CN204465495U - A kind of output driving circuit - Google Patents
A kind of output driving circuit Download PDFInfo
- Publication number
- CN204465495U CN204465495U CN201520202955.5U CN201520202955U CN204465495U CN 204465495 U CN204465495 U CN 204465495U CN 201520202955 U CN201520202955 U CN 201520202955U CN 204465495 U CN204465495 U CN 204465495U
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- constant
- mos fet
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- current source
- circuit
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- Control Of Voltage And Current In General (AREA)
Abstract
The utility model relates to electronic technology field, is specifically related to a kind of output driving circuit with overcurrent protection, comprises constant-current source circuit U1, constant-current source driven MOS FET pipe U2, selection and comparison device U3, output mos FET pipe U4 and pull-up resistor R1.Input is selected to connect constant-current source driven MOS FET pipe U2 grid for one of selection and comparison device U3, another selects input end grounding, export the grid of termination output mos FET pipe U4, the grid voltage produced by constant-current source circuit U1 by the electric current between MOSFET pipe U4 drain electrode and source electrode limited.Output driving circuit of the present utility model utilizes the grid voltage of constant current driven MOS FET pipe control the electric current of output driving circuit and then realize the overcurrent protection function of drive circuit; can avoid increasing current sampling resistor at output mos FET source electrode; and system does not need comparator and reference data power supply yet; the utility model structure is simple, and effectively can avoid the reduction of drive circuit driving force.
Description
Technical field
The utility model relates to electronic technology field, is specifically related to a kind of output driving circuit with overcurrent protection.
Background technology
Output driving circuit will meet except the requirement of driving arrangement except performance, and the safeguard measure of himself is also extremely important, as overvoltage, overcurrent, overtemperature protection etc.Break down once driven equipment; as the short circuit of driven equipment input side or the record of outlet side open circuit; then drive circuit must cut out or control its output voltage; power MOSFET tube and outlet side device etc. could be protected not to be burnt; otherwise the further damage of electronic product may be caused, even cause the phenomenon such as electric shock and fire of operating personnel.
Traditional output driving circuit with overcurrent protection as shown in Figure 1, generally comprises: a MOSFET pipe U3, for as drive circuit output; A sampling resistor R2, for MOSFET pipe ground connection and acquisition output circuit driving current value; A reference voltage source U4 is used for the input of comparator; A voltage comparator U2, for the voltage output logic numerical value by contrast reference voltage and sampling resistor R2; A NOR NOR gate U1, is managed by the output valve control MOSFET of voltage comparator and then plays the effect of overcurrent protection shutoff or control circuit.Traditional output driving circuit with overcurrent protection comprises voltage comparator and base reference voltage; virtually can the complexity of increasing circuit; and the sampling resistor in circuit increases energy ezpenditure, reduce the efficiency of power supply, reduce the driving force of drive circuit.
Summary of the invention
The purpose of this utility model is exactly provide a kind of structure simple for current output driving circuit Problems existing and have the output driving circuit of overcurrent protection.
It is as follows that the utility model solves the technical scheme that its technical problem adopts: a kind of output driving circuit with overcurrent protection is made up of constant-current source circuit U1, constant-current source driven MOS FET pipe U2, selection and comparison device U3, output mos FET pipe U4 and pull-up resistor R1; Described constant-current source circuit U1 provides a constant current for output driving circuit; Described constant-current source driven MOS FET pipe U2 produces a parameter voltages according to the electric current of constant-current source circuit; The grid selecting input to connect constant current driven MOS FET pipe U2 of described selection and comparison device U3, another of selection and comparison device U3 selects input end grounding, and selection and comparison device U3 selects one of fan-in certificate according to the input and output two of function selecting side; The grid of described output mos FET pipe U4 connects the output of selection and comparison device U3, the drain electrode of MOSFET pipe U4 connects the output of pull-up resistor R1 as output driving circuit, the source ground of MOSFET pipe U4, the grid voltage produced by constant-current source circuit U1 by the electric current between MOSFET pipe U4 drain electrode and source electrode limited.
This uses novel output driving circuit to utilize the grid voltage of constant current driven MOS FET pipe control the electric current of output driving circuit and then realize the overcurrent protection function of drive circuit.Novel the avoiding of this use increases sampling resistor at output mos FET source electrode, and system does not need comparator and reference data power supply yet, and this use new structure is simple, and effectively can avoid the reduction of drive circuit driving force.
Accompanying drawing explanation
Fig. 1 is the output driving circuit schematic diagram that tradition has overcurrent protection.
Fig. 2 is circuit theory diagrams of the present utility model.
Embodiment
A kind of output driving circuit as shown in Figure 2, comprises constant-current source circuit U1, constant-current source driven MOS FET pipe U2, selection and comparison device U3, output mos FET pipe U4 and pull-up resistor R1.
Further, the grid of output mos FET pipe U4 connects the output of selection and comparison device U3, the source ground of output mos FET pipe U4, and the drain electrode of output mos FET pipe U4 connects the output of pull-up resistor R1 as drive circuit; Output mos FET pipe U4 is operated in out and leaks pattern formula, and the output of drive circuit accesses power supply by pull-up resistor R1.
Further, selection and comparison device U3 is between output mos FET pipe U4 and constant-current source driven MOS FET pipe U2, two inputs of selection and comparison device U3 access respectively with the grid of constant-current source driven MOS FET pipe U2, selection and comparison device U3 selects the grid of grid level to output mos FET pipe U4 of output low level or constant-current source driven MOS FET pipe U2 according to the input value of function selecting side.
Further, constant-current source driven MOS FET pipe U2 is between constant-current source circuit U1 and ground, the electric current of constant-current source circuit U1 is by constant-current source driven MOS FET pipe U2 ground connection, and constant-current source driven MOS FET pipe U2 produces a grid voltage thus limits the electric current between the source electrode of MOSFET pipe U4 and drain electrode.Further, constant-current source driven MOS FET pipe U2 and output mos FET pipe U4 forms an image current source circuit.
In this example, constant-current source circuit U1 flows to the electric current I on ground by constant-current source driven MOS FET pipe U2
constwith the Limited Current I of output mos FET pipe U4
limitfor 1/N times of relation, wherein N is the enlargement ratio that constant-current source driven MOS FET pipe U2 and output mos FET pipe U4 form an image current source circuit.Output mos FET pipe U4 drains and the electric current of source electrode is determined by pull-up resistor R1 and power supply VCC, when output driving circuit opened a way by driving element outlet side or input side short circuit time, output mos FET pipe U4 is by generation overload current, but owing to there is constant-current source driven MOS FET pipe U2 and output mos FET pipe U4 forms an image current source circuit, the overload current of output mos FET pipe U4 will be limited in I
limit(I
const/ N).
Claims (1)
1. an output driving circuit, is characterized in that comprising: constant-current source circuit U1, constant-current source driven MOS FET pipe U2, selection and comparison device U3, output mos FET pipe U4 and pull-up resistor R1; Described constant-current source circuit U1 provides a constant current for output driving circuit; Described constant-current source driven MOS FET pipe U2 produces a parameter voltages according to the electric current of constant-current source circuit; The grid selecting input to connect constant current driven MOS FET pipe U2 of described selection and comparison device U3, another of selection and comparison device U3 selects input end grounding, and selection and comparison device U3 selects one of fan-in certificate according to the input and output two of function selecting side; The grid of described output mos FET pipe U4 connects the output of selection and comparison device U3, the drain electrode of MOSFET pipe U4 connects the output of pull-up resistor R1 as output driving circuit, the source ground of MOSFET pipe U4, the grid voltage produced by constant-current source circuit U1 by the electric current between MOSFET pipe U4 drain electrode and source electrode limited.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520202955.5U CN204465495U (en) | 2015-04-07 | 2015-04-07 | A kind of output driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520202955.5U CN204465495U (en) | 2015-04-07 | 2015-04-07 | A kind of output driving circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204465495U true CN204465495U (en) | 2015-07-08 |
Family
ID=53672315
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201520202955.5U Expired - Fee Related CN204465495U (en) | 2015-04-07 | 2015-04-07 | A kind of output driving circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN204465495U (en) |
-
2015
- 2015-04-07 CN CN201520202955.5U patent/CN204465495U/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150708 Termination date: 20160407 |