 92 which,
` in turn controls the conduction of the transistor 66, as
will be explained subsequently. The collector 152 of
they transistor 146 is connected to a lead 182 which, in
turn is connected to the junction 132 for receiivng current
overload control circuit 94 and a voltage comparator
from either the transistor 64 during normal regulation
circuit 96. The overload control circuit 94 includes a
or from the transistor 124 during an overload condition,
resistor R1 having one end connected to a junction 100
as will also be explained subsequently. A capacitor 180
which, in turn, is connected to the emitter d2 of the regu 50 is coupled across the leads 102 and 166 to stabilize the
lating transistor 26. The other end of the resistor R1
circuit for providing a low output impedance to signals
is connected through a lead 162 to the resistor RL of the , on the lead 102 at a frequency above the frequency re
load 34. The load current lL is indicated by an arrow
sponse of the transistors. in the circuit, as is well known
101. The resistor R1 in combination with the resistor RL
in the art.
of the load 313i provides a first voltage divider, as will be 55
The operation of the voltage regulator of this inven
explained subsequently. The junction 100 is also con
tion includes both normal voltage regulation of the load
nected through a lead 103 to a resistor R2 which in turn
voltage on the lead 102 to maintain a regulated voltage
is connected to one end of a resistor R3 by Way of a lead
and overload protection during operation when, for ex
166. r[he other end of the resistor R3 is connected to
ample, a fault such as a short circuit of the load 34 occurs.
60
the ground lead 168. The lead 102 is connected to the
During normal regulation, the regulating circuit controls
cathode of a diode 112 which has its anode connected to
the current through the series element which is the tran
one end of a resistor 114 by lead 116. The other end of
sistor» 26, to correct variations of the regulated potential
the resistor 114 is connected to the lead 84.
on the lead 102 caused either by voltage fluctuations
A signal transistor 117 which may be of the NPN type
of the source 2t) or by small variations of the effective
has a base 118, an emitter 126, and a collector 122 with 65 resistance of the load 3.4. A rise of potential on the
the base 118 connected to the lead 116 and the emitter
collector 40 from a positive-goingfluctuation of the un
126 connected to the lead 106. As will be explained
subsequently, the difference in potential drop across the
regulated potential from source 26` decreases the emitter
torcollector potential of the regulating transistor 26 and
resistor R1 and the diode, 112 and across the Aresistor R2,
atgthe value of> the current determined by the potential
which potential difference appears betweenthe leads 116 70 on the b-ase 44, results in a small decrease in collector
and 166, determines whether transistor 117 is biased into
current. This decrease oi collector current is accom
conduction. rlîhe collector 122 of the transistor 117 is
panied by a decrease of the current passing through load
connected to the base 126 of a transistor 124. which may
RL, which results in a rise in potential on the lead 102.
be of the PNP type. I The transistor 124 has an emitter 75 This rise in potential is sensed by thev voltage comparator
3,076,135
5
circuit 96 and, as will be described, >acts to lower the po
tential on base liti. This condition decreases the static
impedance of the transistor 23.6 to slightly increase the
load current so as to increase the potential drop across
the resistor RL and to restore the regulated potential on
the lead 162.
A decrease of the effective value of the resistor RL
the potential on the lead luz is regulated to -25 volts
by the action of a servo loop including a voltage corn
parator 96 and the path to the ‘oase ¿la of the regulating
transistor 2o. An increase of potential on the lead le?.
resulting from a Voltage variation ot the source 2d or
a srnall decrease in the value of the load 3ft impedance,
as discussed, impresses the increase of potential through
the constant voltage Zener diode lod to develop across
also causes an increase of potential on the lead i162. lt
the resistor lío for application to the 'oase 14S of the
is to be noted that this condition causes only a small in
crease of collector current of the regulating transistor Z6 10 transistor lido, as a potential increase substantially similar
in amplitude to the increase on the lead li’lZ. The
as determine by the potential on the base da. The increase
transistor 146 is thus biased so as to decrease its con
of potential on the lead Teil2 is sensed by the voltage
duction and this decreased current iiow through the re
comparator circuit 9o and, as will be described, acts to
sistor 153 results in a decrease of the potential on the
lower the potential on the base ¿i4 of the regulating
collector lSZ, which decrease is impressed on the base
transistor 26 so as to decrease the static impedance of
65 of the transistor 64 to increase its conduction. At
the transistor 26 and to increase the current from emitter
the same time, a small increase of potential is impressed
42 to collector ¿tu a required amount. rthis increase of
on the base lati of the transistor 13S from the tap 172.
collector current increases the current passing through the
However, because of the large decrease or" current through
load RL and causes a fall in potential on the lead lilZ,
the transistor ldd and through the resistor läd, the cur
thus restoring the regulated potential on the lead lûZ.
rent passing through the transistor 133 is increased. This
The operation of the voltage comparator' circuit 96
increase of current results from the diiierential action
and the current amplifier circuit oli during norrnal voltage
of a constant current passing through the current limiting
regulation will now be described. During normal voltage
resistor l59. Thus, there is an increase of potential on
regulation, the transistor il? is biased out of conduction
to interrupt the current path through the transistor 124 25 the collector lll-4i- of the transistor 13S which is impressed
on the ’oase 711i of the transistor do to bias it further out
to the junction 132. Thus, the potential developed on
of conduction. As a result of this action, the potential
the collector 152 of the transistor 146 from current pass~
ing through the transistor ldd and the resistor 158 is
impressed through the lead lil?! to the base ed to control
conduction »of the transistor ed. An increase (positive
going) of potential at the base ldd oi the transistor M6
on the collector '.72 of the transistor ed is increased be
cause of the decrease of potential on the base eff; to
bias the transistor 38 into further conduction and to
decrease the potential on the base
or" the transistor'
26. in response to t‘ne decrease of potential on the base
from the lead lo?. results in a decrease of potential on
4d, the static impedance of the transistor 25 is decreased
the collector 152 of the transistor ido. This decrease
(negative-going) of potential is impressed on the base 68 35 and increased current passes through the load RL to
decrease the potential on the lead
so as to correct
to increase the conduction of the transistor 64, and to in
the original rise in potentie. lt is to be noted that
crease the potential on the base Sil of the transistor Tail.
this operation is continuous. Also, a potential decrease
The transistor 33 is thus biased into further conduction
on the lead lo?. is corrected in a similar but opposite
and the potential on the hase
of the transistor 26 is
manner.
decreased to increase the ernitter to collector current
New that the norrnal regulating action of the power
through the transistor 26.
The potential impressed on the base ldd ot the tran
sistor i353 is also determined by the load potential on
the lead im, which potential acts to Vary the current
passed from the emitter i142 to the collector ldd of the
transistor T138. An increase of potential on the base lé-iâ
results in an increase of potential on the collector les?
of the transistor i3d because of the differential ampliiier
action, as will be described, which potential is impressed
supply has been explained, the action of the overload
control circuit 9d resulting from an overload condition
such as a short circuit of the load 34, will be describe .
rthe ratio oi the value of resistor R1 to that of the re
sistor RL of the load
to the ratio oí the value of re
sistor R2 to that of the resistor R3 is the relation which
determines the condition when an overload condition,
such as a short circuit, or" the load 3d is present. it is
to ‘oe noted that a short circuit of the load 34 results
on the base 74 of the transistor od to decrease its con 50 in the resistance RL being effectively reduced in value
duction. rlfhus, the potentials on the collectors ltd-4l» and
i152 are impressed through the leads 92 and i182 to the
bases 7d and 68 oiî the transistors 6d and ed.
The differential amplifier arrangement is utilized so
that changes of gain characteristics of the transistors ed, 55
66, i3d and lele have a very sinall eiiect on the regulat
and a current il, larger than rated current being sup
plied. The transistor fir? is biased out of conduction
during the normal regulating action when the voltage
drop across the resistor R1 is less than the voltage drop
across the resistor
However, when the voltage drop
across the resistor R1 is greater than the voltage drop
ing action. A. substantially constant current passes
across the resistor R2, resulting from a niaximurn load
through the current limiting resistor ‘£59 and through
current passing through the resistor R1 and the junc
the parallel resistors iSv-i and ldd. Thus, changes of
tion lilo, the transistor ll‘î is biased into conduction.
the gain characteristics due to ageing or temperature 60 Under these conditions, the ratio of R1 to RL is greater
changes, for example, of the transistors i3d and M6 has
than the ratio of R2 to R3 indicating a decrease of the
a relatively small eiiect on the difference in potential on
eiiective value ot the load resistor R .
the collectors las and 152. The difference in potential
effective load resistance lìmmm) is equal to
on the leads 92 and ld?. is the value which controls the
amount of conduction of the transistors 66 and ed and, 65
in turn, the impedance oi the regulating transistor Zd.
