CN112367067B - Differential drive circuit of floating isolating switch - Google Patents
Differential drive circuit of floating isolating switch Download PDFInfo
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- CN112367067B CN112367067B CN202110036597.5A CN202110036597A CN112367067B CN 112367067 B CN112367067 B CN 112367067B CN 202110036597 A CN202110036597 A CN 202110036597A CN 112367067 B CN112367067 B CN 112367067B
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- H03—ELECTRONIC CIRCUITRY
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- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/04—Modifications for accelerating switching
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Abstract
The invention discloses a differential drive circuit of a floating isolating switch, which comprises a power supply side, a power receiving side and a differential current, wherein: the differential current is Ip current and In current respectively, the Ip current and the In current are connected with the isolating switch Q2 and the isolating switch Q3 on the power supply side, the magnitude and the polarity of the Ip current and the In current are controlled on the power receiving side through the differential driving circuit, and the current pole performance of the Ip current and the In current controls the closing and opening of the isolating switch Q1.
Description
Technical Field
The invention belongs to the technical field of circuit design, and particularly relates to a differential driving circuit of a floating isolating switch.
Background
In industrial control circuits, floating isolation between different modules is often required. As shown in the attached figure 1 of the specification, when the isolating switch is turned on, the ground wires of the power supply side and the power receiving side are in short circuit, and both sides can normally supply power and communicate; when the isolating switch is closed, the ground wires of the power supply side and the power receiving side are opened, and the circuits on the two sides are in a high-impedance state, so that the electrical isolation can be realized. The on and off of the isolating switch are controlled by the time division of the power receiving side, the isolating switch is opened at the moment of power supply and communication, and is closed when signals are isolated, and finally a good communication effect is achieved.
In order to achieve the floating isolation, a conventional circuit is shown in fig. 2 of the specification, and a MOS transistor or a transistor Q1 is connected in series between a power supply ground and a power receiving ground as a switch of the floating isolation. The gate of Q1 is connected to ground through a drive resistor Rd. When the power receiving side needs to finish floating isolation, current Id is injected into Rd, and enough driving voltage is generated on the Rd to enable Q1 to be started; when the power receiving side needs to enter the floating isolation, the driving voltage on the closing Id, Rd disappears, and Q1 is closed. The current of Id needs to be precisely controlled to prevent the Q1 driving voltage from being too high to burn out. This implementation has two disadvantages:
1. turning Q1 on requires enough Id to flow all the way through Rd with high losses;
2. to achieve sufficient off/on speed, Rd should choose a smaller resistance.
The two disadvantages are mutually restricted and are difficult to realize at the same time.
As shown in fig. 3 in the specification, an improved floating isolation driving circuit is described. A stage is added on the original basis and is driven by Q2 and Q3, and meanwhile, a power supply voltage VDD suitable for turning on Q1 is needed. After Q2 and Q3 are added, the driving capability of Q1 is enhanced, the switching speed can be realized quickly, and therefore, Rd can select larger resistance. Thus, the defects of large loss and low speed in the prior art are improved. However, this implementation requires the supply side to supply a suitable VDD, which puts high demands on the system.
Disclosure of Invention
The invention aims to provide a differential driving circuit of a floating isolating switch, which solves the problems that in the driving process of the floating isolating switch, the contradiction between loss and driving speed exists, and a power supply side is required to provide a driving power supply independently.
