JP2002358130A - Regulator integrated circuit and voltage stabilizing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the voltage drop and power loss of a current limiting resistance while extremely reducing short currents. SOLUTION: This regulator integrated circuit is provided with an input terminal 1a and output terminal 1b, so that a voltage inputted from the input terminal 1a can be stabilized into a constant voltage, and outputted from the output terminal 1b. The regulator integrated circuit is provided with a control terminal 1c for switching on and off the output voltage of the output terminal 1b, so that the output of the output terminal 1b can be switched on and off by switching an 'H' or 'L' signal to be inputted to the control terminal 1c. The voltage stabilizing circuit is provided with the regulator integrated circuit 1 and a control circuit 2 for controlling on and off the output of the regulator integrated circuit 1. The control circuit 2 detects the output voltage of the output terminal 1b, and outputs the 'H' or 'L' signal to the control terminal 1c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a regulator integrated circuit for stabilizing an input voltage to a constant voltage and outputting the same,
The present invention relates to a voltage stabilizing circuit including the regulator integrated circuit.

[0002]

2. Description of the Related Art FIG. 1 shows a voltage stabilizing circuit provided with a conventional regulator integrated circuit. This voltage stabilization circuit
A current limiting resistor R for limiting a current is connected in series to an input terminal 1a of the regulator integrated circuit 1. Output terminal 1
This is to prevent the regulator integrated circuit 1 from being thermally destroyed by limiting a large short-circuit current in a state where b is short-circuited. However, this voltage stabilization circuit
It is difficult to select the resistance value of the current limiting resistor. In order to effectively limit the short current, it is necessary to increase the resistance value of the current limiting resistor. However, the current limiting resistor with a large resistance value is
The voltage drop increases under normal operating conditions. The voltage drop of the current limiting resistor increases power loss. Therefore, the current limiting resistor consumes useless power. Further, since the voltage drops at the current limiting resistor, it is necessary to increase the voltage input to the voltage stabilizing circuit. If the resistance value of the current limiting resistor is reduced to reduce this adverse effect, the short-circuit current increases and it becomes difficult to effectively protect the regulator integrated circuit.

[0003]

Therefore, in a voltage stabilizing circuit in which a current limiting resistor is connected in series to the input side, it is extremely difficult to optimize the resistance value of the current limiting resistor.
In addition, there is a disadvantage that the current limiting resistor wastes power.

[0004] The present invention has been developed to solve this drawback. An important object of the present invention is to provide a regulator integrated circuit and a voltage stabilization circuit that can minimize a voltage drop and a power loss of a current limiting resistor while minimizing a short-circuit current.

[0005]

SUMMARY OF THE INVENTION A regulator integrated circuit according to the present invention has an input terminal 1a and an output terminal 1b, stabilizes a voltage input from the input terminal 1a to a constant voltage, and outputs the voltage from an output terminal 1b. . The regulator integrated circuit includes a control terminal 1 for switching the output voltage of the output terminal 1b on and off.
c, and switches the "H" or "L" signal input to the control terminal 1c to switch the output of the output terminal 1b on and off.

The regulator integrated circuit 1 has a control terminal 1c.
Can be turned on when "H" is input, and turned off when "L" is input.

The voltage stabilizing circuit according to the present invention has an input terminal 1a
And a regulator integrated circuit 1 having an output terminal 1b, a regulator integrated circuit 1 for stabilizing a voltage input from the input terminal 1a to a constant voltage, and outputting the voltage from the output terminal 1b.
And a control circuit 2 for turning on and off the output. The regulator integrated circuit 1 receives the input “H” or “L”.
And a control terminal 1c for switching the output of the output terminal 1b on and off in response to the signal. The control circuit 2 detects the output voltage of the output terminal 1b and outputs "H" or "L" to the control terminal 1c. The control circuit 2 outputs "H" to the control terminal 1c when the output terminal 1b is "H" to turn on the output of the regulator integrated circuit 1, and when the output terminal 1b is "L", the control terminal 1c To "L" to turn off the output of the regulator integrated circuit 1.

[0008] In the voltage stabilizing circuit, preferably, the control circuit 2 includes a first transistor 8 and a second transistor 9. The first transistor 8 has an input side connected to the output terminal 1 b of the regulator integrated circuit 1 and an output side connected to the input side of the second transistor 9.
The output side of the transistor 9 is the regulator integrated circuit 1
To the control terminal 1c. In this voltage stabilizing circuit, the first transistor 8 is turned on and the second transistor 9 is turned off when the output terminal 1b of the regulator integrated circuit 1 is at "H", and "H" is input to the control terminal 1c. The voltage stabilizing circuit having this structure can control the ON / OFF of the regulator integrated circuit 1 ideally with a very simple circuit configuration of the control circuit. Further, the control circuit 2
A delay circuit 10 can be connected between the first transistor 8 and the second transistor 9. Delay circuit 10
Can be configured by connecting a capacitor 11 in parallel with the input side of the second transistor 9.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below illustrate a regulator integrated circuit and a voltage stabilization circuit for embodying the technical idea of the present invention. Not specific.

Further, in this specification, in order to make it easy to understand the claims, the numbers corresponding to the members shown in the embodiments will be referred to as “claims” and “ In the column of “means”.
However, the members described in the claims are not limited to the members of the embodiments.

The voltage stabilizing circuit shown in FIG. 2 includes a regulator integrated circuit 1 and a control circuit 2. The regulator integrated circuit 1 has an input terminal 1a, an output terminal 1b, and a control terminal 1.
This is a four-terminal integrated circuit including the terminal c and the ground terminal 1d. As shown in FIG. 3, the regulator integrated circuit 1 stabilizes an unstabilized voltage input to an input terminal 1a to a constant voltage and outputs the same to an output terminal 1b.
And the constant voltage circuit 3 when the output terminal 1b is short-circuited.
And an input circuit 4 for switching off a switching element 5 built in the device.

The constant voltage circuit 3 includes a switching element 5 for controlling an output voltage, and a voltage adjusting circuit 6 for controlling the switching element 5. The switching element 5 is a transistor or an FET. The on / off duty is changed or the internal resistance is adjusted to control the output voltage to a set voltage. The switching element 5 that changes the on-off duty increases the output voltage by increasing the on-time with respect to the off-time, and decreases the output voltage by shortening the off-time. Switching element 5 for adjusting internal resistance
Adjusts the base current and the gate voltage to change the internal resistance to keep the output voltage constant. The voltage adjustment circuit 6 detects the output voltage and sets the output voltage to a constant set voltage.
The switching element 5 is controlled.

When the voltage input to the control terminal 1c changes from "H" to "L", the input circuit 4 switches the switching element 5
Is forcibly switched off. When "H" is input to the control terminal 1c, the switching element 5 is not controlled. When "H" is input to the control terminal 1c, the switching element 5 is controlled only by the voltage adjustment circuit 6. This regulator integrated circuit 1 uses the switching element 5 of the constant voltage circuit 3 together with a switch for switching the output on and off. Therefore, the regulator integrated circuit 1 does not need to provide a dedicated switch for switching the output on and off, and can simplify the circuit configuration.

However, the regulator integrated circuit 1 of the present invention
As shown in FIG. 4, a dedicated output switch 7 can be provided on the output side of the constant voltage circuit 3. The regulator integrated circuit 1 switches the output switch 7 on and off by the input circuit 4. When "H" is input to the input circuit 4, the output switch 7 is turned on, and when "L" is input to the input circuit 4, the output switch 7 is turned off. The output switch 7 can also use a transistor or FET.

The control circuit 2 detects the output voltage of the output terminal 1b and outputs "H" or "L". Output terminal 1b
Is "H", "H" is output to the control terminal 1c to turn on the output of the regulator integrated circuit 1. When the output terminal 1b is "L", "L" is output to the control terminal 1c, and the output of the regulator integrated circuit 1 is turned off. The illustrated control circuit 2 includes a first transistor 8 and a second transistor 9. The first transistor 8
The base on the input side is connected to the output terminal 1b of the regulator integrated circuit 1. The collector, which is the output side of the first transistor 8, is connected to the base, which is the input side of the second transistor 9, via a load resistor R1. Second
The transistor 9 has a collector on the output side connected to the control terminal 1 c of the regulator integrated circuit 1. Further, the base of the second transistor 9 has a bias resistor R
3 to the input terminal 1a. The bias resistor R3 supplies a base current for turning on the second transistor 9 when the first transistor 8 is off. The collector of the second transistor 9 is connected to the input terminal 1a via the load resistor R2. The load resistance R2 limits the current flowing when the second transistor 9 is on.

Further, the control circuit 2 of FIG. 2 includes a delay circuit 1 between the first transistor 8 and the second transistor 9.
0 is connected. The delay circuit 10 delays turning on the second transistor 9 and delays turning off the output of the regulator integrated circuit 1. This delay circuit 1
0 delays the rise of the base voltage of the second transistor 9 when the output terminal 1b is short-circuited and the first transistor 8 is switched from on to off,
Delay turning on the second transistor 9. The control circuit 2 delays the turning on of the second transistor 9, so that even if a large current instantaneously flows through the output terminal 1b, the control circuit 2 does not turn off the output of the regulator integrated circuit 1.
Therefore, the output is not turned off in an instantaneous short circuit. At the moment when the power switch is turned on, the output terminal 1b
Even if L ", the second transistor 9 is not turned on.
Therefore, there is a feature that the output of the regulator integrated circuit 1 can be stably turned on when the power switch is turned on.

The delay circuit 10 has a capacitor 11 connected between the base of the second transistor 9 and ground. This capacitor 11 is connected in parallel to the input side of the second transistor 9 to delay the rise of the base voltage and delay the turning on of the second transistor 9. The capacitor 11 is charged via the bias resistor R3. Accordingly, the time constant for delaying the turning on of the second transistor 9 by the delay circuit 10 is determined by the product of the resistance value of the bias resistor R3 and the capacitance of the capacitor 11. When the resistance value of the bias resistor R3 is increased to increase the capacitance of the capacitor 11, the time constant increases and the delay time increases.

The voltage stabilizing circuit of FIG. 2 performs the following operation to switch the output on and off. FIG. 5 shows the first state when the output of the regulator integrated circuit 1 becomes “H” and “L”.
This shows a state in which the transistor 8 and the second transistor 9 are turned on and off, "H" and "L" of the control terminal 1c, and on and off of the output of the regulator integrated circuit 1.

As shown in FIG. 1, the voltage at the output terminal 1b becomes "H" in a state where the output terminal 1b of the regulator integrated circuit 1 is not short-circuited. In this state, the first
The transistor 8 is turned on when a base current flows.
The first transistor 8 in the on state connects the base of the second transistor 9 to the ground, and turns off the second transistor 9. The second transistor 9 in the off state is
The collector voltage becomes “H”, and this “H” signal is input to the control terminal 1 c of the regulator integrated circuit 1. Regulator integrated circuit 1 in which "H" is input to control terminal 1c
Turns on the output and outputs normally.

When the output terminal 1b of the regulator integrated circuit 1 is short-circuited, the voltage of the output terminal 1b changes from "H" to "H".
L ”. In this state, the first transistor 8
Are switched off because the base current stops flowing. The first transistor 8 in the off state does not connect the base of the second transistor 9 to the ground, and the current is supplied to the base of the second transistor 9 from the bias resistor R3. However, since the charging of the capacitor 11 is started after the first transistor 8 is turned off, the second transistor
The base voltage of the transistor 9 increases as the voltage of the capacitor 11 increases. When the capacitor 11 is charged and the voltage of the capacitor 11 increases, the second
A state in which a base current flows through the transistor 9 is obtained. In this state, the second transistor 9 is switched from off to on. The collector voltage of the second transistor 9 switched to the ON state becomes the ground potential and becomes “L”, and this “L” signal is input to the control terminal 1 c of the regulator integrated circuit 1. The regulator integrated circuit 1 in which "L" is input to the control terminal 1c switches the output from on to off and stops outputting. Therefore, no current flows to the output terminal 1b of the regulator integrated circuit 1.

The above-mentioned regulator integrated circuit 1 turns on the output when "H" is input to the control terminal 1c,
When "L" is input, the output is turned off. On the contrary, the regulator integrated circuit outputs "L" to the control terminal.
It is also possible to design such that the output is turned off when "L" is input and the output is turned on when "H" is input. When the voltage is “H”,
L "is input, and" H "is input to the control terminal when the voltage of the output terminal is" L. "For example, the collector of the first transistor 8 in FIG. Connect to control terminal 1c.

