JP2008157652A - Power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a power supply having current-limiting function, and that can reduce the effect on the output voltage, the cost and the mounting area. <P>SOLUTION: The power supply comprises: a current detecting circuit for converting the output current from a current buffer into a voltage value; a comparator for detecting the direction of the output current based on the voltage value; a control circuit for recognizing the direction of the current, and calculating a setting voltage value; a D/A converter set by the setting voltage value from the control circuit; and a current-limiting circuit for generating a clamp voltage for clamping the output signal from the current buffer, based on an output from the D/A converter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply device mounted on a semiconductor test apparatus, and more particularly to a power supply device that has a current limiting function and reduces the influence on an output voltage, thereby reducing cost and mounting area.

  2. Description of the Related Art A semiconductor test apparatus includes a power supply apparatus that applies a voltage to supply power to a device under test (hereinafter referred to as a DUT (Device Under Test)). The present invention relates to a current limiting circuit used in this power supply device.

  Prior art documents related to conventional power supply devices include the following.

Japanese Patent Laid-Open No. 2006-21737

  FIG. 3 is a block diagram showing the configuration of such a conventional power supply apparatus. In FIG. 3, the control circuit 1 includes a CPU (Central Processing Unit) and a memory.

  A D / A (Digital to Analog) converter 2 receives setting data from the control circuit 1 and outputs a voltage based on the setting data. The current buffer 5 outputs a current corresponding to the output voltage of the D / A converter 2.

  The current detection circuit 7 converts the output current of the current buffer 5 into a voltage value by measuring the voltage across the resistor 6. The comparator 8 detects the current direction of the voltage applied to the DUT 100 based on the output from the current detection circuit 7.

  The D / A converter 9 and the D / A converter 10 are each input with setting data from the control circuit 1 and output voltages based on the setting data.

  The selector 11 selects and outputs the output of the D / A converter 9 or the D / A converter 10 based on the output signal of the comparator 8. The current limiting circuit 12 performs control to limit the current of the current buffer 5 based on the output of the selector 11.

  The first output terminal of the control circuit 1 is connected to the input terminal of the D / A converter 2, and the output terminal of the D / A converter 2 is connected to one terminal of the resistor 3. The other terminal of the resistor 3 is connected to one terminal of the resistor 4 and the inverting input terminal of the current buffer 5, and the other terminal of the resistor 4 is connected to the power supply terminal of the DUT 100.

  The output terminal of the current buffer 5 is connected to one terminal of the resistor 6 and one input terminal of the current detection circuit 7, and the other terminal of the resistor 6 is connected to the other input terminal of the current detection circuit 7 and the power supply terminal of the DUT 100. Each is connected. The non-inverting input terminal of the current buffer 5 is grounded.

  The output terminal of the current detection circuit 7 is connected to the input terminal of the comparator 8, and the output terminal of the comparator 8 is connected to the control signal input terminal of the selector 11. The second output terminal of the control circuit 1 is connected to the input terminal of the D / A converter 9, and the output terminal of the D / A converter 9 is connected to one data input terminal of the selector 11.

  The third output terminal of the control circuit 1 is connected to the input terminal of the D / A converter 10, and the output terminal of the D / A converter 10 is connected to the other data input terminal of the selector 11. The output terminal of the selector 11 is connected to the input terminal of the current limiting circuit 12, and the output terminal of the current limiting circuit 12 is connected to the clamp voltage input terminal of the current buffer 5.

  The operation of the conventional example shown in FIG. 3 will be described. In the test program, a voltage value to be applied to the DUT 100 is described, and the control circuit 1 sets a positive / negative voltage value of the voltage value to be applied to the D / A converter 2. The resistors 3 and 4 have the same resistance value, and the resistance value of the resistor 6 is much smaller than the resistance values of the resistors 3 and 4.

