JP3293324B2 - Speed detection circuit of brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed detecting circuit for a brushless motor, and more particularly to a speed detecting circuit for a brushless motor which detects a speed by an induced voltage of each phase coil of the brushless motor.

[0002]

FIG. 3 shows a conventional brushless motor.
1 is a circuit diagram of a speed detection circuit of FIG. PNP type with the same characteristics
Transistor Q₆, Q₇To form a differential pair transistor
Transistor Q₆, Q₇Common emitters
Anti-R_ThreeVia a power supply terminal 13 (hereinafter simply referred to as a power supply voltage Vcc).
To the power supply terminal). Transistor Q
₆, Q₇Each collector has a
Transistor Q that constitutes a Tomirror circuit₈, Q₉Each of
Connected to the collector.

A constant current circuit is constituted by PNP transistors Q ₁ and Q ₂ and a resistor R ₁ constituting a current mirror circuit. The emitter of the PNP transistor Q ₃ are connected to the collector of the transistor Q _2, the collector is grounded is connected to the ground terminal 14. NP
Based N transistor Q ₄ is connected to the emitter of the transistor Q _3, the emitter is grounded through a resistor R _2, the collector is connected to the power source terminal via the transistor Q ₅ of the diode connection.

[0004] connecting point of the collector of the emitter and the transistor Q ₄ of the transistor Q ₅ is connected to the base of the transistor Q ₆ of the differential pair transistors.

[0005] base of an NPN output transistor Q ₁₃ is connected to the collector of the transistor Q _6, the collector is connected to the base of the transistor Q ₇ of the differential pair transistors. The emitter of the transistor Q ₁₃ is grounded via the output resistor R _7, transistor Q
Connected to ₃ bases.

The induced voltage V_UIs supplied to terminal 16
Anti-R_FourAnd diode-connected transistor Q_TenThrough
Transistor Q₇Connected to the base. Similarly, invitation
Electromotive voltage V_VIs supplied to the terminal 17 through the resistor R_FiveAnd Daio
Transistor Q₁₁Through the transistor Q₇
And the induced voltage V_WTerminal 1 to which is supplied
8 is a resistor R₆And diode-connected transistor Q₁₂To
Through the transistor Q ₇Connected to the base.

[0007] Resistance R₇And resistance R_TwoIs the same resistance value
And the resistance R_Four, R_Five, R₆Are the same resistance value
It is. Also, the transistor Q_Ten~ Q₁₂And Transis
TA Q _FiveHave the same characteristics.

Here, a brushless motor having three-phase coils of U-phase, V-phase and W-phase is used. One end of each phase coil (not shown) is connected to the power supply terminal of the power supply voltage Vcc, and the other end is grounded via a switching element (not shown) for each phase. Terminals on the opposite side of the power supply terminals of the U-phase, V-phase, and W-phase coils are terminals 16, 17,.
18.

Next, the operation of the speed detection circuit of the brushless motor shown in FIG. 3 will be described. When the rotor of the brushless motor is rotating, the switching elements connected to the U-phase, V-phase, and W-phase coils are sequentially turned on,
Each coil is energized with the phase shifted by 2π / 3 in the order of phase, V phase, and W phase.

FIG. 4 shows the induced voltages V _U ,
FIG. 4 is an explanatory diagram of V _V and V _W and an output voltage V _O. FIG. 4 (A)
As shown, during period T ₁ is energized are energized U-phase coil, during period T ₂ is energized V-phase coil is energized, during the period T ₃ has W-phase coil is energized is energized .
Each of T ₁ , T ₂ , and T ₃ is a period of 2π / 3.
As described above, the rotor is rotated by the electromagnetic force generated between the coils of each phase which are sequentially excited and the magnet of the rotor.

When the rotor rotates as described above, U
As shown in FIG. 4A, sinusoidal induced voltages V _U , V _V , and V _W whose phases are shifted by 2π / 3 are generated in the phase, V-phase, and W-phase coils. Here, the induced voltage V of each phase
_{U, V} V, V _W amplitude values respectively E _U of, E _V, when the E _W, the induced voltage _{V U,} V V, V _W is expressed by the following (1) to (3).

