CN212628502U - LED backlight driving circuit and control chip for same - Google Patents

LED backlight driving circuit and control chip for same Download PDF

Info

Publication number
CN212628502U
CN212628502U CN202020885106.5U CN202020885106U CN212628502U CN 212628502 U CN212628502 U CN 212628502U CN 202020885106 U CN202020885106 U CN 202020885106U CN 212628502 U CN212628502 U CN 212628502U
Authority
CN
China
Prior art keywords
signal
module
pin
control chip
led
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202020885106.5U
Other languages
Chinese (zh)
Inventor
刘拓夫
周俊
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
On Bright Electronics Shanghai Co Ltd
Original Assignee
On Bright Electronics Shanghai Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by On Bright Electronics Shanghai Co Ltd filed Critical On Bright Electronics Shanghai Co Ltd
Priority to CN202020885106.5U priority Critical patent/CN212628502U/en
Priority to TW109207938U priority patent/TWM601945U/en
Application granted granted Critical
Publication of CN212628502U publication Critical patent/CN212628502U/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Landscapes

  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

The present disclosure provides an LED backlight driving circuit and a control chip for the same. In the control chip, a reference voltage module receives the analog dimming signal and provides a processed analog dimming signal; the loop compensation module generates a first signal based on the processed analog dimming signal and the LED current detection signal; the pulse width modulation dimming module receives an enable or PWM dimming signal to generate a second signal; the logic control module generates a control signal based on the first signal, the second signal, a third signal from the oscillator module, and the current detection signal; the driving module generates a driving signal based on the control signal and provides the driving signal to the GATE pin; the grid electrode of the internal MOS is connected to the pulse width modulation dimming module, the drain electrode is connected to the LED pin, and the source electrode is connected to the FB pin; the output overvoltage protection module is connected to the CS/OVP pin to receive a signal to detect whether the circuit system enters an output overvoltage state.

