JP2594063Y2 - Driver circuit for pin electronics card - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driver circuit for a pin electronics card, and more particularly to a driver circuit for a pin electronics card which always maintains a high impedance state.

[0002]

2. Description of the Related Art A conventional example of a driver circuit for a pin electronics card will be described with reference to FIG. In FIG. 1, Q1 and Q2 are transistors constituting a transistor (PNP transistor) pair of the other conductivity type, and the emitters of these transistors Q1 and Q2 are interconnected and connected to a power supply. Q3 and Q4 are transistors forming one conductive type transistor (NPN transistor) pair.
The emitters of 3 and Q4 are interconnected and connected to the power supply. The collector of the transistor Q1 and the transistor Q3
Is connected via a series connection circuit in which a plurality of diodes D1 to D6 identical to each other are connected in series, and the collector of the transistor Q1 is connected to the transistor Q4.
And the collector of the transistor Q2 is connected to the collector of the transistor Q3. The transistors Q1 to Q4 constitute a switching circuit for switching the pin electronics card driver circuit to an output enable state or an output disable state. Then, a switching signal is input between an intermediate point of a series connection circuit in which a plurality of diodes D1 to D6 are connected in series and the bases of the transistors Q1 to Q4.

The output circuit of the driver circuit which can be switched to the output enable state or the output disable state by the switching circuit described above is an NPN transistor Q5,
It comprises a circuit in which a diode D9, output resistors R1 and R2, a diode D10, and a PNP transistor Q6 are connected in series in the forward direction as shown in FIG.
Reference numeral 5 is connected to a power supply via a PNP transistor, and transistor Q6 is connected to a power supply via an NPN transistor. The common connection point of the output resistors R1 and R2 is the output terminal of the driver circuit, and C1 and C2 are decoupling capacitors. Here, the base of the transistor Q5 is connected to the common connection point of the collector of the transistor Q1 and the collector of the transistor Q4, while the base of the transistor Q6 is connected to the common connection point of the collector of the transistor Q2 and the collector of the transistor Q3. The base of the transistor Q5 is further connected to the cathode of the diode D7, the anode is connected to the positive electrode of the DC power supply V1, and the negative electrode is grounded. Transistor Q
The base of 6 is further connected to the anode of diode D8,
Its cathode is connected to the positive electrode of DC power supply V2, and its negative electrode is grounded.

Next, the operation of the above-described conventional example of the pin electronics card driver circuit will be described. About the output enable state.

The transistors Q1 and Q of the switching circuit
3 to turn on these transistors while turning off the transistors Q2 and Q4, so that the transistors Q5, D9 and D
10. All the transistors Q6 are forward biased,
The output is enabled. In this case, the diode D7 and the diode D8 are reverse-biased and in an off state.

[0006] Regarding the output disable state. A state in which the transistors Q2 and Q4 of the switching circuit are triggered to turn them on while the transistors Q1 and Q3 are turned off is an output disable state. In this state, the base potential of transistor Q5 drops until it is clamped by diode D7, while the base potential of transistor Q6 rises until it is clamped by diode D8. In this case, even if a voltage in the range of V1 or V2 is applied to the output terminal from the outside, the transistor Q5, diode D9,
10. Since all the transistors Q6 are reverse-biased, the output terminal impedance maintains the high impedance state.

[0007]

[Problems to be Solved by the Invention] A driver circuit for a pin electronics card used in an IC tester is as follows.
By making the output impedance high, the I to be tested in the output enabled state
It is configured to prevent a current from flowing into C or a current from flowing into the driver circuit in the output disable state. However,
If the operation speed of the pin electronics card driver circuit is to be increased, it is inevitable that the breakdown voltage between the emitter and the collector of the transistor constituting the driver circuit is reduced.
When the transistor starts to be in a breakdown state due to a decrease in the withstand voltage of the transistor, the output terminal impedance gradually decreases.

