TW201349932A - Integrated dimming control circuit - Google Patents

Abstract

An integrated dimming control circuit includes a gate signal generation unit, a dimming signal generation unit, and a current boost unit. The gate signal generation unit is used for receiving a pulse width modulation signal, and generating a gate signal according to the pulse width modulation signal. The dimming signal generation unit is used for receiving an original dimming signal, and generating a plurality of dimming signals and a predetermined clock according to a resistor-capacitor time constant determined by an external resistor and an external capacitor and the original dimming signal. The dimming signal generation unit determines a phase difference between each adjacent two dimming signal according to the resistor-capacitor time constant. The current boost unit is used for receiving a current boost signal, and scaling duty cycles of the plurality of dimming signals according to the current boost signal.

Description

Integrated dimming control circuit

The invention relates to an integrated dimming control circuit, in particular to an integrated dimming control circuit capable of generating a plurality of dimming signals according to a time constant of a resistor and capacitor determined by an external resistor and an external capacitor and an original dimming signal.

Please refer to FIG. 1. FIG. 1 is a schematic diagram of a dimming control circuit 100 for the prior art. As shown in FIG. 1, the dimming control circuit 100 includes a microprocessor 102 and a dimming boost controller 104. The microprocessor 102 is configured to receive a raw pulse width modulation signal OPWM and generate a plurality of pulse width modulation signals PWM1-PWMn according to the original pulse width modulation signal OPWM, where n is coupled to the dimming boost The number of loads of the controller 104 is determined, and there is a phase difference between each adjacent two pulse width modulation signals. The dimming boost controller 104 is coupled to the microprocessor 102 for generating a gate signal GS and for generating a plurality of dimming signals DS1-DSn according to the plurality of pulse width modulation signals PWM1-PWMn. As shown in FIG. 1, the gate signal GS is used to control the opening and closing of the primary side switch 1202 of a power converter 120 for boosting purposes; and the plurality of dimming signals DS1-DSn are used to transmit the switch. S1-Sn controls the average current flowing through the loads L1-Ln coupled to the secondary side of the power converter 120 for dimming purposes.

However, if a user wants to adjust between each adjacent two pulse width modulation signals When the phase difference is different, the user must write a firmware program and burn it to the microprocessor 102. Then, the microprocessor 102 adjusts the phase difference between each adjacent two pulse width modulation signals according to the firmware program. Therefore, the dimming control circuit 100 is not a convenient and practical dimming control circuit for the user.

An embodiment of the invention provides an integrated dimming control circuit. The integrated dimming control circuit comprises a gate signal generating unit, a dimming signal generating unit and a boosting current unit. The gate signal generating unit is configured to receive a pulse width modulation signal, and generate a pole signal according to the pulse width modulation signal; the dimming signal generating unit is configured to receive an original dimming signal, and according to a resistor and a time constant determined by an external resistor and an external capacitor, and the original dimming signal, generating a plurality of dimming signals and a predetermined clock, wherein the dimming signal generating unit is determined according to the time constant of the resistor and capacitor a phase difference between each adjacent two dimming signals; the boosting current unit is configured to receive a boosting current signal, and scale a duty cycle of the plurality of dimming signals according to the boosting current signal.

The invention provides an integrated dimming control circuit. The integrated dimming control circuit generates a plurality of dimming signals and a predetermined clock according to a resistor-capacitor time constant and an original dimming signal determined by an external resistor and an external capacitor, and according to a boost current signal, Scale the duty cycle of the plurality of dimming signals. Because the integrated dimming control circuit determines the phase difference between each adjacent two dimming signals according to the time constant of the resistor and capacitor, a user only needs to adjust the resistance value of the external resistor and the external By connecting the capacitance value of the capacitor, the phase difference between each adjacent two dimming signals can be controlled without writing a firmware program that drives a microprocessor. In addition, the integrated dimming control circuit can scale the duty cycle of the plurality of dimming signals according to the boosting current signal to prevent the load coupled to the secondary side of a power converter from being burned. Therefore, the present invention is not only convenient and practical, but also has a lower cost than the prior art.

Please refer to FIG. 2. FIG. 2 is a schematic diagram showing an integrated dimming control circuit 200 according to an embodiment of the present invention. As shown in FIG. 2, the integrated dimming control circuit 200 includes a gate signal generating unit 202, a dimming signal generating unit 204, and a boosting current unit 206. The gate signal generating unit 202 is configured to receive a pulse width modulation signal PWM and generate a gate signal GS according to the pulse width modulation signal PWM. The dimming signal generating unit 204 is configured to receive an original dimming signal ODS. And generating a plurality of dimming signals (for example, four dimming signals DS1-DS4) and a predetermined one according to a resistor-resistance time constant (RCTC) determined by an external resistor R and an external capacitor C, and the original dimming signal ODS. The clock CLK, wherein the dimming signal generating unit 204 determines a phase difference (for example, 90°) between each adjacent two dimming signals according to a resistance-capacitance time constant (RCTC). However, the present invention is not limited to the dimming signal generating unit 204 generating four dimming signals DS1-DS4 according to the resistance-capacitance time constant (RCTC) and the original dimming signal ODS. The boost current unit 206 is configured to receive a boost current signal CBS and scale the duty cycle of the four dimming signals DS1-DS4 according to the boost current signal CBS.

