JPH08106331A - Power source controller - Google Patents

Abstract

PURPOSE: To select control over the supply and cutoff of a power source or control over its output voltage by providing a means which forcibly turns ON a transistor(TR) and making its output ineffective, and providing a means which forcibly turning OFF a TR. CONSTITUTION: When an H signal is inputted to an ON/OFF terminal 7, the base voltages of TRs Q5 and Q6 go up to an H level and the TRs Q5 and Q6 turn ON. Therefore, the base voltage of a TR Q3 goes down to an L level and the TR Q3 turns OFF. Further, the base voltage of a TR Q2 also falls to the L level and the TR Q2 turns OFF. Consequently, a resistor R1 has no voltage drop and a voltage control TR Q1 is held OFF, so that an output voltage to a load becomes 0V. Then when an L signal is inputted to the ON/OFF terminal 7 and an H signal is inputted to a switching terminal 6, the TR Q3 turns ON and the voltage control TR Q1 is always in the ON state through similar operation. The output to the load, therefore, becomes 12V at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for power supply control in electronic equipment, and more particularly to a power supply control device capable of easily selecting an output voltage, a current limit value and the like.

[0002]

2. Description of the Related Art Conventionally, there are roughly two types of integrated circuits for power supply control used in electronic equipment, one is an integrated circuit for a switch for controlling the supply and cutoff of the power supply, and the other is an integrated circuit for a power supply.
One was an integrated circuit for a regulator that outputs a desired voltage. Then, some integrated circuits have an additional function such as a current limiting function for preventing overcurrent as necessary.

[0003]

Therefore, in the case of using the conventional integrated circuit, it is necessary to use a plurality of integrated circuits to control the power supply / interruption and the output voltage, which results in high cost. However, there is a problem that the mounting area on the printed circuit board increases and hinders miniaturization. or,
It is desired to increase the versatility of the power supply control integrated circuit, and for that reason, realization of an integrated circuit that can easily set the output voltage and the current limit value is an issue.

Therefore, the present invention solves these problems and problems, and it is possible to select either power supply / interruption control or output voltage control with a simple circuit configuration, and current limit control. It is an object of the present invention to realize a power supply control device that can achieve the above.

[0005]

The present invention, which achieves the above-mentioned object, has a voltage control transistor for controlling the conductivity between a power source and a load, and controlling the supply voltage to the load by the conductivity. In a power supply control device, forced conduction means for forcibly turning on the transistor, and forced non-conduction means for nullifying the output of the forced conduction means and forcibly turning off the voltage control transistor. And is provided.

Further, a voltage control transistor for controlling the conductivity between the power source and the load and controlling the supply voltage to the load by the conductivity is compared with the voltage control transistor for the load and the reference voltage,
A comparator circuit for controlling the conductivity of the voltage control transistor according to the comparison result, which is an integrated circuit sealed in a package, the power source line having one end connected to the power source, the power source line being provided in the package. A reference voltage setting internal resistor connected to the reference voltage input terminal of the comparison circuit and a reference voltage setting terminal protruding to the outside of the package while being connected to the other end is provided, and the reference voltage setting terminal is set to the reference voltage setting terminal. By connecting elements, a desired reference voltage can be applied to the reference voltage input terminal of the comparator.

Further, a voltage control transistor for controlling the conductivity between the power source and the load and controlling the supply voltage to the load by the conductivity, and a diode for current detection connected between the voltage control transistor and the voltage control transistor. A package including: a differential amplifier that amplifies a voltage difference between both ends of the diode; and a current limiting circuit that limits a current to the load when an output voltage of the differential amplifier becomes a predetermined voltage or more, A pair of feedback resistance connection terminals that are respectively connected to the input and output terminals of the differential amplifier and project outside the package, and that connect a resistance element to the feedback resistance connection terminals. Thus, the feedback resistance value of the differential amplifier is set to a desired resistance value, and the amplification factor of the differential amplifier is changed so that the current value at which the current to the load is limited can be changed. It is intended.

[0008]

According to the present invention by the above means, when both the forced conduction means and the forced non-conduction means are in the non-activated state, the output voltage is a voltage determined by the conductivity of the voltage control transistor, that is, the regulation. It becomes the rate voltage. or,
When the forced conduction means is in the activated state and the forced non-conduction means is in the deactivated state, the voltage control transistor is always in the conduction state and the output voltage is the power supply voltage. And
When the forced non-conducting means is activated, the forced conducting means is deactivated, the voltage control transistor is always non-conductive, and the power supply to the load is cut off.