  The voltage value of the inverting input terminal of the current buffer 5 is the voltage value of the non-inverting input terminal, that is, 0 V (GND level), and the output of the current buffer 5 is a value opposite to the output value of the D / A converter 2. . That is, the output voltage of the current buffer 5 becomes a voltage value to be applied to the DUT 100 described in the test program, and the current to the DUT 100 is supplied from the current buffer 5.

  Then, the voltage across the resistor 6 is measured by the current detection circuit 7, and the voltage value is compared with a preset value by the comparator 8, whereby the current direction, that is, the direction output from the current buffer 5 ( Hereinafter, it is detected whether it is a positive direction) or a direction input to the current buffer 5 (hereinafter referred to as a negative direction).

  The D / A converter 9 outputs a set voltage to the current limiting circuit 12 when the current direction is the positive direction, that is, when a current is output from the current buffer 5 to the DUT 100. Similarly, the D / A converter 10 outputs a set voltage to the current limiting circuit 12 when the current direction is negative, that is, when current is input from the DUT 100 to the current buffer 5.

  Output voltages of the D / A converter 9 and the D / A converter 10 are set from the control circuit 1. The current limit value described in the test program is input to the control circuit 1, and the CPU of the control circuit 1 calculates the set voltage value of the D / A converter 9 and the D / A converter 10 according to the current value. Set.

  The selector 11 selects the output of the D / A converter 9 or the output of the D / A converter 10 according to the output of the comparator 8. That is, when the comparator 8 detects the positive direction, the output of the D / A converter 9 is selected, and when the comparator 8 detects the negative direction, the output of the D / A converter 10 is selected.

  The current limiting circuit 12 generates a clamp voltage that clamps the output signal of the current buffer 5 based on the output of the selector 11. Since the output signal of the current buffer 5 is clamped by this clamp voltage, the output current of the current buffer 5 is limited.

  As a result, the D / A converter 9 generates a set voltage in the positive direction, the D / A converter 10 generates a set voltage in the negative direction, and the current detected by the current detection circuit 7 and the comparator 8. Based on the direction, the selector 11 selects the output of either the D / A converter 9 or the D / A converter 10, and the current limit circuit 12 outputs the output of the selected D / A converter. Since the output voltage of the current buffer 5 is limited by generating a clamp voltage based on the above and clamping the output of the current buffer 5, current limitation corresponding to both the positive current direction and the negative current direction can be performed. It becomes possible.

  However, in the conventional example shown in FIG. 3, since the output of the D / A converter 9 and the D / A converter 10 is switched by the selector 11, depending on the characteristics of the selector 11, There was a problem that spikes or the like occurred in the output of the current buffer 5.

Further, since the D / A converters for the positive current direction and the negative current direction are respectively mounted, there is a problem that the cost is increased and the mounting area is increased.
Therefore, the problem to be solved by the present invention is to realize a power supply device that has a current limiting function and reduces the influence on the output voltage, and can reduce the cost and the mounting area.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In the power supply device that converts the output current from the current buffer into a voltage value by the current detection circuit,
A comparator that detects a current direction of the output current based on the voltage value, a control circuit that recognizes the current direction and calculates a set voltage value, and a D / D that sets the set voltage value from the control circuit An A converter and a current limiting circuit for generating a clamp voltage for clamping the output signal of the current buffer based on the output of the D / A converter are provided.

The invention according to claim 2
In the power supply device that converts the output current from the current buffer into a voltage value by the current detection circuit,
An A / D converter that converts the voltage value into digital data, a control circuit that compares the digital data with a preset value to recognize the current direction and calculate a set voltage value; A D / A converter in which the set voltage value is set, and a current limiting circuit that generates a clamp voltage for clamping the output signal of the current buffer based on the output of the D / A converter. And

The present invention has the following effects.
According to the first aspect of the present invention, in a power supply device that converts an output current from a current buffer into a voltage value by a current detection circuit, a comparator that detects a current direction of the output current based on the voltage value, and the current A control circuit that recognizes the direction and calculates a set voltage value, a D / A converter in which the set voltage value is set from the control circuit, and an output of the current buffer based on the output of the D / A converter Since a current limiting circuit for generating a clamping voltage for clamping a signal is provided, one of the selector and the D / A converter used in the conventional example is not required, and thus has a current limiting function and outputs to the output voltage. The effect can be reduced, and the cost and mounting area can be reduced.

