CN206135859U - Pulse width modulation circuit based on TL494 chip - Google Patents
Pulse width modulation circuit based on TL494 chip Download PDFInfo
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- CN206135859U CN206135859U CN201621203503.XU CN201621203503U CN206135859U CN 206135859 U CN206135859 U CN 206135859U CN 201621203503 U CN201621203503 U CN 201621203503U CN 206135859 U CN206135859 U CN 206135859U
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Abstract
The utility model provides a pulse width modulation circuit based on TL494 chip, including the TL494 chip connect on 3 pins of TL494 chip to be connected with on overvoltage crowbar, 15 pin and 16 pins and connect the voltage range regulating circuit on current foldback circuit, 1 pin and 2 pins. The beneficial effect of the utility model: utilize the TL494 chip to realize through designing the peripheral circuit, having realized direct current switch power supply's overvoltage protection, overcurrent protection and output voltage range regulatory function by direct current switch power supply DCDC inverter circuit pulse width control, make the circuit more simplify, improved electronic components's utilization ratio, reduced the power cost, increased the stability and the reliability of power, satisfy railway power supply product safe and reliable's requirement.
Description
Technical field
This utility model belongs to switching power circuit design field, more particularly, to a kind of pulsewidth based on TL494 chips
Modulation circuit.
Background technology
In recent years railway electronic product flourishes, and Switching Power Supply products application extensively, generally should by various power switch pipes
For in circuit, its control circuit mode to be varied.Wherein, PWM control technologies being most widely used in inverter circuit,
Impact to inverter circuit is also deep.At present, in the inverter circuit widely applied, the overwhelming majority is all PWM type inversions
Circuit.TL494 chips are a kind of pulse width modulation circuits of fixed frequency, and it contains the whole needed for Switching Power Supply control
Function, in being widely used in semibridge system, full-bridge type Switching Power Supply.The peripheral auxiliary circuits reasonable in design to TL494 chips, can carry
The integrity of high circuit, while it is more multi-functional to be capable of achieving power supply.
Utility model content
In view of this, this utility model is directed to a kind of pulse-width modulation circuit based on TL494 chips, using TL494
Chip realizes power supply overvoltage protection, overcurrent protection, voltage range regulatory function, by TL494 chips appropriate design periphery electricity
Road, simplifies power circuit, and stability is higher.
To reach above-mentioned purpose, what the technical solution of the utility model was realized in：
A kind of pulse-width modulation circuit based on TL494 chips, including TL494 chips, in 3 pins of the TL494 chips
Current foldback circuit is connected with upper connection overvoltage crowbar, 15 pins and 16 pins, on 1 pin and 2 pins voltage is connected
Range adjusting circuit.
Further, the overvoltage crowbar includes voltage comparator U1, the voltage comparator U1 in-phase input ends
Connect resistance R2 one end and electric capacity C2, resistance R3, one end of resistance R4 respectively, inverting input connection Zener diode Q1 bears
Pole, outfan is connected to 3 pins of the TL494 chips by resistance R5, and the resistance R2 other ends connect power output end,
The Zener diode Q1 negative poles are connected to power supply VCC by resistance R1, and the electric capacity C2, resistance R3 and resistance R4's is another
End, Zener diode Q1 positive poles are grounded.
Further, the current foldback circuit includes voltage follower U2 and current sensor, the current sensor
One end connects power supply DC output end, and the other end is connected to the pin of TL494 chips 16, the power output end by resistance R7
Voltage is connected to the voltage follower U2 in-phase input ends by resistance R15, and the voltage follower U2 inverting inputs connect
Outfan, outfan connection resistance R13 one end, the resistance R13 other ends connection Zener diode Q2 negative poles are connected to, and are connected
To the connected end of resistance R9, R10, the Zener diode Q2 plus earths, the resistance R10 other ends are connected to described
The pin of TL494 chips 15, the resistance R9 other ends are connected to the pin of TL494 chips 13 and 14 pins.
Further, the voltage range adjusts circuit includes resistance R16, R17, the pin of TL494 chips 13 and 14
Pin connection is followed by resistance R16 one end, the pin of resistance R16 other ends connection TL494 chips 2 and resistance R17 one end, institute
State resistance R17 other ends ground connection, the described pin of TL494 chips 1 connection resistance R18 one end, the resistance R18 other ends connection electricity
Hold C430, one end of resistance R22-R25, the electric capacity C430 other ends are sequentially connected resistance R20, R21, micro- by resistance R19
Potentiometer, one end of electric capacity C8 and power output end are adjusted, the other end connection resistance R20-R23's of the trimmer potentiometer is another
End, the other end and electric capacity C8 of described resistance R24, R25 are grounded.
Further, the pin of TL494 chips 5 and 6 pin outer meeting resistances and electric capacity.
Further, the pin of TL494 chips 13 connects datum.
Relative to prior art, the pulse-width modulation circuit based on TL494 chips described in the utility model has following excellent
Gesture：
Pulse-width modulation circuit based on TL494 chips described in the utility model realizes dc switch using TL494 chips
Power supply DC/DC inverter circuit pulse-width controlleds, by designing peripheral circuit, realize overvoltage protection, the excessively stream of direct-current switch power supply
Protection and output voltage range regulatory function, make circuit more simplified, improve the utilization rate of electronic devices and components, reduce power supply into
This, increased the stability and reliability of power supply, meet the safe and reliable requirement of railway power supply product.
Description of the drawings
The accompanying drawing for constituting a part of the present utility model is used for providing further understanding to of the present utility model, and this practicality is new
The schematic description and description of type is used to explain this utility model, does not constitute to improper restriction of the present utility model.
In accompanying drawing：
Fig. 1 is the overvoltage crowbar schematic diagram described in this utility model embodiment；
Fig. 2 is the current foldback circuit schematic diagram described in this utility model embodiment；
Fig. 3 is that the voltage range described in this utility model embodiment adjusts circuit theory diagrams.
Specific embodiment
It should be noted that in the case where not conflicting, the feature in embodiment and embodiment in this utility model can
To be mutually combined.
Below with reference to the accompanying drawings and in conjunction with the embodiments describing this utility model in detail.
As shown in Figures 1 to 3, a kind of pulse-width modulation circuit based on TL494 chips, including TL494 chips, described
Connect overvoltage crowbar on 3 pins of TL494 chips, be connected with current foldback circuit on 15 pins and 16 pins, 1 pin and
Connect voltage range on 2 pins and adjust circuit.
As shown in figure 1, the overvoltage crowbar includes voltage comparator U1, the voltage comparator U1 in-phase input ends
Connect resistance R2 one end and electric capacity C2, resistance R3, one end of resistance R4 respectively, inverting input connection Zener diode Q1 bears
Pole, outfan is connected to 3 pins of the TL494 chips by resistance R5, and the resistance R2 other ends connect power output end,
The 4 pins ground connection of the voltage comparator U1,8 pins are grounded by electric capacity C1, and the capacitance connection is on power supply VCC and ground
Between, the Zener diode Q1 negative poles are connected to power supply VCC by resistance R1, and the electric capacity C2, resistance R3 and resistance R4's is another
One end, Zener diode Q1 positive poles are grounded.
As shown in Fig. 2 the current foldback circuit includes voltage follower U2 and current sensor, the current sensor
One end connects power supply DC output end, and the other end is sequentially connected electric capacity C6 one end by resistance R7 and the TL494 chips 16 draw
Foot, while being grounded by resistance R6, the electric capacity C6 other ends ground connection, the power output end voltage is connected by resistance R15
It is grounded by resistance R14 to the voltage follower U2 in-phase input ends, and the voltage follower U2 in-phase input ends, it is described
Voltage follower U2 inverting inputs are connected to outfan, and outfan connection resistance R13 one end, the resistance R13 other ends connect
Connect Zener diode Q2 negative poles, and be connected to the connected end of resistance R9, R10, the Zener diode Q2 plus earths, the electricity
The resistance R10 other ends are sequentially connected one end of resistance R12, R11 and the pin of TL494 chips 15, and described resistance R12, R11 are another
End is grounded after being connected, and the resistance R9 other ends are connected to the pin of TL494 chips 13 and 14 pins, the TL494 chips
13 pins are also sequentially connected resistance R8, electric capacity C5 one end and electrochemical capacitor C4 positive poles, and the electric capacity C5's and electrochemical capacitor C4 is another
One end is grounded, and the resistance R8 is another to be connected to the pin of TL494 chips 15, and the pin of TL494 chips 12 is connect by electric capacity C3
Ground, the electric capacity C3 is connected between power supply VCC and ground.
As shown in figure 3, the voltage range adjusts circuit includes resistance R16, R17, the pin of TL494 chips 13 and 14
Pin connection is followed by resistance R16 one end, the pin of resistance R16 other ends connection TL494 chips 2 and resistance R17 one end, institute
State resistance R17 other ends ground connection, the described pin of TL494 chips 1 connection resistance R18 one end, the resistance R18 other ends connection electricity
Hold C430, one end of resistance R22-R25, the electric capacity C430 other ends are sequentially connected resistance R20, R21, micro- by resistance R19
Potentiometer, one end of electric capacity C8 and power output end are adjusted, the other end connection resistance R20-R23's of the trimmer potentiometer is another
End, the other end and electric capacity C8 of described resistance R24, R25 are grounded.
The pin of TL494 chips 5 and 6 pin outer meeting resistances and electric capacity, the frequency of oscillation of scalable pulse-width modulation circuit.
The pin of TL494 chips 13 connects datum, and output maximum duty cycle is 48%.
The present embodiment operation principle is as follows：
The pin of TL494 chips 9 and 10 pins are grounded, and 8 pins and 11 pins are pulse-width controlled outfan, be can control
DC/DC inverter circuit power tubes are opened and shut-off, export the width of pulse by the positive polarity sawtooth voltage on electric capacity with
Two control signals are compared to adjust；
The overvoltage crowbar, is that, using voltage comparator U1,2.5V reference voltage sources provide anti-phase input terminal voltage,
Collection power output end voltage, provides homophase input terminal voltage after partial pressure, be compared, if output end voltage is excessive, voltage ratio
High level is exported compared with device U1, the pin of TL494 chips 3 (feedback PWM comparator input terminals) voltage is more than 3.5V, and chip is locked, then
Without output, over-voltage protecting function is realized；
The current protecting circuit, is to utilize current sensor, gathers power supply DC output end electric current, is converted into magnitude of voltage
Pin (comparator in-phase input end in the piece) voltage of TL494 chips 16,5V benchmark electricity integrated on TL494 chips are provided after partial pressure
15 pins (comparator inverting input in piece) voltage is provided after potential source partial pressure, when collection current value it is excessive, 16 pin voltages
Value is more than 15 pin voltages, and electric power output voltage reduces.After electric power output voltage is reduced, Jing after partial pressure by the voltage on right side with
Drive 15 pin reference voltages to reduce with device U2, output current is reduced therewith, realize overcurrent protection；
The voltage range adjusts circuit, is using power supply trimmer potentiometer, 5V reference voltages integrated on TL494 chips
Pin (comparator inverting input in piece) the 2.5V voltages of TL494 chips 2 are provided after the partial pressure of source, during setting output voltage range,
Trimmer potentiometer is transferred to into minima, power output end voltage is gathered, is provided and the pin of TL494 chips 1 provide after suitable partial pressure value
(comparator in-phase input end in piece) voltage, internal comparator is compared, so that it is determined that output voltage range.
Preferred embodiment of the present utility model is the foregoing is only, it is all at this not to limit this utility model
Within the spirit and principle of utility model, any modification, equivalent substitution and improvements made etc. should be included in this utility model
Protection domain within.
Claims (6)
1. a kind of pulse-width modulation circuit based on TL494 chips, it is characterised in that：Including TL494 chips, in the TL494 cores
Connect overvoltage crowbar on 3 pins of piece, current foldback circuit is connected with 15 pins and 16 pins, on 1 pin and 2 pins
Connection voltage range adjusts circuit.
2. a kind of pulse-width modulation circuit based on TL494 chips according to claim 1, it is characterised in that：The overvoltage
Protection circuit includes voltage comparator U1, and the voltage comparator U1 in-phase input ends connect respectively resistance R2 one end and electric capacity
C2, resistance R3, one end of resistance R4, inverting input connection Zener diode Q1 negative poles, outfan is connected to by resistance R5
3 pins of the TL494 chips, the resistance R2 other ends connect power output end, and the Zener diode Q1 negative poles pass through
Resistance R1 is connected to power supply VCC, and the other end of the electric capacity C2, resistance R3 and resistance R4, Zener diode Q1 positive poles are grounded.
3. a kind of pulse-width modulation circuit based on TL494 chips according to claim 1, it is characterised in that：The excessively stream
Protection circuit includes voltage follower U2 and current sensor, and described current sensor one end connects power supply DC output end, separately
One end is connected to the pin of TL494 chips 16 by resistance R7, and the power output end voltage is connected to described by resistance R15
Voltage follower U2 in-phase input ends, the voltage follower U2 inverting inputs are connected to outfan, outfan connection resistance
R13 one end, the resistance R13 other ends connection Zener diode Q2 negative poles, and the connected end of resistance R9, R10 is connected to, it is described
Zener diode Q2 plus earths, the resistance R10 other ends are connected to the pin of TL494 chips 15, and the resistance R9 is another
One end is connected to the pin of TL494 chips 13 and 14 pins.
4. a kind of pulse-width modulation circuit based on TL494 chips according to claim 1, it is characterised in that：The voltage
Range adjusting circuit includes resistance R16, R17, and the pin of TL494 chips 13 and the connection of 14 pins are followed by resistance R16 one end,
The pin of resistance R16 other ends connection TL494 chips 2 and resistance R17 one end, the resistance R17 other ends ground connection is described
The pin of TL494 chips 1 connection resistance R18 one end, the resistance R18 other ends connection electric capacity C430, the one of resistance R22-R25
End, the electric capacity C430 other ends by resistance R19 be sequentially connected resistance R20, R21, trimmer potentiometer, one end of electric capacity C8 and
Power output end, the other end of the trimmer potentiometer connects the other end of resistance R20-R23, and described resistance R24, R25's is another
One end and electric capacity C8 are grounded.
5. a kind of pulse-width modulation circuit based on TL494 chips according to claim 1, it is characterised in that：The TL494
5 pins of chip and 6 pin outer meeting resistances and electric capacity.
6. a kind of pulse-width modulation circuit based on TL494 chips according to claim 1, it is characterised in that：The TL494
13 pins of chip connect datum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621203503.XU CN206135859U (en) | 2016-11-08 | 2016-11-08 | Pulse width modulation circuit based on TL494 chip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621203503.XU CN206135859U (en) | 2016-11-08 | 2016-11-08 | Pulse width modulation circuit based on TL494 chip |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN206135859U true CN206135859U (en) | 2017-04-26 |
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ID=58578367
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201621203503.XU Active CN206135859U (en) | 2016-11-08 | 2016-11-08 | Pulse width modulation circuit based on TL494 chip |
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| Country | Link |
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| CN (1) | CN206135859U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106571793A (en) * | 2016-11-08 | 2017-04-19 | 天津铁路信号有限责任公司 | Pulse width modulation circuit based on TL494 chip |
| CN114362567A (en) * | 2021-12-28 | 2022-04-15 | 深圳市华思旭科技有限公司 | Circuit structure, control method thereof, inverter and energy storage device |
-
2016
- 2016-11-08 CN CN201621203503.XU patent/CN206135859U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106571793A (en) * | 2016-11-08 | 2017-04-19 | 天津铁路信号有限责任公司 | Pulse width modulation circuit based on TL494 chip |
| CN106571793B (en) * | 2016-11-08 | 2023-08-25 | 天津铁路信号有限责任公司 | Pulse width modulation circuit based on TL494 chip |
| CN114362567A (en) * | 2021-12-28 | 2022-04-15 | 深圳市华思旭科技有限公司 | Circuit structure, control method thereof, inverter and energy storage device |
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