CN211152263U - Boost type DC-DC (direct current-direct current) -based noiseless white light L ED (diode) driver - Google Patents

Abstract

The utility model provides a noiseless white light L ED driver based on Boost type DC-DC, on traditional Boost type DC-DC's basis, add pulse input detection circuitry, change external pulse signal, and through the loop control of Boost type DC-DC, produce the feedback voltage that has linear characteristics, adjust the electric current size that flows through L ED with current setting resistance together, because the electric current that flows through L ED also has linear characteristics this moment, its dimming process has avoided the switching action, the noiseless introduction, its peripheral power level components and parts are the same with traditional Boost type DC-DC's peripheral components and parts, simple structure, through adopting the error amplifier who takes the input imbalance elimination function, can realize reaching 0.1% dimming current precision.

Description

Boost type DC-DC (direct current-direct current) -based noiseless white light L ED (diode) driver

Technical Field

The invention relates to the field of circuits, in particular to a white light L ED driver.

Background

A common white light L ED driver control method adopts a Pulse Width Modulation (PWM) principle, and achieves the purpose of changing the average current by adjusting the Pulse duty ratio of current flowing through L ED.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a high-precision noiseless white L ED driver based on Boost type DC-DC.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a Boost type DC-based noiseless white light L ED driver comprises a pulse input detection circuit, an error amplifier circuit, a modulation control circuit, an oscillator circuit, a current sampling circuit, a power tube, an energy storage inductor, a Schottky diode, an input filter capacitor, an output filter capacitor, white light L ED and a current setting resistor;

the error amplifier controls input offset voltage within 0.2mV, external pulse signals pass through a pulse input detection circuit to generate direct current control voltage Vdc in direct proportion to the duty ratio of the pulse signals and output the direct current control voltage Vdc to a non-inverting input end inp of the error amplifier circuit, white light L ED and feedback voltage Vfb generated by current setting resistance voltage division are input to an inverting input end inn of the error amplifier circuit, the error amplifier circuit compares the difference value of the direct current control voltage and the feedback voltage to generate an error amplification signal Verr and outputs the error amplification signal Verr to a modulation control circuit, an oscillator circuit generates pulse square wave signals Clk with constant frequency and outputs the pulse square wave signals Clk to the modulation control circuit, the modulation control circuit outputs high-level driving signals Vdrv to control the opening of a power tube, a current sampling circuit samples current flowing through the power tube to generate sampling voltage Vsen and outputs the sampling voltage Vsen to the modulation control circuit, and when the sampling voltage VseWhen n is equal to the error amplification signal Verr, the modulation control circuit outputs a low-level driving signal Vdrv to control the turn-off of the power tube, the driving signal Vdrv generated by the modulation control circuit is output to the grid electrode of the power tube to drive the turn-on and turn-off of the power tube, the power tube is used as a switch, the turn-on duty ratio D of the power tube determines the magnitude of an output voltage Vout for driving the white light L ED to be turned on, and the formula is met

The power tube switching circuit comprises a Schottky diode, a power tube conduction duty ratio, an input filter capacitor, an energy storage inductor, a current setting resistor and a current setting resistor, wherein Vout is output voltage, Vin is input voltage, D is the conduction duty ratio of the power tube, the input filter capacitor is connected between the input voltage Vin and the ground and filters the input voltage Vin, the output filter capacitor is connected between the cathode of the Schottky diode and the ground and filters the output voltage Vout, the energy storage inductor is connected between the input voltage Vin and the anode of the Schottky diode and stores energy when the power tube is turned on, the Schottky diode is in forward conduction when the power tube is turned off and outputs the energy on an input power supply and the energy storage inductor to L ED together, the current setting resistor determines the

Wherein, I_maxAt the maximum current value, R_setA resistor is provided for the current.

The invention has the advantages that on the basis of the traditional Boost type DC-DC, a pulse input detection circuit is added to convert an external pulse signal, the feedback voltage with linear characteristic is generated through the loop regulation of the Boost type DC-DC, the current flowing through L ED is regulated together with the current setting resistor, the current flowing through L ED has linear characteristic at the moment, the dimming process avoids the switching action and the introduction of no noise, the peripheral power stage component is completely the same as the peripheral component of the traditional Boost type DC-DC, the structure is simple, and the dimming current precision of up to 0.1 percent can be realized by adopting the error amplifier with the input offset elimination function.