  According to a second aspect of the present invention, in a power supply device that converts an output current from a current buffer into a voltage value by a current detection circuit, an A / D converter that converts the voltage value into digital data, the digital data A control circuit for comparing the set value to recognize the current direction and calculating the set voltage value, a D / A converter in which the set voltage value is set from the control circuit, and the D / A converter Since a current limiting circuit that generates a clamp voltage for clamping the output signal of the current buffer based on the output of the current buffer, one of the selector and the D / A converter used in the conventional example is not necessary. In addition to having a current limiting function, the influence on the output voltage can be reduced, and the cost and mounting area can be reduced.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of a power supply apparatus according to the present invention. Components common to those in FIG. In FIG. 1, the control circuit 13 is composed of a CPU, a memory, and the like, similar to the control circuit 1.

  The output terminal of the comparator 8 is connected to the input terminal of the control circuit 13, and one output terminal of the control circuit 13 is connected to the input terminal of the D / A converter 2. The other output terminal of the control circuit 13 is connected to the input terminal of the D / A converter 9, and the output terminal of the D / A converter 9 is connected to the input terminal of the current limiting circuit 12. The other connections are the same as in FIG.

  The operation of the embodiment shown in FIG. 1 will be described. In the test program, a voltage value to be applied to the DUT 100 is described, and the control circuit 13 sets a positive / negative voltage value of the voltage value to be applied to the D / A converter 2. The resistors 3 and 4 have the same resistance value, and the resistance value of the resistor 6 is much smaller than the resistance values of the resistors 3 and 4.

  The voltage value of the inverting input terminal of the current buffer 5 is the voltage value of the non-inverting input terminal, that is, 0 V (GND level), and the output of the current buffer 5 is a value opposite to the output value of the D / A converter 2. . That is, the output voltage of the current buffer 5 becomes a voltage value to be applied to the DUT 100 described in the test program, and the current to the DUT 100 is supplied from the current buffer 5.

  Then, the voltage at both ends of the resistor 6 is measured by the current detection circuit 7, and the voltage value is compared with a preset value by the comparator 8, whereby the current direction, that is, the positive direction or the negative direction is determined. Is detected.

  The control circuit 13 recognizes this current direction based on the input signal from the comparator 8. Then, the voltage value is set in the D / A converter 9 based on this current direction. As in the conventional example, the current limit value described in the test program is input to the control circuit 13, and the CPU of the control circuit 13 calculates the set voltage value of the D / A converter 9 according to the current limit value. Set.

  That is, when the current direction is positive, the set voltage value of the D / A converter 9 is calculated and set according to the current limit value in the positive direction described in the test program, and when the current direction is negative Is set by calculating the set voltage value of the D / A converter 9 corresponding to the current limit value in the negative direction described in the test program.

  The current limiting circuit 12 generates a clamp voltage that clamps the output signal of the current buffer 5 based on the output of the D / A converter 9. Since the output signal of the current buffer 5 is clamped by this clamp voltage, the output current of the current buffer 5 is limited.

  As a result, the control circuit 13 sets a set voltage to the D / A converter 9 based on the current direction detected by the current detection circuit 7 and the comparator 8, and the current limiting circuit 12 outputs the output of the D / A converter 9. By generating a clamp voltage based on the above and clamping the output of the current buffer 5, one of the selector and the D / A converter used in the conventional example is not required, so that it has a current limiting function and outputs the output voltage. Thus, the cost and mounting area can be reduced.

  FIG. 2 is a block diagram showing the configuration of another embodiment of the power supply apparatus according to the present invention, and the same reference numerals are given to the portions common to FIG. In FIG. 2, the A / D converter 14 converts an analog voltage into digital data, and the control circuit 15 includes a CPU, a memory, and the like, similar to the control circuit 13.