Description

LED backlight driving circuit and control chip for same
Technical Field
The present disclosure relates generally to the field of Light Emitting Diode (LED) driving circuits, and more particularly to an LED backlight driving circuit and a control chip for the same.
Background
With the development of LED driving technology, it has become common knowledge in the industry to pursue lower cost and higher integration level while ensuring performance.
For example, fig. 1 shows an example of a conventional LED backlight driving scheme 100. In the conventional LED backlight driving scheme 100, a resistor R5 and a capacitor C3 for loop compensation are required to be provided in order to achieve loop stability, a dimming field effect transistor (MOS) Q2 is required to achieve Pulse Width Modulation (PWM) dimming, and an auxiliary filter capacitor C4 and the like are required to achieve analog dimming. Thus, in the conventional LED backlight driving scheme, more auxiliary devices need to be disposed at the periphery of the chip, and more functional pins are needed for the chip (e.g., chip U), which increases the system complexity and increases the system cost.
Disclosure of Invention
In view of one or more of the problems described above, the present disclosure provides a novel LED backlight driving circuit and a control chip for the same.
According to an aspect of the present disclosure, a control chip for an LED backlight driving circuit is provided. The control chip includes: the circuit comprises a reference voltage module, a loop compensation module, a logic control module, a driving module, an oscillator module, a pulse width modulation dimming module, an output overvoltage protection module and an internal MOS. The reference voltage module receives the analog dimming signal through the analog dimming signal input pin and provides the processed analog dimming signal to the loop compensation module; the loop compensation module generates a first signal based on the processed analog dimming signal and the LED current detection signal from the feedback pin; the pulse width modulation dimming module receives an enable or pulse width modulation dimming signal through an enable or pulse width modulation dimming signal input pin and generates a second signal; the logic control module generates a control signal based on the first signal, the second signal, a third signal from the oscillator module, and a current detection signal received through the current detection and output overvoltage protection detection pin; the driving module generates a driving signal based on the control signal and provides the driving signal for the driving pin; the grid of the internal MOS is connected to the pulse width modulation dimming module, the drain is connected to the LED pin, and the source is connected to the feedback pin; the output overvoltage protection module is connected to the current detection and output overvoltage protection detection pin to receive signals to detect whether the circuit system enters an output overvoltage state; when the control chip is used for the LED backlight driving circuit, the control chip is connected to an external voltage input end through a power supply pin to obtain required power, and is connected to the negative electrode of an LED load through an LED pin.
According to another aspect of the present disclosure, an LED backlight driving circuit including the above control chip is provided.
Drawings
The present disclosure may be better understood from the following description of specific embodiments thereof taken in conjunction with the accompanying drawings, in which like reference numerals generally refer to the same parts throughout the different views, and in which:
fig. 1 shows an example of a conventional LED backlight driving scheme.
Fig. 2 shows a schematic diagram of an LED backlight driving circuit according to an embodiment of the present disclosure.
Fig. 3 shows a schematic block diagram of a control chip for an LED backlight driving circuit according to an embodiment of the present disclosure.
Fig. 4 shows an example signal timing diagram when the LED backlight driving circuit according to the embodiment of the present disclosure operates.
Detailed Description
Features and exemplary embodiments of various aspects of the present disclosure will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art, that the present disclosure may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present disclosure by illustrating examples of the present disclosure. The present disclosure is in no way limited to any specific structure, elements, and configurations set forth below, but rather covers any modifications, substitutions, and alterations of structure, elements, and configurations without departing from the spirit of the present disclosure. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present disclosure.
Fig. 2 shows a schematic diagram of an LED backlight driver circuit 200 (in solid-line box) according to an embodiment of the present disclosure. The LED backlight driving circuit 200 may include, for example, a control chip U1, a power inductor L1, a power switch Q1, a freewheeling diode D1, a chip supply capacitor C1, an output filter capacitor C2, and an LED current detection resistor R1, output overvoltage protection (OVP) resistors R2 and R3, a current detection resistor R4, and the like.
Specifically, as shown in fig. 2, the control chip U1 may include the following pins, for example:
an LPWM pin, also referred to as an enable or Pulse Width Modulation (PWM) dimming signal input pin, configured to receive an external enable or PWM dimming signal;
an HPWM pin, also referred to as an analog dimming signal input pin, configured to receive an external analog dimming signal;
an FB pin, also referred to as a feedback pin, configured to receive an LED current detection signal;
LED Pin-connected to the drain of the chip internal MOS;
GND pin-is a reference ground pin of the control chip U1, configured to connect the control chip U1 to chip ground;
the CS/OVP pin, also called as a current detection and output overvoltage protection detection pin, can play the dual roles of current detection and output overvoltage protection.
The GATE pin, also referred to as a drive pin, is configured to output a drive signal.
VDD pin-is the chip power pin of the control chip U1.
The LED backlight driving circuit 200 is shown as a Boost circuit (also referred to as a "Boost chopper circuit"). One end of the power inductor L1 is configured to be connected to a direct current power supply (V)IN). Optionally, a fuse may be connected between the power inductor L1 and the power supply to protect the circuit. The other end of the power inductor L1 is connected to the anode of a freewheeling diode D1; cathode of freewheeling diode D1One end connected to an output filter capacitor C2; the other end of the output filter capacitor C2 is grounded.