[0012] _{V U = E u sinωt + Vcc} (1) V V = E V sin (ωt-2π / 3) + Vcc (2) V W = E W sin (ωt-4π / 3) + Vcc (3) E U, E The values of _V and E _W increase in proportion to the rotation speed. The induced voltages V _U , V _V , V _W are respectively connected to terminal 1
6, 17, and 18.

A resistor R is connected to each of the terminals 16 to 18._Four~ R₆To
Through the transistor Q_Ten, Q₁₁, Q ₁₂The current flowing through
Transistor Q₁₃Output through collector and emitter of
Resistance R₇Flows to

The differential pair transistors including the transistors Q ₆ and Q ₇ are in a balanced state when the base potential of the transistor Q ₇ is equal to the base potential of the transistor Q ₆ .

Now, the transistor Q₇The base potential of
Transistor Q₆Trying to be higher than the base potential of
Transistor Q₇Collector current and transistor
Q₉, Q ₈The collector current of the transistor Q₆
It looks like the collector current has increased. This allows
Transistor Q₁₃Base current and collector current increase
And the transistor Q₇Is lowered. Subordinate
The transistor Q₇The base potential of
Jista Q₆Is maintained at the same potential as that of the base potential.

Transistor Q₇The base potential of the transistor
Star Q₆If it is going to be lower than the base potential of
Transistor Q₁₃The collector current of the transistor
TA Q ₇Is almost equal to the transistor Q₆Bee
Is kept at the same potential as

Transistor Q₆The base potential of
Jista Q_FiveThe forward voltage of V_F5As Vcc-V_F5In
Therefore, the transistor Q₇The base potential of Transis
TA Q ₆Is maintained at substantially the same potential as the base of Vcc-V_F5Tona
You. Also, the transistor Q_Ten~ Q₁₂Forward voltage V_F10
~ V_F12Is the transistor Q_FiveForward voltage V_F5Same as
Is set to

For this reason, when the induced voltages V _U , V _V , V _W supplied to the terminals 16 to 18 each exceed the power supply voltage Vcc, the transistors Q _{10 to} Q ₁₂ are turned on. Current flowing through the transistor Q ₁₀ to Q ₁₂ is flowing to the output resistor R ₇ via the transistor Q _13, the output voltage V _O is produced at the output terminal.

The current I ₇ flowing through the output resistor R _7, the
It can be expressed by the following equation (4) using the equations (1) to (3).

I ₇ = (E _U / R ₄ ) sin ωt + (E _V / R ₅ ) sin (ωt−2π / 3) + (E _W / R ₆ ) sin (ωt−4π / 3) (4) the current of each term to be a transistor Q ₁₀ ~Q ₁₂ respectively of the current, sinωt, sin (ωt-2π / 3), s
In (ωt−4π / 3) flows only during a period in which each of them has a positive value.

Since the resistors R _{4 to} R ₆ have the same resistance value, the output voltage V _O can be expressed by the following equation (5).

[0022] _{V O = (R 7 / R} 4) (E U sinωt + E V sin (ωt-2π / 3) + E W sin (ωt-4π / 3)) (5) Thus, the induced voltage V _U, V _V, the amplitude value of V _W E _U,
An output voltage V _O proportional to E _V and E _W is generated. FIG.
(B) shows the output voltage V _O.

As described above, the amplitude values E _U , E _V , E
_{Since W} is proportional to the rotation speed, an output voltage V _O proportional to the rotation speed is obtained.

It should be noted that the output voltage V _O depends on the transistor Q ₃
It is supplied to the base and emitter of the transistor Q ₃ is connected to the base of the transistor Q _4. Therefore, the resistor R ₂ at both ends, a voltage is generated equal to the output voltage V _O. As described above, the resistance R ₂ is because you have the same resistance value and the resistance R _7, substantially the same current flows through the resistor R ₇ to the resistor R _2. In this way, the current flowing through the transistor Q ₅ becomes the approximately the same as the current of the transistor Q ₁₀ to Q _12, the forward voltage V _F5 and the forward voltage V _F10 ~V _F12 is maintained at the same value.

A speed control circuit (not shown) controls the speed of the brushless motor according to the value of the supplied output voltage V _O , and keeps the rotation speed of the brushless motor constant.

Next, the minimum operating voltage of the circuit of FIG. 3 will be described. The minimum operating voltage V _MIN can be expressed by the following equation (6).

[0027] _{V MIN = V O + V BE13} + V CE6 + V R3 ≒ V O + V BE13 + V CE6 (6) where, V _BE13 is the base-emitter voltage of the output transistor Q _13, V _CE6 collector-transistor Q ₆ Emitter saturation voltage. Further, the voltage drop of the resistor R ₃ V
_R3 is negligible because it is sufficiently small compared to other voltages.

Output voltage V_OIs the resistance R_FourAnd output resistance R₇
Power supply voltage Vcc = 1V, E_U
In the case of = 1V, the voltage may be set to about 0.2V. output
Transistor Q₁₃Base-emitter voltage V_BE13Is
About 0.6V, transistor Q ₆Collector-emitter
Saturation voltage V_CE6Is about 0.2V.

For this reason, the minimum operating voltage V _MIN is V _MIN
= 0.2 + 0.6 + 0.2 = 1V.

The output resistor R ₇ , the collector-emitter of the transistor Q ₁₃ , the transistor Q ₁₀ , the resistor R ₄ ,
An operating voltage of about 1 V is also required in the path of the terminal 16.

[0031]

As described above, in the conventional circuit shown in FIG. 3, the minimum operating voltage V _MIN is about 1 V, and there is no room for operation with one battery, and the operation becomes unstable. There is a problem of fear.

The present invention has been made in view of the above points, and an object of the present invention is to provide a speed detecting circuit of a brushless motor which can lower the minimum operating voltage and can operate stably at a low voltage.

[0033]

SUMMARY OF THE INVENTION The present invention provides a brushless motor speed detecting circuit for generating an output voltage corresponding to the rotation speed of the brushless motor by using an induced voltage induced in each phase coil of the brushless motor. , An emitter is connected as an active load to a differential pair transistor including a first transistor and a second transistor whose emitters are commonly connected, and to a collector of each of the first transistor and the second transistor of the differential pair transistor. A current mirror circuit, a diode-connected biasing transistor connected between a base of the first transistor and a first power supply terminal and supplied with a predetermined current by a first constant current source, and the induced voltage supplied thereto; And an emitter is provided for each induced voltage supply terminal, and the emitter is a second transistor of the differential pair transistor. The base is connected to the base of the transistor, the base is connected to the respective induced voltage supply terminals via the respective detection resistors, and the collector is connected to the first power supply terminal. Transistor, a second constant current source that is connected to the emitter of the detection transistor and supplies a predetermined current, and is provided corresponding to each of the detection transistors, and the emitter is provided for the corresponding detection transistor. An output transistor connected to a base, the base connected to a collector of a second transistor of the differential pair transistor, and a collector connected to a second power supply terminal via an output resistor.

[0034]

According to the present invention, a detection transistor whose emitter is connected to the base of a second transistor of a differential pair transistor, and each emitter is connected to the base of a corresponding detection transistor, and the base is connected to the second transistor And an output transistor whose collector is connected to an output resistor.

Thus, it is possible to reduce a required operating voltage in a path from the second power supply terminal to the first power supply terminal via the output resistance, the collector of the output transistor, the collector and the emitter of the second transistor, and the first power supply terminal. it can.

Therefore, the minimum operating voltage can be made lower than 1 V, and stable operation can be performed with a power supply voltage of 1 V or less.

[0037]

FIG. 1 is a circuit diagram of a speed detecting circuit of a brushless motor according to an embodiment of the present invention. A PNP transistor Q ₂₄ (first transistor) and a transistor Q ₂₅ (second transistor) having the same characteristics have a differential pair of transistors 4.
The common emitter of the transistors Q ₂₄ and Q ₂₅ is connected to a constant current source 35 having a current value I ₃₅ .
Respective collectors of the transistors Q ₂₄ and Q ₂₅ are connected to respective collectors of NPN transistors Q ₂₆ and Q ₂₇ constituting a current mirror circuit 42 as an active load.

A constant current I _{23 is provided} by NPN transistors Q ₂₁ and Q ₂₃ and a resistor R ₂₁ which constitute a current mirror circuit.
Is configured as a first constant current source that supplies the current. The base of the diode-connected NPN transistor Q ₂₂ (bias transistor) is connected to the first power supply terminal 43 of the power supply voltage Vcc.
(Hereinafter, the power supply terminal referred to as the end) is connected to the emitter is connected to the base of the collector and the transistor Q ₂₄ of the transistor Q _23. To the collector of the transistor Q ₂₃ is, Komu constant current I ₂₃ flows.

The transistors Q ₂₁ and Q ₂₈ and the resistor R ₂₁ constitute a second constant current source for supplying a constant current I ₂₈ . The base and the emitter of the NPN-type transistor Q ₂₈ are each, is connected to the base and emitter of the transistor Q _21, the collector is connected to the base of the transistor Q _25. The collector of the transistor Q ₂₈ is a constant current I ₂₈ equal to current I ₂₃ is Komu flow.

The common characteristics of the NPN transistors Q ₂₉ , Q ₃₀ , and Q ₃₁ (detection transistors) having the same characteristics are connected to the base of the transistor Q ₂₅ , the collector is connected to the power supply terminal, and each base is connected to the detection terminal. Resistance R ₂₂ ,
Through R _23, R _24, induced voltage supply terminal 37,38,3
9 respectively.

The common base of the PNP type output transistors Q ₃₂ , Q ₃₃ , Q _{34 having} the same characteristics is connected to the collector of the transistor Q ₂₅ , the common collector is connected to the output terminal 45, and the output resistance R _It is connected to the ground terminal 44 (second power supply terminal) via ₂₅ and is grounded. The emitter of the output transistor Q _32, Q _33, Q _34, respectively, is connected to the base of the transistor _{Q 29, Q 30, Q 31} .

Terminals 37, 38, and 39 are respectively connected to the U-phase, V-phase, and W-phase three-phase induced voltages V _U ,
V _V and V _W are supplied.

The resistors R ₂₂ , R ₂₃ and R ₂₄ have the same resistance value. The transistors Q ₂₉ , Q ₃₀ , Q ₃₁ and the transistor Q ₂₂ have the same characteristics.

Next, the operation of the speed detection circuit of the brushless motor shown in FIG. 1 will be described. FIG. 2 is an explanatory diagram of the induced voltages V _U , V _V , V _W and the output voltage V _OD of each phase coil. FIG. 2A shows the induced voltages V _U , V _V , and V _W of each phase coil as in FIG. 4A. When the rotor rotates, the coils of each phase of U-phase, V-phase, and W-phase are shown in FIG.
As shown in, 2 [pi / 3 by a sinusoidal phase-shifted induced voltage _{V U,} V V, V _W occurs. The induced voltage V _U ,
V _V and V _W can be expressed by the above equations (1) to (3). These induced voltages V _U , V _V , V _W are respectively connected to terminals 37, 38, 39.
Supplied to

From each of terminals 37, 38 and 39, a resistor R ₂₂ ,
Output transistors Q ₃₂ , Q ₃₃ , Q ₃₄ via R ₂₃ , R ₂₄
Of the output transistors Q ₃₂ and Q
_33, through the collector of Q _34, flows through the output resistor R _25.

[0046] Also, the base of the transistor Q _29, Q _30, Q _31, respectively, the resistance base current is supplied through the _{R 22, R 23, R 24} , transistors Q _29, Q _30, Q ₃₁ emitter current flows as the current I ₂₈ to the collector of the transistor Q _28.

Transistor Q_{twenty four}, Q_{twenty five}Consisting of a differential pair
The transistor 41 has a transistor Q _{twenty five}The base potential of
Transistor Q_{twenty four}When the balun is at the same potential as the base of
It will be in the state of running.

[0048] Now, for example, to increase the base potential of the transistor Q ₂₉ is, when the base potential of the transistor Q ₂₅ is trying to become higher than the base potential of the transistor Q _24, the collector current of the transistor Q ₂₅ is reduced, the transistor Q _24, the collector current of Q _26, Q ₂₇ appears to have increased. Therefore, increasing the base current and the emitter current of the transistor Q ₃₂ is lowered base potential of the transistor Q _29, the base potential of the transistor Q ₂₅ is also lowered. Accordingly, the base potential of the transistor Q ₂₅ is approximately,
It is kept at a base potential and the potential of the transistor Q _24.

Transistor Q₂₉The base potential of
And transistor Q_{twenty five}Of transistor Q_{twenty four}
If it is going to be lower than the base potential of
Star Q ₃₂The collector current of the transistor Q_{twenty five}
Is almost equal to the transistor Q_{twenty four}Base potential
And is kept at the same potential.

Similarly, even when the base potentials of the other transistors Q ₃₀ and Q ₃₁ change, the base potential of the transistor Q ₂₅ is kept substantially the same as the base potential of the transistor Q ₂₄ .

The base potential of the transistor Q ₂₄ is the forward voltage of the transistor Q ₂₂ as V _F22, Vcc-V _F22
Since it is, the base potential of the transistor Q ₂₅ is kept at the base substantially the same potential of the transistor Q _24, Vcc-V
It becomes _F22 .

The transistor Q₂₉, Q₃₀, Q₃₁Is
Transistor Q_{twenty two}Has the same characteristics as
Jista Q₂₉~ Q₃₁Emitter current I₂₈Is the transistor
Q_{twenty two}Current I_{twenty three}Is set to the same value as For this reason,
Transistor Q₂₉, Q₃₀, Q ₃₁Forward voltage V_F29, V
_F30, V_F31Is the transistor Q_{twenty two}Forward voltage V_{F2 Two}
Has the same value as

From the above, the terminals 37, 38, 39
Induced voltage V supplied_U, V_V, V _WEither power
When the voltage exceeds Vcc, the corresponding transistor Q₂₉,
Q₃₀, Q ₃₁Is turned on, and the turned-on transistor Q₂₉,
Q₃₀, Q₃₁Output transistor Q connected to₃₂, Q
₃₃, Q₃₄Becomes conductive.

Conducted output transistors Q ₃₂ , Q ₃₃ , Q
₃₄ collector current of, flowing to the output resistor R _25, the output voltage V _OD is generated at the output terminal.

Output resistance R_{twenty five}Current I flowing through_{twenty five}Is conducting
Output transistor Q₃₂, Q₃₃, Q ₃₄Of the collector current
Is a sum, and is expressed by the following equation (7) using the equations (1) to (3).
Let

I ₂₅ = (E _U / R ₂₂ ) sinωt + (E _V / R ₂₃ ) sin (ωt−2π / 3) + (E _W / R ₂₄ ) sin (ωt−4π / 3) (7) the current of each term corresponding to the transistor Q ₃₂ to Q ₃₄ each of collector current, sinωt, sin (ωt-2
π / 3) and sin (ωt−4π / 3) flow only during a period in which each has a positive value.

Since the resistors R _{22 to} R ₂₄ have the same resistance value, the output voltage V _OD can be expressed by the following equation (8).

[0058] _{V OD = (R 25 / R} 22) (E U sinωt + E V sin (ωt-2π / 3) + E W sin (ωt-4π / 3)) (8) In this way, the induced voltage V _U, V _V, the amplitude value of V _W E _U,
An output voltage V _OD proportional to E _V and E _W is generated. FIG.
(B) shows the output voltage V _OD . As described above, the amplitude value E
_U, E _V, E _W is proportional to the rotational speed, the output voltage V _OD proportional to the rotational speed.

A speed control circuit (not shown) controls the speed of the brushless motor according to the value of the supplied output voltage V _OD , and keeps the rotation speed of the brushless motor constant.

Next, the minimum operating voltage of the circuit of FIG.
explain. Ground terminal 44, output resistance R_{twenty five}, Output tiger
Transistor Q₃₂~ Q₃₄Transistor between collector and base
TA Q _{twenty five}Constant current source 35, power supply
Considering the path of the power supply terminal 43 for the voltage Vcc,
Pressure V_P1Can be expressed by the following equation (9).

V _P1 = V _OD + V _BC32 + V _CE25 (9) Since the voltage of the constant current source 35 may be sufficiently smaller than other voltages, it can be ignored. Where V
_BC32 is the base-collector voltage of the output transistor Q _32, V _CE25 is the collector-emitter saturation voltage of the transistor Q _25.

The output voltage V _O is determined by the resistance R ₂₂ and the output resistance R ₂₅
It will vary depending on the ratio of the power supply voltage Vcc = 1V approximately, E _U
In the case of = 1V, the voltage may be set to about 0.2V. Base-collector voltage V _BC32 of the output transistor Q ₃₂ is 0
Well in V, the collector-emitter saturation voltage V _CE25 of the transistor Q ₂₅ is about 0.2V.

For this reason, the required operating voltage V _P1 is V _P1 =
There is a sufficient margin for a power supply voltage of 0.2 + 0 + 0.2 = 0.4V, that is, 0 or 1V or less.

The minimum operating voltage V _MIN is
4, between the base and emitter of the transistor Q _26, the collector-emitter of the transistor Q _24, the constant current source 35, determined by the path of the power supply terminal 43. The minimum operating voltage V _MIN is
It can be expressed by equation (10).

V_MIN= V_F26+ V_CE24 (10) where V_F26Is the transistor Q₂₆Forward voltage, V
_CE24Is the transistor Q _{twenty four}Collector-emitter saturation current
Pressure. Note that the voltage of the constant current source 35 is
They can all be small enough to be ignored.

[0066] The forward voltage V _F26 is about 0.6V of the transistor Q _26, the collector-emitter saturation voltage V _CE24 of the transistor Q ₂₄ is about 0.2V.

For this reason, the minimum operating voltage V _MIN is V _MIN
= 0.6 + 0.2 = 0.8V. Therefore, even if the power supply voltage Vcc is 1 V or less, stable operation can be performed with a sufficient margin.

[0068] As described above, in the present invention, the emitter and the detection transistor Q ₂₉ to Q ₃₁ of the connected NPN type to the base of the transistor Q _25, the common base is connected to the collector of the transistor Q _25, the emitters There is provided an output transistor Q ₃₂ to Q ₃₄ of PNP type connected to the base of the detection transistor Q ₂₉ to Q ₃₁ each.

As a result, the required operating voltage on the path from the ground terminal 44 to the power supply terminal 43 via the output resistor R ₂₅ , the collectors of the transistors Q _{32 to} Q ₃₄ , and the collector and emitter of the transistor Q ₂₅ can be reduced. And the minimum operating voltage can be made lower than 1V.
Therefore, even when the power supply voltage is generated by one battery, 1 V
It can operate stably with the following power supply voltage.

The bias constant current source 35 may be replaced with a single resistor.

[0071]

As described above, according to the present invention, the output resistance, the collector of the output transistor,
Since the required operating voltage in the path from the collector and the emitter of the second transistor to the first power supply terminal can be reduced, the minimum operating voltage can be made lower than 1 V, and the power supply voltage can be stabilized at a power supply voltage of 1 V or less. Features that can operate.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a speed detection circuit of a brushless motor according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of an induced voltage and an output voltage of each phase coil in the present embodiment.

FIG. 3 is a circuit diagram of a speed detection circuit of a conventional brushless motor.

FIG. 4 is an explanatory diagram of an induced voltage and an output voltage of each phase coil.

[Explanation of symbols]

41 differential pair transistors 42 current mirror circuit Q ₂₂ bias transistor R ₂₂ to R ₂₄ sensing resistor Q ₂₉ to Q ₃₁ detection transistor Q ₃₂ to Q ₃₄ output transistor R ₂₅ output resistance

Claims (1)

(57) [Claims] 1. Induction in each phase coil of a brushless motor
Of the brushless motor using the induced voltage
Brushless motor that generates output voltage corresponding to speed
In a speed detection circuit, a first transistor and a second transistor, whose emitters are commonly connected,
A differential pair transistor comprising: a first transistor and a second transistor;
Connected as an active load to the collector of each transistor
A current mirror circuit connected between the base of the first transistor and a first power supply terminal.
Connected and supply predetermined current by first constant current sourceDoDa
An ion-connected bias transistor,An induced voltage supply terminal to which the induced voltage is supplied, The via is provided corresponding to the induced voltage supply terminal;
Transistors with the same characteristics as
A detection transistor,  A predetermined voltage is connected to the emitter of the detection transistor.
A second constant current source for supplying a current;PNP provided corresponding to each of the detection transistors
An output transistor composed of a transistor.
e,  In the detection transistor, the emitter is the differential pair transistor.
Connected to the base of the second transistor of the transistor
And the base is connected to each of the induction resistors via a respective detection resistor.
A voltage supply terminal, and a collector connected to the first power supply terminal.
Connected to the child,The output transistor has an emitter connected to the detection transistor.
Connected to the base of the transistor
Connected to the collector of the second transistor of the transistor.
And the collector is connected to the second power terminal via the output resistor
Speed detection of the brushless motor
Road.