CN211263687U - Soft-cut measurement circuit of dynamic resistance of gallium nitride power tube - Google Patents

Abstract

The utility model provides a measuring circuit is cut in soft of gallium nitride power tube dynamic resistance, include: the main circuit is connected between the drain electrode and the source electrode of the tested gallium nitride power tube and comprises a high-voltage output circuit and a low-voltage output circuit which are connected in parallel; a high-speed drive circuit for providing drive voltage to the grid electrode of the gallium nitride power tube to be tested; the synchronous program control circuit is used for respectively providing synchronous control signals with set time sequences for the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit and controlling the drive voltage, the high voltage and the low voltage to be synchronously supplied and disconnected according to the time sequences; and the voltage sampling circuit is connected in parallel with the two ends of the drain electrode and the source electrode of the tested gallium nitride power tube. The utility model discloses can realize carrying out the high-low pressure fast and switch, and support the synchro control of a plurality of chronogenesis, can effectively measure the dynamic resistance of gallium nitride power tube under the dynamic behavior.

Description

Soft-cut measurement circuit of dynamic resistance of gallium nitride power tube

technical field

The invention relates to the technical field of integrated circuit measurement, in particular to a soft-cut measurement circuit for the dynamic resistance of a gallium nitride power tube.

Background technique

Gallium nitride (GaN) is a new type of semiconductor material. It has the characteristics of large band gap, high thermal conductivity, high temperature resistance, radiation resistance, acid and alkali resistance, high strength and high hardness. It was widely used in new energy vehicles in the early days. , rail transit, smart grid, semiconductor lighting, new generation of mobile communications, known as the third generation of semiconductor materials. As the cost of technological breakthroughs is controlled, gallium nitride is currently widely used in consumer electronics and other fields, and chargers are one of them. With the increasing demand for gallium nitride and more and more applications, the measurement of gallium nitride is becoming more and more important, and the measurement of gallium nitride is divided into two categories: static parameters and dynamic parameters.

Static parameters mainly refer to related parameters inherent in themselves and independent of their working conditions, including: gate-level turn-on voltage, gate-level breakdown voltage, collector-transmitter withstand voltage, leakage current between collector-transmitter, parasitic capacitance (input Capacitance, Transfer Capacitance, Output Capacitance), and the measurement of the relevant characteristic curves of the above parameters.

The dynamic parameters mainly refer to the dynamic on-resistance of the GaN power transistor under dynamic working conditions. Due to the traps in the GaN power transistor structure and the need to design a long depletion region length in order to adapt to the high voltage breakdown voltage, so When the device is turned on immediately after the high voltage blocking state, the channel electrons are essentially trapped and therefore do not participate in conduction, which results in a higher GaN power transistor in dynamic operation than in static state On-resistance, the dynamic on-resistance or dynamic resistance is of great significance for studying the working characteristics of GaN power transistors. However, in the prior art, there is no simple and effective measurement circuit that can measure the GaN power transistors. In order to reflect the characteristics of the GaN power tube under dynamic working conditions, it is necessary to design a measurement circuit to effectively measure the dynamic resistance of the GaN power tube.

SUMMARY OF THE INVENTION

In view of this, the main purpose of the present invention is to provide a soft-cut measurement circuit and measurement method for the dynamic resistance of a gallium nitride power tube, by designing a soft-cut that can quickly perform high and low voltage switching and supports multiple timing synchronous program controls The measuring circuit can effectively measure the dynamic resistance of the gallium nitride power transistor under dynamic working conditions.

The technical solution adopted in the present invention is a soft-cut measurement circuit for the dynamic resistance of a gallium nitride power tube, comprising:

The main circuit is connected between the drain and the source of the GaN power tube under test. The main circuit includes a parallel high-voltage output circuit and a low-voltage output circuit. A high voltage is provided between the sources, and the low voltage output circuit is used to provide a low voltage between the drain and the source of the gallium nitride power transistor through the main circuit;

A high-speed drive circuit that provides drive voltage to the gate of the GaN power transistor under test;

A synchronous program-controlled circuit, respectively providing a high-speed drive circuit, a high-voltage output circuit and a low-voltage output circuit with a synchronous control signal with a set timing sequence, and controlling the drive voltage, high-voltage and low-voltage to be supplied and cut synchronously according to the timing sequence;

The voltage sampling circuit is connected in parallel between the drain and the source of the gallium nitride power transistor under test.