The current-limiting resistor d2 passing a constant cur
rent into the transistors 64 and ed of the iirst difierential
The minimum
R2
Titus, tl e maximum current if (mx) which is equal to
ampliíier circuit, cancels changes oi gain characteristics
of the transistors 6d and on in a similar manner. rl`hus, 70
RL(mln)
the differential amplilier arrangements of transistors i353,
may be expressed as follows:
145, 64 and do is utilized to provide reliable regulation
independent of temperature changes or ageing of the
-TL( mtlX >=MEOR2
RIRS
transistors, for example.
During the regulating operation of the power supply, 75 where E9 is equal to the potential on the lead 152 which
3,078,135,
7,
is the regulated voltage for determining the maximum
load current at which the overload control circuit 9d
becomes operative. When the load current IL increases
above the maximum rated value so that the voltage
drop across the resistor R1 is greater than the voltage
drop across R2, the transistor 117’ is biased into full con
duction. Thus, the transistor 124 is biased into conduc
tion, passing current from the emitter 12S to the coi
lector 13@ and into the junction 132 and to the lead
132. The positive potential from the lead 34 is im
pressed through the transistor 124i- and upon the base
d8 of the transistor de to bias it out of conduction.
When the transistor 64 is biased out of conduction, the
driver transistor 3S is biased out of conduction and, in
turn, the regulating transistor 26 is biased out of con
duction to develop a high impedance to flow of load
current IL. Thus, the source 20 is effectively discon
nected from the load 34 under this overload condition.
The foregoing overload condition with the transistor
8
rent of l ampere to a grounded load from a -32 volt
unregulated source:
Transistor
Transistor
Transistor
Transistor
2d, Delco (GM) _____________ __
3S, Sylvania _________________ ..„
de, General Electric ___________ __
de, General Electric ___________ __.
Transistor lli?,
Transistor 121i,
Transistor i3d,
Transisto-r'ildá,
General Electric _________ __ 4jD4A5
Philco __________________ __
T 1275
Hughes _________________ __ HA-7550
Hughes _________________ _- IHA-7550
Terminal d8 ____________________ „volts“
Resistor
____________________ „ohms“
Resistor dit _____________________ __do____
Resistor 82 --------------------- „d0“-`
Resistor i312» ____________________ __do_..__.
Resistor R1 _____________________ „do_„„_
Resistor
Resistor
Resistor
3.1"/ biased in a conductive state is maintained by a small 20 Resistor
R2 _____________________ __do„_„_
R3 _____________________ „_do__-„
Rmmm) _________________ „_do____
il@ ____________________ __do_-__
current flow through the leakage resistor 5ft or by a small
Resistor 156 ____________________ .__d0_„__
leakage current through the transistor 2d. it is to be
Resistor 153 ____________________ __do___..
noted that when the transistor Zd is of a type with a small
Resistor 159 ____________________ _-do_.._..
leakage current, the leakage resistor 5d is not required.
„Resistor 16t- ____________________ __do____
This leakage current passes from the resistor RL through
Resistor lied ____________________ __do-..__
the resistor R1 as well as through the resistors R3 and R2
Resistor 174 ____________________ __do____
to the junction litt) to maintain a potential ditterence from
Resistor 176 ____________________ __do____
the base 118 to the emitter i2@ of the signal transistor
Resistor 17S ____________________ __do__.._
li?. The potential drop across the resistor R2 is greater
Capacitor ld@ ____________ __microfarads__
than the drop across the resistor R2 because of their- 30 Diode i12, Hughes _____________________ __
relative values. The base lid of the transistor 1l? is
.Diode 168, Hoffman ___________________ _.-
biased by current passing from the +15 volt unregulated
source at the terminal 88 through the resistor i114, through
2N173
2Nl42
2N123
2N123
+15
2,000
10o
10,000
l0
2
909
11,300
25
39,009
5,110
5,110
8,060
560
1,690
200
75()
1,580
350
6,007
iN 430A
lt is to be noted that although the power supply has
been described as supplying negative potentials relative to
the diode M2 and through the leakage resistor 5d. It is to
be noted that current through the resistor 1M acts 35 ground potential, it may be easily arranged to supply posi
tive potential relative to ground potential by reversing all
to maintain the diode H2 forward biased during both
voltages and changing the transistor types.
normal regulation and an overload condition. Also, the
Referring now to FIG. 2, which is a graph of load
transistor i24- is biased into conduction during an over
load condition by the +15 volt potential from the termi
nal 3S to apply the biasing potential to the junction £32
and the base 68 of the transistor
Thus, the +15
volt terminal dit is required to maintain the transistors
potential versus load current, as well as referring to FiG.
l, the operation of the voltage regulator will be explained
in further detail. The constant regulator dissipation line
184i is shown to indicate the power capabilities of the
regulating transistor 26. The regulated potential is shown
T17 and 124 biased in conduction during an overload
condition.
as -25 volts, and the maximum load current is shown
The transistor lll'í and the diode i12 are of similar type 45 as 1 ampere which is equal to
materials, so that an increase in impedance characteristics
EuRz
of the diode 112 and the transistor lill’î from temperature
RlRa
changes, for example, is similar. Thus, an increase of
impedance characteristics resulting in an increased po
Thus, the voltage regulator can operate anywhere on a
tential diiTerence for biasing the transistor M7 into con
-25 volt line T83. When an overload condition occurs
duction is cancelled by an increase of potential drop
at the maximum load current of 1 ampere, the return
across the diode 112. Therer’ore, the ratio of potential
path of the load potential E0 and the load current IL
drop across the resistors R1 and R2 for biasing the tran
is shown by the turn-oliC curve T36 which is a straight
sister M7 into conduction remains constant and the maxi
line. This straight line results from the linear relation
mum load current lL at which the overload protection cir 55 between the resistors R1, R2 and R3 in relation to the
cuit becomes operative remains constant.
voltage En and ground potential. The slope
'When the load 34 returns to a condition such that there
is a voltage drop across resistor RL indicating a required
load current of maximum load current or less to cause a
En
E
decreased voltage En to be impressed on the lead Th2, 60 of the turn-ofi line may be expressed by the following
the potential drop across resistor R1 will be less than the
relation when the transistor 117 is biased into conduc
potential drop across the resistor R2. Thus, the tran»
tion upon the occurrence of an overload condition:
sistor lil? is biased out of conduction, the transistor 124 is
biased out of conduction, and the transistor d-i- is biased
IL- R2
into conduction to cause the» transistors 38 and 26 to be 65
Thus, the return path of the load current and the load
biased into conduction. Thus, the normal regulating ac
tion of the voltage comparator circuit 96, as previously
described, 'will continue.
While it will be understood that the circuit specifica
tion of the power supply of the invention may vary ac
cording to the design of any particular- application, the
following circuit speciíications for a power supply are in
cluded, by way of example only, suitable to supply a
voltage is determined only by the values of the resistors
R1, R2 and R3 in the two voltage divider circuits. i This
linear turn-on' curve ide allows the voltage regulator to
70 turn completely oli when an overload condition at maxi
mum load current occurs and to turn completely on to
supply maximum load upon removal or" the overload
condition. The operation of the circuit when turning on
to supply a load which is less than maximum is shown by
regulated voltage ofA ~--25 volts at a maximum load cur" 75 a line> t‘ßtl. _lt_ isA to be noted that conventional voltage
adsense
il
impedance element and a load connected between ter
minals of said source, a comparator loop coupled in par
allel with said load for developing a signal proportional
to minor variations in Voltage across said load and means
for connecting said proportional signal to a control ter
minal of said variable impedance element to overcome
said minor variations when said loop is operative, com
prising first impedance means coupled between said varia
ble impedance element and said load for developing a
i2
when said regulating element is disconnected, and a source
oi biasing potential coupled to said overload means for
biasing said overload means to maintain said disconnect
ing signal when said load is in a condition to pass current
which exceeds said maximum value.
ß. A voltage regulator circuit for supplying current
from an unregulated source through a load, comprising
regulating means controlled to vary in impedance to load
current coupled between one terminal of said source and
iirst potential, second impedance means coupled from 10 said load and having a control terminal, voltage compar
one side of said load at a point between said Variable
impedance element and said iirst impedance means to the
opposite side of said load for developing a second poten
tial proportional to the voltage across said load, and
switching means coupled from between said first imp-ed
ance means and said load to said second impedance means
to be rendered conductive or nonconductive in response
ing means including a ñrst differential ampliñer con»
nected to develop a signal proportional to minor varia
tions of potential across said load and including a second
differential amplifier connected to said control terminal
for responding to said proportional signal to control said
regulating means for correcting said minor variations,
iirst voltage dividing means coupled between said regulat
ing means and said load, second voltage dividing means
coupled from one side of said load at a point between
and including means coupled to said comparator loop for 20 said regulating means and said first voltage dividing means
applyingk an overload signal to bias said switching means
to the other side of said load and responsive to the volt~
into conduction for controlling said comparator loop to
age developed across said load, overload means con
be inoperative and to increase the impedance of said im
trollable to be biased into a first state of conduction or
to the diíîerence in potential of said first and second po
tentials across said first and second impedance means
pedance element to disconnect said source from said load
into a second state of nonconductin and coupled between
when said current through said load exceeds a predeter 25 said first and second voltage dividing means responsive
mined value.
to a potential difference having a polarity indicative of a
6. A regulator circuit comprising an unregulated volt
maximum load current for being biased to said iirst state
age source having first and second terminal, a series cir
to apply an overload signal to said second dilierential
cuit including in relative order a variable impedance
amplifier for disconnecting said regulating means, a cur
coupled to said first terminal, a iixed impedance and a 30 rent leakage path coupled in parallel with said regulating
load coupled to said second terminal, means connected
element to conduct current for maintaining said potential
in parallel with said load including a differential amplifier
difference when said regulating element is disconnected,
to develop a proportional signal in response to minor
and a source of biasing potential for biasing said overload
variations of potential across said load and including
means to maintain said overload signal when said polarity
means for coupling said proportional signal to a control 35 is indicative of said maximum load current.
terminal of said variable impedance to overcome said
9. A regulator circuit to supply current at a constant
minor variations, voltage divider means coupled from
potential from an unregulated source through a load
between said variable impedance and said iixed imped
coupled between terminals of said source and comprising
ance to said second terminal, switching means having
a regulating transistor having an emitter-collector path
either a first state of conduction or a second state of non 40 coupled between said source and said load and having a
conduction and coupled from between said fixed imped~
base, an impedance coupled between said ernitter-col~
ance and said load to said voltage divider means to be
lector path and said load to form a first voltage divider
responsive to the difference in potential across said fixed
with said load, a second voltage divider coupled from
impedance and said load and across said voltage divider
between said regulating transistor and said impedance
means to supp-ly a disconnecting signal to said variable 45 across said load for responding to variations of potential
impedance when current through said load exceeds a pre
across said load, a comparator circuit including a first
determined Value to bias said switching means to said
differential amplifier coupled across said load for develop
ñrst state, and a leakage path across said variable imped~
ing a signal proportional to variations of potential across
ance for conducting a current to maintain said discon
said load, a source of maintaining potential, a second dif
necting signal while said load is in a condition to pass 50 ‘erential amplifier coupled between said base of said regu~
a current which exceeds said predetermined value.
lating transistor and said source of maintaining potential
7. A voltage regulator comprising an unregulated
and connected to respond to said proportional signal for
source, a series circuit including a regulating element and
controlling the impedance of said regulating transistor to
a load coupled between terminals of said source, a feed
correct said variations of potential, a first overload tran»
back loopl coupled to develop a signal proportional to
variations of potential across said load and including
sistor having a base coupled to said iirst voltage divider
and having an emitter-collector path coupled to said sec
ond voltage divider, a second overload transistor having
a base coupled to the emitter-collector path of said first
impedance means coupled between said regulating ele
overload transistor and having an emitter-collector path
ment and said load for forming a first Voltage divider 60 coupled between said source of maintaining potential and
with said load, a second voltage divider coupled from
said second differential amplifier to overcome said pro
between said regulating element and said ñrst voltage
portional signal and disconnect said regulating transistor
divider across said load, overload means having a ñrst
when said first overload transistor is biased into conduc
amplifying means for coupling said proportional signal
to a control terminal of said regulating element, a first
state where said overload means is conductive and a sec
tion in response to a predetermined polarity of a poten~
ond state where said overloadV means is nonconductive 65 tial difference between said first and second voltage di~
and coupled to said íirst and second voltage dividers to
viders indicative of a greater than maximum load current,
be responsive to the diderence in potential between said
first and second voltage dividers for developing a discon
and a leakage path across said emitter-collector path of
when current through said load exceeds a maximum value
than maximum current would pass through said load.
