JPH06149610A - Variable type voltage regulator circuit - Google Patents

Abstract

PURPOSE:To provide a variable type voltage regulator circuit capable of always monitoring the voltage of a target power supply and obtaining voltage matched with target operation voltage. CONSTITUTION:The variable type voltage regulator device is provided with a voltage conversion circuit 11 for outputting voltage corresponding to the voltage of the target power supply, a current amplifier 12 for the circuit 11, a system power supply current amplifier 14 for outputting a fixed power supply voltage, a voltage monitoring circuit 13 for detecting the voltage of the target power supply, and an output switching circuit 15 for selectively switching an output from the amplifier 12 connected to the circuit 11 and an output from the amplifier 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable voltage regulator for obtaining a voltage matched to the operating voltage of a target system.
Data circuit.

[0002]

2. Description of the Related Art An in-circuit emulator has a function of monitoring a memory access of a microprocessor, detecting a trigger point or a break point, and stopping the operation of a target microprocessor or stopping a trace. It is used as a microprocessor development support device.

By the way, conventionally, the microprocessor has been
Since it was operating with a + 5V power supply, the output voltage from the inserter kit emulator was + 5V, which was the same as the internal operating voltage, but in recent years, many microprocessors with low voltage have been developed. It can be operated with a + 3V power supply. Therefore, the output voltage from the insert kit emulator must also be output according to the operating voltage of the target system.

[0004]

However, in the prior art, there is no circuit for supplying a voltage matching the target operating voltage to the target interface element, and a voltage higher than the power supply voltage is input to the interface element or the power supply voltage of the target is increased. If the voltage is an abnormal voltage, a voltage exceeding the operating voltage range may be applied, which may damage the interface element.

Therefore, it is an object of the present invention to provide a variable voltage regulator circuit capable of constantly monitoring the voltage of a target power supply and obtaining a voltage matching the target operating voltage.

[0006]

In order to achieve the above object, a variable voltage regulator circuit of the present invention includes a voltage conversion circuit for outputting a voltage according to a voltage of a target power supply and a current amplifier thereof. A system power supply current amplifier that outputs a constant system power supply voltage, a voltage monitoring circuit that detects the voltage of the target power supply, and the output of the current amplifier on the voltage conversion circuit side according to the voltage of the target power supply that is detected by the voltage monitoring circuit. And an output switching circuit for selectively switching the output of the system power supply current amplifier.

[0007]

The variable voltage regulator circuit according to the present invention comprises:
By constantly detecting the voltage of the target power supply by the voltage monitoring circuit and automatically switching the output voltage of the voltage conversion circuit and the system operating voltage by the output switching circuit according to the target voltage and outputting to the interface circuit, A constant voltage of the system power supply or a voltage corresponding to the target operating voltage can be supplied.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an embodiment shown in the drawings. FIG. 1 is a block diagram for explaining the configuration of a variable voltage regulator circuit according to an embodiment of the present invention.

Referring to FIG. 1, the variable voltage regulator circuit 10 of the embodiment of the present invention constantly monitors the voltage of the target power source and transforms the internal dedicated power source so that the target power source is not burdened. A circuit for supplying the same voltage to the interface element, a voltage conversion circuit 11 for converting the voltage according to the voltage of the target power supply, a current amplifier 12 for current-amplifying the voltage converted by the voltage conversion circuit 11, and a target power supply. Of the target power supply or the system power supply is selectively switched according to the voltage of the target power supply detected by the voltage monitoring circuit 13 that detects the voltage of the system power supply, the system power supply current amplifier 14 that supplies the voltage of the system power supply, and the voltage monitoring circuit 12. Output switching circuit 1
5. A noise filter circuit 16 which removes noise of the voltage output from the output switching circuit 15 and outputs the noise to the interface element.

FIG. 3 is a diagram showing a specific circuit example of the variable voltage regulator circuit according to the embodiment of the present invention. The parts corresponding to those in FIG. 1 are designated by the same reference numerals, and the noise filter circuit 16 is omitted.

