CN212423029U - Discharging circuit and power supply circuit for booster circuit - Google Patents
Discharging circuit and power supply circuit for booster circuit Download PDFInfo
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- CN212423029U CN212423029U CN202020718304.2U CN202020718304U CN212423029U CN 212423029 U CN212423029 U CN 212423029U CN 202020718304 U CN202020718304 U CN 202020718304U CN 212423029 U CN212423029 U CN 212423029U
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Abstract
The utility model provides a discharge circuit for boost circuit, first input is used for input control signal, control signal is the same with boost circuit's enable signal, the second input is used for connecting boost circuit's output, discharge circuit is still including branch road and the control circuit that discharges, control circuit is used for putting through or breaking the branch road that discharges according to control signal, set up between second input and ground, control circuit includes first electric capacity and second controllable switch, when the second controllable switch switches on, first electric capacity is to the reverse power supply of first controllable switch's control end, make first controllable switch disconnection, block the branch road that discharges. The utility model provides a supply circuit is shaded with display screen for boost circuit's discharge circuit sets up electric capacity among the control circuit, and when the control signal who is used for enabling boost circuit was effective, electric capacity reverse discharge reduced the control terminal voltage of the first controllable switch of branch road that discharges fast for the branch road that discharges breaks off in time, avoids receiving the highly compressed influence of transient state.
Description
Technical Field
The utility model relates to an automotive filed, concretely relates to a discharge circuit and supply circuit for boost circuit.
Background
In combination instruments, display devices and head-up displays, the backlight control signal of a display screen needs to be boosted to 20-40V. A discharge circuit is usually disposed between the boost circuit and the display screen to discharge the output filter capacitor, so that the output voltage drops to a safe voltage to prevent the display screen from being damaged by the high voltage generated by the residual charge on the filter capacitor.
In vehicle-mounted equipment, such as a head-up display, after a vehicle-mounted power Vin is boosted by a boost circuit, an output voltage Vout drives a display screen backlight LED to light the display screen backlight; the discharging circuit is connected with the output end of the boosting circuit and releases residual charges on a filter capacitor (not shown); the booster circuit and the discharge circuit are controlled by a controller.
The discharge branch of the discharge circuit generally includes a discharge resistor for limiting a current of the discharge branch and a controllable switch for controlling whether to discharge.
In consideration of the requirements of miniaturization and reliability of vehicle-mounted equipment, a chip resistor is generally adopted, the rated power of the chip resistor is low, transient high voltage can appear at the moment when a booster circuit is switched on, and if a discharge branch circuit is not switched off in time, the discharge resistor can be damaged due to overcurrent due to the transient high voltage.
Disclosure of Invention
To the problem that exists among the prior art, the utility model aims to solve the problem that a discharge circuit for boost circuit is provided, sets up electric capacity among the control circuit, and when the control signal who is used for making boost circuit was effective, electric capacity reverse discharge reduced the control terminal voltage of the first controllable switch who discharges the branch road fast for the branch road that discharges breaks off in time, avoids receiving the highly compressed influence of transient state.
The utility model provides a discharge circuit for boost circuit, including first input and second input, first input is used for input control signal, control signal is the same with boost circuit's enable signal, the second input is used for connecting boost circuit's output, a discharge circuit for boost circuit still includes branch road and control circuit of discharging, control circuit is used for putting through or breaking the branch road of discharging according to control signal, the branch road of discharging is including the first resistance and the first controllable switch of series connection, set up between second input and ground, control circuit includes first electric capacity and second controllable switch, first input is connected with the control end of second controllable switch through fourth resistance, when the second controllable switch switches on, first electric capacity is to the reverse power supply of the control end of first controllable switch, make first controllable switch disconnection, block the branch road of discharging.
Further, the discharge circuit further comprises a third input terminal for connection to a first power supply for supplying power to the control circuit.
Further, when the second controllable switch is turned off, the first power supply provides bias voltage to the first controllable switch, the first controllable switch is turned on, and the discharging branch discharges the output end of the voltage boosting circuit.
Further, when the second controllable switch is turned off, the first power supply charges the first capacitor.
Furthermore, the first end of the first capacitor is connected with the control end of the first controllable switch through a second resistor, the second end of the first capacitor is connected with the third input end through a fifth resistor and is connected with the first end of the second controllable switch through a third resistor, and the second end of the second controllable switch is grounded.
Furthermore, the discharge circuit also comprises a diode, wherein the anode of the diode is connected with the ground, and the cathode of the diode is connected with the first capacitor.
Further, the first resistor is one resistor or a plurality of resistors connected in parallel.
Further, the first controllable switch is a triode, a field effect transistor, a silicon controlled rectifier or a relay.
The utility model also provides a power supply circuit, including controller, boost circuit and the above-mentioned discharge circuit who is used for boost circuit, the output of controller is connected with boost circuit's enable end, discharge circuit's first input, and boost circuit's output is connected with discharge circuit's second input.
Further, the power supply circuit is a display screen backlight power supply circuit.
Compared with the prior art, the utility model provides a discharge circuit and supply circuit for boost circuit has following beneficial effect: the capacitor is arranged in the control circuit, when a control signal for enabling the booster circuit is effective, the capacitor discharges reversely, and the control end voltage of the first controllable switch of the discharging branch circuit is reduced rapidly, so that the discharging branch circuit is disconnected in time, and the influence of transient high voltage is avoided.
Drawings
Fig. 1 is a schematic diagram of a display screen backlight power supply circuit according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a discharge circuit of the display backlight power supply circuit shown in FIG. 1;
FIG. 3 is a circuit diagram of another discharge circuit of the display backlight power supply circuit shown in FIG. 1;
fig. 4 is a circuit diagram of still another discharge circuit of the display backlight power supply circuit shown in fig. 1.
Detailed Description
As shown in fig. 1, the power supply circuit of an embodiment of the present invention is, for example, used for a backlight power supply circuit of a head-up display, and the power supply circuit includes a controller, a voltage boost circuit and a discharge circuit.
The discharge circuit comprises a first input end P1 and a second input end P2, the output end of the controller is connected with the enable end EN of the booster circuit and the first input end P1 of the discharge circuit, and the first input end P1 is used for inputting a control signal CS; the second input terminal P2 is used for connecting the output terminal of the voltage boost circuit, and the discharging circuit discharges the output terminal of the voltage boost circuit when in operation.
In this embodiment, the enable terminal EN of the boost circuit is the same as the control signal CS of the discharge circuit, and is a signal from the same output terminal of the controller. Of course in other embodiments both may be the same signal from different outputs of the controller.
The discharge circuit comprises a discharge branch circuit and a control circuit.
As shown in fig. 2, the discharging branch includes a first resistor R1 and a first controllable switch T1, and the first controllable switch T1 is used to turn on or off the discharging branch, in this embodiment, when the first controllable switch T1 is turned on, the output terminal of the voltage boost circuit discharges through the first resistor R1, and the remaining charge on the filter capacitor (not shown) is released.
In this embodiment, the first controllable switch T1 is an NPN transistor. In other embodiments, the first controllable switch may be another type of transistor, such as a PNP transistor, a fet, a thyristor, or a relay.
The control circuit is used for controlling the on/off of the first controllable switch T1 according to a control signal CS, and includes a first capacitor C1, a second controllable switch T2 and a related resistor.
The discharge circuit further comprises a third input terminal P3 for connection to a first power supply VCC for supplying power to the control circuit.
A first terminal of the first capacitor C1 is connected to the control terminal of the first controllable switch T1 through a second resistor R2, a second terminal is connected to the third input terminal P3 through a fifth resistor R5, and is connected to the first terminal (collector) of the second controllable switch T2 through a third resistor R3, and a second terminal (emitter) of the second controllable switch T2 is grounded.
The connection point of the second resistor R2 and the sixth resistor R6 provides a control voltage for the control terminal of the first controllable switch T1.
The control terminal of the second controllable switch T2 is connected to the first input terminal P1 through the fourth resistor R4, and the control signal CS inputted from the first input terminal P1 controls the on/off of the second controllable switch T2.
In this embodiment, the second controllable switch T2 is an NPN transistor. In other embodiments, the second controllable switch may be another type of transistor, such as a PNP transistor, a fet, a thyristor, or a relay.
When the second controllable switch T2 is turned off, the first power VCC supplies a control voltage to the first controllable switch T1 and charges the first capacitor C1, the first controllable switch turns on the T1, and the discharging branch discharges the output terminal of the voltage boost circuit.
When the second controllable switch T2 is turned on, the first capacitor C1 supplies power to the control terminal of the first controllable switch T1 in the reverse direction, so that the first controllable switch T1 is quickly turned off to block the discharging branch.
The enable end EN of the booster circuit is effective, the booster circuit starts to output Vout, and transient high voltage appears at the moment of switching on. Because enable end EN of the boost circuit is the same signal with control signal CS of the discharge circuit, make the branch circuit of discharging break off fast, in time, avoid the first resistance R1 of transient state high pressure damage, in addition when the boost circuit normally outputs, the disconnection of first controllable switch T1 can not produce extra consumption.
Specifically, when the head-up display is powered on, the first power source VCC supplies power to the control circuit, and at this time, the signal at the output end of the controller is invalid.
The first power VCC charges the first capacitor C1, the connection point of the second resistor R2 and the sixth resistor R6 provides a control voltage for the control terminal of the first controllable switch T1, the first controllable switch T1 is turned on, and the node P2 to be discharged at the output terminal of the voltage boost circuit is discharged through the first resistor R1, that is, the residual charge on the filter capacitor (not shown) is released.
When the signal of the output end of the controller is effective, namely, the enable signal EN of the boost circuit and the control signal CS of the discharge circuit are both effective (high level), the boost circuit starts to output Vout, the high level of the control signal CS enables the second controllable switch T2 to be turned on, the first capacitor C1 supplies power to the control end of the first controllable switch T1 in the reverse direction (i.e., along the direction shown by the dotted line), the voltage of the connection point of the second resistor R2 and the sixth resistor R6 is rapidly reduced, so that the first controllable switch T1 is rapidly turned off, the discharge branch is blocked, the first resistor R1 is prevented from being damaged by transient high voltage, and extra power consumption generated when the boost circuit normally outputs is also avoided.
As shown in fig. 3, another discharging circuit of the display panel backlight power supply circuit includes a diode D1, wherein an anode of the diode D1 is connected to ground, and a cathode of the diode D1 is connected to the first capacitor C1.
When the second controllable switch T2 is turned on, the first capacitor C1 supplies power to the control end of the first controllable switch T1 in the reverse direction, the diode D1 is turned on, and the voltage at the connection point of the second resistor R2 and the sixth resistor R6 decreases more rapidly, so that the first controllable switch T1 is turned off rapidly, and the discharge branch is blocked.
As shown in fig. 4, in another discharge circuit of the display panel backlight power supply circuit, the first resistor is a plurality of resistors R11 and R12 connected in parallel, and by connecting in parallel, the current passing through each resistor can be reduced, and the first resistor is prevented from being damaged due to overcurrent.
Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited thereto. Various changes and modifications can be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention is to be determined by the appended claims.
Claims (10)
1. A discharge circuit for a booster circuit, the discharge circuit comprising a first input terminal for inputting a control signal, the control signal being the same as an enable signal of the booster circuit, and a second input terminal for connecting to an output terminal of the booster circuit, the discharging circuit for the booster circuit further comprises a discharging branch circuit and a control circuit, the control circuit is used for switching on or switching off the discharging branch circuit according to a control signal, the discharging branch circuit comprises a first resistor and a first controllable switch which are connected in series and arranged between the second input end and the ground, the control circuit comprises a first capacitor and a second controllable switch, the first input end is connected with the control end of the second controllable switch through a fourth resistor, when the second controllable switch is switched on, the first capacitor supplies power to the control end of the first controllable switch in a reverse direction, so that the first controllable switch is disconnected, and the discharging branch is blocked.
2. The discharge circuit for a boost circuit of claim 1, wherein the discharge circuit further comprises a third input for connection to a first power supply, the first power supply for supplying power to the control circuit.
3. The discharge circuit for a boost circuit of claim 1, wherein when the second controllable switch is off, the first power supply provides a bias voltage to the first controllable switch, the first controllable switch is on, and the discharge branch discharges the output of the boost circuit.
4. A discharge circuit for a boost circuit according to claim 3, in which the first power supply charges the first capacitor when the second controllable switch is open.
5. The discharge circuit for a booster circuit as claimed in claim 2, wherein the first terminal of the first capacitor is connected to the control terminal of the first controllable switch through a second resistor, the second terminal is connected to the third input terminal through a fifth resistor, and is connected to the first terminal of the second controllable switch through a third resistor, and the second terminal of the second controllable switch is grounded.
6. The discharge circuit for a booster circuit of claim 1, wherein the discharge circuit further comprises a diode, an anode of the diode being connected to ground and a cathode of the diode being connected to the first capacitor.
7. The discharge circuit for a booster circuit as claimed in claim 1, wherein the first resistor is one resistor or a plurality of resistors connected in parallel.
8. The discharge circuit for a boost circuit according to claim 1, wherein the first controllable switch is a triode, a field effect transistor, a thyristor or a relay.
9. A power supply circuit, characterized in that, the power supply circuit comprises a controller, a boost circuit and a discharge circuit for the boost circuit of any one of claims 1 to 8, the output terminal of the controller is connected with the enable terminal of the boost circuit and the first input terminal of the discharge circuit, and the output of the boost circuit is connected with the second input terminal of the discharge circuit.
10. The power supply circuit of claim 9 wherein the power supply circuit is a display screen backlight power supply circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020718304.2U CN212423029U (en) | 2020-04-30 | 2020-04-30 | Discharging circuit and power supply circuit for booster circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020718304.2U CN212423029U (en) | 2020-04-30 | 2020-04-30 | Discharging circuit and power supply circuit for booster circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212423029U true CN212423029U (en) | 2021-01-29 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020718304.2U Active CN212423029U (en) | 2020-04-30 | 2020-04-30 | Discharging circuit and power supply circuit for booster circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212423029U (en) |
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2020
- 2020-04-30 CN CN202020718304.2U patent/CN212423029U/en active Active
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