The GATE of the power switch Q1 is connected to the GATE pin of the control chip U1, the drain terminal thereof is connected between the power inductor L1 and the anode of the freewheeling diode D1, and the source thereof is grounded via the current detection resistor R4.
A terminal for connecting the anode of the LED load is provided between the cathode of the freewheeling diode D1 and the output filter capacitor C2. When the LED load is driven using the LED backlight driving circuit 200, the anode of the LED load is connected to the terminal, and the cathode of the LED load is connected to the LED pin of the control chip U1. The LED load may be, for example, an LED lamp for providing backlight for a device such as a display screen, or may be other types of LEDs, and is not limited in particular.
The VDD pin of the control chip U1 is configured to receive an external direct current voltage signal (VDD). The VDD pin of the control chip U1 may be connected to the chip supply capacitor C1, and the other end of the chip supply capacitor C1 is connected to chip ground.
One end of the LED current detection resistor R1 is connected to the FB pin of the control chip U1, and the other end thereof is grounded.
The GND pin of the control chip U1 is connected to chip ground.
One end of the OVP resistor R2 is connected to the CS/OVP pin of the control chip U1, and the other end is connected between the power inductor L1 and the anode of the freewheeling diode D1. One end of the OVP resistor R3 is connected to the CS/OVP pin of the control chip U1, and the other end is connected between the power switch tube Q1 and the current detection resistor R4.
The working scenario of the LED backlight driving circuit 200 will be further described in conjunction with fig. 3 and 4.
Fig. 3 shows a schematic block diagram of the control chip U1 of the LED backlight driving circuit 200. As shown, the control chip U1 may include a reference voltage module 310, a loop compensation module 320, a logic control module 330, a driving module 340, an oscillator module 350, a PWM dimming module 360, an internal MOS 370, and an output overvoltage protection module 380, among others. The various modules described above are merely examples, and the control chip U1 may also include other functional modules according to actual needs, and is not limited in particular herein.
The reference voltage module 310 receives the analog dimming signal through the HPWM pin and provides the processed analog dimming signal to the loop compensation module 320.
The loop compensation module 320 generates a first signal based on the processed analog dimming signal and the LED current detection signal from the FB pin.
The PWM dimming module 360 receives the LPWM signal through the LPWM pin and generates a second signal.
The logic control module 330 is configured to generate a control signal based on the first signal from the loop compensation module 320, the second signal from the PWM dimming module 360, the third signal from the oscillator module 350, and the current detection signal received through the CS/OVP pin, and output the control signal to the driving module 340.
The driver module 340 generates a driver signal based on the control signal and provides the driver signal to the GATE pin.
The gate of the internal MOS 370 is connected to the PWM dimming module 360, the drain thereof is connected to the LED pin, and the source thereof is connected to the FB pin.
The output over-voltage protection module 380 is connected to the CS/OVP pin to receive a signal to detect whether a circuit system (e.g., an LED backlight driving circuit system to which the control chip U1 is applied) enters an output over-voltage state.
As shown in fig. 3, the PWM dimming MOS is integrated inside the control chip U1, a filter capacitor (e.g., the auxiliary filter capacitor C4 in fig. 1) required for analog dimming is omitted, and the loop compensation module is provided to integrate the loop compensation into the control chip. The control chip U1 reduces the function pins through the multiplexing of CS/OVP, that is, detects the switch tube current and performs loop control when the power switch tube Q1 is turned on, and detects the output voltage when the power switch tube Q1 is turned off. The control chip U1 reduces the overall volume of the LED backlight driving circuit by reducing the number of functional pins and reducing the number of auxiliary devices on the periphery of the system, thereby improving the system integration level and reducing the system cost.
The following is combined with the drawing4, the basic operation principle of the LED backlight driving circuit 200 will be described. FIG. 4 shows a timing diagram of the main signals involved in the operation of the LED backlight driver circuit 200 over time, where 410 indicates the chip supply Voltage (VDD) of the control chip U1, 420 indicates the enable or PWM dimming signal (LPWM), 430 indicates the analog dimming signal (HPWM), 440 indicates the driving signal output at the GATE pin of the control chip U1 (S1)GATE) And 450 indicates the operating current (I) of the LEDLED)。
When the LED backlight driving circuit 200 operates, the control chip U1 controls the system to operate in a constant current state, and the compensation loop is fully integrated inside the chip, for example, the loop compensation module 320 shown in fig. 3.
The control chip U1 controls the whole loop by using the logic control module 330 based on the LPWM signal received through the LPWM pin, and controls the on/off of the LED load by using the internal MOS 370, thereby implementing the PWM dimming control.
The control chip U1 converts the analog dimming signal received through the HPWM pin into a reference voltage of an output current inside the chip according to the duty ratio of the analog dimming signal by using the reference voltage module 310, so that the current of the LED load varies with the duty ratio of the analog dimming signal to complete the analog dimming control.
The system can work in PWM dimming mode and analog dimming mode simultaneously, and various dimming requirements are flexibly achieved.
The control chip provided by the application integrates PWM dimming MOS in the chip, omits an auxiliary filter capacitor in the traditional LED backlight driving scheme, integrates the loop compensation module in the control chip, and reduces the pins of the chip through pin multiplexing, so that the whole volume of the LED backlight driving circuit is reduced, the system integration level is improved, and the system cost is reduced.
The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the disclosure being defined by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (10)