In the figure, the voltage conversion circuit 11 is
Its non-inverting input terminal is connected to the target power supply, its inverting input terminal is connected to the anode of the Zener diode 22, its power supply terminal is connected to the + 12V internal dedicated power supply, and its ground terminal is The operational amplifier 21 is grounded.

The current amplifier 12 has its base terminal connected to the output terminal of the operational amplifier 21, its collector terminal connected to an internal dedicated power source of +12 V, and its emitter terminal connected to the cathode of the Zener diode 22. It consists of a transistor 24 connected to the negative terminal and grounded via a resistor 23. That is, the operational amplifier 21 forms a negative feedback circuit via the Zener diode 22.

The voltage monitoring circuit 13 includes resistors 25 and 26, which are connected in series between the target power source and ground to form a bridder, and whose base terminals are connected via the resistor 27 to the resistors 25 and 26. A transistor 2 which is connected to a connection point, has its collector terminal connected to an internal dedicated power source of + 12V through a resistor 28, and has its emitter terminal grounded.
9, the base terminal of which is connected to the collector terminal of the transistor 29 through the resistor 30, the collector terminal of which is connected to the + 12V internal dedicated power source through the resistor 31 and the emitter terminal of which is grounded. Consists of.

The output switching circuit 15 has its base terminal connected to the collector terminal of the transistor 32 through the resistor 33, its collector terminal connected to the emitter terminal of the transistor 24, and its emitter terminal connected to the target interface circuit. The transistor 34 connected to the noise filter circuit on the power output side and its base terminal are connected to the collector terminal of the transistor 32 via the resistor 35, and the collector terminal thereof is + via the resistor 36.
It is composed of a transistor 37 which is connected to an internal dedicated power source of 12 V and whose emitter terminal is grounded.

In the system power supply current amplifier 14, the base terminal is connected to the collector terminal of the transistor 37 through the resistor 38, the collector terminal is connected to the system power supply, and the emitter terminal is the target interface circuit power supply output. It consists of a transistor 39 connected to the side noise filter circuit.

Next, the operation of the variable voltage regulator circuit having the above structure will be described. In this embodiment, the case where the system power supply voltage is 5 V and the target voltage, that is, the input voltage is different from the system power supply voltage will be described.

First, in the voltage conversion circuit 11 and the current amplifier 12 of FIG. 3, the target power supply voltage is input to the non-inverting input terminal of the operational amplifier 21, and the emitter terminal voltage of the transistor 24 is zenered to its inverting input terminal. Dio
The output voltage of the operational amplifier 21 follows the target power supply voltage up to the Zener voltage of the Zener diode 22 by inputting the output voltage of the output terminal of the transistor 24 to the base terminal of the transistor 24. When the target power supply voltage exceeds the zener voltage, a voltage corresponding to a constant zener voltage is output. The output of the operational amplifier 21 is the transistor 24.
The current is amplified by and output from the emitter terminal.

Next, in the voltage monitoring circuit 13 of FIG.
The base terminal of the transistor 29 has resistors 25 and 26 that form a bleeder according to the voltage of the target power supply.
The voltage at the connection point is input via the resistor 27 according to the value determined by The transistor 29 is turned on when the voltage of the target power supply has a constant value, for example, 2V or more, and is turned off when the voltage is 2V or less. When the transistor 29 is turned on, its emitter terminal is grounded and becomes low level,
A low level voltage is input to the base terminal of the transistor 32 via the resistor 30, and the transistor 32 is turned off.
When the transistor 29 is turned off, a high level voltage is input to its emitter terminal via the resistor 30 and a high level voltage is input to its base terminal via the resistor 30 to turn on the transistor 32. That is, the voltage monitoring circuit 13 determines that the target power supply voltage is 2V.
When it exceeds, the high level signal is output, and when it is 2 V or less, the low level signal is output.

Next, in the output switching circuit 15 of FIG.
When a high level signal is output from the voltage monitoring circuit 13,
A high level signal is input to the base terminal of the transistor 34 via the resistor 33, and the transistor 34 is turned on, and the voltage of the emitter terminal of the transistor 24 is output to the target interface circuit power supply side. At this time, a high level signal is input to the base terminal of the transistor 37 via the resistor 35, the transistor 37 is turned on, the emitter terminal thereof is turned to low level, and the transistor 39 is turned off. Further, when a low level signal is output from the voltage monitoring circuit 13, the low level signal is input to the base terminal of the transistor 37 via the resistor 35, the transistor 37 is turned off, and the emitter terminal thereof becomes high level. Then, a high level signal is input to the base terminal of the transistor 39 via the resistor 38, and the transistor 39 is turned on, and the system power supply voltage is output from the emitter terminal thereof to the target interface circuit power supply side. At this time, the low-level signal is input to the base terminal of the transistor 34 via the resistor 33, and the transistor 34 is in the off state.

FIG. 2 is a diagram showing the relationship between the input voltage (target voltage) and the output voltage (interface output voltage) of the variable voltage regulator circuit according to the embodiment of the present invention.

That is, the target voltage is constantly detected by the voltage monitoring circuit 13, and when the value is equal to or less than the specified voltage, for example, 2 V or less, the transistors 34 and 37 of the output switching circuit 15 are turned off, and the system power supply current is reduced. The voltage on the amplifier 14 side, that is, 5V of a constant voltage (AB in FIG. 2) is output. With this, it is determined that the power supply of the target is in the off state, and the voltage supplied to the interface element is switched to the internal operation power supply,
Damage to the interface element is prevented. Next, when the target voltage is the specified voltage or more, for example, 2 V or more, the transistors 34 and 37 of the output switching circuit 15 are turned on, and the transistor 39 on the system power supply side is turned on.
Is turned off, and the same voltage as the emitter terminal voltage of the transistor 24, that is, the target power supply voltage (C to C in FIG.
D) is output. As a result, a voltage corresponding to the target power supply voltage is output, and for example, a voltage corresponding to a low-voltage compatible microprocessor operating at + 3V can be supplied to the interface element. Further, when the target power supply voltage is an abnormal voltage, for example, a high voltage of 6.2 V or higher, the zener voltage determined by the zener diode 22 holds the supply voltage to the interface element within the operating voltage range (D to E in FIG. 2). Therefore, the element is prevented from being damaged. The noise filter circuit 16 removes noise and supplies the supply voltage to the interface element.

In the above embodiment, an example was described in which the system power supply voltage was set to 5V and the abnormal voltage hold voltage was set to 6.3V, but the invention is not limited to this.

[0023]

As described above, the variable voltage regulator circuit of the present invention constantly monitors the voltage of the target power supply by the voltage monitoring circuit, and when the power supply voltage of the target is within the specified voltage range. , The voltage dedicated to the internal power supply is transformed by the voltage conversion circuit and the current amplifier, and the same voltage as the target is always supplied to the interface element without burdening the target power supply. When the target power supply drops below the specified voltage, the interface element is connected. The damage of the interface element can be prevented by switching the supply voltage of the internal operation voltage to the internal operation voltage and preventing the damage of the interface element, and when the power supply voltage of the target is abnormal voltage, the supply voltage to the interface element is held at the specified voltage. effective.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a variable voltage regulator circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing input / output voltages of a variable voltage regulator circuit according to an embodiment of the present invention.

FIG. 3 is a diagram showing a specific circuit example of a variable voltage regulator circuit according to an embodiment of the present invention.

[Explanation of symbols]

10 Variable Type Voltage Regulator Circuit 11 Voltage Converter Circuit 12 Current Amplifier 13 Voltage Monitoring Circuit 14 System Power Supply Current Amplifier 15 Output Switching Circuit 16 Noise Filter Circuit 21 Operational Amplifier 22 Zener Diode 23, 25, 26, 28, 30, 31 , 33, 35, 3
6,38 resistor 24,29,32,34,37,39 transistor

Claims (1)

[Claims] 1. A voltage conversion circuit that outputs a voltage according to the voltage of a target power supply and its current amplifier, a system power supply current amplifier that outputs a constant system power supply voltage, and a voltage monitor that detects the voltage of a target power supply. A variable voltage regulator including a circuit and an output switching circuit that selectively switches between the output of the current amplifier on the voltage conversion circuit side and the output of the system power supply current amplifier according to the voltage of the target power supply detected by the voltage monitoring circuit. -A circuit.