[0022]

The regulator integrated circuit and the voltage stabilizing circuit of the present invention have a feature that the voltage drop and the power loss caused by the current limiting resistor can be reduced while the short-circuit current is reduced. That is, the regulator integrated circuit of the present invention includes a control terminal for switching an output voltage of an output terminal on and off,
The "H" or "L" signal input to the control terminal is switched so that the output of the output terminal is switched on and off. The voltage stabilizing circuit of the present invention includes the regulator integrated circuit and the output of the regulator integrated circuit. This is because there is provided a control circuit that detects the voltage and makes “H” or “L” a control terminal. This regulator integrated circuit switches the output of the output terminal on and off according to the signal input from the control terminal. Therefore, when the output terminal is short-circuited, the short-circuit current is limited to effectively prevent the regulator integrated circuit from being thermally damaged. Can be prevented. Furthermore, in the voltage stabilization circuit, the control circuit controls the on / off of the regulator integrated circuit to minimize the short-circuit current, so that unlike a conventional circuit, a wasteful power loss is minimized without connecting a current limiting resistor. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a conventional voltage stabilizing circuit.

FIG. 2 is a circuit diagram showing a voltage stabilizing circuit according to one embodiment of the present invention.

FIG. 3 is a block diagram showing a regulator integrated circuit of the voltage stabilizing circuit shown in FIG. 2;

FIG. 4 is a block diagram showing another example of the regulator integrated circuit.

FIG. 5 is a table showing an operation state of each part of the voltage stabilizing circuit shown in FIG. 2;

[Explanation of symbols]

1: Regulator integrated circuit 1a: Input terminal
1b ... output terminal 1c ... control terminal 1d ... ground terminal 2 ... control circuit 3 ... constant voltage circuit 4 ... input circuit 5 ... switching element 6 ... voltage adjustment circuit 7 ... output switch 8 ... first transistor 9 ... second transistor 10 ... Delay circuit 11: Capacitor R1: Load resistance R2: Load resistance R3: Bias resistance R: Current limiting resistance

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H410 BB05 CC02 DD02 EA10 EA32 EA39 EB01 EB37 FF03 FF25 LL04 LL13 LL19 5H730 AA12 AA16 AA20 AS01 DD02 DD12 DD26 FD01 FD11 FG01 XX04 XX13 XX15 XX23 XX33 XX33

Claims (6)

[Claims] A voltage regulator integrated circuit having an input terminal (1a) and an output terminal (1b), stabilizing a voltage input from the input terminal (1a) to a constant voltage, and outputting the same from an output terminal (1b). , Has a control terminal (1c) for switching the output voltage of the output terminal (1b) on and off, and inputs “H” or “H” to the control terminal (1c).
A regulator integrated circuit configured to switch an output of an output terminal (1b) on and off by switching an L "signal. 2. The regulator integrated circuit according to claim 1, wherein the output is turned on when "H" is input to the control terminal (1c), and is turned off when "L" is input. 3. A regulator integrated circuit having an input terminal (1a) and an output terminal (1b), stabilizing a voltage input from the input terminal (1a) to a constant voltage, and outputting the same from an output terminal (1b). 1)
And a control circuit (2) for controlling the output of the regulator integrated circuit (1) to turn on and off, wherein the regulator integrated circuit (1) receives an input “H” or “H”.
It has a control terminal (1c) that switches the output of the output terminal (1b) on and off with a signal of L ”, and the control circuit (2) detects the output voltage of the output terminal (1b) and
Output "H" or "L" and output terminal (1b)
When "H", "H" is output to the control terminal (1c) to turn on the output of the regulator integrated circuit (1), and the output terminal (1b)
A voltage stabilizing circuit that outputs "L" to the control terminal (1c) when the signal is at "L" to switch off the output of the regulator integrated circuit (1). 4. The control circuit (2) comprises a first transistor (8) and a second transistor (9), wherein the first transistor
(8) The input side is the output terminal (1b) of the regulator integrated circuit (1)
And the output side is connected to the input side of the second transistor (9), and the output side of the second transistor (9) is connected to the control terminal (1c) of the regulator integrated circuit (1), When the output terminal (1b) of the regulator integrated circuit (1) is "H", the first transistor (8) is turned on, the second transistor (9) is turned off, and "H" is applied to the control terminal (1c). 4. The voltage stabilizing circuit according to claim 3, wherein the voltage is inputted. 5. The voltage stabilizing circuit according to claim 4, wherein a delay circuit (10) is connected between the first transistor (8) and the second transistor (9). 6. The voltage stabilizer according to claim 5, wherein the delay circuit has a capacitor connected in parallel with the input of the second transistor. Circuit.