Further, according to the second invention, by connecting a reference voltage setting element to the reference voltage setting terminal, the reference voltage setting element and the reference voltage setting internal resistance are connected to the reference voltage input terminal of the comparison circuit. A reference voltage determined by and is applied, and the voltage corresponding to that voltage becomes the output voltage to the load. Further, according to the third invention, by connecting a resistance element to the feedback resistance connection terminal, a feedback resistance value of the differential amplifier that outputs a signal for activating the current limiting circuit is set, and the differential resistance is set. The amplification degree of the amplifier is set according to the resistance element. Therefore, the current value to the load when the current limiting circuit is activated, that is, the current limiting value is set by the resistance element connected to the feedback resistance connection terminal.

[0010]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a circuit diagram of a power supply control integrated circuit used in a vehicle-mounted device according to an embodiment of the present invention. The present embodiment will be described below with reference to the drawings. In this embodiment, the H signal and the L signal are voltage level signals for controlling the conduction and non-conduction of the voltage control transistor and the like. For example, the H signal is a 5V signal and the L signal is a 0V signal.

The H level and the L level are voltage levels applied to the control terminal of the voltage control transistor, for example, the H level is 5V and the L level is 0V. Reference numeral 1 denotes a power supply control integrated circuit (power supply IC), which is sealed in a dotted line with a package formed of a resin material or the like, and only terminals protrude from the package. A power input terminal 2 of the power IC 1 is connected to a battery, and a battery voltage (for example, DC 12V) is input into the power IC.

Q1 is a voltage control transistor, the emitter of which is connected to the input terminal 2 and the collector of which is connected to the output terminal 3. The base of the voltage control transistor Q1 is grounded via the transistor Q2 and the transistor Q3. A resistor R1 is connected between the emitter and base of the voltage control transistor Q1.

An output terminal 3 is connected to the load and supplies the load with a voltage applied to the input terminal 2 (battery voltage) or a regulated voltage converted into a desired voltage. Reference numeral 4 denotes a regulated voltage setting terminal, which is connected to the input terminal 2 (battery) via a resistor R2. Then, the setting terminal 4 is connected with a Zener diode 5 or the like having a characteristic suitable for the regulator output voltage to set the regulator output voltage.

OP1 is a comparator, which compares the set voltage Vref of the regulator output voltage with the voltage Vo of the output terminal 3 and outputs a signal of a voltage (a higher voltage of Vo indicates a lower voltage) according to the comparison result to the transistor Q2. Applied to the base of to control the conductivity of transistor Q2. Reference numeral 6 is a switching terminal for switching the output voltage Vo, which is a transistor Q3.
It is connected to the base of the transistor Q4 and the collector of the transistor Q6, and the output voltage of the output terminal 3 can be switched between the battery voltage and the regulated voltage by giving a control signal (H signal, L signal).

Reference numeral 7 is an on / off terminal for switching whether to output a power supply output, which is connected to the bases of the transistors Q5 and Q6, and a control signal is input to the on / off terminal 7 to output the output terminal 3 It is possible to switch whether or not to supply a power source (battery voltage or regulated voltage). Also, resistors (R1 to R15) necessary for voltage division, signal input, etc. are arranged in each part of the circuit.

Next, the operation of the circuit will be described with reference to FIG. FIG. 2 shows the control signal input to the switching terminal 6, the on / off terminal 7, and the operating states of the transistors Q1 to Q6. The control signal input to the switching terminal 6 and the control signal input to the on / off terminal 7 are shown. (H = 5V / L = 0V)
And the relationship between the states of the transistors Q1 to Q6 and the output voltage Vo.

When an H signal is input to the on / off terminal 7,
(The input signal to the switching terminal 6 may be an H signal or an L signal) The base voltage of the transistors Q6 and Q5 becomes H level, and the transistors Q6 and Q5 are turned on. Therefore, the transistor Q3
The base voltage becomes low (grounded by the transistor Q5), and the transistor Q3 is turned off (cut off). Further, the base voltage of the transistor Q2 also becomes L level (grounded by the transistor Q6), and the transistor Q2 is turned off.

Therefore, there is no current flowing through the resistor R1 and no voltage drop occurs due to the resistor R1. Therefore, the base voltage of the voltage control transistor Q1 remains at H level, and the voltage control transistor Q1 is held in the off state. Therefore, when the H signal is input to the on / off terminal 7, the output voltage (output terminal voltage) to the load becomes 0V. next,
When the L signal is input to the on / off terminal 7 and the H signal is input to the switching terminal 6, the base voltages of the transistors Q6 and Q5 become L level, and the transistors Q6 and Q5 are turned off. Therefore, the transistor Q3
Becomes high (the transistor Q6 is off [cutoff], so the control signal [H signal] to the switching terminal 6 is applied to the base of the transistor Q3), and the transistor Q3 is turned on. Therefore, a current flows through the path of the power input terminal 2, the resistor R1, the resistor R6, the transistor Q3, and the ground, and the current flowing through the resistor R1 causes a voltage drop, resulting in a potential difference between the emitter and the base of the voltage control transistor Q1 and voltage control. The transistor Q1 is always on. Therefore, when the L signal is input to the on / off terminal 7 and the H signal is input to the switching terminal 6, the output voltage to the load (output terminal voltage) is always 12 V (battery voltage). That is, by inputting an H or L signal to the on / off terminal 7, the integrated circuit of this embodiment performs a voltage control operation as to whether or not to supply power.

When an L signal is input to the on / off terminal 7 and an L signal is input to the switching terminal 6, the base voltages of the transistors Q3 to Q6 are all at the L level and the transistors Q3 to Q6.
All Q6 are turned off. Therefore, the transistor Q2
The output signal of the comparison circuit OP1 is applied to the base of the transistor Q1, and the conductivity of the transistor Q2 changes according to the output voltage. That is, if the output voltage Vo of the output terminal 3 becomes lower than the reference voltage Vref, the conductivity of the voltage control transistor Q1 increases, and conversely, if the output voltage Vo exceeds the reference voltage Vref, the conductivity of the voltage control transistor Q1 decreases. Then, the output voltage Vo is controlled to become the reference voltage Vref.

As described above, in this embodiment, the switching terminal 6,
With the control signal input to the on / off terminal 7, it is possible to easily control whether or not the power source of the load is supplied and the voltage to be supplied to the load, and to set the regulated voltage value to the setting terminal 4 by an electric signal. This can be performed by a simple work of connecting elements (zener diodes). The electric element for setting the regulated voltage is not limited to the Zener diode, and an element such as a resistor may be used.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention, which is a circuit diagram of a power supply controlling integrated circuit having a current limiting function. The circuit configurations similar to those in FIG. 1 are omitted or given the same numbers. Reference numeral 1 denotes a power supply control integrated circuit (power supply IC), which is sealed in a dotted line with a package formed of a resin material or the like, and only terminals protrude from the package.

D1 is a current detection diode D1 for detecting the current supplied to the load, which is connected between the voltage control transistor Q1 and the output terminal 3, and a voltage corresponding to the current supplied to the load is applied between both terminals. appear. Current detection diode D
The anode side of 1 is two resistors R20 connected in series,
It is grounded via R21, and the cathode side is similarly grounded via resistors R22 and R23.

OP2 is a differential amplifier whose non-inverting input is connected between the resistors R20 and R21, and whose inverting input side is the input resistor R.
It is connected between the resistors R22 and R23 via s. The output of the differential amplifier OP2 is the voltage dividing resistors R24 and R2.
The voltage is divided by 5 and output to the base of the transistor Q10, and also output to the setting terminal 102 for setting the limiting current. Further, the inverting input of the differential amplifier OP2 is also connected to a setting terminal 101 for setting the limiting current, and a resistor Rf (power source I connected between the setting terminals 101 and 102).
Connected to the outside of C) functions as a feedback resistor.

The transistor Q10 is a transistor for cutting off the load current, and controls to cut off the load current when it is turned on (conducting). For example, the collector of the transistor Q10 is the transistor Q2 of FIG.
To prevent malfunction of the transistors Q2 and Q3 at the base of Q3 (to prevent the voltage applied to the base of the transistor Q10 from being applied to the bases of the transistors Q2 and Q3)
It is connected through diodes D2 and D3, and when the transistor Q10 is on, the transistors Q2 and Q3 are forcibly turned off to keep the voltage control transistor Q1 in the off state and cut off the current to the load.

The current for interrupting the current is determined by the amplification degree of the differential amplifier OP2, that is, the ratio of the input resistance Rs and the feedback resistance Rf, and eventually the setting terminal 1 of the power supply IC.
It is determined by the feedback resistance Rf externally connected between 01 and 102. Next, the operation of the circuit will be described. When the current flowing through the load is normal, the potential difference across the current detection diode D1 is small. Therefore, the potential difference between both input terminals of the differential amplifier OP2 is small, and the output voltage thereof is also small. Therefore, the base voltage of the transistor Q10 becomes L level (the level at which the transistor Q10 does not turn on), and the off state is maintained, so that the current limiting operation is not performed.

When the current flowing through the load becomes abnormally large, the potential difference between both ends of the current detection diode D1 becomes large, the potential difference between both input terminals of the differential amplifier OP2 becomes large, and its output voltage also becomes large. Therefore, the base voltage of the transistor Q10 becomes H level (the level at which the transistor Q10 is turned on), and the transistor Q10 is turned on.
The transistors Q2 and Q3 are forcibly turned off (the bases of the transistors Q2 and Q3 are connected to the diodes D2 and S3).
To the ground state) via the voltage control transistor Q1
Is kept off and the current to the load is shut off.

As described above, according to this embodiment, it is possible to prevent an abnormal current from flowing through the load, and it is possible to easily set the current level to the load for interrupting the current.

[0028]

As described above, according to the present invention, it is possible to realize, with a simple configuration, a power supply control device that can easily control whether or not to supply power to a load and control the supply voltage. Further, the power supply voltage supplied to the load can be set by a simple operation of connecting the reference voltage setting element to the reference voltage setting terminal.

Further, the current value for starting the current limiting operation for limiting the current flowing through the load can be set by a simple operation of connecting the resistance element to the feedback resistance connection terminal.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an integrated circuit showing an embodiment of the present invention.

FIG. 2 is a diagram showing a state of each part of the power supply IC.

FIG. 3 is a circuit diagram of an integrated circuit showing a second embodiment of the present invention.

[Explanation of symbols] 1 ... Integrated circuit for power supply control (power supply IC) 2 ... Power supply input terminal 3 ... Output terminal 4 ... Regulated voltage setting terminal 5 ... Zener diode 6 ... Switching terminal 7 ... On / off terminal OP1 ... Comparator Q1 ... ・ Voltage control transistor

Claims (3)

[Claims] 1. A power supply control device having a voltage control transistor for controlling conductivity between a power supply and a load, and controlling a supply voltage to the load by the conductivity, forcibly bringing the transistor into a conductive state. A power supply control device comprising: a forced conduction unit; and a forced non-conduction unit that nullifies an output of the forced conduction unit and forcibly brings the voltage control transistor into a non-conduction state. 2. A voltage control transistor for controlling the conductivity between a power source and a load, and controlling the supply voltage to the load by the conductivity, and the voltage supplied to the load and a reference voltage are compared, and the comparison result is obtained. And a comparator circuit for controlling the conductivity of the voltage control transistor according to the present invention, the integrated circuit being sealed in a package, the integrated circuit being provided in the package and having one end connected to a power supply line connected to the power supply. At the same time, the other end is provided with a reference voltage setting internal resistance connected to the reference voltage input end of the comparison circuit and the reference voltage setting terminal protruding to the outside of the package, and the reference voltage setting element is connected to the reference voltage setting terminal. By so doing, it is possible to apply a desired reference voltage to the reference voltage input terminal of the comparator. 3. A voltage control transistor for controlling conductivity between a power source and a load, and controlling the supply voltage to the load by the conductivity, and a diode for current detection connected between the voltage control transistor. A package including: a differential amplifier that amplifies a voltage difference between both ends of the diode; and a current limiting circuit that limits a current to the load when an output voltage of the differential amplifier becomes a predetermined voltage or more, A pair of feedback resistance connection terminals that are respectively connected to the input and output terminals of the differential amplifier and project outside the package, and that connect a resistance element to the feedback resistance connection terminals. Therefore, the feedback resistance value of the differential amplifier is set to a desired resistance value,
A power supply control device characterized in that a current value at which a current to the load is limited can be changed by changing an amplification degree of the differential amplifier.