CN211019358U - Voltage reduction driving circuit - Google Patents
Voltage reduction driving circuit Download PDFInfo
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- CN211019358U CN211019358U CN201921282442.4U CN201921282442U CN211019358U CN 211019358 U CN211019358 U CN 211019358U CN 201921282442 U CN201921282442 U CN 201921282442U CN 211019358 U CN211019358 U CN 211019358U
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Abstract
The utility model relates to a step-down drive circuit. The voltage reduction driving circuit comprises an input signal circuit, a voltage reduction constant current circuit and an output filter circuit, wherein: the input signal circuit comprises a switching power supply module; the voltage-reducing constant-current circuit comprises: the voltage reduction constant current chip comprises a valley bottom detection pin, a chip driving power switch pin and a primary side current sampling pin; a freewheel circuit; a current sampling circuit; a valley bottom detection circuit; and a power switch tube; and an output filter circuit is connected between the input signal circuit and the freewheel circuit.
Description
Technical Field
The utility model relates to a circuit field, more specifically relates to a step-down drive circuit.
Background
A light Emitting Diode (L light Emitting Diode, L ED) is a semiconductor device that converts electrical energy into light energy. L ED has a core that is a PN junction, and L ED has a luminous flux proportional to the current flowing through L ED. L ED has the advantages of high electrical to optical conversion, low operating voltage, small size, long life, etc., as compared to conventional lighting fixtures such as incandescent lamps.
In the application of medium-large size L ED, L ED lamp beads adopted are gradually developed from the initial 20mA specification to the 800-1000mA specification, at present, a direct type L ED is a L ED solution with higher cost performance at present due to the advantages of high light efficiency, low cost and the like, and in the direct type L ED, the specification of L ED lamp beads adopted is generally 600 mA.
Therefore, for medium and large size L ED applications, a new drive circuit is needed to power L ED.
SUMMERY OF THE UTILITY MODEL
An embodiment of the utility model provides a step-down drive circuit, including input signal circuit, step-down constant current circuit and output filter circuit, wherein: the input signal circuit comprises a switching power supply module and is used for supplying power to the voltage reduction constant current circuit and the output filter circuit; the voltage-reducing constant-current circuit comprises: the voltage reduction constant current chip comprises a valley bottom detection pin, a chip driving power switch pin and a primary side current sampling pin; a freewheel circuit; a current sampling circuit; the output end of the valley bottom detection circuit is connected to the valley bottom detection pin, and the input end of the valley bottom detection circuit is connected to the follow current circuit; the drain electrode of the power switch tube is connected to the input end of the valley bottom detection circuit and the follow current circuit, the grid electrode of the power switch tube is connected to a chip driving power switch pin, and the source electrode of the power switch tube is connected to a primary side current sampling pin and is grounded through the current sampling circuit; and an output filter circuit connected between the input signal circuit and the freewheel circuit.
In one embodiment, the buck constant current chip further comprises a pulse width dimming input pin and a pulse width conversion analog dimming input pin, and the input signal circuit further comprises: the pulse width dimming input end is connected to the pulse width dimming input pin through a first filter resistor; and the pulse width conversion analog dimming input end is connected to the pulse width conversion analog dimming input pin through a second filter resistor.
In one embodiment, the input signal circuit further comprises an enable input connected to the pulse width dimming input pin via a reverse diode.
In one embodiment, the valley bottom detection circuit includes a valley bottom detection capacitor, a first valley bottom detection resistor and a second valley bottom detection resistor connected in series, and wherein one end of the second valley bottom detection resistor is grounded, an output terminal of the valley bottom detection circuit is led out by a common terminal of the first valley bottom detection resistor and the second valley bottom detection resistor, and an input terminal of the valley bottom detection circuit is led out by one end of the valley bottom detection capacitor.
In one embodiment, the freewheel circuit comprises a power inductance and a freewheel diode connected in series, and wherein an input of the valley detection circuit is connected to a common terminal of the power inductance and the freewheel diode.
In one embodiment, the output filter circuit includes a filter capacitor.
In one embodiment, the voltage-reducing constant-current chip further comprises a chip power supply input pin, an abnormal state protection signal pin and a chip reference ground pin.