The reduction in breakdown voltage of a transistor is larger in a PNP transistor than in an NPN transistor.
Referring to the PNP transistor Q6 having a low emitter-collector withstand voltage, when the emitter-collector voltage between the points B and D in FIG. 1 increases, the transistor Q6 starts to be in a breakdown state. When transistor Q6 begins to enter the breakdown state, its emitter potential begins to drop, and diode D10 conducts according to the degree of the drop. That is, the breakdown current of the transistor Q6 flows from the point D to the point B, and as a result, the output terminal impedance is reduced by that much. Similar discussion can be made for the transistor Q5. When the operation speed of the driver circuit is increased by using a high-frequency transistor, the breakdown voltage of the transistor is generally reduced. However, when the operable voltage range of the driver circuit is widened, the problem of breakdown becomes more serious. .

The present invention is to provide a driver circuit for a pin electronics card which always maintains a high impedance state and solves the above-mentioned problems.

[0010]

In a pin electronics card driver circuit which can be switched to an output enable state or an output disable state by a switching circuit, first and second transistors of the other conductivity type (PNP transistors) are used. A transistor pair consisting of two transistors Q1 and Q2, and the emitters of the first and second transistors Q1 and Q2 are interconnected and connected to a power supply, and are transistors of one conductivity type (NPN transistors). A transistor pair comprising third and fourth transistors Q3 and Q4, wherein the emitters of the third and fourth transistors Q3 and Q4 are interconnected and connected to a power supply; The same duplicate as the collector of the third transistor Q3 Diodes D1 to thereby connect through a series connection circuit which is connected in series D6, first
The collector of the transistor Q1 is the fourth transistor Q
4, the collector of the second transistor Q2 is connected to the collector of the third transistor Q3, wherein the first to fourth transistors Q1 to Q4 constitute a switching circuit. A switching signal input terminal is formed between an intermediate point of a series connection circuit in which a plurality of diodes D1 to D6 are connected in series and bases of the first transistor Q1 to the fourth transistor Q4. Are the fifth transistor Q5, one of the conductivity type transistors,
Output circuit diode D9, first output resistor R1 and second output resistor R2, second output circuit diode D1
0, a circuit in which a sixth transistor Q6, which is a transistor of the other conductivity type, is connected in series in the forward direction. Here, the fifth transistor Q5 is connected to a power supply via a PNP transistor, and the sixth transistor Q6 is NPN
The transistor is connected to a power supply via a transistor. The base of the fifth transistor Q5 is connected to a common connection point between the collector of the first transistor Q1 and the collector of the fourth transistor Q4, while the base of the sixth transistor Q6 is connected. Is connected to a common connection point between the collector of the second transistor Q2 and the collector of the third transistor Q3, the base of the fifth transistor Q5 is further connected to the cathode of the diode D7, and the anode of the diode D7 is connected to the first. And the negative terminal of the first DC power source V1 is grounded, the base of the sixth transistor Q6 is further connected to the anode of a diode D8,
8 is connected to the positive electrode of the second DC power supply V2, the negative electrode of the second DC power supply V2 is grounded, and the common connection point of the first output resistance R1 and the second output resistance R2 is a driver. It constitutes the output end of the circuit, where:
The anode of the first breakdown current commutation diode D11 is connected to the common connection point between the emitter of the fifth transistor Q5 of the output circuit of the driver circuit and the anode of the first output circuit diode D9, while the cathode is connected to the first. The collector of the transistor Q1 and the fourth transistor Q4
Of the second breakdown current commutation diode D12 at the common connection point between the emitter of the sixth transistor Q6 of the output circuit of the driver circuit and the cathode of the diode D10 of the second output circuit. A pin electronics card driver circuit is characterized in that the cathode is connected and the anode is connected to a common connection point between the collector of the second transistor Q2 and the collector of the third transistor Q3.

[0011]

An embodiment of the present invention will be described with reference to FIGS. The circuit of FIG. 2 is substantially the same as the circuit of FIG. According to the present invention, in the circuit of FIG. 1, the first transistor Q1 to the fourth transistor Q4 constitute a switching circuit, and the intermediate point of the series connection circuit in which a plurality of diodes D1 to D6 are connected in series is connected to the first transistor Q1. And a base of each of the fourth to fourth transistors Q1 to Q4 constitutes a switching signal input terminal. The output circuit of the driver circuit includes a fifth transistor Q5, which is a transistor of one conductivity type, and a first output diode. D
9, a circuit in which a first output resistor R1 and a second output resistor R2, a second output diode D10, and a sixth transistor Q6, which is the other conductivity type transistor, are connected in series in the forward direction. 5 transistor Q5 is PN
The sixth transistor Q6 is connected to the power supply via an NPN transistor, and the base of the fifth transistor Q5 is connected to the collector of the first transistor Q1 and the fourth transistor Q4.
While the base of the sixth transistor Q6 is connected to the common connection point of the collector of the second transistor Q2 and the collector of the third transistor Q3, and is connected to the common connection point of the fifth transistor Q5. The base is further connected to the cathode of the diode D7, the anode of the diode D7 is connected to the positive terminal of the DC power supply V1, and the negative terminal of the DC power supply V1 is grounded.
Is connected to the anode of a diode D8, the cathode of the diode D8 is connected to the positive terminal of the DC power supply V2, and the negative terminal of the DC power supply V2 is grounded, and the first output resistance R1 and the second output resistance The common connection point of R2 constitutes the output terminal of the driver circuit, where:
A first breakdown current commutation diode D1 is connected to a common connection point between the emitter of the fifth transistor Q5 of the output circuit of the driver circuit and the anode of the first output diode D9.
1 and the cathode thereof is connected to a common connection point between the collector of the first transistor Q1 and the collector of the fourth transistor Q4. The emitter of the sixth transistor Q6 of the output circuit of the driver circuit and the second Of the second breakdown current commutation diode D12 is connected to the common connection point of the cathode of the output diode D10, while its anode is connected to the second transistor Q2.
And the collector of the third transistor Q3.

The operation of the pin electronics card driver circuit of the present invention will now be described.
In the output disable state where both the second transistor Q2 and the fourth transistor Q4 of the switching circuit are on, even if the fifth transistor Q5 starts to be in the breakdown state and a breakdown current occurs, the breakdown current is , The first output circuit diode D9
Are reverse-biased and are always turned off, so that they flow through the first breakdown current commutation diode D11 without flowing through the first output circuit diode D9 (FIG. 3 (a)). reference). As for the breakdown current of the sixth transistor Q6, the second output circuit diode D10 is reverse-biased and is always turned off. The current flows through the current commutating diode D12 (FIG. 3B).
reference). That is, in the output disable state, no current flows from the output terminal into the driver circuit,
Therefore, the impedance as seen from the output end into the driver circuit is in a high impedance state. Then, the first transistor Q1 and the third transistor Q1 of the switching circuit
In the output enable state in which both the switches 3 and 3 are on, the first breakdown current commutation diode D11 and the second breakdown current commutation diode D12 are both in the off state, which does not hinder the output enable state. .

A first breakdown current commutation diode D11 and a second breakdown current commutation diode D12, which are breakdown current commutation elements.
Can be replaced with a transistor.

[0014]

[Effects of the Invention] In a driver circuit for a pin electronics card, a high-frequency transistor is used as an output circuit to speed up the operation of the driver circuit and adopt a design that widens the operable voltage range of the driver circuit. However, by providing the diode for the breakdown current commutation as described above, the impedance of the output circuit of the driver circuit for the pin electronics card can always be kept in a high impedance state.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional example of a pin electronics card driver circuit.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing a part of an embodiment of the present invention.

[Explanation of symbols]

Q1 First transistor Q2 Second transistor Q3 Third transistor Q4 Fourth transistor Q5 Fifth transistor Q6 Sixth transistor D1 to D6 Multiple diodes D7, D8 Diode D9 First output circuit diode D10 Second Output circuit diode R1 First output resistance R2 Second output resistance V1 First DC power supply V2 Second DC power supply R1 First output resistance R2 Second output resistance D11 First breakdown current commutation diode D12 Output terminal of second breakdown current commutation diode T0

Claims (1)

(57) [Scope of request for utility model registration] 1. A pin electronics card driver circuit in which an output circuit is switched to an output enable state or an output disable state by a switching circuit, wherein the output circuit is a transistor of one conductivity type, a first output circuit diode, A first output resistor, a second output resistor, a second output circuit diode, and a circuit in which transistors of the other conductivity type are connected in series in a forward direction ;
Connect to the common connection point of the output resistance and the second output resistance
A driver circuit output terminal; and a breakdown current commutating element for commutating a breakdown current to be passed through the first output circuit diode and the second output circuit diode in an output disable state. Driver circuit for pin electronics card.