An LED linear drive VOS voltage adaptive regulation circuit

Abstract

The present invention discloses an LED linear drive vos voltage adaptive regulation circuit, comprising a transistor M1, a transistor M2, a transistor M3, a transistor M4, a transistor M5, a transistor M6, a transistor M7, an LED, an LED current configuration module Iled control, a current source Idc, a resistor R and a class AB amplifier ClassAB. The present invention realizes adaptive regulation of the vos voltage when the LED configuration current changes, and minimizes the voltage across the transistor M1, thereby reducing working power consumption, improving efficiency, and improving LED current accuracy.

Description

Technical Field

[0001] The invention relates to a regulating circuit, in particular to an LED linear drive vos voltage adaptive regulating circuit, belonging to the technical field of semiconductor integrated circuits. Background Art

[0002] The infrared LED driver on the PC side usually adopts a linear drive method to meet the requirement that the output current can be linearly adjusted between 100mA~800mA or even higher current, thereby achieving the functional requirement of controlling the brightness of the infrared LED. LED is generally powered by a buck, such as Figure 2 As shown in the figure, VOUT is the output of the buck inside the chip, VLED is the PN junction voltage of the LED, and the voltage difference between VOUT and VLED is the voltage difference between PMOS, which is called vos voltage. In practical applications, in order to improve efficiency and reduce power consumption, vos should not be too large, but in order to ensure the normal operation of PMOS under different currents, vos should not be too small. In addition, due to different types of VLED, its voltage varies between 1.5V and 2.5V, so the vos voltage needs to be adaptively adjusted according to the changes in VLED to meet the power consumption requirements of different applications.

[0003] Traditional architecture 1 usually anchors the buck output according to the VLED value and the required current range of the LED, that is, the maximum vos voltage that meets the required LED current. Assuming VLED is 2.5V and VOUT is set to 2.9V, the vos voltage is determined to be 400mV, and the output PMOS loss is also determined accordingly. However, it limits the application range of the VLED voltage and has its limitations in chip applications.

[0004] In the traditional architecture, the vos voltage is set to several levels, such as 200mV, 400mV, and 600mV. According to the VLED voltage and current of different applications, it is selected through I2C configuration to determine the vref voltage of EA in the buck circuit and finally the output voltage VOUT. Although this solution solves the application problem under different VLED voltages, the vos voltage cannot be changed flexibly under a wide range of current applications, which affects the consistency of current accuracy under different conditions and the power consumption cannot be used most effectively.

[0005] In summary, an architecture is needed to achieve adaptive regulation of the vos voltage, and to improve the current accuracy of the LED at various currents while flexibly meeting the power consumption requirements. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an LED linear drive vos voltage adaptive regulation circuit to achieve adaptive regulation of the voltage difference vos between VOUT and VLED.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A LED linear drive vos voltage adaptive regulation circuit comprises a transistor M1, a transistor M2, a transistor M3, a transistor M4, a transistor M5, a transistor M6, a transistor M7, an LED, an LED current configuration module Iled control, a current source Idc, a resistor R and a class AB amplifier ClassAB, the source of the transistor M1, the source of the transistor M2 and the source of the transistor M3 are connected to a power supply VOUT, the gate of the transistor M1 is connected to the gate of the transistor M2, the drain of the transistor M2, the output end of the LED current configuration module Iledcontrol and the gate of the transistor M3 are connected, the drain of the transistor M1 is connected to the anode of the LED and generates an output signal VLED, the drain of the transistor M3 is connected to the drain of the transistor M7, the gate of the transistor M7 and the gate of the transistor M6, the cathode of the LED and the source of the transistor M7 are connected to the gate of the transistor M7. The gate of the transistor M4 and the source of the transistor M6 are grounded, the drain of the transistor M6 is connected to the drain of the transistor M4, the gate of the transistor M4 and the gate of the transistor M5, the source of the transistor M4, the source of the transistor M5 and one end of the current source Idc are connected to the power supply AVDD, the drain of the transistor M5 is connected to the other end of the current source Idc and one end of the resistor R to generate an output signal vos_pre, the other end of the resistor R is connected to the output end of the class AB amplifier ClassAB and the inverting input end of the class AB amplifier ClassAB, and the non-inverting input end of the class AB amplifier ClassAB is connected to the voltage division signal VLED_div.