In order to achieve the purpose, the invention provides the following technical scheme: a differential driving circuit of a floating isolation switch comprises a power supply side, a power receiving side and a differential current, wherein:
the differential current is Ip current and In current respectively, and the Ip current and the In current are connected with the isolating switch Q2 and the isolating switch Q3 on the power supply side;
the power receiving side controls the magnitude and polarity of Ip current and In current through a differential driving circuit, and the current polarity of the Ip current and the In current controls the isolation switch Q1 to be closed or opened;
when Ip current is output and In current is not output, the grid voltage Vgp of the isolating switch Q3 is pulled high, the grid voltage Vgn of the isolating switch Q2 is pulled low by the opened isolating switch Q3, the isolating switch Q2 is closed, at the moment, the isolating switch Q1 and the isolating switch Q3 are In an opening state, and the floating isolation is In the opening state;
when In current is output and Ip current is not output, the grid voltage Vgn of the isolating switch Q2 is pulled high, the grid voltage Vgp of the isolating switch Q3 is pulled low by the opened isolating switch Q2, so that the isolating switch Q3 is closed, at the moment, the isolating switch Q1 and the isolating switch Q3 are In a closed state, and the floating isolation is In an isolation state;
when the grid voltage Vgp of the isolating switch Q3 is pulled high and the isolating switch Q3 is completely started, the differential drive circuit controls Ip current to be reduced until the grid voltage Vgp of the isolating switch Q3 is stabilized to a preset voltage;
when the gate voltage Vgn of the isolating switch Q2 is pulled high and the isolating switch Q2 is turned on completely, the differential driving circuit controls the In current to be reduced until the gate voltage Vgn of the isolating switch Q2 is stabilized to a preset voltage.
Preferably, the Ip current and the In current are In a voltage-limiting constant current source mode.
Preferably, the method further comprises the following steps: an operational amplifier OPA1 for controlling the MOS transistor Qp to regulate the Ip current; and an operational amplifier OPA2 for controlling the MOS transistor Qn to regulate the In current.
Preferably, the voltage divider further comprises a voltage divider resistor R1, a voltage divider resistor R2, a voltage divider resistor R3, a voltage divider resistor R4 and a preset voltage Vd, wherein the voltage divider resistor R1 and the voltage divider resistor R2 collect a gate voltage Vgp of the isolation switch Q3; the voltage divider resistor R3 and the voltage divider resistor R4 collect the grid voltage Vgn of the isolating switch Q2; the predetermined voltage Vd sets a predetermined voltage for Vgp and Vgn.
Preferably, the voltage dividing resistor R1 has the same resistance as the voltage dividing resistor R3, and the voltage dividing resistor R2 has the same resistance as the voltage dividing resistor R4.
Preferably, the final voltage of the gate voltage Vgn of the isolating switch Q2 is: vd (1+ R4/R3), the final voltage of the gate voltage Vgp of the isolating switch Q3 is: vd (1+ R2/R1).
Preferably, the predetermined voltage Vd is dropped by using a diode D1 and a diode D2.
Preferably, the isolation switch Q2 and the isolation switch Q3 are MOS transistors or triodes.
Preferably, the isolation switch Q3 is a resistor.
Preferably, the isolation switches Q1, Q2 and Q3 are ground-side isolation switches or power-side isolation switches.
The technical effects and advantages of the invention are that the differential drive circuit of the floating isolating switch comprises:
1. the power consumption problem in the drive of the floating isolating switch is solved, and the isolating effect of hundreds of kilohms can be realized only by dozens of microamps of current;
2. the differential floating isolating switch is designed to provide enough high switching speed, and can complete switching conversion within several microseconds;
3. a power supply side is not required to additionally provide a separate driving power supply VDD, so that the system design is simplified;
4. the differential drive of the power receiving side can be realized by discrete devices or an integrated circuit, and the output in the form of open-circuit drain is adopted, so that the differential drive can be easily integrated on a chip to realize the effect of floating isolation.