  The output terminal of the current detection circuit 7 is connected to the input terminal of the A / D converter 14, and the output terminal of the A / D converter 14 is connected to the input terminal of the control circuit 15. One output terminal of the control circuit 15 is connected to the input terminal of the D / A converter 2, and the other output terminal of the control circuit 15 is connected to the input terminal of the D / A converter 9. The other connections are the same as in FIG.

  The operation of the embodiment shown in FIG. 2 will be described. In the test program, a voltage value to be applied to the DUT 100 is described, and the control circuit 15 sets a positive / negative voltage value of the voltage value to be applied to the D / A converter 2. The resistors 3 and 4 have the same resistance value, and the resistance value of the resistor 6 is much smaller than the resistance values of the resistors 3 and 4.

  The voltage value of the inverting input terminal of the current buffer 5 is the voltage value of the non-inverting input terminal, that is, 0 V (GND level), and the output of the current buffer 5 is a value opposite to the output value of the D / A converter 2. . That is, the output voltage of the current buffer 5 becomes a voltage value to be applied to the DUT 100 described in the test program, and the current to the DUT 100 is supplied from the current buffer 5.

  Then, the voltage across the resistor 6 is measured by the current detection circuit 7 and the voltage value is converted into digital data by the A / D converter 14. This digital data is input to the control circuit 15 and compared with a value set in advance by the control circuit 15 to detect the current direction, that is, the positive direction or the negative direction.

  Then, the control circuit 15 sets a voltage value to the D / A converter 9 based on this current direction. As in the embodiment shown in FIG. 1, the current limit value described in the test program is input to the control circuit 15, and the CPU of the control circuit 15 sets the set voltage value of the D / A converter 9 according to the current limit value. Is calculated and set.

  That is, when the current direction is positive, the set voltage value of the D / A converter 9 is calculated and set according to the current limit value in the positive direction described in the test program, and when the current direction is negative Is set by calculating the set voltage value of the D / A converter 9 corresponding to the current limit value in the negative direction described in the test program.

  The current limiting circuit 12 generates a clamp voltage that clamps the output signal of the current buffer 5 based on the output of the D / A converter 9. Since the output signal of the current buffer 5 is clamped by this clamp voltage, the output current of the current buffer 5 is limited.

  As a result, the control circuit 15 compares the output of the A / D converter 14 with a preset value to detect the current direction and sets the set voltage to the D / A converter 9 based on the detected current direction. Then, the current limiting circuit 12 generates a clamp voltage based on the output of the D / A converter 9 and clamps the output of the current buffer 5, whereby the selector and the D / A converter used in the conventional example are used. Since one is not necessary, it has a current limiting function and reduces the influence on the output voltage, thereby reducing the cost and mounting area.

1 is a configuration block diagram illustrating an embodiment of a power supply device according to the present invention. It is a block diagram which shows the other Example of the power supply device which concerns on this invention. It is a block diagram which shows the conventional power supply device.

Explanation of symbols

1, 13, 15 Control circuit 2, 9, 10 D / A converter 3, 4, 6 Resistance 5 Current buffer 7 Current detection circuit 8 Comparator 11 Selector 12 Current limit circuit 14 A / D converter 100 DUT

Claims (2)

In the power supply device that converts the output current from the current buffer into a voltage value by the current detection circuit,
A comparator that detects a current direction of the output current based on the voltage value;
A control circuit that recognizes the current direction and calculates a set voltage value;
A D / A converter in which the set voltage value is set from the control circuit;
And a current limiting circuit for generating a clamp voltage for clamping the output signal of the current buffer based on the output of the D / A converter. In the power supply device that converts the output current from the current buffer into a voltage value by the current detection circuit,
An A / D converter for converting the voltage value into digital data;
A control circuit for comparing the digital data with a preset value to recognize the current direction and calculating a set voltage value;
A D / A converter in which the set voltage value is set from the control circuit;
And a current limiting circuit for generating a clamp voltage for clamping the output signal of the current buffer based on the output of the D / A converter.

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