[0009] Furthermore, the transistor M1 , the transistor M2 , the transistor M3 , the transistor M4 and the transistor M5 are PMOS transistors, and the transistor M6 and the transistor M7 are NMOS transistors.

[0010] Furthermore, the transistor M1 and the transistor M2 form a current mirror circuit, and the ratio of the width to length of the transistor M1 and the transistor M2 is k1:1.

[0011] Furthermore, the transistor M2 and the transistor M3 form a current mirror circuit, the transistor M4 and the transistor M5 form a current mirror circuit, and the ratio of the width to length of the transistor M2, the transistor M3, the transistor M4 and the transistor M5 is k2:1:1:1.

[0012] Furthermore, the transistor M6 and the transistor M7 form a current mirror circuit, and the ratio of the width to length of the transistor M6 to the transistor M7 is 1:1.

[0013] Further, the voltage division signal VLED_div is a voltage division signal of the output signal VLED.

[0014] Furthermore, the output signal vos_pre is used as a reference voltage of the EA module in the buck circuit, and the output signal vos_pre determines the size of VOUT, that is, VOUT=K*vos_pre.

[0015] Compared with the prior art, the present invention has the following advantages and effects: the present invention provides an LED linear drive vos voltage adaptive regulation circuit, which realizes the adaptive regulation of the vos voltage when the LED configuration current changes, and minimizes the voltage across the transistor M1, thereby reducing the working power consumption, improving the efficiency, and improving the LED current accuracy; since the transistor M1 is generally in the linear region when working normally, its over-drive voltage will increase with the increase of the LED current, and when the current changes, through current conversion, the current on the transistor M5 will also increase with the LED current, thereby increasing vos_pre, and finally achieving the purpose of increasing VOUT, and vos also increases, so that the drain-source voltage vds of the transistor M1 increases with the increase of the saturated drain-source voltage vdsat, and the power consumption is saved to the maximum extent under the same conditions, and the transistor M1 will not enter the deep linear region under certain current configurations, thereby improving the LED current accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of an LED linear drive vos voltage adaptive regulation circuit of the present invention.

[0017] Figure 2 Schematic diagram of an LED power supply circuit in the prior art. DETAILED DESCRIPTION

[0018] In order to elaborate on the technical scheme adopted by the present invention to achieve the predetermined technical purpose, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments, and the technical means or technical features in the embodiments of the present invention can be replaced without paying creative work. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0019] like Figure 1As shown, an LED linear drive vos voltage adaptive regulation circuit of the present invention comprises a transistor M1, a transistor M2, a transistor M3, a transistor M4, a transistor M5, a transistor M6, a transistor M7, an LED, an LED current configuration module Iledcontrol, a current source Idc, a resistor R and a class AB amplifier ClassAB, the source of the transistor M1, the source of the transistor M2 and the source of the transistor M3 are connected to a power supply VOUT, the gate of the transistor M1 is connected to the gate of the transistor M2, the drain of the transistor M2, and the LED current configuration module Iled The output end of control is connected to the gate of transistor M3, the drain of transistor M1 is connected to the anode of LED and generates output signal VLED, the drain of transistor M3 is connected to the drain of transistor M7, the gate of transistor M7 and the gate of transistor M6, the cathode of LED, the source of transistor M7 and the source of transistor M6 are grounded, the drain of transistor M6 is connected to the drain of transistor M4, the gate of transistor M4 and the gate of transistor M5, the source of transistor M4, the source of transistor M5 and one end of current source Idc are connected to power supply AVDD, the drain of transistor M5 is connected to the other end of current source Idc and one end of resistor R and generates output signal vos_pre, the other end of resistor R is connected to the output end of class AB amplifier ClassAB and the inverting input end of class AB amplifier ClassAB, and the non-inverting input end of class AB amplifier ClassAB is connected to voltage division signal VLED_div.

[0020] The current flowing through transistor M2 is the configuration current of the LED, which generates the real current of the LED flowing through transistor M1 at a certain amplification ratio, generates the sampling current flowing through transistor M3 at a certain sampling ratio, and then converts it from the voltage domain of VOUT to the voltage domain of AVDD through the current mirror, and finally flows to the resistor R through transistor M5, superimposing the initial Idc to generate the vos_pre voltage.

[0021] The transistor M1 , the transistor M2 , the transistor M3 , the transistor M4 and the transistor M5 are PMOS transistors, and the transistor M6 and the transistor M7 are NMOS transistors.

[0022] The transistor M1 and the transistor M2 form a current mirror circuit, and the ratio of the width to length of the transistor M1 and the transistor M2 is k1:1.

[0023] The transistor M2 and the transistor M3 form a current mirror circuit, the transistor M4 and the transistor M5 form a current mirror circuit, and the ratio of the width to length of the transistor M2, the transistor M3, the transistor M4 and the transistor M5 is k2:1:1:1.

[0024] The transistor M6 and the transistor M7 form a current mirror circuit, and the ratio of the width to length of the transistor M6 and the transistor M7 is 1:1.

[0025] The current flowing through transistor M1 is I LED , the configuration current flowing through transistor M2 is I2. Since the width-to-length ratio of transistor M1 and transistor M2 is k1:1, I LED =k1*I2.

[0026] Since the ratio of the width to length of the transistors M2 and M3 is k2:1, the current flowing through the transistor M3 is I2 / k2, and the current flowing through the transistor M7 is also I2 / k2. Since the ratio of the width to length of the transistors M6 and M7 is 1:1, the current flowing through the transistor M6 is I2 / k2, and the current flowing through the transistor M4 is also I2 / k2. Since the ratio of the width to length of the transistors M4 and M5 is 1:1, the current flowing through the transistor M5 is I5 = I2 / k2.

[0027] The voltage at the lower end of resistor R is equal to VLED_div, and the output signal vos_pre is:

[0028]

[0029] The voltage-divided signal VLED_div is a voltage-divided signal of the output signal VLED.

[0030] The output signal vos_pre is used as the reference voltage of the EA module in the buck circuit. The output signal vos_pre determines the size of VOUT, that is, VOUT=K*vos_pre.

[0031] The current I on the LED LED The minimum is generally 100mA. When the configuration current increases, the current I2 on transistor M2 increases, the overdrive voltage of transistor M2 increases, and the current I3 on ​​transistor M3 also increases, so the current I5 with a certain proportional coefficient to I3 also increases, so the voltage Vr falling on the resistor R also increases. vos_pre is the sum of the voltage divider signal VLED_div and the Vr voltage, so the voltage of vos_pre will also increase. And vos_pre is equivalent to the vref voltage of the EA module in the buck circuit, which determines the voltage of VOUT. The voltage expression of VOUT is

[0032] Vout = K*vos_pre;

[0033] Then the vos voltage expression is

[0034] vos=VOUT-VLED.

[0035] The change trend of the power supply VOUT is consistent with the output signal vos_pre, so the voltage of VOUT also increases. Since the value of VLED remains basically unchanged, the vos voltage also increases. On the contrary, when the configuration current decreases, the current I2 on the transistor M2 decreases, and I LED It also becomes smaller, which eventually causes the vos voltage to become smaller.