Drawings

FIG. 1 is a block diagram of an embodiment of a control system of the present invention.

Fig. 2 is a block diagram of an error amplifier with input offset cancellation according to the present invention.

The LED driving circuit comprises a power tube 1, an energy storage inductor 2, a Schottky diode 3, an input filter capacitor 4, an output filter capacitor 5, a white light L ED 6 and a current setting resistor 7.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

As shown in fig. 1, a Boost type DC-DC based high-precision noiseless white light L ED driver is characterized by comprising a pulse input detection circuit and an error amplifier circuit with an input offset cancellation function, wherein the error amplifier controls an input offset voltage within 0.2mV, and comprises a modulation control circuit, an oscillator circuit, a current sampling circuit, a power tube (1), an energy storage inductor (2), a schottky diode (3), an input filter capacitor (4), an output filter capacitor (5), a white light L ED (6) and a current setting resistor (7);

an external pulse signal is input into a detection circuit through a pulse to generate a direct current control voltage Vdc in direct proportion to the duty ratio of the pulse signal and output to a non-inverting input terminal inp of an error amplifier circuit, a white light L ED (6) and a feedback voltage Vfb generated by dividing the voltage of a current setting resistor (7) are input to an inverting input terminal inn of the error amplifier circuit, the error amplifier circuit compares the difference value of the direct current control voltage and the feedback voltage to generate an error amplification signal Verr and outputs the error amplification signal Verr to a modulation control circuit, an oscillator circuit generates a pulse square wave signal Clk with constant frequency and outputs the pulse square wave signal Clk to the modulation control circuit, the modulation control circuit outputs a high-level driving signal Vdrv and controls the opening of a power tube (1), a current sampling circuit samples the current flowing through the power tube (1) to generate a sampling voltage Vsen and outputs the sampling voltage Vsen to the modulation control circuit, when the sampling voltage Vsen is equal to the error amplification signal Verr, the modulation control circuit outputs a low-level driving signal Vdrv and controls the closing of the power tube (1) and a gate of the white light switch (35D) to determine the duty ratio of the power tube (D, the white light switch (L) is turnedThe magnitude of the output voltage Vout on satisfies the formula

The white light LED driving circuit comprises a power tube conduction duty ratio, an input filter capacitor, an energy storage inductor, a current setting resistor and a Schottky diode (3), wherein Vout is output voltage, Vin is input voltage, D is power tube conduction duty ratio, the input filter capacitor is connected between the input voltage Vin and the ground and used for filtering the input voltage Vin, the output filter capacitor is connected between the cathode of the Schottky diode (3) and the ground and used for filtering the output voltage Vout, the energy storage inductor (4) is connected between the input voltage Vin and the anode of the Schottky diode (3) and used for storing energy when the power tube (1) is turned on, the Schottky diode (3) is turned on in the forward direction when the power tube (1) is turned off and used for outputting the energy on an input power supply and the energy storage inductor (2) to L ED together, the current setting resistor (7)

Wherein, I_maxAt the maximum current value, R_setA resistor is provided for the current.

In the embodiment, an error amplifier amplifies the voltage difference between the in-phase input end and the anti-phase input end of the error amplifier, an error amplification signal Verr is output to a modulation control circuit, an oscillator circuit generates a pulse square wave signal Clk and outputs the pulse square wave signal Clk to the modulation control circuit, when the falling edge of the pulse square wave signal comes, the modulation control circuit enables a driving signal Vdrv to be high and outputs the driving signal Vdrv to a grid g of a power tube, the power tube is opened, an input power voltage Vin is stored in an energy storage inductor through the energy storage inductor and the power tube, in the opening process of the power tube, a current sampling circuit samples a drain voltage Vsw of the power tube, a sampling signal Vsen is output to the modulation control circuit, when the sampling signal Vsen is equal to the error amplification signal Verr, the modulation control circuit enables the driving signal Vdrv to be low and outputs the grid g of the power tube, the power tube is turned off, a Schottky diode is turned on at the moment, the energy in the input power source and the energy in the energy storage inductor is output to an output filter capacitor, the output voltage on-side of the output capacitor, the output filter capacitor is repeatedly turned on, the output voltage of the output capacitor, the output voltage Vdrv, the linear current is changed into a linear current with a linear duty ratio equal to a linear control signal Rfset, the linear duty ratio of a linear regulation signal Vfset is changed by a linear regulation signal Rdc feedback signal Rdc, so that a linear regulation signal Vfset is equal to a linear regulation signal of.