From the above, the present invention outputs the synchronous control signal of the set timing through the synchronous program control circuit, so as to control the high-voltage output circuit, the low-voltage output current and the high-speed driving circuit in the soft-cut measurement circuit to be turned on in sequence according to the set timing, and measure the nitridation. The voltage value and current value of the gallium power tube at each time sequence, so as to calculate the resistance value corresponding to each time sequence, the invention supports the synchronization of the control signal and the processing function of the hardware data, and realizes the drain and the voltage of the gallium nitride power tube. Fast high and low voltage switching measurement between sources, so as to effectively measure the dynamic resistance of GaN power transistors under dynamic operating conditions.

Preferably, the high-voltage output circuit includes:

a high voltage source, a first switch and a first resistor connected in series in sequence;

The first switch is turned on or off by receiving a synchronous control signal provided by the synchronous program control circuit.

From the above, the high-voltage source can be used to provide a voltage not higher than 1000V, and its maximum current capability is 10mA. The first switch can receive a synchronous control signal to control the on or off of the high-voltage source, and the first resistor is used to switch the high-voltage circuit to the low-voltage circuit. , the current clamping of the high voltage source is realized.

Preferably, the voltage sampling circuit includes:

A voltmeter and high voltage clamp circuit in series.

From the above, the voltage sampling circuit can collect the voltage at both ends of the GaN power tube in real time through a high-precision voltmeter, and the high-voltage clamping circuit can clamp the high voltage of the drain of the GaN power tube under test when it is turned off. bit to protect the high-precision voltmeter from being damaged by high voltage.

Preferably, the low-voltage output circuit includes:

A low-voltage source, the low-voltage source connects the drain and source of the GaN power transistor under test through a four-wire Kelvin circuit;

Wherein, the low-voltage source is connected to the drain of the tested gallium nitride power transistor through the Force_High line of the four-wire Kelvin circuit in series with the third switch; the low-voltage source is also connected in series with the high-voltage through the Sense_High line of the four-wire Kelvin circuit The clamping circuit is connected to the drain of the tested gallium nitride power transistor, and the third switch is turned on or off by receiving the synchronous control signal provided by the synchronous programming circuit;

The Force_Low line and the Sense_Low line of the four-wire Kelvin circuit are respectively connected between the negative output end of the low voltage source and the source of the GaN power transistor under test.

From the above, the high-voltage output circuit provides high voltage for the drain and source of the GaN power tube under test, so that after a period of time in a high-voltage environment, the low-voltage output circuit will connect the drain and source of the GaN power tube under test. The high voltage between the poles is quickly switched to the low voltage, and then the current value and voltage value of the tested GaN power tube are measured to obtain its resistance value change parameters under the dynamic operating voltage. The low voltage output circuit passes the four-wire Kelvin The circuits (Force_High line, Sense_High line, Force_Low line, Sense_Low line) are connected to the drain and source of the GaN power transistor under test, wherein the Force_High line (or high-side driving current line) of the four-wire Kelvin circuit passes through a third The switch is connected to the drain of the GaN power transistor under test. The third switch is used to isolate the high-voltage source and the low-voltage source. Connect to the drain of the tested GaN power transistor to provide low voltage for the tested GaN power transistor.

Preferably, the low-voltage output circuit further includes a reverse current suppression circuit connected in parallel to both ends of the third switch, including: a second resistor and a fourth switch connected in series;

The fourth switch is turned on or off by receiving the synchronous control signal provided by the synchronous program control circuit.

From the above, the second resistor is a shunt resistor. By controlling the turn-on or turn-off of the fourth switch, the switching speed from high voltage to low voltage can be reduced, so as to reduce the reverse current flowing to the drain of the tested GaN power transistor.

Preferably, a second switch is connected in series between the Force_High line and the Sense_High line, and the second switch receives a synchronous control signal provided by the synchronous program control circuit to turn on or off, so as to control the formation between the Force_High line and the Sense_High line. short circuit or open circuit.

From the above, when the high voltage output circuit applies high voltage to the drain and source electrodes of the GaN power tube under test, the low voltage output circuit is in an off state. Before switching from high voltage to low voltage, the second switch needs to be turned on to ensure that When the high voltage is switched to the low voltage, the Kelvin circuit at the output of the low-voltage source is short-circuited and reaches the preset low-voltage value in advance. Otherwise, if the Kelvin circuit at the output of the low-voltage source is open, the low-voltage source needs about 20ms of adjustment time to bring it to the preset low pressure value.

Based on the above-mentioned soft-cut measurement circuit of the dynamic resistance of the gallium nitride power tube, the present invention also provides a method for measuring the dynamic resistance of the gallium nitride power tube, comprising the steps of:

A. Provide the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit with a synchronous control signal with a set timing through the synchronous program control circuit, and control the drive voltage provided by the high-speed drive circuit to the gate of the GaN power tube under test. The high voltage provided by the output circuit between the drain and the source of the gallium nitride power transistor and the low voltage provided by the low voltage output circuit between the drain and the source of the gallium nitride power transistor are supplied and disconnected synchronously according to the timing sequence;

B. Obtain each current value and voltage value corresponding to each time sequence through the low-voltage output circuit and the voltage sampling circuit;

C. Calculate each corresponding resistance value according to each current value and voltage value corresponding to each time sequence, and obtain the parameters of the dynamic resistance of the gallium nitride power transistor under test.

From the above, the measurement method realizes that the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit are turned on and off according to the set timing through the synchronous control signal provided by the synchronous program-controlled circuit. The current value is measured synchronously. According to Ohm's law, the resistance value under each time sequence can be calculated by using the measured voltage value and current value, so as to obtain the parameters of the dynamic resistance of the tested GaN power tube.

Preferably, after step C, also include:

Whether the tested gallium nitride power transistor is normal is determined according to whether the characteristic curve corresponding to the parameter of the dynamic resistance conforms to the corresponding characteristic curve of the normal gallium nitride power transistor.

From the above, according to the characteristics of the gallium nitride material, the on-resistance of the normal gallium nitride power tube is small in the low-voltage working state. When a high voltage is applied to the gallium nitride power tube for a period of time, it is switched to In the low-voltage working state, its on-resistance will increase, so according to this characteristic, it can be judged whether the measurement result is correct, so as to judge whether the tested GaN power tube is normal.

Preferably, the synchronization control signal for the set timing includes:

Controlling the high-speed driving circuit to drive the tested gallium nitride power tube to conduct and controlling the low-voltage output circuit to provide a low voltage between the drain and the source of the gallium nitride power tube, and the duration is T1;

The high-speed driving circuit is controlled to drive the gallium nitride power transistor under test to disconnect and the high-voltage output circuit is controlled to provide a high voltage between the drain and the source of the gallium nitride power transistor, and the duration is T2, and T2>T1.

From the above, in the present invention, by outputting a low voltage and a high voltage between the drain and the source of the tested gallium nitride power tube, it is under the dynamic working voltage, so as to measure the resistance value under the dynamic working voltage to obtain Get the parameters of its dynamic resistance.

Description of drawings

Fig. 1 is the circuit schematic diagram of the soft-cut measurement circuit of the dynamic resistance of the gallium nitride power tube of the present invention;

2 is a flow chart of a method for measuring dynamic resistance of a gallium nitride power tube according to the present invention;

Fig. 3 is the waveform schematic diagram of each circuit part under the setting sequence of the present invention;

FIG. 4 is a schematic diagram of a dynamic resistance characteristic curve of a gallium nitride power transistor according to the present invention.

Detailed ways

The specific implementation of the soft-cut measurement circuit for the dynamic resistance of a gallium nitride power tube according to the present invention will be described in detail below with reference to FIGS. 1 to 4 .

As shown in FIG. 1, the circuit principle diagram of the soft-cut measurement circuit of the dynamic resistance of the gallium nitride power tube of the present invention is shown, and the soft-cut measurement circuit includes:

The synchronous program control circuit (not shown in the figure) can be realized by a programmable FPGA chip, and through programming control, it outputs a synchronous control signal with a set timing, so that the soft-cut measurement circuit of the present invention is turned on or off synchronously. turn off, and synchronously measure the voltage value and current value of the GaN power tube each time it is turned on;

The high voltage source VI1, the positive output terminal of the high voltage source VI1 is connected in series with a MOS switch K1 and a resistor R1 and then connected to the drain (D) of the gallium nitride power transistor under test. The MOS switch K1 receives the synchronization provided by the synchronous programming circuit. The control signal CTRL1, the resistance value of the resistor R1 is 1000 ohms, which can be used to realize the current clamping of the output terminal of the high voltage source when switching from high voltage to low voltage; the negative output terminal of the high voltage source VI1 is connected to the source of the GaN power tube under test. pole(S);

The low-voltage source VI2, whose output end performs low-voltage output and current measurement through a four-wire Kelvin circuit, the four-wire Kelvin circuit includes a driving current line Force_High and a sensing voltage line Sense_High connected to the positive output of the low-voltage source VI2, and connected to the low-voltage source VI2 The driving current line Force_Low and the sensing voltage line Sense_Low at the negative output end; wherein, a MOS switch K3 is connected in series with the driving current line Force_High and then connected to the drain (D) of the GaN power transistor under test. The MOS switch K3 receives the synchronous signal The synchronous control signal CTRL3 provided by the program control circuit can be used to isolate the low-voltage source VI2 and the high-voltage source VI1 to protect the low-voltage source VI2. At the same time, its fast turn-on capability enables the low-voltage provided by the low-voltage source VI2 to quickly establish to the tested nitridation. The drain (D) of the gallium power tube, and the two ends of the MOS switch K3 are also connected in parallel with a series-connected MOS switch K4 and a resistor R2, the MOS switch K4 receives the synchronous control signal CTRL4 provided by the synchronous programming circuit, and can be used to reduce the high voltage to Low-voltage switching speed, resistor R2 is a shunt resistor, which can be used to reduce the reverse current flowing to the drain of the GaN power tube under test; the sensing voltage line Sense_High is connected in series with the attenuator Attenuator in the voltage sampling circuit described later, and then connected to The drain (D) of the tested gallium nitride power transistor provides a low voltage to the drain (D) of the tested gallium nitride power transistor; a MOS switch K2 is also connected in series between the driving current line Force_High and the sensing voltage line Sense_High , the MOS switch K2 receives the synchronous control signal CTRL2 provided by the synchronous program control circuit, when the high voltage is continuously applied to the tested gallium nitride power transistor, the above-mentioned MOS switch K3 is in the off state, and the MOS switch K2 is turned on at this time, So that the Kelvin circuit of the low-voltage source VI2 is short-circuited, the low-voltage source VI2 can reach the preset low-voltage value in advance, so as to avoid that when the high-voltage switches to the low-voltage, the high-voltage at the moment of switching will cause a certain impact on the low-voltage source VI2. The low-voltage source VI2 It takes about 20ms of adjustment time to reach the preset low voltage value;

The driver Driver, whose output terminals are respectively connected to the gate (G) and the source (S) of the GaN power transistor under test, the driver Driver receives the synchronous control signal CTRL0 provided by the synchronous programming circuit, and is controlled by the synchronous control signal CTRL0 , output a high-speed driving signal, that is, driving voltage, to the tested GaN power tube to control its turn-on or turn-off;

A voltage sampling circuit, connected in parallel with both ends of the drain (D) and source (S) of the gallium nitride power transistor, includes a series-connected high-precision voltmeter V1 and an attenuator Attenuator, and the Sense_High of the four-wire Kelvin circuit is connected in series with the The Attenuator provides low voltage to the GaN power tube to be tested. The high-precision voltmeter V1 is controlled by the synchronous control signal of the set timing provided by the synchronous program control circuit, and real-time collects the voltage of the GaN power tube corresponding to each timing. Voltage value, the Attenuator mainly plays the role of high-voltage clamping protection in the circuit. When the tested GaN power tube is turned off, it clamps the high-voltage of its drain to protect the high-precision voltmeter and low voltage source VI2 are not damaged by high voltage;

Under the above set timing, the synchronous control signal logic provided by the synchronous program-controlled circuit is:

When the high-voltage source applies high voltage to the tested GaN power tube, the driver does not output the driving voltage, and the tested GaN power tube is not turned on;

When the low-voltage source is turned on, and the high voltage applied to the GaN power tube under test is switched to a low voltage, the driver Driver outputs the driving voltage to drive the GaN power tube under test to turn on. At the same time, the voltage sampling circuit and the low-voltage source VI2 synchronize the voltage measurement of values and current values;

The above-mentioned high pressure and low pressure are applied at intervals, and the duration of low pressure application is much shorter than the duration of high pressure application. Generally, the duration of low pressure is 5ms, and the duration of high pressure is 100ms.

As shown in Figure 2, when the dynamic resistance measurement of the gallium nitride power tube is performed according to the above-mentioned soft-cut measurement circuit, the following steps are included:

S100: Provide the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit with a synchronous control signal with a set timing through the synchronous program control circuit, and control the drive voltage provided by the high-speed drive circuit to the gate of the gallium nitride power tube under test. The high voltage provided by the output circuit between the drain and the source of the gallium nitride power transistor and the low voltage provided by the low voltage output circuit between the drain and the source of the gallium nitride power transistor are supplied and disconnected synchronously according to the timing sequence;

Figure 3 is a schematic diagram of the waveforms of each circuit part under the set timing output of the synchronous program-controlled circuit. Under the set timing, the synchronous program-controlled circuit provides synchronous control signals to the high-speed drive circuit, the high-voltage output circuit, and the low-voltage output circuit, respectively. It is controlled to be turned on or off under the set timing. In the present invention, the switching from high voltage to low voltage of the soft-cut measurement circuit is mainly realized by turning on or off the low-voltage output circuit. In actual measurement, the high-voltage output circuit The switch K1 can always remain in an on state. Specifically, a complete timing synchronization control cycle is as follows:

At time t1, the driver is controlled to output a 5V driving voltage to the gate (G) of the GaN power tube under test, and it is driven to turn on, the switches K1 and K3 are turned on, and the switches K2 and K4 are turned off. At this time, the high-voltage source The high voltage 500V output by VI1 is pulled down by the turned-on switch K3, the voltage applied to the tested GaN power tube is low voltage 0.1V, and the low voltage state is maintained for 5ms until time t1';

At time t1', the driver is controlled to disconnect the 5V driving voltage output to the gate (G) of the GaN power transistor under test, drive it off, turn on the switches K1 and K2, and turn off the switches K3 and K4. At this time, the high voltage 500V output by the high voltage source VI1 is applied to the tested GaN power tube, the low voltage source is isolated from the high voltage source, and the switch K2 is turned on to short-circuit the driving current line Force_High and the sensing voltage line Sense_High of the Kelvin circuit, and the low voltage source passes through the The short-circuited Kelvin circuit reaches the preset voltage value in advance, and maintains the high-voltage state for 100ms until time t2;

At time t2, the driver is controlled to output a 5V drive voltage to the gate (G) of the GaN power transistor under test, and it is driven to turn on, the switches K1 and K4 are turned on, the switches K2 and K3 are turned off, the switch K4 and the resistor R2 can reduce the reverse current flowing to the tested GaN power tube at the moment of switching from high voltage to low voltage; then the switches K1 and K3 are turned on, the switches K2 and K4 are turned off, and the voltage applied to the tested GaN power tube is reset Pull down to a low voltage of 0.1V, and keep the low voltage state for 5ms until time t2'.

S200: obtain each current value and voltage value corresponding to each time sequence through the low-voltage output circuit and the voltage sampling circuit;

In this step, each voltage value and current value within the low-voltage duration corresponding to each time sequence are obtained by synchronously measuring the voltage sampling circuit and the low-voltage source VI2;

Among them, the waveform of the current value IC measured by the low voltage source VI2 during each low voltage duration is shown in Figure 3. According to the current value IC measured by the low voltage source VI2 and the voltage measured by the voltmeter V1, the measured gallium nitride can be calculated. The resistance value of the power tube at each timing.

S300: Calculate the corresponding resistance values according to the current values and voltage values corresponding to the time sequences, and obtain parameters of the dynamic resistance of the gallium nitride power transistor under test;

S400: Determine whether the tested GaN power tube is normal according to whether the characteristic curve corresponding to the parameter of the dynamic resistance conforms to the corresponding characteristic curve of the normal GaN power tube;

Figure 4 is a schematic diagram of the dynamic resistance characteristic curve of the GaN power tube, wherein RON1 and RON2 are the measurement results of the resistance value RON of the GaN power tube corresponding to the timing shown in Figure 3. The measurement results are integrated to generate the characteristic curve corresponding to the parameters of the dynamic resistance as shown in Figure 4. According to the characteristics of the gallium nitride material, the on-resistance of a normal gallium nitride power transistor in the low-voltage working state is small. After a period of high voltage is applied to its drain and source, according to its characteristics, its on-resistance will increase in the next low-voltage action state, and the increase process may last for several cycles of high-voltage and low-voltage switching. , the region is stable; therefore, according to the dynamic resistance characteristic curve obtained by the soft-cut measurement circuit, it can be judged whether the GaN power tube conforms to its characteristics, if so, it is judged to be normal, if not, it is judged to be unusual;

It can be seen from the change curve in Figure 4 that at the time T1 (t1-t1'), the resistance value RON1 of the GaN power transistor in the ON state is lower, and at the time T2 (t2-t2'), the resistance value RON1 of the GaN power transistor is low. The resistance value RON2 in the ON state of the power tube starts to rise, and from this measurement result:

RON1<RON2;

((RON2-RON1)/RON1)*100%>x%;

Among them, x% is the floating limit proposed by the designer of the GaN power tube, which is used to reflect the dynamic parameter change of the GaN power tube under the dynamic working state;

According to the measurement results, it can be determined that the performance of the above-mentioned gallium nitride power transistor conforms to its characteristics, and it is determined to be in a normal state.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (6)

1. a soft-cut measurement circuit of gallium nitride power tube dynamic resistance, is characterized in that, comprises: The main circuit is connected between the drain and the source of the GaN power tube under test. The main circuit includes a parallel high-voltage output circuit and a low-voltage output circuit. A high voltage is provided between the sources, and the low voltage output circuit is used to provide a low voltage between the drain and the source of the gallium nitride power transistor through the main circuit; A high-speed drive circuit that provides drive voltage to the gate of the GaN power transistor under test; A synchronous program-controlled circuit, respectively providing a high-speed drive circuit, a high-voltage output circuit and a low-voltage output circuit with a synchronous control signal with a set timing sequence, and controlling the drive voltage, high-voltage and low-voltage to be supplied and cut synchronously according to the timing sequence; The voltage sampling circuit is connected in parallel between the drain and the source of the gallium nitride power transistor under test. 2. The circuit according to claim 1, wherein the high-voltage output circuit comprises: a high voltage source, a first switch and a first resistor connected in series in sequence; The first switch is turned on or off by receiving a synchronous control signal provided by the synchronous program control circuit. 3. The circuit according to claim 1, wherein the voltage sampling circuit comprises: A voltmeter and high voltage clamp circuit in series. 4. The circuit of claim 3, wherein the low-voltage output circuit comprises: A low-voltage source, the low-voltage source connects the drain and source of the GaN power transistor under test through a four-wire Kelvin circuit; Wherein, the low-voltage source is connected to the drain of the tested gallium nitride power transistor through the Force_High line of the four-wire Kelvin circuit in series with the third switch; the low-voltage source is also connected in series with the high-voltage through the Sense_High line of the four-wire Kelvin circuit The clamping circuit is connected to the drain of the tested gallium nitride power transistor, and the third switch is turned on or off by receiving the synchronous control signal provided by the synchronous programming circuit; The Force_Low line and the Sense_Low line of the four-wire Kelvin circuit are respectively connected between the negative output end of the low voltage source and the source of the GaN power transistor under test. 5. The circuit according to claim 4, wherein the low-voltage output circuit further comprises a reverse current suppression circuit connected in parallel to both ends of the third switch, comprising: a second resistor and a fourth switch connected in series; The fourth switch is turned on or off by receiving the synchronous control signal provided by the synchronous program control circuit. 6 . The circuit according to claim 4 , wherein a second switch is connected in series between the Force_High line and the Sense_High line, and the second switch receives a synchronous control signal provided by the synchronous program control circuit to turn on or off 6 . to control the formation of a short or open circuit between the Force_High line and the Sense_High line.

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