CN204376399U - Self-recovering type overvoltage crowbar - Google Patents

Abstract

The utility model relates to a kind of self-recovering type overvoltage crowbar.Input power is connected with current-limiting circuit, current-limiting circuit is connected with voltage clamping circuit, encryption circuit, N-channel MOS FET switch control circuit respectively by control circuit, N-channel MOS FET switch control circuit is connected with output filter circuit, and output filter circuit is connected with follow-up load circuit; Feature is: only need less components and parts can realize the over-voltage protecting function of DC circuit; and output voltage can be clamped within normal operating voltage range when suppressing of short duration high-voltage transient; can ensure that subsequent conditioning circuit continues normal work; do not affect by of short duration high-voltage transient; after the high pressure duration exceedes set point; output voltage zero volt can be clamped at, and after high pressure disappears, normal work can be automatically recovered.

Description

Self-recovering type overvoltage crowbar

Technical field

The utility model relates to a kind of self-recovering type overvoltage crowbar that can be applicable to DC power-supply circuit front end.

Background technology

High-voltage transient is also voltage surge, is generally to occur in microsecond even other violent pulse of Millisecond, and the reason that high pressure may be caused to suddenly change has: jumbo starts, be short-circuited, electrical source exchange or big-block engine.Overvoltage crowbar is the indispensable circuit in DC suppling equipment front end; it not only can protect subsequent conditioning circuit to exempt from the damage of high-voltage transient; also can useful life of extension device, this circuit be aim at various electronic equipment, circuit that instrument and meter, communication line provide security protection.Existing overvoltage crowbar reaction speed is slower; during startup overvoltage protection, have more high-voltage pulse impact load circuit; and after startup overvoltage protection; output voltage is in lasting off state; switch input power can only be passed through again and just can cancel overvoltage protection state; and of short duration high-voltage pulse cannot be clamped within normal operating voltage range by existing overvoltage crowbar, subsequent conditioning circuit cannot be realized and continue normal work.

Summary of the invention

In view of the deficiency that prior art exists; the utility model provides a kind of self-recovering type overvoltage crowbar; output voltage can be clamped within normal operating voltage range when suppressing of short duration high-voltage transient; normal work can be automatically recovered after high-voltage pulse disappears; and the high-voltage pulse of short time can be clamped within normal working range, make the sustainable work of equipment.

The utility model for achieving the above object, the technical scheme taked is: a kind of self-recovering type overvoltage crowbar, it is characterized in that: comprise the current-limiting circuit being limited in circuit front-end, control circuit, encryption circuit, N-channel MOS FET switch control circuit, voltage clamping circuit and output filter circuit, input power is connected with described current-limiting circuit, current-limiting circuit by control circuit respectively with voltage clamping circuit, encryption circuit, N-channel MOS FET switch control circuit connects, N-channel MOS FET switch control circuit is connected with output filter circuit, output filter circuit is connected with follow-up load circuit,

Physical circuit connects: direct current input is just being leaded up to resistance R1 and connect VDD pin and the SD pin of control chip U1, another road connects the drain D of fet M1, direct current input is born ground connection and is connect VSS pin and the BASE pin of control chip U1 by resistance R2 mono-tunnel, electric capacity C1 of separately leading up to connects the TIM pin of control chip U1, the GATE pin of control chip U1 connects the grid G of fet M1 by resistance R5, the FB pin connecting resistance R3 of control chip U1 and one end of resistance R4, the other end of resistance R3 connects the OUT pin of control chip U1 respectively, the source S of fet M1, one end of inductance L 1, one end of one termination capacitor C2 of inductance L 1 is also for direct current is just exporting, the other end ground connection of electric capacity C2, the other end ground connection of resistance R4 is also for direct current exports negative,

Feature of the present utility model is: only need less components and parts can realize the over-voltage protecting function of DC circuit; and output voltage can be clamped within normal operating voltage range when suppressing of short duration high-voltage transient; can ensure that subsequent conditioning circuit continues normal work; do not affect by of short duration high-voltage transient; after the high pressure duration exceedes set point; output voltage zero volt can be clamped at, and after high pressure disappears, normal work can be automatically recovered.

Accompanying drawing explanation

Fig. 1 is that circuit of the present utility model connects block diagram;

Fig. 2 is circuit theory diagrams of the present utility model.

Embodiment

As shown in Figure 1, 2; a kind of self-recovering type overvoltage crowbar; comprise the current-limiting circuit, control circuit, encryption circuit, N-channel MOS FET switch control circuit, voltage clamping circuit and the output filter circuit that are limited in circuit front-end; input power is connected with described current-limiting circuit; current-limiting circuit is connected with voltage clamping circuit, encryption circuit, N-channel MOS FET switch control circuit respectively by control circuit; N-channel MOS FET switch control circuit is connected with output filter circuit, and output filter circuit is connected with follow-up load circuit.

Physical circuit connects: direct current input is just being leaded up to resistance R1 and connect VDD pin and the SD pin of control chip U1, another road connects the drain D of fet M1, direct current input is born ground connection and is connect VSS pin and the BASE pin of control chip U1 by resistance R2 mono-tunnel, electric capacity C1 of separately leading up to connects the TIM pin of control chip U1, the GATE pin of control chip U1 connects the grid G of fet M1 by resistance R5, the FB pin connecting resistance R3 of control chip U1 and one end of resistance R4, the other end of resistance R3 connects the OUT pin of control chip U1 respectively, the source S of fet M1, one end of inductance L 1, one end of one termination capacitor C2 of inductance L 1 is also for direct current is just exporting, the other end ground connection of electric capacity C2, the other end ground connection of resistance R4 is also for direct current exports negative.

Operation principle: resistance R1 and input voltage form current-limiting circuit, for control chip U1 and metal-oxide-semiconductor and fet M1 provide normal operating current; Control chip U1 provides reference voltage and timing controller control signal for other circuit parts, is the core component of control circuit; Electric capacity C1 and resistance R2 forms encryption circuit, constant electric current is provided to be that electric capacity C1 charges by the TIM pin of coremaking sheet U1, the clamping time of overvoltage protection is set by the length in charging interval, when clamping time exceedes set point, then control follow-up switching circuit and turn off output, make clamping voltage be zero volt; Resistance R5 and metal-oxide-semiconductor M1 forms ON-OFF control circuit, when the Instantaneous high-pressure duration exceedes set point, control chip U1 sends pick-off signal, by the on-off action breaking circuit of metal-oxide-semiconductor M1, make output voltage clamp to zero volt, thus protect follow-up load to damage from high pressure, after long high-voltage pulse disappears, control chip U1 sends cancellation pick-off signal automatically, thus makes equipment can continue normal work; Resistance R3 and resistance R4 form voltage clamping circuit, by regulating its resistance ratio, set the volt value of clamping voltage, interim to ensure to come at instantaneous high pressure, subsequent conditioning circuit can within the scope of normal working voltage continuous firing; Inductance L 1 and electric capacity C2 form output filter circuit, for follow-up load circuit provides reliable and stable operating voltage.

The model of control chip U1 is LT4366.

Claims (1)

1. a self-recovering type overvoltage crowbar, it is characterized in that: comprise the current-limiting circuit, control circuit, encryption circuit, N-channel MOS FET switch control circuit, voltage clamping circuit and the output filter circuit that are limited in circuit front-end, input power is connected with described current-limiting circuit, current-limiting circuit is connected with voltage clamping circuit, encryption circuit, N-channel MOS FET switch control circuit respectively by control circuit, N-channel MOS FET switch control circuit is connected with output filter circuit, and output filter circuit is connected with follow-up load circuit;

Physical circuit connects: direct current input is just being leaded up to resistance R1 and connect VDD pin and the SD pin of control chip U1, another road connects the drain D of fet M1, direct current input is born ground connection and is connect VSS pin and the BASE pin of control chip U1 by resistance R2 mono-tunnel, electric capacity C1 of separately leading up to connects the TIM pin of control chip U1, the GATE pin of control chip U1 connects the grid G of fet M1 by resistance R5, the FB pin connecting resistance R3 of control chip U1 and one end of resistance R4, the other end of resistance R3 connects the OUT pin of control chip U1 respectively, the source S of fet M1, one end of inductance L 1, one end of one termination capacitor C2 of inductance L 1 is also for direct current is just exporting, the other end ground connection of electric capacity C2, the other end ground connection of resistance R4 is also for direct current exports negative.