1. A control chip for an LED backlight driving circuit is characterized by comprising:
the circuit comprises a reference voltage module, a loop compensation module, a logic control module, a driving module, an oscillator module, a pulse width modulation dimming module, an output overvoltage protection module and an internal MOS (metal oxide semiconductor);
the reference voltage module receives an analog dimming signal through an analog dimming signal input pin (HPWM) of the control chip and provides the processed analog dimming signal to the loop compensation module;
the loop compensation module generates a first signal based on the processed analog dimming signal and an LED current detection signal from a feedback pin (FB) of the control chip;
the pulse width modulation dimming module receives an enable or pulse width modulation dimming signal through an enable or pulse width modulation dimming signal input pin (LPWM) of the control chip and generates a second signal;
the logic control module is configured to generate a control signal based on the first signal, the second signal, a third signal from the oscillator module, and a current sense signal received through a current sense and output over-voltage protection sense pin (CS/OVP) of the control chip;
the driving module generates a driving signal based on the control signal from the logic control module and provides the driving signal to a driving pin (GATE) of the control chip;
a gate of the internal MOS is connected to the pulse width modulation dimming module, a drain of the internal MOS is connected to an LED pin (LED) of the control chip, and a source of the internal MOS is connected to the feedback pin (FB);
the output overvoltage protection module is connected to the current detection and output overvoltage protection detection pin (CS/OVP) to receive signals to detect whether a circuit system enters an output overvoltage state; and is
When the control chip is used for an LED backlight driving circuit, the control chip is connected to an external voltage input end through a power supply pin (VDD) to obtain required power, and is connected to the negative electrode of an LED load through an LED pin (LED).
2. The control chip of claim 1, further comprising: a reference ground pin (GND) for connecting the control chip to a chip ground.
3. An LED backlight driving circuit, characterized by comprising: a control chip as claimed in claim 1 or 2.
4. The LED backlight driving circuit according to claim 3, comprising a first resistor for LED current detection, said first resistor having one end connected to said feedback pin (FB) of said control chip and the other end connected to chip ground; and is
The loop compensation module of the control chip is configured to ensure that the LED backlight driving circuit operates in a constant current state based on the LED current detection signal of the feedback pin (FB).
5. The LED backlight driver circuit according to claim 3, comprising a chip supply capacitor having one end connected to said supply pin (VDD) of said control chip and the other end connected to a chip ground.
6. The LED backlight driving circuit according to claim 3, wherein:
the LED backlight driving circuit is a Boost circuit, and further comprises a power inductor, a freewheeling diode, an output filter capacitor, a current detection resistor and a power switch tube;
one end of the power inductor is connected to an input voltage end, the other end of the power inductor is connected to the anode of the freewheeling diode, the cathode of the freewheeling diode is connected to one end of the output filter capacitor, and the other end of the output filter capacitor is grounded;
the grid electrode of the power switch tube is connected to the driving pin (GATE) of the control chip, the drain electrode of the power switch tube is connected between the inductor and the anode of the diode, and the source electrode of the power switch tube is grounded through the current detection resistor; and is
And a terminal used for connecting the anode of the LED load is arranged between the cathode of the freewheeling diode and the output filter capacitor.
7. The LED backlight driver circuit of claim 6, wherein the logic control module is configured to control the LED backlight driver circuit based on the second signal.
8. The LED backlight driving circuit according to claim 6, wherein the LED backlight driving circuit is configured to control the switching of the LED load using the internal MOS.
9. The LED backlight driving circuit as claimed in claim 6, wherein the reference voltage module is configured to convert the analog dimming signal into a reference voltage of an output current inside the control chip according to a duty ratio of the analog dimming signal, so that a current of the LED load varies with the duty ratio of the analog dimming signal.
10. The LED backlight driving circuit according to claim 6, further comprising a second resistor and a third resistor:
one end of the second resistor is connected to a current detection and output overvoltage protection detection pin (CS/OVP) of the control chip, and the other end of the second resistor is connected between the power inductor and the anode of the freewheeling diode; and is
One end of the third resistor is connected to a current detection and output overvoltage protection detection pin (CS/OVP) of the control chip, and the other end of the third resistor is connected between the source electrode of the power switch tube and the current detection resistor.
CN202020885106.5U 2020-05-22 2020-05-22 LED backlight driving circuit and control chip for same Active CN212628502U (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN202020885106.5U CN212628502U (en) 2020-05-22 2020-05-22 LED backlight driving circuit and control chip for same
TW109207938U TWM601945U (en) 2020-05-22 2020-06-22 LED backlight driving circuit and control chip applied in the same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202020885106.5U CN212628502U (en) 2020-05-22 2020-05-22 LED backlight driving circuit and control chip for same