The embodiment of the utility model provides a step-down drive circuit is still provided, including input signal circuit, step-down constant current circuit, output filter circuit and chip power supply constant voltage circuit, wherein: the input signal circuit comprises a switching power supply module and is used for supplying power to the voltage reduction constant current circuit and the output filter circuit; the voltage-reducing constant-current circuit comprises: the voltage reduction constant current chip comprises a valley bottom detection pin, a chip driving power switch pin, a primary side current sampling pin, a chip power supply voltage sampling pin and a chip power supply voltage sampling feedback modulation pin; a freewheel circuit; a current sampling circuit; the output end of the valley bottom detection circuit is connected to the valley bottom detection pin, and the input end of the valley bottom detection circuit is connected to the follow current circuit; the drain electrode of the power switch tube is connected to the input end of the valley bottom detection circuit and the follow current circuit, the grid electrode of the power switch tube is connected to a chip driving power switch pin, and the source electrode of the power switch tube is connected to a primary side current sampling pin and is grounded through the current sampling circuit; the output filter circuit is connected between the input signal circuit and the follow current circuit; and the chip power supply constant voltage circuit is connected between the input signal circuit and the voltage reduction constant current chip.
In one embodiment, the buck constant current chip further comprises a pulse width dimming input pin and a pulse width conversion analog dimming input pin, and the input signal circuit further comprises: the pulse width dimming input end is connected to the pulse width dimming input pin through a first filter resistor; and the pulse width conversion analog dimming input end is connected to the pulse width conversion analog dimming input pin through a second filter resistor.
In one embodiment, the input signal circuit further comprises an enable input connected to the pulse width dimming input pin via a reverse diode.
In one embodiment, the valley bottom detection circuit includes a valley bottom detection capacitor, a first valley bottom detection resistor and a second valley bottom detection resistor connected in series, and wherein one end of the second valley bottom detection resistor is grounded, an output terminal of the valley bottom detection circuit is led out by a common terminal of the first valley bottom detection resistor and the second valley bottom detection resistor, and an input terminal of the valley bottom detection circuit is led out by one end of the valley bottom detection capacitor.
In one embodiment, the freewheel circuit comprises a power inductance and a freewheel diode connected in series, and wherein an input of the valley detection circuit is connected to a common terminal of the power inductance and the freewheel diode.
In one embodiment, the output filter circuit includes a filter capacitor.
In one embodiment, the chip power supply constant voltage circuit comprises a chip power supply voltage division detection circuit, wherein the input end of the chip power supply voltage division detection circuit is connected to the input signal circuit, and the output end of the chip power supply voltage division detection circuit is connected to the chip power supply voltage sampling pin.
In one embodiment, the chip supply voltage division detection circuit comprises a first division detection resistor and a second division detection resistor which are connected in series, and the output end of the chip supply voltage division detection circuit is led out from the common end of the first division detection resistor and the second division detection resistor.
In one embodiment, the chip supply constant voltage circuit includes a loop compensation circuit having a first terminal connected to the switching power supply module and the chip supply voltage sampling feedback modulation pin, and a second terminal connected to the chip supply voltage sampling pin.
In one embodiment, the loop compensation circuit includes a first loop compensation capacitance, a second loop compensation capacitance, and a loop compensation resistance, wherein the second loop compensation capacitance is connected in series with the loop compensation resistance and then in parallel with the first loop compensation capacitance, and wherein a first end of the loop compensation circuit is drawn from a common end of the first loop compensation capacitance and the second loop compensation capacitance, and a second end of the loop compensation circuit is drawn from a common end of the first loop compensation capacitance and the loop compensation resistance.
In one embodiment, the chip power supply constant voltage circuit comprises an optical coupling current limiting circuit, and the switching power supply module further comprises a power management circuit, wherein an input end of the optical coupling current limiting circuit is connected to the switching power supply module, an output end of the optical coupling current limiting circuit is connected to an input end of the power management circuit, and an output end of the power management circuit is connected to the chip power supply voltage sampling feedback modulation pin.
In one embodiment, the optocoupler current limiting circuit includes an optocoupler current limiting resistor.
In one embodiment, the voltage-reducing constant-current chip further comprises a chip power supply input pin, an abnormal state protection signal pin and a chip reference ground pin.
Drawings
The invention may be better understood from the following description of particular embodiments thereof taken in conjunction with the accompanying drawings, in which:
fig. 1 shows a schematic structural diagram of a buck driving circuit according to an embodiment of the present invention;
fig. 2 shows a schematic structural diagram of a buck driving circuit according to another embodiment of the present invention.
Detailed Description
Features and exemplary embodiments of various aspects of the present invention will be described in detail below with reference to the accompanying drawings. Example implementations can be embodied in many forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example implementations to those skilled in the art. In the drawings, the size of regions and components may be exaggerated for clarity. Further, in the drawings, the same reference numerals denote the same or similar structures, and thus detailed descriptions thereof will be omitted.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring the primary technical ideas of the invention.
According to the utility model discloses a step-down drive circuit of embodiment is applicable to jumbo size L ED in the drive and uses to can select different dimming mode by the user, specifically, according to the utility model discloses a step-down constant current circuit that step-down drive circuit includes can detect power switch's drain electrode resonance waveform's bottom of a valley voltage and sampling resistance voltage to open or close power switch according to this bottom of a valley voltage and sampling resistance voltage.
Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Fig. 1 shows a schematic structural diagram of a buck driving circuit 100 according to an embodiment of the present invention. As shown in fig. 1, the step-down driving circuit 100 may include an input signal circuit 110, a step-down constant current circuit 120, and an output filter circuit 130.
As an example, the input signal circuit 110 may be configured to power the buck constant current circuit 120 and the output filter circuit 130. in addition, for example, the input signal circuit 110 may also be configured to provide a dimming mode signal and an external control signal As shown in FIG. 1, the input signal circuit 110 may include a switching power module 1101, and a corresponding control chip, the switching power module 1101 may be a flyback switching power supply, a forward switching power supply, an LL C switching power supply, or the like, or other system solutions known in the art, without limitation.
Specifically, the switching power supply module 1101 may include L ED supply voltage terminal V + and a chip U1 supply voltage terminal VIN to supply power to the buck constant current circuit 120 and the output filter circuit 130, respectively.
As shown in fig. 1, the step-down constant current circuit 120 may include a step-down constant current chip U1, a valley detection circuit 1201, a freewheel circuit 1202, a power switch Q1, and a current sampling circuit 1203. Specifically, the buck constant current chip U1 may include a valley detection pin ZVS, a chip drive power switch pin GATE, and a primary current sampling pin CS.
For example, the output terminal of the valley detection circuit 1201 may be connected to the valley detection pin ZVS of the step-down constant current chip U1, and the input terminal of the valley detection circuit 1201 may be connected to the freewheel circuit 1202. In addition, the drain of the power switch Q1 may be connected to the input terminal of the valley detection circuit 1201 and the freewheeling circuit 1202, the GATE of the power switch Q1 may be connected to the chip-driving power switch pin GATE of the step-down constant-current chip U1, and the source of the power switch Q1 may be connected to the primary-side current sampling pin CS of the step-down constant-current chip U1 and grounded via the current sampling circuit 1203.
As shown in FIG. 1, the output filter circuit 130 may be coupled between the input signal circuit 110 and the freewheel circuit 1202. As an example, the output filter circuit 130 may include filter capacitors C1 and L ED strings coupled in parallel.A first terminal of the filter capacitor C1 may be coupled to the positive pole of the L ED string and a second terminal of the filter capacitor C1 may be coupled to the negative pole of the L ED string.
L ED lights can include any suitable number of L ED light beads in the embodiment of FIG. 1, L ED light beads included in the L ED lights are shown connected together in series, but in other embodiments L ED light beads can be connected in parallel, furthermore, L ED light beads can be direct or side-entry L ED light beads, without limitation.
Still referring to fig. 1, in this embodiment, the buck constant current chip U1 may further include a pulse-width-dimming input pin L PWM and a pulse-width-to-analog-dimming input pin HPWM, and the input signal circuit 110 may further include a pulse-width-dimming input terminal L PWM and a pulse-width-to-analog-dimming input terminal HPWM, for example, the pulse-width-dimming input terminal L PWM of the input signal circuit 110 may be connected to the pulse-width-dimming input pin L PWM of the buck constant current chip U1 via a first filter resistor R1, and the pulse-width-to-analog-dimming input terminal HPWM of the input signal circuit 110 may be connected to the pulse-width-to-analog-dimming input pin HPWM of the buck constant current chip U1 via a second filter resistor R2.
In an embodiment of the present invention, the PWM dimming and the PWM-to-analog dimming can be selected by a user to be used alone or in cooperation with each other.
In the embodiment shown in fig. 1, for example, the input signal circuit 110 may further include an enable input terminal ENA, which may be connected to the pulse-width dimming input pin L PWM of the buck constant-current chip U1 via a reverse diode D1-for example, the anode of the diode D1 may be connected to the pulse-width dimming input pin L PWM of the buck constant-current chip U1, and the cathode of the diode D1 may be connected to the enable input terminal ENA.
In the embodiment shown in fig. 1, for example, the valley detection circuit 1201 may include a valley detection capacitor C2, a first valley detection resistor R3, and a second valley detection resistor R4 connected in series. For example, one end of the second bottom detection resistor R4 may be grounded, an output terminal of the bottom detection circuit 1201 may be led out from a common terminal of the first bottom detection resistor R3 and the second bottom detection resistor R4, and an input terminal of the bottom detection circuit 1201 may be led out from one end of the bottom detection capacitor C2.
It should be understood that although fig. 1 shows that the valley detection circuit 1201 includes one valley detection capacitor (C2) and two valley detection resistors (R3 and R4), in other embodiments, the valley detection circuit 1201 may include other suitable numbers of valley detection capacitors and valley detection resistors, which are not limited by the present invention.
Still referring to fig. 1, for example, the freewheel circuit 1202 may include a power inductor L1 and a freewheel diode D2. connected in series-specifically, an input terminal of the valley detection circuit 1202 may be connected to a common terminal of the power inductor L1 and the freewheel diode D2.
In an embodiment of the present invention, in addition to the above-mentioned pins (including the valley bottom detection pin ZVS, the chip driving power switch pin GATE, the primary side current sampling pin CS, the pulse width dimming input pin L PWM, and the pulse width conversion analog dimming input pin HPWM), the step-down constant current chip U1 may further include a power supply input pin VIN, an abnormal state protection signal pin FAU L T, and a chip reference ground GND, for example, the power supply input pin VIN may be connected to the switching power supply module 1101 to supply power to the step-down constant current chip U1, the abnormal state protection signal pin FAU L T may transmit and receive various abnormal state signals, and the chip reference ground GND may be connected to the chip reference ground.
In addition, as shown in fig. 1, one end of the current sampling circuit 1203 may be connected to the primary side current sampling pin CS of the step-down constant current chip U1 and the source of the power switch Q1, and the other end of the current sampling circuit 1203 may be grounded. It should be appreciated that although fig. 1 shows that the current sampling circuit 1203 includes only one current sampling resistor R5, in other embodiments, the current sampling circuit 1203 may also include one or more current sampling resistors connected in series to detect the sampling resistor voltage.
According to the embodiment of the present invention, the operation states of the buck driving circuit 100 shown in fig. 1 when applied to the medium-large size L ED backlight application may include the following three operation states:
in the first state, the output filter circuit 130 and the buck constant-current chip U1 are respectively supplied by the L ED power supply voltage end V + of the switching power supply module 1101 of the input signal circuit 110 and the power supply voltage end VIN of the chip U1.
When the voltage of the pulse width dimming input pin L PWM of the buck constant-current chip U1 is higher than the internal reference voltage of the buck constant-current chip U1, the buck constant-current chip U1 starts to operate.
And in the second state, the voltage reduction constant current chip U1 starts to work, and the valley bottom detection circuit 1201 detects the valley bottom voltage, specifically, the valley bottom voltage is the valley bottom voltage of the drain resonance waveform of the power switch tube Q1 after the demagnetization of the power inductor L1 is finished.
When the valley detection circuit 1201 detects the valley voltage, the power switch tube Q1. is turned on by the chip driving power switch pin GATE of the step-down constant current chip U1, and current can flow through the L ED string, the power inductor L1, the power switch tube Q1, and the current sampling circuit 1203.
After the sampled resistor voltage reaches the preset voltage inside the buck constant-current chip U1, the power switch tube Q1. is turned off by the chip driving power switch pin GATE of the buck constant-current chip U1, and then the current may flow through L ED string, the power inductor L, and the freewheeling diode D2., for example, the current sampling circuit 1203 may be used to set the maximum output current of L ED string.
In addition, in the second state, pulse width dimming and pulse width conversion analog dimming can be respectively realized through the pulse width dimming input pin L PWM and the pulse width conversion analog dimming input pin HPWM of the buck constant current chip U1.
And in the third state, when the voltage of the pulse width dimming input pin L PWM of the buck constant-current chip U1 is lower than the internal reference voltage of the buck constant-current chip U1 and lasts for a period of time, the buck constant-current chip U1 enters a standby mode.
Fig. 2 shows a schematic structural diagram of a buck driving circuit 200 according to another embodiment of the present invention. As shown in fig. 2, the step-down driving circuit 200 may include an input signal circuit 210, a step-down constant current circuit 220, an output filter circuit 230, and a chip supply constant voltage circuit 240.
For example, the step-down constant current circuit 220 may include a step-down constant current chip U1, a valley detection circuit 2201 and a freewheeling circuit 2202, a power switch Q1, and a current sampling circuit 2203. As shown in fig. 2, the input signal circuit 210 may include a switching cell module 2101, which may be similar to the switching power supply module 1101 shown in fig. 1.
Specifically, the input signal circuit 210, the step-down constant current circuit 220, and the output filter circuit 230 included in the step-down driving circuit 200 shown in fig. 2 may be similar to the input signal circuit 110, the step-down constant current circuit 120, and the output filter circuit 130 of the step-down driving circuit 100 described above with respect to fig. 1. For some specific details of the input signal circuit 210, the step-down constant current circuit 220, and the output filter circuit 230, reference may be made to the corresponding description above with respect to fig. 1, and they are not repeated here.
In addition, the step-down constant current chip U1 of the step-down driving circuit 200 may include a chip supply voltage sampling pin VREF and a chip supply voltage sampling feedback modulation pin VREF _ OUT in addition to the pins described with respect to the step-down constant current chip U1 of the step-down driving circuit 100 shown in fig. 1 (including the valley detection pin ZVS, the chip driving power switch pin GATE, the primary side current sampling pin CS, the pulse width dimming input pin L PWM, the pulse width conversion analog dimming input pin HPWM, the chip supply input pin VIN, the abnormal state protection signal pin FAU L T, and the chip reference ground GND).
As shown in fig. 2, the step-down driving circuit 200 may further include a chip-supply constant voltage circuit 240, and the chip-supply constant voltage circuit 240 may be connected between the input signal circuit 210 and the step-down constant current chip U1.
Referring to fig. 2, the chip supply constant voltage circuit 240 may include a chip supply voltage division detection circuit 2401, wherein an input terminal of the chip supply voltage division detection circuit 2401 may be connected to a chip supply voltage terminal VIN of the chip U1 of the switching power supply module 2101, and an output terminal of the chip supply voltage division detection circuit 2401 may be connected to a chip supply voltage sampling pin VREF of the step-down constant current chip U1 of the step-down driving circuit 200.
In the embodiment shown in fig. 2, for example, the chip supply voltage division detection circuit 2401 may include a first division detection resistor R7 and a second division detection resistor R8 connected in series, and an output terminal of the chip supply voltage division detection circuit 2401 may be led out from a common terminal of the first division detection resistor R7 and the second division detection resistor R8.
It should be understood that although fig. 2 shows that the chip supply voltage division detection circuit 2401 includes two serially connected division detection resistors (R7 and R8), in other embodiments, the chip supply voltage division detection circuit 2401 may include any suitable number of serially connected division detection resistors, and the output of the chip supply voltage division detection circuit 2401 may be drawn from between two adjacent division detection resistors as needed.
Still referring to fig. 2, the chip supply constant voltage circuit 240 may further include a loop compensation circuit 2402, a first terminal of the loop compensation circuit 2402 may be connected to the switching power supply module 2101 and the chip supply voltage sampling feedback modulation pin VREF _ OUT of the step-down constant current chip U1, and a second terminal of the loop compensation circuit 2402 may be connected to the chip supply voltage sampling pin VREF of the step-down constant current chip U1.
