JP2001112160A - Method of inputting output of current monitor terminal into microcomputer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance usage efficiency of the A/D input terminal equipped with an A/D converting function, provided in a microcomputer to a current monitor terminal. SOLUTION: Resistors Rs1, Rs2, Rs3, and Rs4 for current detection are connected to the drain sides of semiconductor relays 2, 10, 16, and 22. A plurality of loads 3, 11, 17, and 23 are provided, respectively, with load current monitor circuits 6, 13, 19, and 25 for monitoring the values of the currents flowing to the loads 3, 11, 17, and 23. The analog output values of the load current monitor circuits 6, 13, 19, and 25, in the plural loads 3, 11, 17, and 23 optionally selected through analog multiplexers 28 are fetched in CPU through an A/D converter built in a microcomputer 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor relay system using a semiconductor relay, and more particularly to a semiconductor relay system using a single A / D converter built in a microcomputer.
The present invention relates to a method of inputting to a microcomputer a current monitor terminal which can efficiently take in data to the microcomputer with a small number of A / D converters.

[0002]

2. Description of the Related Art Generally, in a vehicle, power from a vehicle-mounted battery is supplied to loads disposed in various parts of the vehicle via a power line covered with a power MOSFET and an insulating film. The power supply line is routed along the vehicle body in an engine room or the like that is constantly vibrating, but a dead short or a rare short occurs in the power supply line for some reason, and an overcurrent may flow. In recent years, power MOSFETs and IPS (I
ntelligent Power Switch) has been used.
In such semiconductor relays and IPSs, various current limiter methods for limiting a current flowing to a load have conventionally been adopted in order to prevent heat generation of the device.

A microcomputer monitors a current flowing through a load by sampling a current value at predetermined intervals, reads the current monitor value, constantly checks the current flowing through the load, and checks whether the current flowing through the load is in an overcurrent state. It is necessary to monitor whether or not.

Conventionally, as shown in FIG. 2, a power supply voltage VB from a vehicle-mounted battery includes a current detecting resistor (shunt resistor) Rs1 for detecting a current supplied to a load, and a drain D- The power is supplied to a load 3 such as a stop lamp via the sources S. The semiconductor relay 2 is, for example, a MOSFET with a built-in heat cutoff circuit. The built-in MOSFET with a built-in heat cutoff circuit is a logic-level (4 V or more) drive type power MOSFET, which has a built-in heat cutoff circuit and is overheated. The overheat protection method is of a latch type, and is restored with a gate voltage of 0 bias after the operation of the overheat protection circuit.

The driving circuit 4 includes, for example, an NPN type switching (SW) transistor having a collector connected to a charge pump output voltage VP (= VB + 10 [V]) obtained by boosting the power supply voltage VB by the charge pump circuit 5, and
NP with collector connected to emitter of W transistor
A contact point between the emitter of the SW transistor connected to the charge pump circuit 5 and the collector of the SW transistor connected to the ground side is connected to the gate G of the semiconductor relay 2. It has a configuration.

The drive circuit 4 turns on the SW transistor connected to the charge pump circuit 5 side of the two serially connected SW transistors, and switches the SW transistor.
By turning off the transistor, the charge pump output voltage VP is applied to the gate G of the semiconductor relay 2,
The semiconductor relay 2 is turned on and two series-connected S
By turning off the SW transistor connected to the charge pump circuit 5 side of the W transistor and turning on the SW transistor, the application of the charge pump output voltage VP to the gate G of the semiconductor relay 2 is stopped. Has the function of turning off the power.

A shunt resistor Rs1 provided between the vehicle-mounted battery and the semiconductor relay 2 has a low resistance for converting a current flowing through a power supply line between the vehicle-mounted battery and the load 3 into a voltage. The current flowing through the power supply line is detected by detecting the voltage. Both ends of the shunt resistor Rs1 are connected to a load current monitor circuit 6. The load current monitor circuit 6 functions as current detection means, and outputs a voltage corresponding to the voltage across the shunt resistor Rs1 to load current. Has been detected. The shunt resistor Rs1 uses a resistor of, for example, several tens of mΩ, and determines a hard overcurrent determination value, for example, several tens of amps.

The output of the load current monitor circuit 6 is supplied to a microcomputer (microcomputer) 8, and the microcomputer 8
After being converted into a digital value by an A / D converter 9 incorporated in the microcomputer 8, the digital value is taken into the CPU of the microcomputer 8. The microcomputer 8 includes a CPU that operates in accordance with a preset control program, a ROM that stores the control program of the CPU in advance, and a RAM that temporarily stores data necessary for the CPU to execute calculations. The microcomputer 8 is turned on by turning on the switch SW.
It has a function of outputting a drive instruction signal to the gate logic circuit 7.

The power supply voltage VB from the vehicle battery
Is supplied to a load 11 such as a tail lamp different from the load 3 via a current detection resistor (shunt resistor) Rs2 for detecting a current supplied to the load and a drain D-source S of the semiconductor relay 10. Is done.

The semiconductor relay 10 is a semiconductor relay 2
, And the drive circuit 12 is configured similarly to the drive circuit 4. Further, the shunt resistor Rs2 is a low resistor for converting a current flowing through the power supply line between the vehicle-mounted battery and the load 11 into a voltage. By detecting the voltage at both ends, the current flowing through the power supply line is detected. I have. Both ends of the shunt resistor Rs2 are connected to a load current monitor circuit 6
And the same load current monitor circuit 13 is connected.
The output of the load current monitor circuit 13 is supplied to a microcomputer (microcomputer) 8, converted into a digital value by an A / D converter 15 built in the microcomputer 8, and taken into the CPU of the microcomputer 8.

The microcomputer 8 includes a CPU that operates according to a preset control program, a ROM that stores the control program of the CPU in advance, and a RAM that temporarily stores data necessary for the CPU to execute calculations. The microcomputer 8 has a function of outputting a drive instruction signal to the gate logic circuit 14 when the microcomputer 8 turns on the switch SW.

Also, the power supply voltage VB from the vehicle battery
Is a load such as a back lamp different from the loads 3 and 11 via a current detection resistor (shunt resistor) Rs3 for detecting a current supplied to the load and a portion between the drain D and the source S of the semiconductor relay 16. 17 is supplied. The semiconductor relay 16 has the same configuration as the semiconductor relay 2, and the drive circuit 18 has the same configuration as the drive circuit 4. Further, the shunt resistor Rs3 is a low resistor for converting the current flowing through the power supply line between the vehicle-mounted battery and the load 17 into a voltage. By detecting the voltage at both ends, the current flowing through the power supply line is detected. I have. The same load current monitor circuit 19 as the load current monitor circuit 6 is connected to both ends of the shunt resistor Rs3. The output of the load current monitor circuit 19 is supplied to a microcomputer (microcomputer) 8 and is converted into a digital value by an A / D converter 21 built in the microcomputer 8.
It is taken in.

The microcomputer 8 includes a CPU that operates in accordance with a preset control program, a ROM that stores the control program of the CPU in advance, and a RAM that temporarily stores data necessary for the CPU to execute calculations. The microcomputer 8 has a function of outputting a drive instruction signal to the gate logic circuit 20 by turning on the switch SW of the microcomputer 8.

The power supply voltage VB from the vehicle battery
Are connected to the loads 3, 11, 17 via a current detection resistor (shunt resistor) Rs4 for detecting a current supplied to the load and between the drain D and the source S of the semiconductor relay 22.
Is supplied to a load 23 such as a back lamp different from the above. The semiconductor relay 22 has the same configuration as the semiconductor relay 2, and the drive circuit 24 has the same configuration as the drive circuit 4. Further, the shunt resistor Rs4 is a low resistor for converting the current flowing through the power supply line between the vehicle-mounted battery and the load 23 into a voltage. By detecting the voltage at both ends, the current flowing through the power supply line is detected. I have. This shunt resistor R
The same load current monitor circuit 25 as the load current monitor circuit 6 is connected to both ends of s4. The output of the load current monitor circuit 25 is supplied to the microcomputer 8, converted into a digital value by an A / D converter 27 built in the microcomputer 8, and then taken into the CPU of the microcomputer 8.

The microcomputer 8 includes a CPU that operates according to a preset control program, a ROM that stores the control program of the CPU in advance, and a RAM that temporarily stores data necessary for the CPU to execute calculations. The microcomputer 8 has a function of outputting a drive instruction signal to the gate logic circuit 26 when the microcomputer 8 turns on the switch SW.

[0016]

As described above, in the conventional semiconductor relay system, when there are a plurality of loads (multiple channels), the power supply voltage VB from the vehicle battery is supplied to each load via the semiconductor relay. The current value supplied to each load is individually detected, and each is converted into a digital value by A / D converters 9, 15, 21, and 27 built in the microcomputer 8 and taken into the CPU. It has a configuration.

