[0023] Rectifier bridge 1, full-wave rectification of the 85V-265V/50Hz sinusoidal voltage waveform; it is a full-wave rectifier bridge, which is connected with the filter circuit and the high-voltage voltage regulator circuit through wires;
[0024] The filter circuit 2 is used to filter out the high frequency components in the rectified pulsating voltage; the filter circuit is composed of electrolytic capacitors to achieve filtering.
[0025] The constant current source circuit 3 is used to limit the current flowing through the load LED light string and provide a constant current power supply for the LED light. The constant current source circuit has four branches, and each constant current branch includes a constant current device CRD at both ends. The CRD has a wide constant current voltage range. Because the LED itself has a certain voltage clamping function, when the input AC voltage changes in a wide range, the fluctuation of the output voltage of the rectifier bridge basically falls on both ends of the CRD, thus ensuring The voltage across the LED and the current flowing through it are basically kept constant.
[0026] Switching array circuit (4): When the external voltage changes, use the switching characteristics of the LDMOS tube to convert the series-parallel connection of the LED string and the constant current branch of the constant current source circuit;
[0027] The switch array circuit is composed of LED light string, LDMOS tube and gate driver. When the external voltage changes, the switching characteristics of the LDMOS tube are used to convert the series-parallel mode of the LED string. There are three types of series-parallel modes: 4 series, 2 series-2 parallel and 4 parallel. When the external voltage is high, choose the 4-string working mode, that is, 4 groups of LED lights are connected in series, which has a higher forward voltage; when the external voltage is low, choose the 4-parallel working mode, that is, 4 groups of LEDs When the lamps are connected in parallel, only a low forward voltage is required; when the external voltage is medium, the 2-string-2 parallel operation mode is selected, so that the LED lamp can work in a wide voltage range. The gate driver is used to drive a high-voltage LDMOS whose source is not grounded.
[0028] The high-voltage voltage-stabilizing and step-down circuit 5 uses a high-voltage LDMOS tube to charge the RC circuit, and a linear voltage-stabilizing circuit is used to obtain a stable output voltage to provide a working voltage for the low-voltage module.
[0029] The high-voltage voltage stabilizing and step-down circuit is mainly composed of an LDMOS tube and a capacitor, and a voltage within a certain range can be obtained at both ends of the capacitor. After the voltage is stabilized by the Zener zener tube, a stabilized value is obtained for the pre-band The gap reference voltage source and the linear regulator work. The pre-band gap reference voltage source has a small temperature drift coefficient and high power supply rejection ratio, which can be used as the reference voltage of the linear regulator. The voltage at both ends of the capacitor is used as the input voltage of the linear regulator. The linear regulator is formed by the regulator tube, the resistance feedback network and the operational amplifier, which can obtain a stable output voltage and has a strong load capacity, which can provide work for low-voltage modules Voltage.
[0030] Attached below figure 1 The technical scheme of the present invention is described in detail:
[0031] Rectifier bridge 1, selects a full-wave rectifier bridge to perform full-wave rectification on the 85V-265V/50Hz sinusoidal voltage waveform, wherein the reverse withstand voltage of the diode on each bridge arm is above 800V, and the forward current capacity is above 500mA; and The filter circuit 2 is connected by wires, and is connected with the high-voltage voltage-stabilizing and step-down circuit 5 by wires.
[0032] The filter circuit 2, mainly composed of a capacitor C0, is used for filtering and converts the full-wave pulsating voltage output by the rectifier bridge into a direct current voltage; it is connected with the constant current source circuit 3 through a wire. Circuit structure: The electrolytic capacitor C0 is connected to the output voltage of the rectifier bridge.
[0033] The constant current source circuit 3 is mainly composed of four two-terminal constant current modules CRD1, CRD2, CRD3 and CRD4, which are used to limit the current flowing through the load LED and provide a constant current power supply for the LED lamp. The constant current value of the selected CRD is determined by the rated current of the LED load used, and the constant current voltage range is determined by the effective value range of the input AC voltage required by the product and the number of LED loads. Adjust the number of LEDs connected in series so that the voltage across the CRD is greater than its constant current starting voltage to ensure that the current flowing through the LED is near its rated current value to achieve constant current driving of the LED. Since the LED itself has a voltage clamping function when the forward conduction is turned on, the part of the voltage when the input voltage V exceeds the forward conduction of the LED string is basically all dropped on the CRD, and the LED will not be overvoltage; and the switch array circuit 4 Connect by wire. Circuit structure: all CRD positive ends are connected to the input voltage V, the reverse end of CRD1 is connected to the forward end of the light string LED1, the reverse end of CRD2 is connected to the drain of LDMOS7, the reverse end of CRD3 is connected to the drain of LDMOS8, CRD4 The drain of the reverse terminal LDMOS9.
[0034] Switch array circuit 4 is mainly composed of light string LED1, light string LED2, light string LED3, light string LED4, LDMOS1, LDMOS2, LDMOS3, LDMOS4, LDMOS5, LDMOS6, LDMOS7, LDMOS8, LDMOS9 and gate drivers Gatedrive1, Gate drive2, Gate It is composed of drive3, Gate drive4, Gate drive5, and Gate drive6. LDMOS1 is controlled by HO1, HO1 is controlled by external enable EN2; LDMOS2 is controlled by HO2, HO2 is controlled by external enable EN1; LDMOS3 is controlled by HO3, HO3 is controlled by external enable EN2; LDMOS4 and LDMOS6 are controlled by external enable EN2; LDMOS5 Controlled by external enable EN1; LDMOS7 is controlled by HO4, HO4 is controlled by external enable EN2; LDMOS8 is controlled by HO5, HO5 is controlled by external enable EN1; LDMOS9 is controlled by HO6, HO6 is controlled by external enable EN2, that is, LDMOS is controlled by external Enable EN1 or EN2 control, of which two external enable EN1 and EN2 correspond to two threshold voltages V1 and V2 respectively. V1 and V2 are determined by the CRD constant current voltage range and the number of LED lights. When 120V≤V < At V2, EN1 controls LDMOS2 to turn off, LDMOS5 and LDMOS8 turn on, N2 controls LDMOS4, LDMOS6, LDMOS7, LDMOS9 to turn off, LDMOS1 and LDMOS3 turn on, at this time CRD1, light string LED1, LDMOS1, light string LED2, LDMOS5, CRD3, LDMOS8 , Light string LED3, LDMOS3, and light string LED4 form two parallel branches; when V2≤V<375V, EN1 controls LDMOS5 and LDMOS8 to turn off, LDMOS2 turns on, N2 controls LDMOS4, LDMOS6, LDMOS7, LDMOS9 to turn off, LDMOS1 and LDMOS3 is turned on, at this time CRD1, light string LED1, LDMOS1, light string LED2, LDMOS2, light string LED3, LDMOS3, and light string LED4 form a loop. Circuit structure: the forward end of the light string LED1 is connected to the reverse end of CRD1, the reverse end is connected to the drain of LDMOS1 and the drain of LDMOS4, the forward end of the light string LED2 is connected to the source of LDMOS1, the source of LDMOS7, the floating VS1 of Gate drive1, and the gate drive4 Floating VS4, reverse terminal LDMOS2 drain and LDMOS5 drain, light string LED3 forward terminal to LDMOS8 source, LDMOS2 source, Gate drive2 floating VS2, Gate drive5 floating VS5, reverse terminal to LDMOS3 drain And LDMOS drain, the forward end of the light string LED4 is connected to the LDMOS3 source, LDMOS9 source, Gate drive3 floating VS3, Gatedrive6 floating VS6, the reverse end is grounded, LDMOS4, LDMOS5, LDMOS6 sources are all grounded, LDMOS1, LDMOS2 The gates of LDMOS3, LDMOS7, LDMOS8, and LDMOS9 are respectively connected to the gate drivers HO1, HO2, HO3, HO4, HO5, and HO6, and the input voltage VDD of the gate driver is connected to the output voltage VDD of the high-voltage voltage regulator circuit.
[0035] The high-voltage voltage regulator and step-down circuit 5 is composed of LDMOS10 and capacitor C1 to form an RC charging branch. The voltage VCC across the capacitor is the detection signal of the hysteresis comparator COM1. Two different threshold voltage values can be obtained by adjusting the resistance of R2 and R3 As a predetermined voltage value for detecting the fluctuating voltage of VCC, when the circuit is powered on, the gate of LDMOS11 has no control signal, LDMOS11 is in the off state, R1 provides bias voltage for LDMOS10, and the gate of LDMOS10 is at high level, so LDMOS10 is turned on. The pulsating DC high voltage charges the RC circuit through the high voltage LDMOS1. When the voltage VCC across the capacitor C1 reaches a predetermined voltage value, the detection signal controls the gate terminal of the LDMOS11, so that the LDMOS11 is turned on. At this time, the external input voltage forms a loop through the resistor R1 and LDMOS11 to ground. The gate terminal voltage of LDMOS10 is pulled down to a low level. LDMOS1 is in the off state, so the charging circuit is turned off. When the subsequent load consumption voltage is lower than a certain value, The detection signal control branch LDMOS11 is in the cut-off state. At this time, LDMOS10 is turned on again, the charging circuit is activated again, and the capacitor is charged again. After that, the working state is repeated as above, so that the voltage across the capacitor changes within a certain range. The VCC voltage passes through the resistor R6 and Zener diode Z1 to obtain a regulated value for the pre-reference voltage source Pre-BAG and operational amplifier OPA1 to work. The pre-reference voltage source generates Vref1 as the OPA1 reference voltage, and OPA1 is adjusted according to the feedback voltage change on R5 The gate voltage of M1 makes the output voltage VDD stable and provides the working voltage for the gate driver. Circuit structure: R1 provides gate voltage for LDMOS10 and is connected to the drain of LDMOS11, R7 and C1 are connected in series with the source of LDMOS10, the drain of LDMOS10 is connected to the input voltage, and the source of LDMOS11 is grounded. The voltage across C1 is stabilized by R6 and Z1. R3 is connected in series to the same direction terminal of the comparator COM1, R2 is connected to the output terminal and the non-inverting terminal of the comparator, the reverse terminal is connected to the reference voltage Vref2 of the pre-reference output, and the output terminal of COM1 is connected to the gate of LDMOS11. The resistance feedback network R4 and R5 are connected in series to the drain terminal of the power tube M1, the source terminal of the power tube M1 is connected to the capacitor voltage VCC, and the voltage drop on the resistance R5 is fed back to the non-inverting terminal of the op amp OPA1, and the inverting terminal of the op amp is connected The band gap reference voltage Vref1, the output signal of the operational amplifier is connected to the gate terminal of the power tube M1.