In the embodiment shown in fig. 2, for example, the loop compensation circuit 2402 may include a first loop compensation capacitor C3, a second loop compensation capacitor C4, and a loop compensation resistor R9, wherein the second loop compensation capacitor C4 may be connected in series with the loop compensation resistor R9 and then may be connected in parallel with the first loop compensation capacitor C3. For example, a first terminal of the loop compensation circuit 2402 may be drawn from a common terminal of the first loop compensation capacitor C3 and the second loop compensation capacitor C4, and a second terminal of the loop compensation circuit 2402 may be drawn from a common terminal of the first loop compensation capacitor C3 and the loop compensation resistor R9. It should be understood that although fig. 2 shows that the loop compensation circuit 2402 includes two loop compensation capacitors (C3 and C4) and one loop compensation resistor (R9), in other embodiments, the loop compensation circuit 2402 may include other suitable numbers of loop compensation capacitors and loop compensation resistors.
In the embodiment shown in fig. 2, the chip supply constant voltage circuit 240 may further include an optical coupling current limiting circuit 2403, and the switching power supply module 2101 may further include a power management circuit U2. For example, the power management circuit U2 may include an isolation optocoupler.
As shown in fig. 2, for example, an input end of the optical coupling current limiting circuit 2403 may be connected to a chip supply voltage end VIN of the switching power supply module 2101, an output end of the optical coupling current limiting circuit 2403 may be connected to an input end of a power management circuit U2 of the switching power supply module 2101, and an output end of the power management circuit U2 may be connected to a chip supply voltage sampling feedback modulation pin VREF _ OUT of the buck constant current chip U1.
For example, in the embodiment shown in fig. 2, the optocoupler current limiting circuit 2403 may include an optocoupler current limiting resistor R6. It should be understood that although fig. 2 shows that the optocoupler current limiting circuit 2403 includes only one optocoupler current limiting resistor (R6), in other embodiments, the optocoupler current limiting circuit 2403 may include other suitable number of optocoupler current limiting resistors, which is not limited by the invention.
According to the embodiment of the present invention, the operation states of the buck driving circuit 200 shown in fig. 2 when applied to the medium-large size L ED backlight application may include the following three operation states:
in the first state, the output filter circuit 130 and the buck constant-current chip U1 are respectively supplied with power by an L ED power supply voltage end V + of the switching power supply module 2101 of the input signal circuit 210 and a power supply voltage end VIN of the chip U1.
When the voltage of the pulse width dimming input pin L PWM of the buck constant-current chip U1 is higher than the internal reference voltage of the buck constant-current chip U1, the buck constant-current chip U1 starts to operate.
And in the second state, the voltage reduction constant current chip U1 starts to work, and the valley bottom detection circuit 2201 detects the valley bottom voltage, specifically, the valley bottom voltage is the valley bottom voltage of the drain resonance waveform of the power switch tube Q1 after the demagnetization of the power inductor L1 is finished.
When the valley detection circuit 2201 detects the valley voltage, the power switch tube Q1. is turned on by the chip driving power switch pin GATE of the step-down constant current chip U1, and current can flow through the L ED string, the power inductor L1, the power switch tube Q1, and the current sampling circuit 2203.
After the sampled resistor voltage reaches the preset voltage inside the buck constant-current chip U1, the power switch tube Q1. is turned off by the chip driving power switch pin GATE of the buck constant-current chip U1, and then the current may flow through L ED string, the power inductor L, and the freewheeling diode D2., for example, the current sampling circuit 2203 may be used to set the maximum output current of L ED string.
In the second state, pulse width dimming and pulse width conversion analog dimming can be respectively realized through the pulse width dimming input pin L PWM and the pulse width conversion analog dimming input pin HPWM of the buck constant current chip U1.
In addition, the step-down constant current chip U1 samples the chip U1 supply voltage provided by the chip U1 supply voltage terminal VIN of the switching power module 2101 through the chip supply voltage division detection circuit 2401, and realizes a constant chip U1 supply voltage through the feedback modulation of the power management circuit U2.
And in the third state, when the voltage of the pulse width dimming input pin L PWM of the buck constant-current chip U1 is lower than the internal reference voltage of the buck constant-current chip U1 and lasts for a period of time, the buck constant-current chip U1 enters a standby mode.
According to the utility model discloses a step-down constant current circuit that step-down drive circuit included can detect power switch's drain electrode resonance waveform's bottom of a valley voltage and sampling resistance voltage to open or close power switch according to this bottom of a valley voltage and sampling resistance voltage. Furthermore, according to the utility model discloses a step-down drive circuit still includes chip power supply constant voltage circuit, realizes that chip supply voltage is invariable through feedback modulation. According to the utility model discloses a step-down drive circuit has advantages such as high accuracy constant current output, high efficiency, low system cost.
The invention is not limited to the specific configurations described above and shown in the drawings. A detailed description of known configurations is omitted herein for the sake of brevity. Various changes, modifications, and additions may be made by those skilled in the art in view of the spirit of the present invention. The scope of protection of the invention is defined by the appended claims.
Claims (20)
1. A step-down driving circuit comprises an input signal circuit, a step-down constant current circuit and an output filter circuit, wherein:
the input signal circuit comprises a switching power supply module and is used for supplying power to the voltage reduction constant current circuit and the output filter circuit;
the step-down constant current circuit comprises:
the voltage reduction constant current chip comprises a valley bottom detection pin, a chip driving power switch pin and a primary side current sampling pin;
a freewheel circuit;
a current sampling circuit;
the output end of the valley bottom detection circuit is connected to the valley bottom detection pin, and the input end of the valley bottom detection circuit is connected to the follow current circuit; and
a drain electrode of the power switch tube is connected to the input end of the valley bottom detection circuit and the follow current circuit, a gate electrode of the power switch tube is connected to the chip driving power switch pin, and a source electrode of the power switch tube is connected to the primary side current sampling pin and grounded through the current sampling circuit; and
the output filter circuit is connected between the input signal circuit and the freewheel circuit.
2. The buck driving circuit according to claim 1, wherein the buck constant current chip further includes a pulse width dimming input pin and a pulse width to analog dimming input pin, and the input signal circuit further includes:
the pulse width dimming input end is connected to the pulse width dimming input pin through a first filter resistor; and
and the pulse width conversion analog dimming input end is connected to the pulse width conversion analog dimming input pin through a second filter resistor.
3. The buck driver circuit of claim 2, wherein the input signal circuit further comprises an enable input connected to the pulse width dimming input pin via a reverse diode.
4. The step-down driving circuit according to claim 1, wherein the valley bottom detection circuit includes a valley bottom detection capacitor, a first valley bottom detection resistor and a second valley bottom detection resistor connected in series, and wherein one end of the second valley bottom detection resistor is grounded, the output terminal of the valley bottom detection circuit is led out by a common terminal of the first valley bottom detection resistor and the second valley bottom detection resistor, and the input terminal of the valley bottom detection circuit is led out by one end of the valley bottom detection capacitor.
5. The buck driver circuit of claim 1, wherein the freewheeling circuit includes a power inductor and a freewheeling diode connected in series, and wherein the input of the valley detection circuit is connected to a common terminal of the power inductor and the freewheeling diode.
6. The buck drive circuit of claim 1, wherein the output filter circuit comprises a filter capacitor.
7. The buck driving circuit according to any one of the preceding claims, wherein the buck constant current chip further comprises a chip supply input pin, an abnormal state protection signal pin and a chip reference ground pin.
8. The utility model provides a step-down drive circuit, includes input signal circuit, step-down constant current circuit, output filter circuit and chip power supply constant voltage circuit, wherein:
the input signal circuit comprises a switching power supply module and is used for supplying power to the voltage reduction constant current circuit and the output filter circuit;
the step-down constant current circuit comprises:
the voltage reduction constant current chip comprises a valley bottom detection pin, a chip driving power switch pin, a primary side current sampling pin, a chip power supply voltage sampling pin and a chip power supply voltage sampling feedback modulation pin;
a freewheel circuit;
a current sampling circuit;
the output end of the valley bottom detection circuit is connected to the valley bottom detection pin, and the input end of the valley bottom detection circuit is connected to the follow current circuit; and
a drain electrode of the power switch tube is connected to the input end of the valley bottom detection circuit and the follow current circuit, a gate electrode of the power switch tube is connected to the chip driving power switch pin, and a source electrode of the power switch tube is connected to the primary side current sampling pin and grounded through the current sampling circuit;
the output filter circuit is connected between the input signal circuit and the follow current circuit; and
the chip power supply constant voltage circuit is connected between the input signal circuit and the voltage reduction constant current chip.
9. The buck driver circuit of claim 8, wherein the buck constant current chip further includes a pulse width dimming input pin and a pulse width to analog dimming input pin, and the input signal circuit further comprises:
the pulse width dimming input end is connected to the pulse width dimming input pin through a first filter resistor; and
and the pulse width conversion analog dimming input end is connected to the pulse width conversion analog dimming input pin through a second filter resistor.
10. The buck driver circuit of claim 9, wherein the input signal circuit further comprises an enable input connected to the pulse width dimming input pin via a reverse diode.
11. The step-down driving circuit according to claim 8, wherein the valley bottom detection circuit includes a valley bottom detection capacitor, a first valley bottom detection resistor and a second valley bottom detection resistor connected in series, and wherein one end of the second valley bottom detection resistor is grounded, the output terminal of the valley bottom detection circuit is led out by a common terminal of the first valley bottom detection resistor and the second valley bottom detection resistor, and the input terminal of the valley bottom detection circuit is led out by one end of the valley bottom detection capacitor.
12. The buck driver circuit of claim 8, wherein the freewheeling circuit includes a power inductor and a freewheeling diode connected in series, and wherein the input of the valley detection circuit is connected to a common terminal of the power inductor and the freewheeling diode.
13. The buck drive circuit of claim 8, wherein the output filter circuit comprises a filter capacitor.
14. The buck driver circuit of claim 8, wherein the chip supply constant voltage circuit includes a chip supply voltage division detection circuit having an input coupled to the input signal circuit and an output coupled to the chip supply voltage sampling pin.
15. The step-down driving circuit of claim 14, wherein the chip supply voltage division detection circuit comprises a first division detection resistor and a second division detection resistor connected in series, and the output terminal of the chip supply voltage division detection circuit is led out from a common terminal of the first division detection resistor and the second division detection resistor.
16. The buck driver circuit of claim 8, wherein the chip supply constant voltage circuit includes a loop compensation circuit having a first terminal connected to the switching power supply module and the chip supply voltage sampling feedback modulation pin and a second terminal connected to the chip supply voltage sampling pin.
17. The buck driver circuit of claim 16, wherein the loop compensation circuit includes a first loop compensation capacitor, a second loop compensation capacitor, and a loop compensation resistor, wherein the second loop compensation capacitor is connected in series with the loop compensation resistor and then in parallel with the first loop compensation capacitor, and wherein the first end of the loop compensation circuit is drawn from a common end of the first and second loop compensation capacitors and the second end of the loop compensation circuit is drawn from a common end of the first and loop compensation capacitors.
18. The buck driver circuit according to claim 8, wherein the chip supply constant voltage circuit includes an optical coupling current limiting circuit, and the switching power supply module further includes a power management circuit, an input of the optical coupling current limiting circuit is connected to the switching power supply module, an output of the optical coupling current limiting circuit is connected to an input of the power management circuit, and an output of the power management circuit is connected to the chip supply voltage sampling feedback modulation pin.
19. The buck driver circuit of claim 18, wherein the optocoupler current limiting circuit comprises an optocoupler current limiting resistor.
20. The step-down driving circuit according to any one of claims 8 to 19, wherein the step-down constant current chip further includes a chip power supply input pin, an abnormal state protection signal pin, and a chip reference ground pin.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921282442.4U CN211019358U (en) | 2019-08-07 | 2019-08-07 | Voltage reduction driving circuit |
| TW108213582U TWM591747U (en) | 2019-08-07 | 2019-10-15 | Voltage step-down driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921282442.4U CN211019358U (en) | 2019-08-07 | 2019-08-07 | Voltage reduction driving circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211019358U true CN211019358U (en) | 2020-07-14 |
Family
ID=70768053
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201921282442.4U Active CN211019358U (en) | 2019-08-07 | 2019-08-07 | Voltage reduction driving circuit |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN211019358U (en) |
| TW (1) | TWM591747U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113423159A (en) * | 2021-06-19 | 2021-09-21 | 浙江榆阳电子有限公司 | LED dimming power supply with ultralow dimming depth and dimming method thereof |
-
2019
- 2019-08-07 CN CN201921282442.4U patent/CN211019358U/en active Active
- 2019-10-15 TW TW108213582U patent/TWM591747U/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113423159A (en) * | 2021-06-19 | 2021-09-21 | 浙江榆阳电子有限公司 | LED dimming power supply with ultralow dimming depth and dimming method thereof |
| CN113423159B (en) * | 2021-06-19 | 2023-08-18 | 浙江榆阳电子股份有限公司 | LED dimming power supply with ultralow dimming depth and dimming method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| TWM591747U (en) | 2020-03-01 |
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