Therefore, when the load is multi-channel (for example, 4 channels), the number of A / D input terminals of the microcomputer also needs to be multi-channel (for example, 4 channels). However, although the number of I / O terminals provided in the microcomputer 8 is large, an A / D having an A / D conversion function is provided.
Since the number of D input terminals is limited, it is more efficient to use the A / D input terminal to take in the detected value from the sensor into the microcomputer 8 because the A / D input terminal is used more efficiently and the lamp load is increased. Is used for monitoring the load current which simply detects the current flowing through the lamp load, and for monitoring the load current which does not need to be monitored frequently, such as a lamp load, is used as the A / D input terminal. There is a problem that it is not suitable for use efficiency. Also, the number of I / O terminals provided in the microcomputer is limited to the number of A / D input terminals having an A / D conversion function. Can be used to reduce the number of A / D input terminals used,
There is a problem in that the mounting area becomes large and it is not suitable in terms of miniaturization.

An object of the present invention is to provide an A / D converter having an A / D conversion function provided in a microcomputer for a current monitor terminal.
It is to improve the use efficiency of the / D input terminal.

[0019]

According to a first aspect of the present invention, there is provided a method for inputting a current monitor terminal to a microcomputer, wherein the power supply voltage is boosted by a charge pump circuit by the microcomputer. By applying an output voltage to a gate of a semiconductor relay connected in series to each of a plurality of loads via a drive circuit, the semiconductor relay is turned on and off to supply power to each load. In a system, a load current monitor circuit is provided for each of a plurality of loads, and a load current monitor circuit is provided for each of the plurality of loads, and a current detection resistor is connected to a drain side of the semiconductor relay to monitor a current value flowing through the load. The analog output value is arbitrarily selected via the analog multiplexer. It is obtained by the capture to the CPU via one A / D converter built in the Yuta.
With this configuration, according to the first aspect of the invention, it is possible to improve the use efficiency of the A / D input terminal having the A / D conversion function provided in the microcomputer for the current monitor terminal. .

[0020]

Embodiments of the present invention will be described below. FIG. 1 is a circuit diagram of a semiconductor monitor system showing an embodiment of a method for inputting a current monitor terminal to a microcomputer according to the present invention.

In FIG. 1, a power supply voltage VB from a vehicle-mounted battery includes a current detecting resistor (shunt resistor) Rs1 for detecting a current supplied to a load 3, and a semiconductor relay 2 (for example, a thermal cutoff circuit as a semiconductor switch element). Built-in MO
SFET) is supplied to a load 3 such as a stop lamp via the drain D and the source S. This semiconductor relay 2
For example, a MOSFET with a built-in thermal cut-off circuit is used. The MOSFET with a built-in thermal cut-off circuit is a power MOSFET driven at a logic level (4 V or more). The overheat shut-off method is a latch type, and after the operation of the overheat cut-off circuit, the circuit is restored with a gate voltage of 0 bias.

The drive circuit 4 includes, for example, an NPN type switching (SW) transistor having a collector connected to a charge pump output voltage VP (= VB + 10 [V]) obtained by boosting the power supply voltage VB by the charge pump circuit 5, and the S
NP with collector connected to emitter of W transistor
A contact point between the emitter of the SW transistor connected to the charge pump circuit 5 and the collector of the SW transistor connected to the ground side is connected to the gate G of the semiconductor relay 2. It has a configuration.

The drive circuit 4 turns on the SW transistor connected to the charge pump circuit 5 side of the two serially connected SW transistors, and switches the SW transistor.
By turning off the transistor, the charge pump output voltage VP is applied to the gate G of the semiconductor relay 2,
The semiconductor relay 2 is turned on and two series-connected S
By turning off the SW transistor connected to the charge pump circuit 5 side of the W transistor and turning on the SW transistor, the application of the charge pump output voltage VP to the gate G of the semiconductor relay 2 is stopped, and the semiconductor relay 2 Has the function of turning off the power.

A shunt resistor Rs1 provided between the vehicle battery and the semiconductor relay 2 is a low resistor for converting a current flowing through a power supply line between the vehicle battery and the load 3 into a voltage. The current flowing through the power supply line is detected by detecting the voltage. Both ends of the shunt resistor Rs1 are connected to a load current monitor circuit 6. The load current monitor circuit 6 functions as current detection means, and outputs a voltage corresponding to the voltage across the shunt resistor Rs1 to load current. Has been detected. The shunt resistor Rs1 uses a resistor of, for example, several tens of mΩ, and determines a hard overcurrent determination value, for example, several tens of amps. The output of the load current monitor circuit 6 is input to the analog multiplexer 28. The analog multiplexer 28 selects one of a number of analog signals (up to the maximum capacity of the multiplexer) and selects A /
This is given to the input of the D converter.

The power supply voltage VB from the vehicle battery
Is a current detection resistor (shunt resistor) Rs2 for detecting a current supplied to a load 11 different from the load 3, and a drain D of a semiconductor relay 10 (for example, a MOSFET with a built-in heat cutoff circuit as a semiconductor switch element). -Is supplied to the lamp load 11 such as a tail lamp via the source S and the source S. The semiconductor relay 10 uses, for example, a MOSFET with a built-in heat shut-off circuit.
The SFET is a logic-level (4V or more) drive type power MOSFET with a built-in thermal cutoff circuit, which enables protection of the power MOSFET in the overheated state. The overheat cutoff method is a latch type, and after the overheat cutoff circuit operates Restores with a gate voltage of 0 bias.

The drive circuit 12 includes, for example, an NPN type switching (SW) transistor in which a charge pump output voltage VP (= VB + 10 [V]) obtained by boosting the power supply voltage VB by the charge pump circuit 5 is connected to a collector, and the SW N with collector connected to emitter of transistor
A contact point between the emitter of the SW transistor connected to the charge pump circuit 5 and the collector of the SW transistor connected to the ground is connected to the gate G of the semiconductor relay 2. It has a configuration.

The drive circuit 12 is a charge pump circuit 5 of the two serially connected SW transistors.
Turn on the SW transistor connected to the
By turning off the W transistor, the charge pump output voltage VP is applied to the gate G of the semiconductor relay 10 to turn on the semiconductor relay 10 and to the charge pump circuit 5 side of the two serially connected SW transistors. By turning off the connected SW transistor and turning on the SW transistor, the semiconductor relay 10
The function of stopping the application of the charge pump output voltage VP to the gate G of the semiconductor relay 10 and turning off the semiconductor relay 10 is provided.

A shunt resistor Rs2 provided between the vehicle battery and the semiconductor relay 10 is a low resistor for converting a current flowing through a power supply line between the vehicle battery and the lamp load 11 into a voltage. The current flowing in the power supply line is detected by detecting the voltage between both ends. Both ends of the shunt resistor Rs2 are connected to the load current monitor circuit 13
The load current monitoring circuit 13 is connected to
It functions as current detection means and detects a load current by outputting a voltage corresponding to the voltage across the shunt resistor Rs2. The shunt resistor Rs2 is, for example,
Using a resistor of several tens of mΩ, a hardware-based overcurrent determination value, for example, several tens of amperes is determined. The output of the load current monitor circuit 13 is input to the analog multiplexer 28. The analog multiplexer 28 selects one of a large number of analog signals (up to the maximum capacity of the multiplexer) and supplies it to the input of the A / D converter.

The power supply voltage VB from the vehicle battery
Is a current detection resistor (shunt resistor) Rs3 for detecting a current supplied to a load 17 different from the lamp load 11,
The power is supplied to a lamp load 17 such as a back lamp via a portion between a drain D and a source S of a semiconductor relay 16 (for example, a MOSFET with a built-in heat cutoff circuit as a semiconductor switching element). The semiconductor relay 16 is, for example, a MOSFET with a built-in heat cutoff circuit. The built-in MOSFET with a built-in heat cutoff circuit is a logic-level (4 V or more) drive type power MOSFET with a built-in heat cutoff circuit. Power MOSFET protection is possible,
The overheat shut-off method is a latch type, and is restored with a gate voltage of 0 bias after the operation of the overheat cut-off circuit.

The drive circuit 19 includes, for example, an NPN type switching (SW) transistor having a collector connected to a charge pump output voltage VP (= VB + 10 [V]) obtained by boosting the power supply voltage VB by the charge pump circuit 5, and the SW. N with collector connected to emitter of transistor
A contact point between the emitter of the SW transistor connected to the charge pump circuit 5 and the collector of the SW transistor connected to the ground is connected to the gate G of the semiconductor relay 11. It has a configuration.

Then, the drive circuit 19 includes the charge pump circuit 5 of the two series-connected SW transistors.
Turn on the SW transistor connected to the
By turning off the W transistor, the charge pump output voltage VP is applied to the gate G of the semiconductor relay 16 to turn on the semiconductor relay 16 and to the charge pump circuit 5 side of the two serially connected SW transistors. By turning off the connected SW transistor and turning on the SW transistor, the semiconductor relay 16
Has the function of stopping the application of the charge pump output voltage VP to the gate G of the semiconductor device and turning off the semiconductor relay 16.

A shunt resistor Rs3 provided between the vehicle battery and the semiconductor relay 16 is a low resistor for converting a current flowing in a power supply line between the vehicle battery and the lamp load 17 into a voltage. The current flowing in the power supply line is detected by detecting the voltage between both ends. Both ends of the shunt resistor Rs3 are connected to the load current monitor circuit 19.
This load current monitor circuit 19 is connected to
It functions as current detection means and detects a load current by outputting a voltage corresponding to the voltage across the shunt resistor Rs3. And this shunt resistor Rs3 is, for example,
Using a resistor of several tens of mΩ, a hardware-based overcurrent determination value, for example, several tens of amperes is determined. The output of the load current monitor circuit 19 is input to the analog multiplexer 28. The analog multiplexer 28 selects one of a large number of analog signals (up to the maximum capacity of the multiplexer) and supplies it to the input of the A / D converter.

The power supply voltage VB from the vehicle battery
Is a current detection resistor (shunt resistor) Rs4 for detecting a current supplied to a load 23 different from the lamp load 17,
A lamp load 23 such as a parking lamp via a drain D and a source S of a semiconductor relay 22 (for example, a MOSFET with a built-in heat cutoff circuit as a semiconductor switch element).
Supplied to The semiconductor relay 22 is, for example, a MOSFET with a built-in heat cutoff circuit. The built-in MOSFET with a built-in heat cutoff circuit is a logic-level (4 V or more) drive type power MOSFET, which has a built-in heat cutoff circuit and is overheated. The overheat protection method is of a latch type, and is restored with a gate voltage of 0 bias after the operation of the overheat protection circuit.

The drive circuit 25 includes, for example, an NPN type switching (SW) transistor having a collector connected to a charge pump output voltage VP (= VB + 10 [V]) obtained by boosting the power supply voltage VB by the charge pump circuit 5, and the SW. N with collector connected to emitter of transistor
A contact point between an emitter of the SW transistor connected to the charge pump circuit 5 and a collector of the SW transistor connected to the ground side is connected to the gate G of the semiconductor relay 22. It has a configuration.

The drive circuit 25 is a charge pump circuit 5 of the two serially connected SW transistors.
Turn on the SW transistor connected to the
By turning off the W transistor, the charge pump output voltage VP is applied to the gate G of the semiconductor relay 22 to turn on the semiconductor relay 22 and to the charge pump circuit 5 side of the two serially connected SW transistors. By turning off the connected SW transistor and turning on the SW transistor, the semiconductor relay 22
Has the function of stopping the application of the charge pump output voltage VP to the gate G of the semiconductor device and turning off the semiconductor relay 22.

A shunt resistor Rs4 provided between the vehicle-mounted battery and the semiconductor relay 22 is a low resistance for converting a current flowing through a power supply line between the vehicle-mounted battery and the lamp load 23 into a voltage. The current flowing in the power supply line is detected by detecting the voltage between both ends. Both ends of the shunt resistor Rs4 are connected to a load current monitor circuit 25.
This load current monitor circuit 25 is connected to
It functions as current detection means, and detects a load current by outputting a voltage corresponding to the voltage across the shunt resistor Rs4. And this shunt resistor Rs4 is, for example,
Using a resistor of several tens of mΩ, a hardware-based overcurrent determination value, for example, several tens of amperes is determined. The output of the load current monitor circuit 25 is input to the analog multiplexer 28. The analog multiplexer 28 selects one of a large number of analog signals (up to the maximum capacity of the multiplexer) and supplies it to the input of the A / D converter.

An OR circuit 29 is connected to an output terminal of the analog multiplexer 28. This OR circuit 29
Has a function of outputting the input analog signal when any of a large number of analog signals output from the analog multiplexer 28 is input.
As described above, the analog multiplexer 28 selects and outputs one of the analog signals output from the load current monitoring circuits 6, 13, 19, and 25.
The analog signal output from the R circuit 29 (any one of the output analog signals of the load current monitoring circuits 6, 13, 19, and 25) is amplified by the amplifier 30 and supplied to the microcomputer (microcomputer) 8. And
After being converted into a digital value by an A / D converter 31 built in the microcomputer 8, the digital value is taken into the CPU of the microcomputer 8.

The microcomputer 8 includes a CPU that operates in accordance with a preset control program, a ROM that stores the control program of the CPU in advance, and a RAM that temporarily stores data necessary for the CPU to execute calculations. When the switch SW is turned on by the microcomputer 8, the gate logic circuits 7, 14, 2
It has a function of outputting a drive instruction signal to each of 0 and 26.

The circuit operation of the semiconductor monitor system showing the method of inputting the current monitor terminal thus configured to the microcomputer will be described. First, when the power is turned on, when a voltage Vin is applied from the microcomputer 8 to the gate logic circuits 7, 14, 20, 26 of the lamp load circuit to be operated, this voltage is applied to the gate logic circuits 7, 14 , 20, 26 via the driving circuits 4, 1,
The voltage is applied to the gates G of the semiconductor relays (MOSFETs with a built-in thermal cutoff circuit) 2, 10, 16, and 22 through 2, 18, and 24. Then, the semiconductor relays 2, 10, 17, 22
The voltage VGS between the gate G and the source S gradually increases, and the semiconductor relays 2, 10, 17, and 22 are completely turned on in a period in which the voltage shifts from the active region to the saturation region.

Also, the microcomputer 8 always loads the load current monitoring circuits 6, 13, 1 which are digitally converted by the A / D converter 31 every predetermined time (for example, every several msec).
The current value (detected by the potential difference between both ends of the shunt resistors Rs1, Rs2, Rs3, and Rs4) flowing through the operating lamp load among the load lamps 9 and 25 is detected by the load current monitor circuit 6,
One of the output analog signals selected from 13, 19, and 25 is sampled, and an overcurrent is detected based on a load current flowing through the sampled load. When detecting this overcurrent, the microcomputer 8 stops outputting the drive instruction signal S2 to the gate logic circuit 14.

The current value flowing through the operating lamp load (detected by the potential difference between both ends of the shunt resistors Rs1, Rs2, Rs3, Rs4) is detected by the load current monitor circuits 6, 1
The sampling of the analog signals output from 3, 19 and 25 is performed by the analog multiplexer 28 from the microcomputer 8.
Load current monitoring circuits 6, 13, 19, and 25 selected by the selection command signal to the analog multiplexer 2
8 to perform the selection.

[0042]

As described above, according to the present invention, the A / D converter having the A / D conversion function provided to the microcomputer for the current monitor terminal is provided. The use efficiency of the / D input terminal can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a semiconductor monitor system showing an embodiment of a method for inputting a current monitor terminal to a microcomputer according to the present invention.

FIG. 2 is a circuit diagram of a conventional semiconductor monitor system.

[Explanation of symbols]

1 ………………………………………………………………………………………………… Semiconductor relays 3, 11, 17, 23 , 18,24 ... Drive circuit 5 ... Charge pump circuit 6,13,19,25 ... Load current monitor circuit 7, 14, 20, 26… Gate logic circuit 8…… …… ………… Microcomputer 28 ………………………………… Analog multiplexer 29 …………………………………………………………………………………………………………………………………………… A / D converter

Continued on the front page F-term (reference) 2G014 AA03 AA27 AB24 AB26 AB38 AC16 5G004 AA04 AB03 BA03 BA04 DA02 DC05 DC07 DC13 EA01 FA01 5J055 AX36 AX46 AX62 AX67 BX03 BX16 CX28 DX13 DX22 DX44 DX48 DX53 DX54 EX09 EZ17 EZ EY EZ29 EZ30 EZ39 EZ55 EZ57 FX04 FX32 GX01

Claims (1)

[Claims] A microcomputer that applies a charge pump output voltage whose power supply voltage has been boosted by a charge pump circuit to a gate of a semiconductor relay connected in series to each of a plurality of loads via a drive circuit; In a semiconductor relay system for controlling a semiconductor relay on / off and supplying power to each load, a load current monitor circuit for monitoring a current value flowing through the load by connecting a current detection resistor to a drain side of the semiconductor relay. A single A / D converter built in the microcomputer, wherein an analog output value obtained by arbitrarily selecting an output of a load current monitor circuit provided for each of the plurality of loads via an analog multiplexer is provided for each of the plurality of loads; Current monitor terminal characterized in that it is taken in to the CPU via a heater Input method to the micro-computer.