Utility model content
Based on this, it is necessary in view of the above-mentioned problems, providing a kind of constant current protection regulated power supply.
A kind of constant current protection regulated power supply, comprising:
Voltage detection unit is converted into DC voltage for realizing alternating current, and realizes that voltage stabilization exports;
Constant current chip is used for current constant control;
Secondary coil feedback unit, for charging for constant current chip;
DC output unit, for voltage conversion and direct current output;
The voltage detection unit, constant current chip and secondary coil feedback unit are sequentially connected electrically, the direct current output list
It is first to be connect with the constant current chip output end.
The CS pin of the constant current chip connects resistance R3 in one of the embodiments, and the resistance R3 ground connection is described
R3 resistance is sampling resistor, and sampling resistor R3 is for realizing open-circuit-protection
The ST pin of the constant current chip connects with the start-up resistor R4, capacitor C3 respectively in one of the embodiments,
It connects, the start-up resistor R4 connects with the capacitor C3, and the other end ground connection of capacitor C3.
The OUT pin of the constant current chip passes through field-effect tube and the direct current output list in one of the embodiments,
Member connection, the on-off of the field-effect tube realize the on-off of capacitor C3 charging circuit.
It in one of the embodiments, further include RCD absorbing circuit, the RCD absorbing circuit is described for inhibiting surge
The input terminal of the DC output unit RCD absorbing circuit in parallel.
The outer connecting resistance R5 of the FB pin of the constant current chip in one of the embodiments, resistance R5 other end ground connection are right
Constant current chip carries out earthing short circuit protection.
The FB pin of the constant current chip and the secondary coil feedback unit pass through resistance R6 in one of the embodiments,
Connection.
The COMP pin of the constant current chip connects capacitor C2 in one of the embodiments, and another pin of capacitor C2 connects
Ground, for pressing compensation.
Regulated power supply is protected in above-mentioned constant current, including the voltage detection unit, constant current chip, secondary coil feedback unit and
DC output unit, the voltage detection unit, constant current chip and secondary coil feedback unit are sequentially connected electrically, and the direct current is defeated
Unit is connect with the constant current chip output end out, and the constant current protection regulated power supply uses the height with active power factor correction
Precision primary side feedback constant current chip is electric in inductance due to working, it can be achieved that very high power factor and very low total harmonic distortion
Critical continuous conduction mode is flowed, constant current protects regulated power supply loss to reduce, and utilization rate is high, circuit stability.
Specific embodiment
In order to make the purpose of the utility model, technical solutions and advantages more clearly understood, below in conjunction with attached drawing and implementation
Example, the present invention will be further described in detail.It should be appreciated that specific embodiment described herein is only used to explain
The utility model is not used to limit the utility model.
A kind of constant current protection regulated power supply, including voltage detection unit 110, constant current chip 120, secondary coil feedback unit
130 and DC output unit 140, RCD absorbing circuit 150, the RCD absorbing circuit 150 is for inhibiting surge, the voltage
Detection unit 110, constant current chip 120 and secondary coil feedback unit 130 are sequentially connected electrically, the DC output unit 140
The input terminal RCD absorbing circuit 150 in parallel, the DC output unit 140 are connect with 120 output end of constant current chip.
The voltage detection unit 110 is converted into DC voltage for realizing alternating current, and realizes that voltage stabilization exports, packet
It includes by 4 diodes D1, D2, D3, D4 rectifier bridge formed and first capacitor C1.Input voltage is rectified into direct current by rectifier bridge
Output, and the direct current output is corresponding with input voltage, i.e., and when input voltage becomes larger, direct current output accordingly becomes larger, input electricity
Buckling hour, direct current output accordingly become smaller.In the present embodiment, the input ac voltage range is 85V~265V.
Voltage detection unit 110 both ends the parallel resistance R1 and R2, the R1 and R2 are in parallel, and with the constant current core
The LN pin of piece 120 connects.
The CS pin of the constant current chip 120 connects resistance R3, the resistance R3 ground connection, and the R3 resistance is sampling electricity
Resistance, sampling resistor R3 is for realizing open-circuit-protection.
The COMP pin of the constant current chip 120 connects capacitor C2, capacitor C2 other end ground connection, for pressing compensation.
The GND pin of the constant current chip 120 is grounded, and realizes that constant current chip 120 is connected to ground.
The ST pin of the constant current chip 120 is connect with the start-up resistor R4, capacitor C3 respectively, the start-up resistor R4
It connects with the capacitor C3, and the other end ground connection of capacitor C3.The start-up resistor R4 connects the voltage detection unit 110
Output end, i.e., the described voltage detection unit 110 export DC voltage, and the activated resistance R4 of DC voltage is filled to the capacitor C3
Electricity, while the voltage of the VCC pin meeting of the constant current chip 120 can follow ST pin voltage to rise, when the voltage of VCC pin meeting
After rising to starting threshold voltage, 120 output pulse signal of constant current chip, while capacitor C3 charging circuit is cut off, the VCC
The voltage of pin is powered by the secondary coil feedback unit 130.
In the present embodiment, the capacitor C3 value is 470nF, and the start-up resistor R4 value is 1M Ω, input ac voltage
For 85V, experiment proves that, constant current chip 120 charges to 140 turn-on time of DC output unit and is shorter than 200ms.
The outer connecting resistance R5 of the FB pin of the constant current chip 120, resistance R5 other end ground connection carry out constant current chip 120
Earthing short circuit protection.The FB pin of the constant current chip 120 is also connect with the secondary coil feedback unit 130 by resistance R6.
In the present embodiment, FB pin is used to detect the state of output current over-zero, and the falling-threshold value of the FB pin is set to 0.4V,
Hysteresis voltage is 0.6V.Similarly, the FB pin can be used to detect output over-voltage protection, and threshold value is set as 5.5V.
The OUT pin of the constant current chip 120, connect with field-effect tube, realizes the output of pulse, the field-effect tube
On-off realizes the on-off of capacitor C3 charging circuit.
In the present embodiment, the ST pin of the grid a connection constant current chip 120 of the field-effect tube, the field-effect tube
Source electrode b connect the OUT pin of the constant current chip 120, the drain electrode c connection direct current output list of the constant current chip 120
Member 140.
The DC output unit 140 is converted for voltage and direct current output, including transformer and direct current regulation circuit DC-
DC, the transformer are connect with the direct current regulation circuit DC-DC.In the present embodiment, the drain electrode c connection of the field-effect tube
Transformer side, the input end side parallel connection RCD absorbing circuit 150 of the transformer, the RCD absorbing circuit 150 is for inhibiting
Input voltage surge.The RCD absorbing circuit 150 is that diode D5, the diode are connected after resistance R7 is in parallel with capacitor C4
The drain electrode c of the input terminal connection field-effect tube of D5.Direct current regulation circuit is connected after the output end shunt capacitance C6 of the transformer
DC-DC。
Multiple protection functions built in circuit ensure that regulated power supply reliability is protected in constant current.When the constant current chip
120COMP pin voltage is begun to ramp up, and when reaching 4.5V, meeting trigger protection logic is simultaneously locked, and constant current protection regulated power supply stops
Only switch work.When some abnormal situations occur, such as the CS sampling resistor R3 short circuit or change of the constant current chip 120
Depressor is saturated, and trigger protection logic is understood inside constant current chip 120 and is locked, regulated power supply horse back shutdown switch work is protected in constant current
Make.After constant current protection regulated power supply enters guard mode, the end the VCC voltage in constant current chip 120 is begun to decline, when VCC is reached
When under-voltage protection threshold value, constant current protection regulated power supply will restart, while constant current protection regulated power supply constantly detects constant current protection
Regulated power supply state, if trouble shooting, constant current protection regulated power supply can restart to work normally.
Each technical characteristic of embodiment described above can be combined arbitrarily, for simplicity of description, not to above-mentioned reality
It applies all possible combination of each technical characteristic in example to be all described, as long as however, the combination of these technical characteristics is not deposited
In contradiction, all should be considered as described in this specification.
Above-described embodiments merely represent several embodiments of the utility model, the description thereof is more specific and detailed,
But it cannot be understood as the limitations to utility model patent range.It should be pointed out that for the common skill of this field
For art personnel, without departing from the concept of the premise utility, various modifications and improvements can be made, these are belonged to
The protection scope of the utility model.Therefore, the scope of protection shall be subject to the appended claims for the utility model patent.