Drawings
FIG. 1 is a circuit for floating isolation provided by the prior art;
FIG. 2 is another circuit for floating isolation provided by the prior art;
FIG. 3 is a prior art improved floating isolation driver circuit;
FIG. 4 is a schematic diagram of a circuit according to the present invention;
FIG. 5 is a schematic circuit diagram of a differential drive implementation of the present invention;
FIG. 6 is a circuit layout of an embodiment of the present invention;
FIG. 7 is a specific circuit layout diagram according to the fourth embodiment of the present invention;
FIG. 8 is a specific circuit layout diagram according to a fifth embodiment of the present invention;
fig. 9 is a specific circuit layout diagram according to a sixth embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to fig. 1 to 9 in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The present invention provides a differential driving circuit of a floating isolation switch as shown in fig. 1-9, comprising a power supply side, a power receiving side and a differential current, wherein:
on the basis of the original single-strand drive current Id, one path of differential current is added, the differential current is Ip current and In current respectively, and the Ip current and the In current are connected with an isolating switch Q2 and an isolating switch Q3 on the power supply side;
the power receiving side controls the magnitude and polarity of the Ip current and the In current through the differential driving circuit, and the current polarity of the Ip current and the In current can rapidly control the closing or opening of the isolating switch Q1.
The first embodiment is as follows:
referring to fig. 4, fig. 4 is a schematic diagram of a circuit according to the present invention;
the specific process is as follows:
1. when the current receiving side controls Ip current output and In current is not output, the grid voltage Vgp of the isolating switch Q3 is pulled high, the grid voltage Vgn of the isolating switch Q2 is pulled low by the isolating switch Q3 which is turned on, the isolating switch Q2 is further turned off, at the moment, the isolating switch Q1 and the isolating switch Q3 are In an on state, and the floating isolation is In an on state;
2. when the power receiving side controls In current output and Ip current is not output, the grid voltage Vgn of the isolating switch Q2 is pulled high, the grid voltage Vgp of the isolating switch Q3 is pulled low by the opened isolating switch Q2, the isolating switch Q3 is further closed, at the moment, the isolating switch Q1 and the isolating switch Q3 are In a closed state, and the floating isolation is In an isolation state.
Example two:
the polarity of the Ip current and the In current can control the closing and opening of the isolating switch, but it should be noted that the Ip current and the In current need to stop outputting the current after the gate voltage Vgp of the isolating switch Q3 and the gate voltage Vgn of the isolating switch Q2 are completely opened at the isolating switch Q2 and the isolating switch Q3, otherwise the gate voltage Vgp of the isolating switch Q3 and the gate voltage Vgn of the isolating switch Q2 will be charged to the VPP voltage, possibly reaching the gate withstand voltage limit of the isolating switch Q1, the isolating switch Q2 and the isolating switch Q3, and therefore, the Ip current and the In current are set to the voltage-limiting constant current source mode.
Referring to fig. 5, fig. 5 is a schematic circuit diagram of a differential driving implementation according to the present invention;
through the increase of divider resistance R1, divider resistance R2, divider resistance R3, divider resistance R4 and preset voltage Vd, make divider resistance R1 and divider resistance R2 can gather isolator Q3 grid voltage Vgp, divider resistance R3 and divider resistance R4 can gather isolator Q2 grid voltage Vgn, and through the setting to preset voltage Vd, can set for the preset voltage of Vgp and Vgn, isolator Q2 grid voltage Vgn final voltage is: vd (1+ R4/R3), the final voltage of the grid voltage Vgp of the isolating switch Q3 is: vd (1+ R2/R1).
And an operational amplifier OPA1 and an operational amplifier OPA2 are added, wherein the operational amplifier OPA1 can control the MOS tube Qp to regulate the Ip current, and the operational amplifier OPA2 can control the MOS tube Qn to regulate the In current.
The specific differential driving process is as follows:
1. when the isolating switch Q3 needs to be started and the grid voltage Vgp of the isolating switch Q3 needs to be high, the current of the power receiving side is controlled to be started, and the In current stops;
2. when the grid voltage Vgp of the isolating switch Q3 gradually rises to turn on the isolating switch Q3, the grid voltage Vgn of the isolating switch Q2 is pulled down to the ground voltage, and the isolating switch Q2 is turned off;
3. the grid voltage Vgp of the isolating switch Q3 is continuously increased, meanwhile, the grid electrode Vfp of the MOS tube Qp is also gradually increased, when the Vfp voltage is equal to the voltage Vdn + the preset voltage Vvd of the grid electrode Vfn of the MOS tube Qp, the operational amplifier OPA1 controls the MOS tube Qp, the Ip current is reduced until the Vgp stably stays at the preset voltage, meanwhile, the isolating switch Q3 and the isolating switch Q1 are in an open state, and the isolating switch Q2 is in a close state;
4. when the isolating switch Q1 is required to be turned off, the operational amplifier OPA1 controls the MOS tube Qp to stop the Ip current, the operational amplifier OPA2 controls the MOS tube Qn to turn on the In current, the grid voltage Vgn of the isolating switch Q2 is stopped at a preset voltage, the isolating switch Q3 and the isolating switch Q1 are turned off, and the isolating switch Q2 is turned on.
After the grid voltage Vgp of the isolating switch Q3 and the grid voltage Vgn of the isolating switch Q2 stay at the preset voltage, In current and Ip current only maintain one static current, and the power consumption is extremely low.
Example three:
referring to fig. 6, fig. 6 is a specific circuit layout of the present invention;
the resistance of the divider resistor R1 is the same as that of the divider resistor R3, a 100K resistor is adopted, the resistance of the divider resistor R2 is the same as that of the divider resistor R4, a 2M resistor is adopted, and then the Vfp and the Vfn are the same;
the preset voltage Vd adopts a diode D1 and a diode D2 to generate voltage drop, and adopts 0.7V;
then, the final voltage of the gate voltage Vgn of the isolation switch Q2 is: vd (1+ R4/R3) = 14.7V;
then, the final voltage of the gate voltage Vgp of the isolating switch Q3 is: vd (1+ R2/R1) = 14.7V.
Example four:
referring to fig. 7, fig. 7 is a specific circuit design diagram of the present invention, and the isolation switch Q2 and the isolation switch Q3 employ transistors, which have the same effect.
Example five:
referring to fig. 8, fig. 8 is a specific circuit layout of the present invention, and the isolation switch Q3 uses a resistor, which has the same effect.
Example six:
referring to fig. 9, fig. 9 shows a specific circuit design of the present invention, and the isolation switch Q1, the isolation switch Q2, and the isolation switch Q3 employ a ground-side isolation switch or a power-side isolation switch, which has the same effect.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.
Claims (10)
1. The utility model provides a differential drive circuit of floating isolator, includes power supply side, power receiving side and a differential current, its characterized in that:
the differential current is Ip current and In current respectively, and the Ip current and the In current are connected with the isolating switch Q2 and the isolating switch Q3 on the power supply side;
the power receiving side controls the magnitude and polarity of Ip current and In current through a differential driving circuit, and the current polarity of the Ip current and the In current controls the isolation switch Q1 to be closed or opened;
when Ip current is output and In current is not output, the grid voltage Vgp of the isolating switch Q3 is pulled high, the grid voltage Vgn of the isolating switch Q2 is pulled low by the opened isolating switch Q3, the isolating switch Q2 is closed, at the moment, the isolating switch Q1 and the isolating switch Q3 are In an opening state, and floating isolation is opened;
when In current is output and Ip current is not output, the grid voltage Vgn of the isolating switch Q2 is pulled high, the grid voltage Vgp of the isolating switch Q3 is pulled low by the opened isolating switch Q2, the isolating switch Q3 is closed, at the moment, the isolating switch Q1 and the isolating switch Q3 are In a closed state, and floating isolation is finished;
when the grid voltage Vgp of the isolating switch Q3 is pulled high and the isolating switch Q3 is completely started, the differential drive circuit controls Ip current to be reduced until the grid voltage Vgp of the isolating switch Q3 is stabilized to a preset voltage;
when the gate voltage Vgn of the isolating switch Q2 is pulled high and the isolating switch Q2 is turned on completely, the differential driving circuit controls the In current to be reduced until the gate voltage Vgn of the isolating switch Q2 is stabilized to a preset voltage.
2. The differential drive circuit of a floating isolation switch of claim 1, wherein: the Ip current and the In current are In a voltage-limiting constant current source mode.
3. The differential driving circuit of a floating isolation switch of claim 1, further comprising:
an operational amplifier OPA1 for controlling the MOS transistor Qp to regulate the Ip current;
and an operational amplifier OPA2 for controlling the MOS transistor Qn to regulate the In current.
4. The differential driving circuit of claim 3, further comprising a voltage divider R1, a voltage divider R2, a voltage divider R3, a voltage divider R4, and a predetermined voltage Vd,
the voltage divider resistor R1 and the voltage divider resistor R2 collect the grid voltage Vgp of the isolating switch Q3;
the voltage divider resistor R3 and the voltage divider resistor R4 collect the grid voltage Vgn of the isolating switch Q2;
the predetermined voltage Vd sets a predetermined voltage for Vgp and Vgn.
5. The differential driving circuit of a floating isolation switch according to claim 4, wherein: the resistance of the voltage dividing resistor R1 is the same as that of the voltage dividing resistor R3, and the resistance of the voltage dividing resistor R2 is the same as that of the voltage dividing resistor R4.
6. The differential driving circuit of a floating isolation switch according to claim 4, wherein:
the final voltage of the grid voltage Vgn of the isolating switch Q2 is as follows: vd (1+ R4/R3);
the final voltage of the grid voltage Vgp of the isolating switch Q3 is as follows: vd (1+ R2/R1).
7. The differential driving circuit of a floating isolation switch according to claim 4, wherein: the predetermined voltage Vd is dropped by using a diode D1 and a diode D2.
8. The differential drive circuit of a floating isolation switch of claim 1, wherein: the isolating switch Q2 and the isolating switch Q3 adopt MOS tubes or triodes.
9. The differential drive circuit of a floating isolation switch of claim 1, wherein: the isolating switch Q3 adopts a resistor.
10. The differential drive circuit of a floating isolation switch of claim 1, wherein: the isolating switch Q1, the isolating switch Q2 and the isolating switch Q3 adopt an isolating switch at the ground end or an isolating switch at the power end.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110036597.5A CN112367067B (en) | 2021-01-12 | 2021-01-12 | Differential drive circuit of floating isolating switch |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110036597.5A CN112367067B (en) | 2021-01-12 | 2021-01-12 | Differential drive circuit of floating isolating switch |
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| CN112367067A CN112367067A (en) | 2021-02-12 |
| CN112367067B true CN112367067B (en) | 2021-04-02 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103346773A (en) * | 2013-07-10 | 2013-10-09 | 昆山锐芯微电子有限公司 | Level conversion circuit |
| CN104253609A (en) * | 2013-06-28 | 2014-12-31 | 比亚迪股份有限公司 | Low-voltage differential signal driving circuit |
| US20200321944A1 (en) * | 2019-04-02 | 2020-10-08 | Seiko Epson Corporation | LVDS Driver Circuit, Integrated Circuit Device, Oscillator, Electronic Apparatus, And Vehicle |
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2021
- 2021-01-12 CN CN202110036597.5A patent/CN112367067B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104253609A (en) * | 2013-06-28 | 2014-12-31 | 比亚迪股份有限公司 | Low-voltage differential signal driving circuit |
| CN103346773A (en) * | 2013-07-10 | 2013-10-09 | 昆山锐芯微电子有限公司 | Level conversion circuit |
| US20200321944A1 (en) * | 2019-04-02 | 2020-10-08 | Seiko Epson Corporation | LVDS Driver Circuit, Integrated Circuit Device, Oscillator, Electronic Apparatus, And Vehicle |
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| CN112367067A (en) | 2021-02-12 |
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