An encoder power switching circuit

Abstract

The application discloses an encoder power supply switching circuit, which is characterized by comprising a first switching circuit, a second switching circuit and a power output end, wherein the power output end is used for connecting an encoder load, the first switching circuit is arranged between an encoder power supply and the power output end, the first switching circuit comprises a first diode, the positive electrode of the first diode is connected with the encoder power supply, and the negative electrode of the first diode is connected with the power output end; the second switching circuit is arranged between an encoder battery and the power output end, the second switching circuit comprises a first Pmos tube, the drain electrode of the first Pmos tube is connected with the encoder battery, the source electrode of the first Pmos tube is connected with the power output end, and the gate electrode of the first Pmos tube is connected with the encoder power supply. The application has the advantages that the automatic switching of the power supply of the encoder is realized, the problem of power supply voltage drop is solved, and the power supply switching circuit has a smaller voltage drop.

Description

Technical Field

[0001] This application relates to the field of encoder technology, and in particular to an encoder power switching circuit. Background Technology

[0002] Currently, encoders are becoming increasingly important in the field of servo systems, and electronic multi-turn encoders based on the magnetic switch principle are an important type of encoder. This type of electronic multi-turn encoder mainly has two power supply methods: when the driver is powered, the electronic multi-turn section is powered by the driver's power supply side; when the driver is powered off, the electronic multi-turn section is powered by an external battery.

[0003] Currently, the main power switching methods used are, such as Figure 1 As shown, the switching between power and battery is accomplished using two diodes. However, this switching method has the following problems:

[0004] 1. Voltage drop problem: Whether it is the power supply on the driver side or the battery side, there is a voltage drop problem after passing through the diode. In actual use, such voltage drop loss often leads to insufficient input voltage supply.

[0005] 2. Reverse current issue: Most batteries cannot accept direct current flow. For safety reasons, it is not recommended to use this method for automatic switching between batteries and power sources. Summary of the Invention

[0006] This application provides an encoder power switching circuit, which has the advantages of realizing automatic switching of encoder power supply, solving the power supply voltage drop problem, and the power switching circuit has a smaller voltage drop.

[0007] The above-mentioned objective of this application is achieved through the following technical solution: an encoder power switching circuit, comprising a first switching circuit, a second switching circuit, and a power output terminal, wherein the power output terminal is used to connect to the encoder load, wherein:

[0008] The first switching circuit is set between the encoder power supply and the power output terminal. The first switching circuit includes a first diode. The encoder power supply is connected to the positive terminal of the first diode, and the power output terminal is connected to the negative terminal of the first diode.

[0009] The second switching circuit is located between the encoder battery and the power output terminal. The second switching circuit includes a first PMOS transistor. The encoder battery is connected to the drain of the first PMOS transistor, the power output terminal is connected to the source of the first PMOS transistor, and the gate of the first PMOS transistor is connected to the encoder power supply.

[0010] When the encoder is powered on, the first switch circuit is turned on and the second switch circuit is turned off; when the encoder is powered off, the first switch circuit is turned off and the second switch circuit is turned on.

[0011] Furthermore, the gate of the first Pmos transistor is connected to a resistor R2, and the other end of the resistor R2 is grounded.

[0012] In summary, the beneficial effects of this application are: by setting a first PMOS transistor for switching in the second switching circuit, the voltage drop problem caused by diode switching can be solved, the working voltage at the load end can be increased when the encoder is powered by battery, and zero voltage drop can be achieved when the encoder is powered by power supply. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of an existing coded power switching method;

[0014] Figure 2 This is a schematic diagram of the circuit principle of Embodiment 1;

[0015] Figure 3 This is a schematic diagram of the circuit principle of Embodiment 2;

[0016] Figure 4 This is a schematic diagram of the circuit principle of Embodiment 3;

[0017] Figure 5 This is a schematic diagram of the circuit principle of Embodiment 4;

[0018] Figure 6 This is a schematic diagram of the circuit principle of Example 6. Detailed Implementation

[0019] The specific embodiments of this application are described in detail below with reference to the accompanying drawings.

[0020] Example 1: An encoder power switching circuit includes a first switching circuit, a second switching circuit, and a power output terminal, wherein: the first switching circuit is disposed between the encoder power supply and the power output terminal, and the second switching circuit is disposed between the encoder battery and the power output terminal; when the encoder power supply is on, the first switching circuit is turned on and the second switching circuit is turned off; when the encoder power supply is off, the first switching circuit is turned off and the second switching circuit is turned on.

[0021] It should be noted that in this application, encoder power supply refers to the power provided by the encoder driver, while encoder battery refers to the external battery in the encoder.

[0022] refer to Figure 2 The first switching circuit includes a first diode, with the encoder power supply connected to the positive terminal of the first diode and the power output terminal connected to the negative terminal of the first diode.

[0023] The second switching circuit includes a first PMOS transistor Q1, whose gate is connected to the encoder power supply. The encoder battery is connected to the drain of the first PMOS transistor Q1, the power output terminal is connected to the source of the first PMOS transistor Q1, and the gate of the first PMOS transistor Q1 is connected to the encoder power supply. A resistor R2 is connected to the gate of the first PMOS transistor Q1, and the other end of the resistor R2 is grounded. A large resistance value is chosen for resistor R2, such as... Figure 2 The 10K ohm resistor shown is used to control the voltage of the gate of the first PMOS transistor Q1 at a high voltage when the encoder is powered on, so as to prevent the first PMOS transistor Q1 from being turned on.

[0024] When the drive-side power supply is on, switch J1 is closed; at this time, the gate of Pmos Q1 is H, Pmos is turned off, and P5V goes through D1 to the load R3. The theoretical voltage value at the load end is VL=P5V-Vf(D1).

[0025] Example 2: Based on Example 1, with reference to Figure 3 The second switching circuit also includes a second diode D7, which is connected in parallel across the first PMOS transistor Q1.

[0026] In the first embodiment, the power switching efficiency is affected by a combination of factors, including the parameters of the MOSFET, the resistance of R2, the filter capacitor at the load end, the capacitor at the input end, and the power consumption of the load. The switching efficiency will be affected. However, the second embodiment can improve the switching speed.

[0027] If the drain and source terminals of the first PMOS transistor Q4 are reversed, then when the encoder power supply (P5V) and the encoder battery (BAT) are powered simultaneously, the encoder power supply voltage will directly charge BAT through D6 and then through the internal diode of Q4, which will damage the battery.

[0028] In addition, when the encoder power is turned off and then on again, the output voltage will not reach the initial value. This is due to the body diode clamping of D6 and the first PMOS transistor Q4.

[0029] Example 3: An encoder power switching circuit includes a first switching circuit, a second switching circuit, and a power output terminal, wherein: the first switching circuit is disposed between the encoder power supply and the power output terminal, and the second switching circuit is disposed between the encoder battery and the power output terminal; when the encoder power supply is on, the first switching circuit is turned on and the second switching circuit is turned off; when the encoder power supply is off, the first switching circuit is turned off and the second switching circuit is turned on.

[0030] refer to Figure 4The second switching circuit includes a first PMOS transistor Q9, with the encoder battery connected to the source of the first PMOS transistor Q9, the power output terminal connected to the drain of the first PMOS transistor Q9, and the gate of the first PMOS transistor Q9 connected to the encoder power supply. The second switching circuit also includes a third diode D7, which is connected in series with the first PMOS transistor Q9.

[0031] In the first embodiment, when the power supply is on, there will be a reverse current flowing into the battery through the body diode of the first PMOS transistor Q1, which will damage the battery. Connecting a diode in series can effectively solve the reverse charging problem.

[0032] This embodiment takes into account the protection of the circuit, using the first PMOS transistor Q9 body diode and the external D7 to prevent BAT from flowing out and the encoder power supply P5V from flowing back.

[0033] If the first PMOS transistor Q9 is in the reverse direction, then the body diode and the external D7 are in the same direction; in this case, BAT can output to the terminal through the voltage drop of the body diode and D7, and cannot achieve the purpose of control.

[0034] Example 4: Based on Example 1, refer to Figure 5 The first PMOS transistor is Q4, and the second switching circuit also includes a second PMOS transistor Q5. The second PMOS transistor Q5 is connected in series with the first PMOS transistor Q4 and in opposite directions. Specifically, the drains of the second PMOS transistor Q5 and the first PMOS transistor Q4 are connected to each other, and the gates of the second PMOS transistor Q5 and the first PMOS transistor Q4 are connected to each other.

[0035] When the power supply is on, the voltage at the load is the same as in Example 1. However, when the power supply is off, both Q4 and Q5 are turned on, and at this time, the load achieves zero voltage drop and the reverse charging problem is solved.

[0036] Example 5: Based on Example 1, the second switching circuit further includes a second diode, a third diode, and a second PMOS transistor. The second diode is connected in parallel across the first PMOS transistor. The third diode is connected in series with the first PMOS transistor. The second PMOS transistor is connected in series with the first PMOS transistor in opposite directions. The gates of the second PMOS transistor and the first PMOS transistor are connected to each other.

[0037] Example 6: Based on any one of Examples 1 to 5, with reference to Figure 6 The first switching circuit does not use a diode, but instead adopts the following first switching circuit scheme:

[0038] The first switching circuit includes a first NMOS transistor Q6 and a third PMOS transistor Q4. The third PMOS transistor Q4 is connected between the encoder power supply and the power output terminal. The gate of the third PMOS transistor Q4 is grounded through the first NMOS transistor Q6. The gate of the first NMOS transistor Q6 is connected to the encoder power supply, and the gate of the third PMOS transistor Q4 is also connected to the power output terminal. The gate of the third PMOS transistor is connected to the power output terminal through a first resistor R9.

[0039] In this scheme, when the power supply is on, the first NMOS transistor Q6 is turned on, the first PMOS transistor Q5 is turned off, and the third PMOS transistor Q4 is turned on. At this time, the encoder power supply P5V achieves zero voltage drop at the load end. When the power supply is off, Q6 is turned off, Q4 is turned off, and Q5 is turned on. At this time, the encoder battery BAT achieves zero voltage drop at the load end.

[0040] Furthermore, the first switching circuit also includes a fourth PMOS transistor and / or a fourth diode, wherein the fourth PMOS transistor or the fourth diode is connected in parallel with the third PMOS transistor, and the fourth PMOS transistor and the third PMOS transistor are in opposite directions, and the gates of the fourth PMOS transistor and the third PMOS transistor are connected to each other.

[0041] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of this application, and these all fall within the protection scope of this application.

Claims

1. An encoder power switching circuit, characterized in that, It includes a first switching circuit, a second switching circuit, and a power output terminal. The power output terminal is used to connect to the encoder load, wherein: The first switching circuit is set between the encoder power supply and the power output terminal. The first switching circuit includes a first diode. The encoder power supply is connected to the positive terminal of the first diode, and the power output terminal is connected to the negative terminal of the first diode. The second switching circuit is located between the encoder battery and the power output terminal. The second switching circuit includes a first PMOS transistor. The encoder battery is connected to the drain of the first PMOS transistor, the power output terminal is connected to the source of the first PMOS transistor, and the gate of the first PMOS transistor is connected to the encoder power supply. When the encoder is powered on, the first switch circuit is turned on and the second switch circuit is turned off; when the encoder is powered off, the first switch circuit is turned off and the second switch circuit is turned on.

2. The encoder power switching circuit according to claim 1, characterized in that, The gate of the first PMOS transistor is connected to a resistor R2, and the other end of the resistor R2 is grounded.

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