CN204441850U - A kind of stagnant ring current foldback circuit based on GJB181 surge suppressor - Google Patents

Abstract

The utility model relates to the field of electronic engineering, and proposes a hysteresis loop overcurrent protection circuit based on a GJB181 surge suppressor. The circuit has a simple structure and can effectively shut down the output of the GJB181 surge suppressor in the event of an overcurrent to protect the subsequent circuit as required, and can restore the normal output after the overcurrent fault is removed, and can also conveniently control the overcurrent time and overcurrent detection period. The technical solution adopted by the utility model is, a hysteresis loop overcurrent protection circuit based on GJB181 surge suppressor, including: hysteresis loop overcurrent time control/overcurrent detection action cycle setting circuit and GJB181 surge suppressor output control circuit .

Description

A hysteresis overcurrent protection circuit based on GJB181 surge suppressor

technical field

The utility model relates to the field of electronic engineering, in particular to an overcurrent protection circuit applied in the field of aviation airborne equipment.

Background technique

According to the standard "GJB181 Aircraft Power Supply Characteristics and Requirements for Electrical Equipment", airborne equipment should be able to withstand a maximum surge input voltage of 80V/50ms. In this context, surge voltage suppressors are widely used in the field of aviation. Among them, the GJB181 surge suppressor based on the principle of making the MOSFET work in the linear region to suppress the output voltage when the input surge voltage occurs is widely used.

Accompanying drawing 1 shows the recoverable overcurrent protection circuit used in traditional airborne equipment, the overcurrent judgment is carried out through the current detection in the circuit, under the action of the control circuit, the power switch tube is controlled by the power switch drive circuit (such as an external MOSFET ) to protect and cut off the input power.

Accompanying drawing 2 is the circuit of the utility model, by controlling the gate pole of the power MOSFET in the GJB181 surge suppressor, the purpose of the hysteresis loop overcurrent protection is achieved, and one less power switching device (such as the power MOSFET ), through the application of the hysteretic loop overcurrent time control/overcurrent detection action cycle setting circuit, the hysteretic loop overcurrent protection circuit based on the GJB181 surge suppressor is more efficient than the recoverable overcurrent protection circuit used in traditional airborne equipment. For simplicity, reliability, flexibility and economy.

Contents of the invention

The purpose of this utility model is to propose a hysteresis loop overcurrent protection circuit based on the GJB181 surge suppressor, which provides the function of overcurrent protection for airborne equipment.

The technical solution adopted by the utility model is, a hysteresis loop overcurrent protection circuit based on GJB181 surge suppressor, including: hysteresis loop overcurrent time control/overcurrent detection action cycle setting circuit and GJB181 surge suppressor output control circuit ,in,

Hysteresis overcurrent time control/overcurrent detection action period setting circuit, used to adjust the overcurrent duration and overcurrent detection action period;

The GJB181 surge suppressor output control circuit is a power tube drive circuit for the power MOSFET used in the specific GJB181 surge suppressor, which is used to control the opening and closing of the surge suppressor;

Hysteresis overcurrent time control/overcurrent detection action period setting circuit, including: voltage comparator, first resistor (R1), second resistor (R2), diode (D1) and capacitor (C1), voltage comparator (including But not limited to LM139) The positive terminal of the input comparison voltage is connected to the current detection voltage; the negative terminal of the input comparison voltage of the voltage comparator is connected to the overcurrent reference voltage; the power supply VCC terminal of the voltage comparator is connected to the positive power supply VCC; the VEE terminal of the voltage comparator power supply is grounded; the first The upper end of the resistor (R1) is connected to the VCC power supply; the lower end of the first resistor (R1) is respectively connected to the left end of the second resistor (R2), the output end of the comparator and the cathode of the diode (D1); the anode of the diode (D1) is respectively connected to The right end of the second resistor (R2) and the upper end of the capacitor (C1); the lower end of the capacitor (C1) is grounded.

When the level output by the overcurrent detection circuit is turned from low to high, the first resistor, diode and capacitor form a charging network, and the time constant is the resistance value of the first resistor multiplied by the capacitance value of the capacitor; the output level of the overcurrent detection circuit is at When switching from high to low, the second resistor and capacitor form a discharge network, and the time constant is the resistance value of the second resistor multiplied by the capacitance value of the capacitor.

The utility model has the advantages and beneficial effects: no additional power MOSFET is used, but the overcurrent protection is carried out by controlling the output of the GJB181 surge suppressor; The resistance value can be easily adjusted arbitrarily respectively.

The practice of various power supplies proves that the invention can be applied to power supply circuits of various airborne equipment, and provides the function of overcurrent protection for the airborne equipment.

Description of drawings

Fig. 1 is a schematic block diagram of a recoverable overcurrent protection circuit used in traditional airborne equipment.

Fig. 2 is a schematic block diagram of a hysteresis loop overcurrent protection circuit based on a GJB181 surge suppressor of the present invention.

FIG. 3 is a schematic diagram of a hysteresis loop overcurrent time control/overcurrent detection action cycle setting circuit included in the present invention.

Detailed ways

The utility model provides a hysteresis loop overcurrent protection circuit based on a GJB181 surge suppressor, which provides the function of overcurrent protection for airborne equipment.

The technical solution adopted by the utility model is, a hysteresis loop overcurrent protection circuit based on GJB181 surge suppressor, including: overcurrent detection circuit, hysteresis loop overcurrent time control/overcurrent detection action cycle setting circuit, GJB181 surge suppressor output control circuit.

A hysteretic loop overcurrent protection circuit based on GJB181 surge suppressor, which does not need to use additional power switching devices (including but not limited to MOSFET).

A hysteresis loop overcurrent protection circuit based on GJB181 surge suppressor, in which the hysteresis loop overcurrent time control/overcurrent detection action cycle setting circuit, the belonging circuit includes as shown in Figure 3:

Voltage comparator (including but not limited to LM139) input comparison voltage positive terminal connected to current detection voltage; voltage comparator input comparison voltage negative terminal connected to overcurrent reference voltage; voltage comparator power supply VCC terminal connected to positive power supply VCC; voltage comparator power supply VEE The terminal is grounded; the upper terminal of the first resistor (R1) is connected to the VCC power supply; the lower terminal of the first resistor (R1) is respectively connected to the left terminal of the second resistor (R2), the output terminal of the comparator and the cathode of the diode (D1); the diode (D1) The anode of the anode is respectively connected to the right end of the second resistor (R2) and the upper end of the capacitor (C1); the lower end of the capacitor (C1) is grounded.

When the comparator output turns from low to open collector, resistor R1 (for example, 5.1Kohm), diode D1 (for example, 1N4148) and capacitor C1 (for example, 0.1uF) form a charging network, and the time constant T1 is the resistance value of resistor R1 multiplied by 5.1K The capacitance of capacitor C1 is 0.1u; when the output of the comparator turns from open collector to low, the resistor R2 (510Kohm) and capacitor C1 (0.1uF) form a discharge network, and the time constant T2 is the resistance value of resistor R2 510K multiplied by capacitor C1 Capacitance 0.1u.

work process:

As shown in Figure 2, the current in the line passes through a current sensing device, typically a series resistor or current sensor element in practical applications, to generate a current sensing voltage. Voltage comparator (including but not limited to LM139) input comparison voltage positive terminal connected to current detection voltage; voltage comparator input comparison voltage negative terminal connected to overcurrent reference voltage; voltage comparator power supply VCC terminal connected to positive power supply VCC; voltage comparator power supply VEE end grounded. Wherein the overcurrent reference voltage is usually generated by a voltage reference device. When an overcurrent occurs in the line and the current detection voltage exceeds the overcurrent reference voltage, the output collector of the voltage comparator is open circuited, and the shutdown command level of the surge suppressor is changed from low (invalid) through the RCD network composed of R1, D1, and C1. To high (active) charging, the charging time constant is R1*C1. Finally, a shutdown command is given, and the surge suppressor is cut off through the GJB181 surge suppressor output control circuit in Figure 2, so as to achieve the purpose of cutting off the circuit and limiting the current; at the same time, the overcurrent time can be conveniently controlled by adjusting R1.

When the output of the GJB181 surge suppressor is cut off and the current detection level is lower than the overcurrent reference voltage, the voltage comparator outputs the ground level, the capacitor C1 is discharged through R2, and the shutdown command level of the surge suppressor is formed by R2 and C1 The RC network discharges from high (effective) to low (ineffective), and the discharge time constant is R2*C1. During the discharge process, the surge suppressor is cut off by the GJB181 surge suppressor output control circuit in Figure 2 to achieve the function of generating an overcurrent protection cycle, which can be easily set by adjusting R1.

When C1 finishes discharging, the circuit will automatically perform a new cycle of overcurrent detection. If the current fault is removed, the GJB surge suppressor will resume normal output. Otherwise, the GJB surge suppressor will shut down and enter the aforementioned overcurrent protection state.

The GJB181 surge suppressor output control circuit is a drive circuit for the power MOSFET used in a specific GJB181 surge suppressor, usually including a drive circuit with a totem pole output structure and a drive current limiting resistor.

To sum up, the utility model has the advantages and beneficial effects: overcurrent protection is performed by controlling the output of the GJB181 surge suppressor without additional use of power MOSFETs; The resistance values of R1 and R2 are conveniently adjusted arbitrarily.

Claims (1)

1. based on a stagnant ring current foldback circuit for GJB181 surge suppressor, comprising: stagnant ring overcurrent time controling/over-current detection action cycle arranges circuit and GJB181 surge suppressor output control circuit, wherein,

Stagnant ring overcurrent time controling/over-current detection action cycle arranges circuit, for adjusted current duration and over-current detection action cycle;

GJB181 surge suppressor output control circuit be one in specific GJB181 surge suppressor adopt the power tube drive circuit of power MOSFET, for controlling turning on and off of surge suppressor;

Stagnant ring overcurrent time controling/over-current detection action cycle arranges circuit, comprise: voltage comparator, the first resistance (R1), the second resistance (R2), diode (D1) and electric capacity (C1), the positive termination current detection voltage of voltage comparator input comparative voltage; Voltage comparator input comparative voltage negative terminal takes over current reference voltage; Voltage comparator is powered VCC termination positive supply VCC; Voltage comparator power VEE hold ground connection; The upper termination VCC power supply of the first resistance (R1); The lower end of the first resistance (R1) receives the negative electrode of the second resistance (R2) left end, comparator output terminal and diode (D1) respectively; The anode of diode (D1) receives the second resistance (R2) right-hand member and electric capacity (C1) upper end respectively; Electric capacity (C1) lower end ground connection.