[0036] Since the overdrive voltage of M1 changes exponentially with the increase of LED current, the vos voltage also changes exponentially with the increase of LED current, realizing adaptive adjustment of the vos voltage when the LED configuration current changes, ensuring that the vos voltage can minimize power consumption and improve efficiency under different LED currents, while also preventing the transistor M1 from entering the deep linear region under large currents, thereby improving the LED current accuracy.

[0037] The present invention provides an LED linear drive vos voltage adaptive regulation circuit, which realizes the adaptive regulation of the vos voltage when the LED configuration current changes, and minimizes the voltage across the transistor M1, thereby reducing the working power consumption, improving the efficiency, and improving the LED current precision; since the transistor M1 is generally in a linear region when working normally, its over-driving voltage will increase with the increase of the LED current, and when the current changes, through current conversion, the current on the transistor M5 will also increase with the LED current, so that vos_pre increases, and finally the purpose of increasing VOUT is achieved, and vos also increases, so that the drain-source voltage vds of the transistor M1 increases with the increase of the saturated drain-source voltage vdsat, and the power consumption is saved to the maximum extent under the same conditions, and the transistor M1 will not enter the deep linear region under certain current configurations, thereby improving the LED current precision.

[0038] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. An LED linear drive vos voltage adaptive regulation circuit, characterized by: It includes a transistor M1, a transistor M2, a transistor M3, a transistor M4, a transistor M5, a transistor M6, a transistor M7, an LED, an LED current configuration module Iled control, a current source Idc, a resistor R and a class AB amplifier ClassAB, the source of the transistor M1, the source of the transistor M2 and the source of the transistor M3 are connected to the power supply VOUT, the gate of the transistor M1 and the gate of the transistor M2, the drain of the transistor M2, and the LED current configuration module Iled The output end of control is connected to the gate of transistor M3, the drain of transistor M1 is connected to the anode of LED and generates output signal VLED, the drain of transistor M3 is connected to the drain of transistor M7, the gate of transistor M7 and the gate of transistor M6, the cathode of LED, the source of transistor M7 and the source of transistor M6 are grounded, the drain of transistor M6 is connected to the drain of transistor M4, the gate of transistor M4 and the gate of transistor M5, the source of transistor M4, the source of transistor M5 and one end of current source Idc are connected to power supply AVDD, the drain of transistor M5 is connected to the other end of current source Idc and one end of resistor R and generates output signal vos_pre, the other end of resistor R is connected to the output end of class AB amplifier ClassAB and the inverting input end of class AB amplifier ClassAB, the non-inverting input end of class AB amplifier ClassAB is connected to the voltage division signal VLED_div; the output signal vos_pre is used as the reference voltage of EA module in buck circuit, and the output signal vos_pre determines the size of VOUT, that is, VOUT=K*vos_pre.

2. The LED linear drive vos voltage adaptive regulation circuit according to claim 1, characterized in that: The transistor M1 , the transistor M2 , the transistor M3 , the transistor M4 and the transistor M5 are PMOS transistors, and the transistor M6 and the transistor M7 are NMOS transistors.

3. The LED linear drive vos voltage adaptive regulation circuit according to claim 1, characterized in that: The transistor M1 and the transistor M2 form a current mirror circuit, and the ratio of the width to length of the transistor M1 and the transistor M2 is k1:

1.

4. The LED linear drive vos voltage adaptive regulation circuit according to claim 3, characterized in that: The transistor M2 and the transistor M3 form a current mirror circuit, the transistor M4 and the transistor M5 form a current mirror circuit, and the ratio of the width to length of the transistor M2, the transistor M3, the transistor M4 and the transistor M5 is k2:1:1:

1.

5. The LED linear drive vos voltage adaptive regulation circuit according to claim 3, characterized in that: The transistor M6 and the transistor M7 form a current mirror circuit, and the ratio of the width to length of the transistor M6 to the transistor M7 is 1:

1.

6. The LED linear drive vos voltage adaptive regulation circuit according to claim 1, characterized in that: The voltage division signal VLED_div is a voltage division signal of the output signal VLED.

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