Publications (1)

Publication Number Publication Date
CN212628502U true CN212628502U (en) 2021-02-26

Family

ID=74094664

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202020885106.5U Active CN212628502U (en) 2020-05-22 2020-05-22 LED backlight driving circuit and control chip for same

Country Status (2)

Country Link
CN (1) CN212628502U (en)
TW (1) TWM601945U (en)

Cited By (2)

* Cited by examiner, † Cited by third party
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
CN114641112A (en) * 2022-05-17 2022-06-17 西蒙电气（中国）有限公司 Circuit structure, method and device for realizing smooth dimming of output pulse width feedback based on power supply chopping, processor and storage medium thereof

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI774572B (en) * 2021-05-25 2022-08-11 大陸商昂寶電子（上海）有限公司 Multi-mode dimming circuit and method

Cited By (3)

* Cited by examiner, † Cited by third party
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
CN114641112A (en) * 2022-05-17 2022-06-17 西蒙电气（中国）有限公司 Circuit structure, method and device for realizing smooth dimming of output pulse width feedback based on power supply chopping, processor and storage medium thereof

Also Published As

Publication number Publication date
TWM601945U (en) 2020-09-21

Similar Documents

Publication Publication Date Title
CN212628502U (en) LED backlight driving circuit and control chip for same
US8188679B2 (en) Self-powered LED bypass-switch configuration
US7224128B2 (en) Device for driving light emitting diode strings
US7358685B2 (en) DC-DC converter having protective function of over-voltage and over-current and led driving circuit using the same
US10152926B2 (en) Driving circuit for light emitting element, light emitting device using same, and display apparatus
US7675240B2 (en) Light emitting diode circuit having even current
KR101005796B1 (en) Light-emitting diode driving circuit
US20110227503A1 (en) System and method for led backlight driver for lcd panels
US9041310B2 (en) Load driving apparatus related to light emitting diodes
GB2534098A (en) Over-current protection circuit, LED backlight driving circuit and liquid crystal display
US8115536B2 (en) Self-oscillating switch circuit for use in a switching DC-DC converter
US11265981B2 (en) Light emitting element driving device
US9661705B1 (en) Power conversion apparatus for decreasing number of pins
US10143061B2 (en) Constant current power supply with a plurality of current outputs for LED lamps
CN112351551B (en) Dimming circuit
EP2914064A1 (en) Drive circuit and illumination device comprising the drive circuit
CN102036450A (en) LED driving circuit
CN212628493U (en) LED drive circuit and control chip for same
KR101518554B1 (en) Power supplies to drive the multiple LED modules and the lighting apparatus including the same
US11350501B2 (en) LED driving circuit based on t-shaped lamp tube
US20090295305A1 (en) Led driver circuit
US8692476B2 (en) Boost circuit for LED backlight driver circuit
CN216217660U (en) Light emitting diode driving circuit
CN215734942U (en) LED drive circuit
CN111063311A (en) Boost circuit, backlight drive circuit and display panel

Legal Events

Date Code Title Description
GR01 Patent grant
GR01 Patent grant