As shown in FIG. 2, the gate signal GS is used to control a power converter 220. The primary side switch 2202 is turned on and off to boost an input voltage VIN to an output voltage VOUT. The dimming signal generating unit 204 includes a logic gate 2042. The logic gate 2042 is configured to sequentially generate four dimming signals DS1-DS4 according to the original dimming signal ODS and the resistance-capacitance time constant (RCTC), that is, the logic gate 2042 is based on the original dimming signal ODS and the resistance-capacitance time constant. (RCTC), generating a dimming signal DS1; then generating a dimming signal DS2 according to the dimming signal DS1 and a resistance-capacitance time constant (RCTC); and then generating a dimming signal according to the dimming signal DS2 and the resistance-capacitance time constant (RCTC) DS3; Finally, according to the dimming signal DS3 and the resistance-capacitance time constant (RCTC), the dimming signal DS4 is generated. Because the dimming signal generating unit 204 determines the phase difference between each adjacent two dimming signals according to the resistance-capacitance time constant (RCTC), when a user wants to change the resistance-capacitance time constant (RCTC), the user Only the resistance value of the external resistor R and the capacitance value of the external capacitor C are required. In addition, the predetermined clock CLK is the original dimming signal used as input to a slave integrated dimming control circuit 240. Therefore, the slave integrated dimming control circuit 240 can generate another dimming signal and another predetermined clock according to the predetermined clock CLK. In this way, the user can determine the number of slave integrated dimming control circuits according to the number of loads (for example, the number of strings of light-emitting diodes). However, the invention is not limited to the load being a string of light-emitting diodes.

As shown in FIG. 2, the four dimming signals DS1-D4 are controlled by the switches S1-S4 to pass through the load coupled to the secondary side of the power converter 220 (for example, 4 LED strings LD1-LD4). The average current (because the average current flowing through a load is proportional to the duty cycle of a dimming signal). Thus, the 4-light diode string LD1-LD4 can be based on the relative The average current should be illuminated. In another embodiment of the invention, switches S1-S4 are integrated within integrated dimming control circuit 200. The boost current unit 206 in the integrated dimming control circuit 200 can scale the duty cycle of the four dimming signals DS1-DS4 according to the boost current signal CBS. That is, the boost current unit 206 can scale the duty cycle of the four dimming signals DS1-DS4 according to the boost current signal CBS to adjust the load flowing through the secondary side of the power converter 220 (4 LED strings) The average current of LD1-LD4) and avoid burning of the four LED strings LD1-LD4. However, when the boost current unit 206 scales the duty cycle of the four dimming signals DS1-DS4 according to the boost current signal CBS, if the duty cycle of the four dimming signals DS1-DS4 is less than a threshold, the logic gate 2042 is removed. Can and 4 dimming signals DS1-DS4 are for synchronization. That is, when the duty cycle of the four dimming signals DS1-DS4 is less than the critical value, since the logic gate 2042 is deenergized, the four LED strings LD1-LD4 can be simultaneously synchronized according to the four dimming signals DS1-DS4. Turn it on or off at the same time.

As shown in FIG. 2, the integrated dimming control circuit 200 further includes an overcurrent protection unit 208. The overcurrent protection unit 208 is configured to generate an overcurrent protection signal OCPS to gate signal generating unit 202 according to whether a current IF flowing through the primary side switch 2202 is greater than a predetermined current value. Then, the gate signal generating unit 202 can remove the gate signal GS to turn off the primary side switch 2202 to generate overcurrent protection. As shown in FIG. 2, the integrated dimming control circuit 200 further includes an overvoltage protection unit 210. The overvoltage protection unit is configured to generate an overvoltage protection signal OVPS to the gate signal generating unit 202 according to whether the divided voltage VD of the output voltage VOUT of the secondary side of the power converter 220 is greater than a predetermined voltage value. Then, the gate signal generating unit 202 The gate signal GS can be removed to turn off the primary side switch 2202 to generate overvoltage protection. As shown in FIG. 2, the integrated dimming control circuit 200 further includes an over temperature protection unit 212. The over temperature protection unit 212 is configured to generate an over temperature protection signal OTPS to the gate according to whether the temperature of the four LED strings LD1-LD4 coupled to the secondary side of the power converter 220 is greater than a predetermined temperature value. Signal generation unit 202. Then, the gate signal generating unit 202 can remove the gate signal GS to turn off the primary side switch 2202 to generate temperature protection.

In summary, the integrated dimming control circuit provided by the present invention generates a plurality of dimming signals and predetermined clocks according to a resistor-capacitance time constant and an original dimming signal determined by an external resistor and an external capacitor, and according to the boost. The current signal, which scales the duty cycle of a plurality of dimming signals. Because the integrated dimming control circuit determines the phase difference between each adjacent two dimming signals according to the time constant of the resistor and capacitor, the user only needs to adjust the resistance value of the external resistor and the capacitance value of the external capacitor to control each The phase difference between two adjacent dimming signals does not require writing a firmware that drives a microprocessor. In addition, the integrated dimming control circuit can scale the duty cycle of the plurality of dimming signals according to the boosting current signal to avoid the load being burned to the secondary side of the power converter. Therefore, compared with the prior art, the integrated dimming control circuit provided by the present invention is not only convenient and practical, but also has low cost.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100‧‧‧ dimming control circuit

102‧‧‧Microprocessor

104‧‧‧ dimming boost controller

120, 220‧‧‧ power converter

200‧‧‧Integrated dimming control circuit

240‧‧‧ Follow-up integrated dimming control circuit

202‧‧‧gate signal generation unit

204‧‧‧Dimming signal generation unit

206‧‧‧Upper current unit

208‧‧‧Overcurrent protection unit

210‧‧‧Overvoltage protection unit

212‧‧‧Over temperature protection unit

1202, 2202‧‧‧ primary side switch

2042‧‧‧Logic gate

C‧‧‧External capacitor

CBS‧‧‧Raise current signal

CLK‧‧‧ scheduled clock

DS1-DS4, DS1-DSn‧‧‧ dimming signal

GS‧‧‧ gate signal

IF‧‧‧ current

OCPS, OVPS, OTPS‧‧‧ signals

OPWM‧‧‧ raw pulse width modulation signal

ODS‧‧‧ original dimming signal

PWM, PWM1-PWMn‧‧‧ pulse width modulation signal

R‧‧‧ external resistor

S1-S4, S1-Sn‧‧‧ switch

LD1-LD4‧‧‧Light Diode String

L1-Ln‧‧‧ load

VIN‧‧‧ input voltage

VOUT‧‧‧ output voltage

VD‧‧‧ partial pressure

Figure 1 is a schematic diagram of a dimming control circuit for the prior art.

2 is a schematic diagram showing an integrated dimming control circuit according to an embodiment of the present invention.

200‧‧‧Integrated dimming control circuit

202‧‧‧gate signal generation unit

204‧‧‧Dimming signal generation unit

206‧‧‧Upper current unit

208‧‧‧Overcurrent protection unit

210‧‧‧Overvoltage protection unit

212‧‧‧Over temperature protection unit

220‧‧‧Power Converter

240‧‧‧ Follow-up integrated dimming control circuit

2202‧‧‧primary side switch

2042‧‧‧Logic gate

C‧‧‧External capacitor

CBS‧‧‧Raise current signal

CLK‧‧‧ scheduled clock

DS1-DS4‧‧‧ dimming signal

GS‧‧‧ gate signal

IF‧‧‧ current

OCPS, OVPS, OTPS‧‧‧ signals

ODS‧‧‧ original dimming signal

PWM‧‧‧ pulse width modulation signal

R‧‧‧ external resistor

S1-S4‧‧‧ switch

LD1-LD4‧‧‧Light Diode String

VIN‧‧‧ input voltage

VOUT‧‧‧ output voltage

VD‧‧‧ partial pressure

Claims (9)

An integrated dimming control circuit includes: a gate signal generating unit for receiving a pulse width modulation signal, and generating a gate signal according to the pulse width modulation signal; and a dimming signal generating unit Receiving an original dimming signal, and generating a plurality of dimming signals and a predetermined clock according to a resistor-capacitor time constant determined by an external resistor and an external capacitor, and the predetermined dimming signal, wherein the dimming signal is generated The unit determines a phase difference between each adjacent two dimming signals according to the time constant of the resistor and capacitor; and a boosting current unit for receiving a boosting current signal, and scaling the plurality of dimming according to the boosting current signal The working cycle of the signal. The integrated dimming control circuit of claim 1, wherein the gate signal is used to control the opening and closing of a primary side switch of a power converter. The integrated dimming control circuit of claim 1, further comprising: an overcurrent protection unit for generating an overcurrent protection according to a current flowing through the primary side switch. The integrated dimming control circuit of claim 1, further comprising: an overvoltage protection unit for generating an overvoltage protection according to an output voltage of the secondary side of the power converter. The integrated dimming control circuit of claim 1, further comprising: an over temperature protection unit for generating an over temperature protection according to a temperature of a load coupled to the secondary side of the power converter. The integrated dimming control circuit of claim 1, wherein the predetermined clock is used as an input to an original dimming control circuit of the integrated dimming control circuit. The integrated dimming control circuit of claim 1, wherein the dimming signal generating unit comprises: a logic gate for sequentially generating the plurality of dimming according to the original dimming signal and the resistance-capacitance time constant Signal. The integrated dimming control circuit of claim 7, wherein when the duty cycle of the plurality of dimming signals is less than a threshold, the logic gate deactivation and the plurality of dimming signals are synchronized. The integrated dimming control circuit of claim 1, wherein the plurality of dimming signals are used to control an average current flowing through a load coupled to a secondary side of the power converter.