JPH1038962A - Voltage-adding circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage-adding circuit which can add a predetermined voltage to a voltage output from a DC measurement unit and impress the voltage to an element to be measured, or impress the voltage output from the DC measurement unit directly to the element to be measured when required. SOLUTION: In a DC-DC converter 31, a predetermined voltage is added to a voltage output from a DC measurement unit 2, and the added voltage is converted to a stable voltage at a regulator 32 and impressed to an element to be measured. When the voltage output from the DC measurement unit 2 is to be directly impressed to the element to be measured, the operation of the regulator 32 is switched at a relay 33, so that the voltage output from the DC measurement unit 2 is directly impressed to the element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage adding circuit for adding a predetermined voltage to a voltage output from a DC measuring unit for measuring a power supply current of an IC such as an LCD driver.

[0002]

2. Description of the Related Art Conventionally, when measuring a power supply current for an IC such as an LCD driver, a DC measurement unit for applying a predetermined voltage to the IC has been used.

FIG. 2 is a diagram showing an example of conventional power supply current measurement for an IC.

As shown in FIG. 2, in this conventional example, a DC measuring unit 102 is connected to an IC 101 to be measured, and a predetermined voltage is applied from the DC measuring unit 102 to the IC 101. Is measured.

[0005]

In the prior art as described above, the power supply current is measured for an IC that requires a voltage higher than the maximum applied voltage of the DC measurement unit connected to the IC. , DC measurement unit with IC
Must be replaced by one that can apply the required voltage, in which case the cost will increase.

Therefore, without replacing the DC measurement unit,
As means for applying a voltage required by the IC, it is conceivable to add a voltage adding circuit for adding a predetermined voltage to the DC measurement unit.

FIG. 3 shows the DC measurement unit 1 shown in FIG.
FIG. 11 is a diagram illustrating an example in which a voltage addition circuit is added to 02.

However, when a voltage adding circuit 103 is added to the DC measuring unit 102 as shown in FIG.
Although the voltage output from the DC measurement unit 102 is 0 V, the voltage adding circuit 103 is provided in the IC 101.
However, there is a problem that the added voltage is applied in the above.

If the current limiting function is not provided in the voltage adding circuit 103, the IC 1
01 may be damaged.

The present invention has been made in view of the above-mentioned problems of the conventional technology, and adds a predetermined voltage to a voltage output from a DC measurement unit and applies the voltage to a device under test. On the other hand, it is an object of the present invention to provide a voltage adding circuit that can directly apply a voltage output from a DC measurement unit to a device under test when desired.

[0011]

To achieve the above object, the present invention is directed to a first measuring means for outputting a predetermined voltage for measuring a power supply current to a device under test,
A voltage adding circuit for applying a voltage output from the first measuring means to the device under test, wherein a power supply voltage and a voltage output from the first measuring means are input, and the first measuring means Adding means for adding a predetermined voltage to the voltage output from the output means, and converting the voltage output from the adding means into a stable voltage and outputting the same, or outputting the voltage output from the first measuring means. And a first switching means for switching the operation of the voltage varying means.

[0012] Further, there is provided a second measuring means for controlling the operation of the first switching means.

[0013] Further, there is provided a second switching means for controlling the supply of the output of the voltage varying means to the outside.

(Operation) In the present invention configured as described above, the adding means adds a predetermined voltage to the voltage output from the first measuring means, and the added voltage is stabilized by the voltage varying means. The measured voltage is applied to the device under test. When the voltage output from the first measuring means is directly applied to the device under test, the operation of the voltage varying means is switched by the first switching means, so that the voltage output from the first measuring means is changed. It is applied to the device under test as it is.

As described above, even when the power supply current is measured for the device under test that requires a voltage higher than the maximum output voltage of the first measuring device, the device under test requires the first measuring device. It is not necessary to change the voltage to be applied to the element to be measured to 0 V, and even if the voltage output from the first measuring means is set to 0 V, The voltage added to the voltage output from the first measuring means in the adding means is not applied to the device under test.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a voltage adding circuit according to the present invention.

In this embodiment, as shown in FIG. 1, a DC measuring unit 2 serving as first measuring means for outputting a predetermined voltage for measuring a power supply current to a device under test (not shown).
The power supply voltage (+5 V) and the voltage output from the DC measurement unit 2 are input, and a predetermined voltage (24 V in this embodiment) is added to the voltage output from the DC measurement unit 2 and output. A DC-DC converter 31 which is an insulation type adding means for converting the voltage output from the DC-DC converter 31 into a stable voltage with small noise (the voltage output from the DC-DC converter 31 is 24
(In the case of V, 20 V), and a regulator 32 which is a voltage fluctuation means for outputting the voltage outputted from the DC measurement unit 2 as it is, and resistors R1, R2 for controlling the characteristics of the regulator 32. And the resistor R2
And a relay 33 serving as first switching means for switching the operation of the regulator 32 by controlling the supply of current to the resistor R2 to change the characteristics of the regulator 32 and controlling the operation of the relay 33. DC measuring unit 35 as a second measuring means for performing
And a control word 4 for controlling the operation of the optical MOS relay 34 as second switching means for controlling the supply of the output to the outside.

Hereinafter, the operation of the voltage adding circuit configured as described above will be described. In this embodiment, the maximum output voltage of the DC measurement unit 2 is set to 60 V, and the applied voltage required for the device under test is set to 80 V.

(1) When the voltage to be applied to the device under test is set to 0 V The output voltage of the DC measurement unit 2 is set to 0 V.

Then, the DC-DC converters 31 to 2
A voltage of 4 V is output.

Here, since the relay 33 is normally in the ON state, no current flows through the resistor R2, thereby controlling the characteristics of the regulator 32. The output terminal of the regulator 32 is connected to the output voltage of the DC measurement unit 2. 0V appears as it is.

In the state described above, the optical MOS relay 34 is turned on.
In the state, a voltage of 0 V is output from the voltage adding circuit 3.

(2) The voltage applied to the device under test is 80 V
The output voltage of the DC measurement unit 2 is set to 60V.

Then, the DC-DC converters 31 to 8
A voltage of 4 V is output.

Next, when the relay 33 is turned off under the control of the DC measurement unit 35, the characteristics of the regulator 32 are controlled, and the regulator 32 outputs a voltage of 80 V having a small noise component.

In the state described above, the optical MOS relay 34 is turned on.
In the state, a voltage of 80 V is output from the voltage adding circuit 3.

Here, in the relay 33, the ON / OFF operation is controlled by controlling the current flowing through the coil by a program in the DC measuring unit 35.

In the optical MOS relay 34, the control word 4 (TTL level negative logic) causes O
Since the N / OFF operation is controlled (usually in the OFF state) and has its own current limiting function, a complicated current limiting circuit can be omitted.

When the above-described voltage adding circuit is used, since all the voltages applied to the device under test are supplied from the DC measurement unit 2, the voltage of the device under test is measured based on the current measurement function of the DC measurement unit 2. Power supply current measurement can be performed.

In the above-described embodiment, D
The voltage added in the C-DC converter 31 is 24
V, but it goes without saying that the present invention is not limited to this.

The DC measuring unit 35 for controlling the operation of the relay 33 may be provided outside the voltage adding circuit 3.

[0033]

Since the present invention is configured as described above, it has the following effects.

According to the first and second aspects, an adding means for adding a predetermined voltage to the voltage output from the first measuring means and outputting the added voltage, and a voltage output from the adding means, Since the voltage variation means for converting the voltage into a stable voltage and applying the voltage to the device under test is provided, the power supply current measurement is performed on the device under test requiring a voltage higher than the maximum output voltage of the first measuring device. Also, the measurement can be performed without replacing the first measuring means with a device capable of applying a voltage required by the device under test.

Further, since the voltage output from the first measuring means is directly applied to the device to be measured by switching the operation of the voltage changing means in the first switching means, the voltage is applied to the device to be measured. Even when the voltage output from the first measuring means is set to 0 V in order to set the voltage to 0 V, the voltage added to the voltage output from the first measuring means is applied to the element to be measured by the adding means. Never.

According to the third aspect of the present invention, the second switching means for controlling the supply of the output of the voltage varying means to the outside is provided, so that a complicated current limiting circuit is not provided.
Damage to the device under test due to occurrence of a short circuit or the like can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a voltage adding circuit according to the present invention.

FIG. 2 is a diagram showing an example of a conventional power supply current measurement for an IC.

FIG. 3 is a diagram illustrating an example in which a voltage adding circuit is added to the DC measurement unit illustrated in FIG. 2;

[Explanation of symbols]

 2,35 DC measurement unit 3 Voltage addition circuit 4 Control word 31 DC-DC converter 32 Regulator 33 Relay 34 Optical MOS relay R1, R2 Resistance

Claims (3)

[Claims] 1. A device connected to a first measuring means for outputting a predetermined voltage for measuring a power supply current to the device under test, and applying a voltage output from the first measuring device to the device under test. A voltage addition circuit, which receives a power supply voltage and a voltage output from the first measurement means, and adds a predetermined voltage to a voltage output from the first measurement means and outputs the result. A voltage changing means for converting the voltage output from the adding means to a stable voltage and outputting the same, or outputting the voltage output from the first measuring means as it is, and switching the operation of the voltage changing means. A voltage adding circuit comprising: a first switching unit. 2. The voltage addition circuit according to claim 1, further comprising: a second measurement unit that controls an operation of the first switching unit. 3. The voltage addition circuit according to claim 1, wherein a second supply of the output of said voltage varying means is controlled.
A voltage adding circuit comprising: