CN215256934U - PWM driving fan speed regulating circuit of switch power supply - Google Patents
PWM driving fan speed regulating circuit of switch power supply Download PDFInfo
- Publication number
- CN215256934U CN215256934U CN202121335316.8U CN202121335316U CN215256934U CN 215256934 U CN215256934 U CN 215256934U CN 202121335316 U CN202121335316 U CN 202121335316U CN 215256934 U CN215256934 U CN 215256934U
- Authority
- CN
- China
- Prior art keywords
- resistor
- power supply
- pole
- voltage comparator
- thermistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Dc-Dc Converters (AREA)
Abstract
The embodiment of the utility model discloses switching power supply's PWM drive fan speed governing circuit, including the fan, triode Q2, triode Q3, switch diode D4, voltage comparator A, voltage comparator B, resistance R1, resistance R2, resistance R3, resistance R4, resistance R10, resistance R11, resistance R12, resistance R14, resistance R15, thermistor R28 and thermistor R13, wherein, switch diode D4 is SOT23 encapsulation; the thermistor R28 is connected with the negative input end of the power supply voltage and voltage comparator A; the thermistor R13 is connected with a power supply voltage and voltage comparator B; the output end is connected with a switch diode D4; the switch diode D4 is connected with the triode Q3 and the PWM signal end; the D pole of the triode Q2 is connected with the fan, the S pole is connected with the negative power supply end of the fan, and the G pole is connected with the negative pole of the switch diode D4; the S-pole of the transistor Q3 is connected to the S-pole of the transistor Q2. The utility model has the advantages of simple structure, peripheral circuit is few, and is with low costs, has reduced the loss of circuit.
Description
Technical Field
The utility model relates to a power technology field especially relates to a switching power supply's PWM drive fan speed governing circuit.
Background
The fan speed regulating circuit of the traditional heat radiating system of the switching power supply changes the rotating speed of a fan through a linear voltage stabilizing circuit, and partial energy is directly consumed on a triode body. Therefore, the efficiency of the switching power supply is affected.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a technical problem who solves lies in, provides a switching power supply's PWM drive fan speed governing circuit to solve triode power consumption problem.
In order to solve the above technical problem, an embodiment of the present invention provides a speed regulation circuit for a PWM-driven fan of a switching power supply, including a fan, further including a transistor Q2, a transistor Q3, a switching diode D4, a voltage comparator a, a voltage comparator B, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R10, a resistor R11, a resistor R12, a resistor R14, a resistor R15, a thermistor R28 for detecting an internal ambient temperature of the switching power supply, and a thermistor R13 for detecting a temperature of a power transistor of the switching power supply,
wherein, the switch diode D4 is packaged by SOT 23; one end of the thermistor R28 is connected with a power supply voltage, and the other end of the thermistor R28 is connected with the negative input end of the voltage comparator A through a resistor R1; the positive input end of the voltage comparator A is respectively connected with the power supply voltage and the ground through a resistor R3 and a resistor R4, the negative input end of the voltage comparator A is connected with the ground through a resistor R2, and the output end of the voltage comparator A is connected with the G pole of a triode Q3;
one end of the thermistor R13 is connected with a power supply voltage, and the other end of the thermistor R13 is connected with the positive input end of the voltage comparator B through a resistor R11; the positive input end of the voltage comparator B is grounded through a resistor R12, the negative input end of the voltage comparator B is respectively connected with the power supply voltage and the ground through a resistor R14 and a resistor R15, and the output end of the voltage comparator B is connected with the anode of a switch diode D4; the other anode of the switching diode D4 is connected with the D pole of the triode Q3 and connected with the PWM signal end of the switching power supply through a resistor R10;
the D pole of the triode Q2 is connected with the fan, the S pole is connected with the negative power supply end of the fan, and the G pole is connected with the negative pole of the switch diode D4; the S-pole of the transistor Q3 is connected to the S-pole of the transistor Q2.
Furthermore, the circuit also comprises a resistor R8 and a resistor R9, wherein two ends of the resistor R8 are respectively connected with the S pole and the G pole of the triode Q2, and two ends of the resistor R9 are respectively connected with the S pole and the G pole of the triode Q3.
Furthermore, the device also comprises a capacitor C5, wherein one end of the capacitor C5 is grounded, and the other end is connected with a power supply voltage.
Further, the fan power supply device further comprises a diode D1 connected with the fan in parallel, wherein the anode of the diode D1 is connected with the D pole of the triode Q2, and the cathode of the diode D1 is connected with the positive power supply end of the fan.
Furthermore, the circuit also comprises a capacitor C6, and the two ends of the capacitor C6 are respectively connected with the D pole and the S pole of the triode Q2.
The utility model has the advantages that: the utility model has the advantages of simple structure, peripheral circuit is few, and is with low costs, has reduced the loss of circuit.
Drawings
Fig. 1 is a circuit diagram of a conventional fan speed control circuit.
Fig. 2 is a signal diagram of a PWM driving transformer of a switching power supply according to an embodiment of the present invention.
Fig. 3 is a circuit diagram of a PWM-driven fan speed regulation circuit of a switching power supply according to an embodiment of the present invention.
Detailed Description
It should be noted that, in the present application, the embodiments and features of the embodiments may be combined with each other without conflict, and the present invention is further described in detail with reference to the accompanying drawings and specific embodiments.
Referring to fig. 3, the PWM driving fan speed regulation circuit of the switching power supply of the embodiment of the present invention includes a fan, a transistor Q2, a transistor Q3, a switching diode D4, a voltage comparator a, a voltage comparator B, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R10, a resistor R11, a resistor R12, a resistor R14, a resistor R15, a thermistor R28, and a thermistor R13.
The thermistor R28 is used for detecting the internal environment temperature of the switching power supply, and the thermistor R28 is used for detecting the internal environment temperature of the switching power supply; the thermistor R13 is used to detect the power transistor temperature of the switching power supply. The switching diode D4 is a SOT23 package. One end of the thermistor R28 is connected with a power supply voltage, and the other end of the thermistor R28 is connected with the negative input end of the voltage comparator A through a resistor R1; the positive input end of the voltage comparator A is respectively connected with a power supply voltage (namely VCC) and ground through a resistor R3 and a resistor R4, the negative input end of the voltage comparator A is grounded through a resistor R2, and the output end of the voltage comparator A is connected with the G pole of the triode Q3. Transistor Q3 and transistor Q2 are MOSFETs.
One end of the thermistor R13 is connected with a power supply voltage, and the other end of the thermistor R13 is connected with the positive input end of the voltage comparator B through a resistor R11; the positive input end of the voltage comparator B is grounded through a resistor R12, the negative input end of the voltage comparator B is respectively connected with the power supply voltage and the ground through a resistor R14 and a resistor R15, and the output end of the voltage comparator B is connected with the anode of a switch diode D4; the other positive pole of the switching diode D4 is connected to the D pole of the transistor Q3 and to the PWM signal terminal of the switching power supply through the resistor R10. SR _ PWM drive signal as shown in fig. 2, the SR _ PWM drive signal passes through R10, the switching diode D4 is directly turned on with Vgs of Q2 (MOSFET), and the fan speed is controlled by controlling the turn-on time of Vgs of Q2, i.e. controlling the SR _ PWM duty cycle to the turn-on time of Q2.
When the switching power supply is in light load, the SR _ PWM duty ratio is small, the Q2 conduction time is short, and the fan rotating speed is slow;
when the switching power supply is under heavy load, the SR _ PWM duty ratio is large, the conduction time of Q2 is long, and the rotating speed of the fan is high;
when the internal environment temperature of the switching power supply is lower than 25 ℃, the fan stops working;
the fan operates at full speed when the switching power supply power transistor is above 73 c.
The D pole of the triode Q2 is connected with the fan, the S pole is connected with the negative power supply end of the fan, and the G pole is connected with the negative pole of the switch diode D4; the S-pole of the transistor Q3 is connected to the S-pole of the transistor Q2. The switching diode D4 prevents voltage from flowing backwards.
As an implementation manner, the PWM-driven fan speed regulation circuit of the switching power supply further includes a resistor R8 and a resistor R9, two ends of the resistor R8 are respectively connected to the S pole and the G pole of the transistor Q2, and two ends of the resistor R9 are respectively connected to the S pole and the G pole of the transistor Q3. The resistor R8 and the resistor R9 are used for electrostatic protection and protecting the triode Q3 and the triode Q2.
In one embodiment, the PWM-driven fan speed regulation circuit of the switching power supply further includes a capacitor C5, one end of the capacitor C5 is grounded, and the other end is connected to the power supply voltage. C5 filters the VCC for U4 (LM 2904).
In one embodiment, the PWM-driven fan speed regulation circuit of the switching power supply further includes a diode D1 connected in parallel with the fan, wherein an anode of the diode D1 is connected to a D pole of the transistor Q2, and a cathode of the diode is connected to a positive power supply terminal of the fan. Diode D1 is used to protect transistor Q2.
In one embodiment, the PWM-driven fan speed regulation circuit of the switching power supply further includes a capacitor C6, and two ends of the capacitor C6 are respectively connected to the D pole and the S pole of the transistor Q2. Capacitor C6 is used to protect transistor Q2.
Example 1, as shown in fig. 3, the voltage comparator a and the voltage comparator B may directly adopt a dual operational amplifier U4, the model may be LM2904, the LM2904 internally includes two independent dual operational amplifiers with high gain and internal frequency compensation, and the dual operational amplifier is suitable for a single power supply with a wide power supply voltage range and is also suitable for a dual power supply operation mode.
The utility model discloses a theory of operation does: after the power supply is started, firstly, PIN2 and PIN3 of U4 (LM 2904) are compared, if the internal ambient temperature of the power supply is higher than 25 ℃ (the resistance of thermistor R28 is smaller than 10K Ω at this time), VCC voltage is compared with the detection level of PIN2 of U4 (LM 2904) after R28 (thermistor) and R1, R2 are divided, and the level of PIN3 of U4 (LM 2904) after VCC voltage is divided by R3 and R4, at this time, PIN2 of U4 (LM 2904) is higher than the level of PIN3 of U4 (LM 2904). Therefore, U4 (LM 2904) PIN1 goes low, Q3 is cut off, and Q2 is controlled by SR _ PWM to regulate speed.
Conversely, the U4 (LM 2904) PIN1 outputs a high level, at which time Q3 turns on forcing Vgs of Q2 low turning Q2 off (open state). The fan will not operate.
When the temperature of a power transistor in the power supply is higher than 73 ℃ (the resistance of a thermistor R13 is less than 2K omega), VCC is divided by R13, R11 and R12, and then the level is detected on U4 (LM 2904) PIN 5; the other VCC is divided by R14 and R15, and the level is detected on U4 (LM 2904) PIN 6. At this time, the level at the PIN5 of U4 (LM 2904) is higher than the level at the PIN6 of U4 (LM 2904), so that the PIN7 of U4 (LM 2904) outputs a constant high level, which is directly connected to Vgs of Q2 through D4, so that Q2 is always in a saturated conduction state, and as a result, the fan is in a full speed operation state.
Conversely, PIN7 of U4 (LM 2904) outputs low, and Q2 is controlled only by PIN1 of U4 (LM 2904) and SR _ PWM.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. A PWM driving fan speed regulation circuit of a switching power supply comprises a fan and is characterized by further comprising a triode Q2, a triode Q3, a switching diode D4, a voltage comparator A, a voltage comparator B, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R10, a resistor R11, a resistor R12, a resistor R14, a resistor R15, a thermistor R28 for detecting the internal environment temperature of the switching power supply and a thermistor R13 for detecting the temperature of a power transistor of the switching power supply,
wherein, the switch diode D4 is packaged by SOT 23; one end of the thermistor R28 is connected with a power supply voltage, and the other end of the thermistor R28 is connected with the negative input end of the voltage comparator A through a resistor R1; the positive input end of the voltage comparator A is respectively connected with the power supply voltage and the ground through a resistor R3 and a resistor R4, the negative input end of the voltage comparator A is connected with the ground through a resistor R2, and the output end of the voltage comparator A is connected with the G pole of a triode Q3;
one end of the thermistor R13 is connected with a power supply voltage, and the other end of the thermistor R13 is connected with the positive input end of the voltage comparator B through a resistor R11; the positive input end of the voltage comparator B is grounded through a resistor R12, the negative input end of the voltage comparator B is respectively connected with the power supply voltage and the ground through a resistor R14 and a resistor R15, and the output end of the voltage comparator B is connected with the anode of a switch diode D4; the other anode of the switching diode D4 is connected with the D pole of the triode Q3 and connected with the PWM signal end of the switching power supply through a resistor R10;
the D pole of the triode Q2 is connected with the fan, the S pole is connected with the negative power supply end of the fan, and the G pole is connected with the negative pole of the switch diode D4; the S-pole of the transistor Q3 is connected to the S-pole of the transistor Q2.
2. The PWM-driven fan speed regulation circuit of a switching power supply according to claim 1, further comprising a resistor R8 and a resistor R9, wherein two ends of the resistor R8 are respectively connected to an S pole and a G pole of the transistor Q2, and two ends of the resistor R9 are respectively connected to an S pole and a G pole of the transistor Q3.
3. The PWM driven fan speed regulation circuit of a switching power supply according to claim 1, further comprising a capacitor C5, wherein one end of the capacitor C5 is grounded and the other end is connected to a supply voltage.
4. The PWM driven fan speed regulation circuit of claim 1 further comprising a diode D1 connected in parallel with the fan, wherein the diode D1 has an anode connected to the D of the transistor Q2 and a cathode connected to the positive supply terminal of the fan.
5. The PWM-driven fan speed regulation circuit of a switching power supply according to claim 1, further comprising a capacitor C6, wherein the two terminals of the capacitor C6 are connected to the D pole and the S pole of the transistor Q2, respectively.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121335316.8U CN215256934U (en) | 2021-06-16 | 2021-06-16 | PWM driving fan speed regulating circuit of switch power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121335316.8U CN215256934U (en) | 2021-06-16 | 2021-06-16 | PWM driving fan speed regulating circuit of switch power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN215256934U true CN215256934U (en) | 2021-12-21 |
Family
ID=79479838
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202121335316.8U Active CN215256934U (en) | 2021-06-16 | 2021-06-16 | PWM driving fan speed regulating circuit of switch power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN215256934U (en) |
-
2021
- 2021-06-16 CN CN202121335316.8U patent/CN215256934U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11431242B2 (en) | Oscillation control circuit for ultrasonic atomization sheet and ultrasonic electronic cigarette | |
| US8198838B2 (en) | Circuit for controlling rotation speed of computer fan | |
| US9553576B2 (en) | Driving circuit for IGBT module | |
| CN105991005B (en) | Intelligent power module integrated circuit and household electrical appliance | |
| CN110635669A (en) | High-voltage MOSFET switch driving and protecting circuit | |
| CN204423290U (en) | A kind of system closedown automatic heat radiation circuit, heat abstractor and electronic equipment | |
| CN215256934U (en) | PWM driving fan speed regulating circuit of switch power supply | |
| CN105822578A (en) | Multi-mode fan control circuit, cooling device and electronic equipment | |
| CN104754800B (en) | A kind of control device of LED modules inrush current | |
| CN210899112U (en) | Electronic switch circuit with low power consumption | |
| US20120092061A1 (en) | Fan control system | |
| CN102403896B (en) | Self excited Boost converter based on MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) | |
| CN204419661U (en) | A kind of multi-mode fan control circuitry, sink and electronic equipment | |
| CN109185212B (en) | Speed regulating circuit of direct current fan | |
| CN101956724A (en) | Fan drive device and fan system | |
| CN203775499U (en) | LED (light-emitting diode) pulse drive circuit | |
| CN102510216B (en) | MOSFET-based auto-excitation type Cuk converter | |
| CN109545178A (en) | A kind of double control buzzer drive circuit | |
| CN105140997A (en) | Intelligent lamp charger of intelligent traffic system | |
| CN105822585B (en) | A kind of multi-mode fan control circuitry, heat abstractor and electronic equipment being delayed | |
| CN204517641U (en) | Intelligent Power Module integrated circuit and comprise the household electrical appliance of this Intelligent Power Module integrated circuit | |
| CN211349131U (en) | Reference voltage temperature control heat dissipation circuit | |
| CN206442293U (en) | Improve underloading mode of operation EMC drive circuit | |
| US8093850B2 (en) | Fan control system | |
| CN204419662U (en) | A kind of can the multi-mode fan control circuitry of time delay, sink and electronic equipment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |