LED driving circuit and protection circuit for DC/DC converter
A protection circuit for an LED driver and a DC/DC converter. The LED driver includes a DC/DC converter and a protection circuit. The DC/DC converter is used to convert the input voltage of the DC voltage input terminal into an output voltage, which comprises a high frequency switch and an inductor. The protection circuit comprises a detection module, a trigger module and a locking module. The detection module is coupled to the inductor for detecting the output voltage and outputting the voltage detection signal. The trigger module is used to receive the voltage detection signal and output a voltage trigger signal when the voltage detection signal is a negative voltage and the absolute value of the negative voltage is greater than or equal to the preset value. The locking module is coupled to the trigger module and stops the high frequency switch from operating after receiving the voltage trigger signal.
1. An LED driver, comprising:
a DC/DC converter for converting an input voltage at a DC voltage input terminal into an output voltage, the DC/DC converter comprises a high frequency switch and a first inductor; and
a protection circuit, comprising:
a detection module coupled to the first inductor for detecting the output voltage and outputting a voltage detection signal;
a trigger module for receiving the voltage detection signal and outputting a voltage trigger signal when the voltage detection signal is a negative voltage and the absolute value of the negative voltage is greater than or equal to the preset value; and
a locking module coupled to the trigger module and stopping the high frequency switch from operating after receiving the voltage trigger signal;
wherein the DC/DC converter further comprises a peak limiting circuit of the high frequency switch, the peak limiting circuit comprising a comparator, and when the operating voltage of the high frequency switch is greater than the preset value of the comparator, the high frequency switch is short-circuited by the peak limiting circuit.
2. The driver of claim 1 , wherein the detection module comprises a first capacitor and a second inductor, the second inductor is coupled to the first inductor for detecting the output voltage, and the first capacitor is coupled to the second inductor to output the voltage detection signal based on the detection of the output voltage.
3. The driver of claim 2 , wherein the DC/DC converter further comprises a second capacitor in series with a driving resistor, the second capacitor is coupled to the second inductor, the driving resistor is coupled to the driving terminal of the high frequency switch, and the second capacitor, the second inductor and the driving resistor work together to control the resonance of the high frequency switch.
4. The driver of claim 1 , wherein the DC/DC converter further comprises a damping circuit coupled to the DC voltage input terminal, the damping circuit comprising a third capacitor and a damping resistor in series.
5. The driver of claim 1 , wherein when the DC/DC converter is operating as normal, the locking module is not operating.
6. The driver of claim 1 , wherein the locking module comprises a thyristor or at least two discrete transistors, and when the thyristor or the gate of at least two discrete transistors receives the voltage signal output from the trigger module, the thyristor or at least two discrete transistors turn on after being triggered.
7. The driver of claim 6 , wherein the locking module further comprises a first diode, the first diode is coupled between the thyristor and the gate of the high frequency switch, and is used to prevent a reverse voltage from being delivered to the thyristor during normal operations of the DC/DC converter.
8. The driver of claim 1 , wherein the trigger module comprises a Zener diode, the cathode of the Zener diode is coupled to the locking module, and when the voltage detection signal output from the detection module is greater than or equal to the preset value, the Zener diode is turned on.
9. The driver of claim 8 , wherein the trigger module further comprises a current limiting resistor and a second diode connected in series between the Zener diode and the ground terminal.
10. The driver of claim 1 , wherein at least one LED is coupled to the output terminal of the DC/DC converter to form an optical device.
11. A DC/DC converter protection circuit, wherein the DC/DC converter is used to convert an input voltage at a DC voltage input terminal into an output voltage, the DC/DC converter comprising a high frequency switch and a first inductor, and wherein the protection circuit comprises:
a detection module coupled to the first inductor for detecting the output voltage and outputting a voltage detection signal;
a trigger module for receiving the voltage detection signal and outputting a voltage trigger signal when the voltage detection signal is a negative voltage and the absolute value of the negative voltage is greater than or equal to the preset value; and
a locking module coupled to the triggering module and stopping the high frequency switch from operating after receiving the voltage trigger signal, wherein the locking module comprises a thyristor or at least two discrete transistors, and when the thyristor or the gate of at least two discrete transistors receives the voltage signal output from the trigger module, the thyristor or at least two discrete transistors turn on after being triggered.
12. The protection circuit of claim 11 , wherein the detection module comprises a first capacitor and a second inductor, the second inductor is coupled to the first inductor for detecting the output voltage, and the first capacitor is coupled to the second inductor for outputting the voltage detection signal based on the detection of the output voltage.
13. The protection circuit of claim 11 , wherein when the DC/DC converter is operating as normal, the locking module is not operating.
14. The protection circuit of claim 11 , wherein the locking module further comprises a first diode coupled between the thyristor and the gate of the high frequency switch for preventing a reverse voltage from being delivered to the thyristor when the DC/DC converter is operating as normal.
15. The protection circuit of claim 11 , wherein the trigger module comprises a Zener diode, the cathode of the Zener diode is coupled to the locking module, and when the voltage detection signal output from the detection module is greater than or equal to the preset value, the Zener diode is turned on.
16. The protection circuit of claim 15 , wherein the trigger module further comprises the current limiting resistor and the second diode connected in series between the Zener diode and the ground terminal.