10. A power supply circuit to provide load current at
said regulating transistor for passing current through said
necting signal for increasing the impedance of said regu~
first and second voltage dividers to maintain said poten
lating element to disconnect said source from said load 70 tial diiïerence when said polarity is indicative that greater
and said overload means is biased to said first state, a cur
rent leakage path coupled in parallel to said regulating
element for passing a current through said first and second
a constant potential from an unregulated source to a load
to disconnect said source from said load during an
voltage dividers to maintain said difference in potential 515 >and
overload condition when said> load currentexceeds a pre
8,076,135
13
determined value, comprising a regulating transistor hav
ing a load current path coupled between said source and
said load and having a base terminal, signal amplitier
means coupled to said base terminal for controlling the
impedance of said regulating transistor and having a con
trol terminal, a voltage comparator coupled across said
load to respond to potential variations and coupled to
said control terminal of said amplilier means for correct
ing said potential variations, a iirst resistor coupled between said load current path of said regulating transistor
and said load for forming a first voltage divider with
said load, a second voltage divider coupled from one
14
pliiier coupled to develop a signal proportional to the
potential variation across said load and including a sec~
ond differential amplifier coupled between said base ter
minal and a source of biasing potential being positive rela.
tive to said positive terminal of said source for responding
to said proportional signal developed by said comparator
loop to vary the impedance of said regulating transistor
for correcting said potential variation, a first control tran.
sistor having a base coupled to said first voltage divider
and to said source of biasing potential and having an
emitter-collector path with one end coupled to said sec
ond voltage divider for responding to the potential de
veloped thereby, a second control transistor having a base
coupled to the other end of said emitter-collector path of
path of said regulating element and said lirst resistor to
the other side of said load for responding to the potential 15 said first control transistor and having an emitter-col
lector path coupled between said source of biasing po
across said load, a tirst signal forming transistor having
tential and said second dilferential amplifier, said first
a base coupled to said tirst voltage divider and having
control transistor responding to the potential difference
an emitter-collector path coupled to said second voltage
across said first and second voltage dividers for being
divider, a second signal forming transistor coupled be
tween said emitter-collector path of said first signal fortn 20 biased into conduction to in turn bias said second control
transistor into conduction to develop an overload signal
ing transistor and said amplifier means and being biased
for disconnecting said regulating transistor in response to
into »conduction for developing an overload signal in re
an overload current condition, said source of biasing po
sponse to a predetermined polarity of potential between
tential maintaining said overload signal, and a leakage
said first and second voltage dividers for biasing said iirst
signal forming transistor into conduction indicative of 25 path across said regulating transistor for passing current
from said first and second voltage dividers to render them
an overload condition causing said load current to exceed
responsive for maintaining said control transistor biased
said predetermined value, said overload signal acting to
in conduction during said overload condition.
increase the impedance of said regulating element to de
side of said load at a point between said load current
crease said load current to a maintaining current having
a small value relative to said predetermined value, said 30
maintaining current passing through said first and second
voltage dividers to maintain said overload signal for dis
connecting said source from said load during the occur
rence of said overload condition.
11. A circuit connected between the positive and nega 35
tive terminals of an unregulated source to supply current
through a load at a constant potential, comprising a regu
lating transistor having an emitter-collector path coupled
References Cited in the iile of this patent
UNITED STATES PATENTS
825,023
2,832,900
2,888,633
2,896,151
2,904,742
2,915,693
2,922,945
Marantette ___________ __ Feb. 25,
Ford ________________ __ Apr. 29,
Carter ______________ __ May 26,
Zelinka _____________ __ July 21,
Chase ______________ .__ Sept. 15,
Harrison _____________ __ Dec. 1,
Norris et al ___________ __ I an. 26,
1958
1958
1959
1959
1959
1959
1960
between said negative terminal of said source and said
OTHER REFERENCES
load and having a base terminal, a resistor coupled be 40
tween said regulating transistor and said load to form a
“The Emitter-Coupled Dilïerential Amplifier,” Slaugh
first voltage divider with said load, a second voltage di
ter, IRE Transactions, March 1956, pp. 51-53.
vider coupled between said regulating transistor and said
Dodge: “A Transistorized Overload-Proof Electronic
resistor to said positive terminal for developing a poten
Regulator,” Transistor and Solid State Circuit Conference,
tial proportional to the potential developed across said
load, a comparator loop including a íirst diiierential arn
Digest of Technical Papers, Feb. 2G, 1958, pp. 35-36.
Документ
Категория
Без категории
Просмотров
2
Размер файла
1 421 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа