KR20210062915A - Load current monitoring apparatus and method - Google Patents

Abstract

A load current monitoring device according to a preferred embodiment of the present invention includes a comparison part for comparing an input voltage and a reference voltage according to a load current; a reference voltage processing part for converting the comparison result of the comparison part into a digital signal; and a reference voltage generation part for varying and outputting the reference voltage according to the digital signal. It is possible to remove the noise of a comparison voltage.

Description

LOAD CURRENT MONITORING APPARATUS AND METHOD

The present invention relates to a load current monitoring apparatus and method, for example, to a load current monitoring apparatus and method for monitoring the current of a load such as a motor for driving a vehicle.

With the advancement of automobiles, the number of motors constituting automobile parts and their roles are increasing day by day. In recent years, there is a tendency that more motors are installed in vehicles. In particular, as the spread of hybrid vehicles and electric vehicles begins to expand, the status of the motor as an automobile part continues to increase. Accordingly, the motor control technology is positioned as a core technology of automobiles.

In general, a driver circuit is applied to a motor control system for a vehicle to drive and control a motor (load).

In such a vehicle motor control system, a short circuit failure (hereinafter, StB: Short circuit to Battery), a short circuit to ground failure (hereinafter, StG: Short Circuit to Ground), or an open load failure (hereinafter, OL: Open Load) in a driver circuit It detects the occurrence of such problems and improves the stability of circuits and systems.

A conventional method for diagnosing a short-circuit failure such as StG or StB of a load is to measure the current consumed by the load to determine the normal or malfunctioning state. In general, the current consumption is directly measured using an ADC (Analog Digital Converter) and have.

Conventionally, since the ADC samples the current or voltage value of the load at a specific point in time, there is a problem that it is somewhat vulnerable to noise.

Republic of Korea Patent Publication No. 2015-0140430

Accordingly, the present invention has been devised in consideration of the above circumstances, and it is possible to measure the load current using a comparator circuit instead of the ADC, and the load current capable of removing noise from the comparison voltage as the reference voltage is varied by tracking the comparison voltage. An object of the present invention is to provide a monitoring device and method.

A load current monitoring apparatus according to a preferred embodiment of the present invention for achieving the above object includes a comparator for comparing an input voltage and a reference voltage according to the load current; a reference voltage processing unit converting the comparison result of the comparator into a digital signal; and a reference voltage generator for varying and outputting the reference voltage according to the digital signal.

The reference voltage generator includes a reference resistor array for dividing a driving voltage, a switch that is turned on or off according to the digital signal to vary the total resistance of the reference resistor array, and a constant reference resistor array. A current source for applying a current may be included.

The reference resistor array unit includes a plurality of reference resistors connected in series with each other, a reference resistor at one end of the plurality of reference resistors is connected to a rectifier for outputting the driving voltage, and the other end of the plurality of reference resistors is connected to a rectifier for outputting the driving voltage. A reference resistor may be connected to an input terminal of the comparator.

The switch unit may include a plurality of switches corresponding to the plurality of reference resistors, and the plurality of switches may be connected in parallel to the corresponding reference resistors.

Each of the plurality of switches may be turned on or turned off by the digital signal to change the total resistance of the reference resistor array unit.

The reference voltage may be determined according to a difference between the driving voltage and a voltage applied to the reference resistor array unit.

The digital signal may be an n-bit gray code.

The n-bit gray code may further include a load current calculating unit for calculating a consumption current of the load.

The load current calculating unit multiplies the resistance value of the reference resistance corresponding to the reference resistance array unit by the bit value of the n-bit gray code, adds the multiplied bit values to each other, and multiplies the added result by the current value of the current source, , by dividing a result of multiplying the current value by a resistance value of a resistor to which the load current is applied, the current consumption of the load may be calculated.

A first resistor connected between the rectifier outputting the driving voltage and the load, and a second resistor having one end connected between the first resistor and the load and the other end connected to the input terminal of the comparator can

A load current monitoring method according to a preferred embodiment of the present invention for achieving the above object, a first comparison step of comparing the input voltage and the reference voltage according to the load current; a first conversion step of converting a first comparison result of the first comparison step into a digital signal; and a reference voltage varying step of varying and outputting the reference voltage according to the digital signal.

a second comparison step of comparing the input voltage with the changed reference voltage; a second conversion step of converting a second comparison result of the second comparison step into a digital signal; and calculating the current consumption of the load by using the digital signal according to the second comparison result.

The digital signal may be an n-bit gray code.

In the first conversion step and the second conversion step, when the first comparison result or the second comparison result is a high level, the bit value 0 close to the most significant bit of the gray code is inverted into the bit value 1 to be converted. have.

In the first conversion step and the second conversion step, when the first comparison result or the second comparison result is a low level, the bit value 1 close to the least significant bit of the gray code is inverted to the bit value 0 to be converted. have.

According to the load current monitoring apparatus and method according to the preferred embodiment of the present invention, the circuit structure is simplified as a comparator circuit is applied instead of the ADC, and the function of the noise filter is improved without a separate low pass filter circuit. effective to implement.

1 is a block diagram of a load current monitoring device according to a preferred embodiment of the present invention.
2 is a schematic circuit configuration diagram of a load current monitoring device according to a preferred embodiment of the present invention.
3 is a circuit configuration diagram showing an example of a load current monitoring device of the present invention.
4 is a flowchart of a load current monitoring method according to a preferred embodiment of the present invention.
FIG. 5 is a flowchart showing the process of the conversion step of FIG. 4 .
6 is a diagram showing an example of an application to which the load current monitoring apparatus according to a preferred embodiment of the present invention is applicable.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to elements of each drawing, it should be noted that the same elements are assigned the same numerals as possible, even if they are indicated on different drawings. In addition, a preferred embodiment of the present invention will be described below, but the technical idea of the present invention is not limited or limited thereto, and may be modified and variously implemented by a person skilled in the art.

1 is a block diagram of a load current monitoring device according to a preferred embodiment of the present invention. 2 is a schematic circuit configuration diagram of a load current monitoring device according to a preferred embodiment of the present invention.

1 and 2 , the load current monitoring apparatus 100 according to a preferred embodiment of the present invention monitors the current of the load 20 operated by the DC voltage of the rectifier 10 to monitor the load 20 . As an apparatus for diagnosing a short-circuit failure of , it includes a resistor unit 110 , a comparison unit 120 , a reference voltage processing unit 130 , a reference voltage generation unit 140 , and a load current calculating unit 150 .

The resistor unit 110 may be connected between the rectifier unit 10 and the load 20 for an appropriate voltage drop of the driving voltage for driving the load. Here, the rectifier 10 maintains a constant driving voltage and outputs it. The load 20 may be a motor. The resistor unit 110 includes a first resistor R connected between the rectifying unit 10 and the load 20 , and a second resistor with one end connected between the first resistor R and the load 20 . RL) may be included. Resistance values of the first resistor R and the second resistor RL may be appropriately set according to a user's needs.

The comparator 120 may compare voltages across the first resistor R to measure the current of the load 20 . In the comparator 120 , the other end of the second resistor RL may be connected to a negative input terminal, and the reference voltage generator 140 may be connected to a positive input terminal. Here, the reference voltage generator 140 may be connected between the rectifier 10 and one end of the first resistor R.

The comparator 120 may compare the input voltage input to the negative input terminal with the reference voltage output from the reference voltage generator 140 to output a comparison result. Here, the reference voltage may be varied according to the currently output comparison result. The comparator 120 may compare the variable reference voltage and the input voltage again. The comparison result according to the re-comparison may have noise removed.

The reference voltage processing unit 130 may convert the comparison result of the comparison unit 120 into a digital signal. The digital signal may be an n-bit (n is an integer greater than or equal to 4) gray code. In an embodiment, the reference voltage processing unit 130 may be a resistor array control. The n-bit gray code may be used to calculate the current consumption of the load 20 . Also, the reference voltage processing unit 130 may change the reference voltage of the reference voltage generation unit 140 using an n-bit gray code.

The reference voltage generator 140 may generate a reference voltage according to the digital signal of the reference voltage processor 130 . The reference voltage generator 140 may vary the reference voltage according to the current consumption of the load 20 . The reference voltage generator 140 may include a reference resistor array unit R _S1 , R _S2 , R _Sn-1 , R _Sn , a switch unit SW1 , SW2 , SWn-1 , SWn, and a current source CS. can

The reference resistor array unit R _S1 , R _S2 , R _Sn-1 , R _Sn and the switch unit SW1 , SW2 , SWn-1 , SWn are composed of n according to the number of gray code bits of the reference voltage processing unit 130 . can be The reference resistor array units R _S1 , R _S2 , R _Sn-1 , and R _Sn may include a plurality of reference resistors connected in series with each other. The reference resistor array unit R _S1 , R _S2 , R _Sn-1 , and R _Sn may have a reference resistance R _Sn at one end connected between the rectifier 10 and one end of the first resistor R . In the reference resistance array unit R _S1 , R _S2 , R _Sn-1 , and R _Sn , the reference resistance R _S1 of the other end may be connected to the positive input terminal of the comparator 120 and the current source CS. The reference resistor array units R _S1 , R _S2 , R _Sn-1 , and R _Sn may divide the driving voltage of the rectifier 10 by a predetermined ratio.

The switch units SW1, SW2, SWn-1, and SWn may be connected in parallel to each of the corresponding reference resistors. The switch units SW1 , SW2 , SWn-1 , and SWn may be controlled on or off by the reference voltage processing unit 130 . Each of the switch units SW1, SW2, SWn-1, and SWn may adjust the number of reference resistors connected between the rectifier 10 and the current source CS in an on or off state. As the number of reference resistors is adjusted, the reference voltage input to the positive input terminal of the comparator 120 may vary.

The current source CS may be connected between the positive input terminal of the comparator 120 and the ground. The current source CS may apply a constant current to the _{reference resistor array units RS1} , _RS2 , R _Sn-1 , and R _{Sn .} The reference voltage input to the positive input terminal of the comparator 120 may be determined through a voltage difference between the driving voltage of the rectifying unit 10 and the voltages of the reference resistor array units R _S1 , R _S2 , R _Sn-1 , and R _{Sn .} .

The load current calculating unit 150 may calculate the current flowing through the first resistor R using the n-bit gray code output from the reference voltage processing unit 130 . That is, the load current calculating unit 150 may calculate the consumption current of the load 20 . Details related to the consumption current calculation will be described later with reference to FIG. 3 .

3 is a circuit configuration diagram showing an example of a load current monitoring device of the present invention.

Referring to FIG. 3 , the reference resistor array units _RS1 , R _S2 , R _Sn-1 , and R _Sn may include four reference resistors. That is, the reference resistance array unit R _S1 , R _S2 , R _Sn-1 , R _Sn is a first reference resistance R _S1 , a second reference resistance _RS2 , and a third reference resistance R _Sn-1 ). , and a fourth reference resistor R _Sn .

The switch units SW1, SW2, SWn-1, and SWn may include four switches. That is, the switch units SW1 , SW2 , SWn-1 , and SWn may include a first switch SW1 , a second switch SW2 , a third switch SW3 , and a fourth switch SW4 .

An input voltage according to a difference between _{the voltage V OUT of the rectifier 10 and the resistance voltage I lOAD} *R1 applied to the first resistor R may be applied to the negative input terminal of the comparator 120 .

The comparator 120 may compare the voltage value input to the negative input terminal with the reference voltage input to the positive input terminal and transmit the comparison result to the reference voltage processing unit 130 .

The reference voltage processing unit 130 may convert the comparison result of the comparison unit 120 into a 4-bit gray code and output the converted result. In one embodiment, the 4-bit gray code may be represented as 4b1100. The reference voltage processing unit 130 may change the reference voltage using a 4-bit gray code.

The first switch SW1 may be controlled to be turned off according to the least significant bit value '0' of the 4-bit gray code. The second switch SW2 may be controlled to be turned off according to the lower second bit value '0' of the 4-bit gray code. The third switch SW3 may be turned-on-controlled according to the upper third bit value '1' of the 4-bit gray code. The fourth switch SW4 may be turned-on controlled according to the most significant bit value '1' of the 4-bit gray code. _{In this case} , the voltages of the reference resistor array units R S1 , R _S2 , R _Sn-1 , R _Sn may be expressed as I _SYNC *(R _S2 + R _S1 ).

At the positive input terminal of the comparator 120 , the reference voltage VOUT- according to the difference between the voltage _{V OUT} of the rectifier 10 and the voltages of the reference resistor array units R _S1 , R _S2 , R _Sn-1 , R _{Sn )} I _SYNC *(R _S2 + R _S1 ) may be input. As described above, the reference voltage may be varied by tracking the comparison result of the comparator 120 . Through this, it is possible to remove noise from the voltage related to the current consumption of the load 20 input to the negative input terminal of the comparator 120 .

The load current calculating unit 150 may calculate the consumption current of the load 20 using the n-bit gray code of the reference voltage processing unit 130 . The current consumption calculation formula can be expressed as Equation 1 below.

<Equation 1>

In Equation 1, I _LOAD represents the current value flowing through the first resistor R, I _SYNC represents the current value of the current source CS, GC[3] represents the most significant bit value of the gray code, and GC[ 2] represents the second upper bit value of the gray code, GC[1] represents the lower third bit value of the gray code, GC[0] represents the least significant bit value of the gray code, and R is the first resistor ( R) represents the resistance value.

The load current calculating unit 150 multiplies the resistance value of the corresponding reference resistance of the reference resistance array unit by the bit value of the n-bit gray code according to Equation 1, adds the result of multiplying the bit value, and adds the result to the current source ( SC), and dividing the multiplied result by the resistance value of the resistor R to which the load current is applied, the current consumption of the load 20 may be calculated.

Equation 1 can be expressed as Equation 2 below when the n-bit gray code is a 4-bit gray code and has a code value of 4b1100.

<Equation 2>

In Equation 2, R _S1 represents the resistance value of the first reference resistor (R _{S1 ),} R _S2 represents a resistance value of the second reference resistor R _{S2 .}

The load current calculating unit 150 may calculate and obtain the consumption current of the load 20 in the same manner as described above without the ADC circuit. The consumption current of the load 20 obtained in this way may be used to determine the short-circuit failure state of the load.

4 is a flowchart of a load current monitoring method according to a preferred embodiment of the present invention.

1 and 4 , the load current monitoring method according to a preferred embodiment of the present invention includes a first comparison step (S410), a first conversion step (S420), a reference voltage varying step (S430), and a second comparison step. It may include a step S440, a second conversion step S450, and an operation step S460.

In the first comparison step ( S410 ), the comparator 120 compares the input voltage according to the load current with the reference voltage and outputs a first comparison result. Here, the input voltage may be a difference between the driving voltage of the rectifier 10 and the resistance voltage of the first resistor R. The reference voltage may be an output voltage of the reference voltage generator 140 .

In the first conversion step ( S420 ), the reference voltage processing unit 130 converts the first comparison result into a digital signal. Here, the digital signal may be an n-bit gray code. When the first comparison result is a high level, the reference voltage processing unit 130 may convert a bit value 0, which is close to the most significant bit of the gray code, into a bit value 1 by inverting it. Also, when the first comparison result is the low level, the reference voltage processing unit 130 may convert the bit value 1 close to the least significant bit of the gray code to the bit value 0 by inverting it. The bit value inversion conversion will be described later with reference to FIG. 5 .

In the step of varying the reference voltage ( S430 ), the reference voltage generator 140 may vary and output the reference voltage according to the digital signal. Here, the reference voltage may be output from the _{reference resistance array units R S1} , _RS2 , R _Sn-1 , R _Sn in which the total resistance is changed according to the digital signal.

In the second comparison step ( S440 ), the comparator 120 compares the input voltage according to the load current with the changed reference voltage and outputs a second comparison result.

In the second conversion step (S450), the reference voltage processing unit 130 converts the second comparison result into a digital signal. Here, when the second comparison result is a high level, the reference voltage processing unit 130 may convert a bit value 0 close to the most significant bit of the gray code into a bit value 1 by inverting it. In addition, when the second comparison result is the low level, the reference voltage processing unit 130 may convert the bit value 1 close to the least significant bit of the gray code to the bit value 0 by inverting it.

In the operation step S460 , the load current calculating unit 150 calculates the consumption current by using the digital signal according to the second comparison result.

In the load current monitoring method according to a preferred embodiment of the present invention, by varying the reference voltage by tracking the comparison result, it is possible to remove the noise of the comparison result output according to the comparison of the variable reference voltage and the input voltage.

FIG. 5 is a flowchart showing the process of the conversion step of FIG. 4 .

Referring to FIGS. 1, 4, and 5 , a conversion process applied to each of the first conversion step S420 and the second conversion step S440 may be confirmed.

First, in the default setting step ( S510 ), the reference voltage processing unit 130 may set '4b1100' as a default value as a gray code value.

In the first determination step S520 , the reference voltage processing unit 130 may determine whether the comparison result of the comparison unit 120 is high level (H). Here, the comparison result may be determined as a high level (H) when the input voltage is equal to or greater than the reference voltage, and may be determined as a low level (L) when the input voltage is less than the reference voltage.

In the first gray code setting step S530 , the reference voltage processing unit 130 , when it is determined that the comparison result of the comparison unit 120 is high level (H), a gray code value at a default value of '4b1100' (gray code) It can be changed to '4b1110'.

In the second gray code setting step S540 , when the comparison result of the comparison unit 120 is determined to be the low level L, the reference voltage processing unit 130 sets the gray code value at a default value of '4b1100'. (gray code) It can be changed to '4b1000'.

In a second determination step ( S550 ) after step S530 , the reference voltage processing unit 130 may determine whether the comparison result of the comparison unit 120 is high level (H).

In addition, in a third determination step ( S560 ) after step S540 , the reference voltage processing unit 130 may determine whether the comparison result of the comparison unit 120 is high level (H).

In the third gray code setting step (S570), the reference voltage processing unit 130, when the comparison result of the comparison unit 120 is determined to be high level (H) in the second determination step (S550), the gray code value ' It is possible to change from 4b1110' to a gray code value '4b1111'. On the other hand, the reference voltage processing unit 130, when the comparison result of the comparison unit 120 is determined to be the low level (L) in the second determination step (S550), the gray code value '4b1110' in the default value ' 4b1100' can be changed.

In the fourth gray code setting step S580 , the reference voltage processing unit 130 , when the comparison result of the comparison unit 120 is determined to be the low level L in the third determination step S560 , the gray code value ( gray code) can be changed from '4b1000' to a gray code value of '4b0000'. On the other hand, the reference voltage processing unit 130, when the comparison result of the comparison unit 120 is determined to be high level (H) in the third determination step (S560), the gray code value '4b1110' in the default value ' 4b1100' can be changed.

In a fourth determination step ( S590 ) after step S570 , the reference voltage processing unit 130 may determine whether the comparison result of the comparison unit 120 is high level (H). Here, when the determination result of the fourth determination step S590 is the high level (H), the gray code value '4b1111' may be maintained as it is. Also, when the determination result of the fourth determination step S590 is the low level (L), the gray code value '4b1110' may be changed.

Also, in a fifth determination step S600 after step S580 , the reference voltage processing unit 130 may determine whether the comparison result of the comparison unit 120 is high level (H). Here, when the determination result of the fifth determination step S600 is high level (H), it may be changed to a gray code value '4b1000'. In addition, when the determination result of the fourth determination step S600 is the high level (H), the gray code value '4b0000' may be maintained as it is.

As described above, since the gray code value is changed in real time according to the comparison result of the comparator 120 , the reference voltage may also be varied in real time according to the gray code value. The comparator 120 may output a comparison result by removing noise from the input voltage when comparing the variable reference voltage with the input voltage.

6 is a diagram showing an example of an application to which the load current monitoring apparatus according to a preferred embodiment of the present invention is applicable.

Referring to FIG. 6 , the load current monitoring apparatus 100 according to the preferred embodiment of the present invention may be applied to the PSI5 communication circuit 2100 . Here, the PSI5 communication circuit 2100 may be provided in the receiver 2000 for communication connection between the MCU 1000 and the sensor 3000 .

The load current monitoring apparatus 100 may monitor the consumption current of the sensor 3000 connected to the PSI5 communication circuit 2100 .

The MCU 1000 may determine whether the sensor 3000 is faulty by using the current consumption monitoring result of the load current monitoring apparatus 100 .

As described above, the load current monitoring apparatus 100 according to the preferred embodiment of the present invention may be used in applications requiring a relatively simple circuit configuration because it is insensitive to monitoring speed or accuracy.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the technical field to which the present invention pertains can make various modifications, changes, and substitutions within the scope not departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical idea of the present invention, but are for illustration, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings .

The steps and/or actions according to the invention may occur simultaneously in different embodiments in different orders, or in parallel, or in different embodiments for different epochs, etc., as can be understood by one of ordinary skill in the art. I can.

Depending on the embodiment, some or all of the steps and/or actions drive instructions, programs, interactive data structures, clients and/or servers stored on one or more non-transitory computer-readable media. At least some may be implemented or performed using one or more processors. The one or more non-transitory computer-readable media may be illustratively software, firmware, hardware, and/or any combination thereof. In addition, the functions of the "module" discussed herein may be implemented in software, firmware, hardware, and/or any combination thereof.

10: rectification unit
20: load
100: load current monitoring device
110: resistance unit
120: comparison unit
130: reference voltage processing unit
140: reference voltage generator
150: load current calculation unit

Claims (15)

a comparator comparing the input voltage and the reference voltage according to the load current;
a reference voltage processing unit converting the comparison result of the comparator into a digital signal; and
a reference voltage generator for varying and outputting the reference voltage according to the digital signal;
A load current monitoring device comprising a. The method of claim 1,
The reference voltage generator,
a reference resistor array unit that divides the driving voltage;
a switch unit which is turned on or off according to the digital signal to vary the total resistance of the reference resistance array unit; and
A current source for applying a constant current to the reference resistor array unit
Load current monitoring device comprising a. The method of claim 2,
The reference resistor array unit,
A plurality of reference resistors connected in series with each other,
Load current monitoring device, characterized in that a reference resistor at one end of the plurality of reference resistors is connected to a rectifier for outputting the driving voltage, and a reference resistor at the other end of the plurality of reference resistors is connected to an input terminal of the comparator. . The method of claim 3,
The switch unit includes a plurality of switches corresponding to the plurality of reference resistors,
The plurality of switches are load current monitoring device, characterized in that connected in parallel to the corresponding reference resistance. The method of claim 4,
Each of the plurality of switches is turned on or turned off by the digital signal to change the total resistance of the reference resistor array unit. The method of claim 4,
The reference voltage is a load current monitoring device, characterized in that determined according to a difference between the driving voltage and the voltage applied to the reference resistor array unit. The method of claim 2,
The digital signal is a load current monitoring device, characterized in that the n-bit gray code. The method of claim 7,
Load current monitoring apparatus according to claim 1, further comprising a load current calculating unit for calculating a consumption current of a load by using the n-bit gray code. The method of claim 8,
The load current calculating unit,
The resistance value of the reference resistor corresponding to the reference resistor array unit is multiplied by the bit value of the n-bit gray code, the result of multiplying the bit value is added to each other, the result of the addition is multiplied by the current value of the current source, and the current value is multiplied. A load current monitoring device, characterized in that by dividing a result by a resistance value of a resistor to which the load current is applied, the current consumption of the load is calculated. The method of claim 2,
A first resistor connected between the rectifier for outputting the driving voltage and the load, and a second resistor having one end connected between the first resistor and the load and the other end connected to the input end of the comparator Load current monitoring device, characterized in that. a first comparison step of comparing the input voltage and the reference voltage according to the load current;
a first conversion step of converting a first comparison result of the first comparison step into a digital signal; and
a reference voltage varying step of varying and outputting the reference voltage according to the digital signal;
A load current monitoring method comprising a. The method of claim 11,
a second comparison step of comparing the input voltage with the changed reference voltage;
a second conversion step of converting a second comparison result of the second comparison step into a digital signal; and
an operation step of calculating a consumption current of a load using a digital signal according to the second comparison result;
Load current monitoring method, characterized in that it further comprises. The method of claim 12,
The digital signal is a load current monitoring method, characterized in that the n-bit gray code. The method of claim 13,
In the first conversion step and the second conversion step, when the first comparison result or the second comparison result is at a high level, converting a bit value 0 close to the most significant bit of the gray code into a bit value 1 by inverting it A method for monitoring load current. The method of claim 14,
In the first conversion step and the second conversion step, when the first comparison result or the second comparison result is at a low level, the bit value 1 close to the least significant bit of the gray code is converted to the bit value 0 by inverting it. A method for monitoring load current.

Images