Fig. 2 is a block diagram of an error amplifier with input offset cancellation according to the present invention, wherein the error amplifier with input offset cancellation includes a logic controller, a first stage control switch, a first stage amplifying circuit, a second stage control switch, and a second stage amplifying circuit.

The circuit connection relationship is as follows: the direct current voltage signal Vdc and the feedback voltage signal Vfb are respectively input into the inp end and the inn end of the first-stage control switch; the outputs ina1 and inb1 of the first stage control switch are coupled to the first stage amplification circuit; the outputs outa1 and outb1 of the first stage of amplification circuitry are coupled to the second stage control switch; the outputs outa2 and outb2 of the second stage control switch are coupled to the second stage amplification circuit; the second-stage amplifying circuit outputs an error amplifying signal Verr; an external clock signal Clk is input into a logic controller, and the logic controller outputs a control signal phase; the control signal phase is respectively input to the first-stage control switch and the second-stage control switch.

As shown in fig. 2, the working flow of the error amplifier with the input offset cancellation function is as follows: an external clock signal Clk is input into a logic controller, and the logic controller outputs a periodic switch control signal phase; the control signal phase is respectively input to the first stage control switch and the second stage control switch to control the on and off of the two stages of switches. When the Clk signal is high, the phase signal goes high, the first stage control switch connects Vdc to ina1, Vfb to inb 1; the second stage control switch connects outa1 to outa2 and outb1 to outb 2. When the Clk signal is low, the phase signal goes low, the first stage control switch connects Vdc to inb1, and Vfb to ina 1; the second level control switch connects outa1 to outb2 and outb1 to outa 2. By switching the respective input and output signals of the first stage and the second stage, the mismatch trim caused by each stage of the amplifying circuit can be evenly distributed, thereby reducing the influence on the output and realizing high-precision error amplification.

Claims (1)

1. The utility model provides a noiseless white light L ED driver based on Boost type DC-DC, includes pulse input detection circuitry, error amplifier circuit, modulation control circuit, oscillator circuit, current sampling circuit, power tube, energy storage inductance, schottky diode, input filter capacitor, output filter capacitor, white light L ED and current set resistance, its characterized in that:

the error amplifier controls input offset voltage within 0.2mV, external pulse signals are input into a detection circuit through pulses to generate direct current control voltage Vdc in direct proportion to the duty ratio of the pulse signals and output to a non-inverting input end inp of the error amplifier circuit, white light L ED and feedback voltage Vfb generated by current setting resistance voltage division are input to an inverting input end inn of the error amplifier circuit, the error amplifier circuit compares the difference value of the direct current control voltage and the feedback voltage to generate an error amplification signal Verr and outputs the error amplification signal Verr to a modulation control circuit, an oscillator circuit generates a pulse square wave signal Clk with constant frequency and outputs the pulse square wave signal Clk to the modulation control circuit, the modulation control circuit outputs a high-level driving signal Vdrv to control the opening of a power tube, a current sampling circuit samples current flowing through the power tube to generate a sampling voltage Vsen and outputs the sampling voltage Vsen to the modulation control circuit, when the sampling voltage is equal to the error amplification signal Verr, the modulation control circuit outputs a low-level driving signal Vdrv to control the closing of the power tube when the sampling voltage is equal to the error amplification signal Verr, the gate of the power tube is output, the white light power tube is used as a formula Rv, the white light output power tube is used for switching on and switching on, the white light

Wherein, Vout is the output voltage,vin is input voltage, D is power tube conduction duty ratio, an input filter capacitor is connected between the input voltage Vin and the ground to filter the input voltage Vin, an output filter capacitor is connected between the cathode of a Schottky diode and the ground to filter the output voltage Vout, an energy storage inductor is connected between the input voltage Vin and the anode of the Schottky diode to store energy when the power tube is opened, the Schottky diode is in forward conduction when the power tube is closed to output the energy on an input power supply and the energy storage inductor to L ED together, a current setting resistor determines the maximum current value which can flow through L ED to satisfy the formula

Wherein, I_maxAt the maximum current value, R_setA resistor is provided for the current.

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