A driving power supply with fine dimming scale

Abstract

The present application relates to the technical field of driving power supply, in particular to a driving power supply with fine dimming scale, a dimming output module is integrated and coupled with a dimming chip U1 with double dimming channels and its peripheral circuit, a controller and the dimming chip U1 are electrically connected, and the controller outputs an analog dimming signal and a chopping dimming signal to the dimming chip U1; when the analog dimming signal is adjusted to the lowest, the chopping dimming signal intervenes in dimming; the negative pole of the output end of the dimming output module is electrically connected with the controller through an amplification detection module and a first voltage division detection module respectively; the controller compares the detection data read from the first voltage division detection module with a preset boundary value; when the detection data is greater than the preset boundary value, the data read from the first voltage division detection module is selected, otherwise the data read from the amplification detection module is selected; the problems that the traditional driving power supply is difficult to expand to a smaller dimming scale and cannot guarantee the accuracy of the output voltage detection after expansion are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of driving power supply, in particular to a driving power supply with fine dimming scale. BACKGROUND

[0002] For traditional driving power supply (for example, DALI dimming constant current power supply), the load output voltage range is generally 0.6Vout~1.0Vout, for example, in the case of the output Vbus of the front-stage flyback module being 60V, the load output voltage range of the BUCK dimming output module output to the lamp is generally 24V~40V, in order to facilitate the detection of the load output voltage value, the selected voltage value is relatively large. However, this can only achieve one percent dimming, which has great limitations and can only be used in daily use scenarios; when used in medical lighting or scientific research lighting and other scenarios requiring high-precision dimming, a driving power supply with smaller dimming scale is needed to make the lamp dimming transition softer and the dimming degree richer.

[0003] However, to set a smaller dimming scale, the load output voltage range of the traditional driving power supply needs to be expanded, and in order to ensure that the load output voltage is not too large (overvoltage damage to the lamp), it is usually expanded to a lower load output voltage (for example, the load output voltage range is expanded to 2.5V~49V), and a lower load output voltage is prone to inaccurate detection (especially when the voltage is below 24V), which in turn causes problems such as inaccurate short-circuit detection and overvoltage detection. At present, there is no driving power supply that can achieve a smaller dimming scale (i.e., smaller than one percent dimming scale, such as one ten-thousandth dimming) while ensuring the accuracy of load output voltage detection. SUMMARY

[0004] In view of the above defects, the purpose of the present application is to provide a driving power supply with fine dimming scale, which solves the problems of traditional driving power supply that is difficult to expand to a smaller dimming scale and cannot guarantee the accuracy of load output voltage detection after expansion.

[0005] To achieve this purpose, the present application adopts the following technical solutions:

[0006] A driving power supply with fine dimming scale, comprising a dimming output module and a controller; the dimming output module is integrated with a dimming chip U1 with double dimming channels and its peripheral circuit, and further comprises an amplification detection module and a first voltage division detection module; the controller and the dimming chip U1 are electrically connected, and output an analog dimming signal and a chopping dimming signal to the dimming chip U1; when the analog dimming signal is adjusted to the lowest, the chopping dimming signal intervenes in dimming;

[0007] The negative output end of the dimming output module is electrically connected with the controller through the amplification detection module, and the negative output end of the dimming output module is also electrically connected with the controller through the first voltage division detection module; the amplification detection module is used for large load output voltage detection, and the first voltage division detection module is used for small load output voltage detection;

[0008] The controller compares the detection data read from the first voltage division detection module with a preset demarcation value; when the detection data is greater than the preset demarcation value, the controller selects the data read from the first voltage division detection module; when the detection data is less than or equal to the preset demarcation value, the controller selects the data read from the amplification detection module.

[0009] Further, a subtracter detection module and a second voltage division detection module are further included; the negative output end of the dimming output module is also electrically connected with the dimming chip U1 through the subtracter detection module, and the negative output end of the dimming output module is also electrically connected with the controller through the second voltage division detection module.

[0010] Further, a ghost switch module is further included; the negative output end of the dimming output module passes through the ghost switch module first, and then passes through the amplification detection module, and is electrically connected with the controller; the negative output end of the dimming output module passes through the ghost switch module first, and then passes through the first voltage division detection module, and is electrically connected with the controller;

[0011] The negative output end of the dimming output module passes through the ghost switch module first, and then passes through the subtracter detection module, and is electrically connected with the dimming chip U1; the negative output end of the dimming output module passes through the ghost switch module first, and then passes through the second voltage division detection module, and is electrically connected with the controller;

[0012] The ghost switch module is electrically connected with the controller; the ghost switch module is used for being controlled by the controller to disconnect the loop passing through the ghost switch module when the driving power supply is in standby.

[0013] Further, the ghost switch module includes a resistor R44, a resistor R37, a triode Q4 and a triode Q5; one end of the resistor R44 is electrically connected with the controller, the other end of the resistor R44 is electrically connected with the base of the triode Q5, the emitter of the triode Q5 is connected with the SGND ground end, the collector of the triode Q5 is electrically connected with the base of the triode Q4 through the resistor R37, the emitter of the triode Q4 is electrically connected with the negative output end of the dimming output module, and the amplification detection module, the first voltage division detection module, the subtracter detection module and the second voltage division detection module are all electrically connected with the collector of the triode Q4.

[0014] Further, the subtracter detection module comprises a module closing unit, an operational amplifier U4B, a resistor R50, a resistor R56, a resistor R62, a resistor R69, a resistor R70, a resistor R63, a resistor R67, a resistor R71 and a diode D11; one end of the resistor R63 is negatively connected with the output end of the dimming output module, the other end of the resistor R63 is connected with one end of the resistor R67, the other end of the resistor R67 and one end of the resistor R71 are both connected with one end of the resistor R70, the other end of the resistor R71 is connected with an SGND ground end, the other end of the resistor R70 and one end of the resistor R69 are both connected with a negative input end of the operational amplifier U4B, the other end of the resistor R69 and an anode of the diode D11 are both connected with an output end of the operational amplifier U4B, a cathode of the diode D11 is connected with the dimming chip U1;

[0015] A power voltage is connected with one end of the resistor R50 through the module closing unit, and the other end of the resistor R50 is connected with one end of the resistor R56; the other end of the resistor R56 and one end of the resistor R62 are both connected with a positive input end of the operational amplifier U4B, and the other end of the resistor R62 is connected with an SGND ground end;

[0016] The module closing unit is connected with the controller; and the module closing unit is used for disconnecting a loop passing through the module closing unit under the control of the controller when a driving power supply is on standby.

[0017] Further, the module closing unit comprises a resistor R49, a resistor R46, a triode Q6 and a triode Q7; one end of the resistor R49 is connected with the controller, the other end of the resistor R49 is connected with a base of the triode Q7, an emitter of the triode Q7 is connected with an SGND ground end, a collector of the triode Q7 is connected with a base of the triode Q6 through the resistor R46, an emitter of the triode Q6 is connected with a power voltage, and a collector of the triode Q6 is connected with one end of the resistor R50.

[0018] Further, the amplification detection module comprises an operational amplifier U4A, a resistor R65, a resistor R66, a resistor R51, a resistor R53 and a resistor R57; one end of the resistor R51 is used for being connected with a negative output end of the dimming output module, the other end of the resistor R51 is connected with one end of the resistor R53, the other end of the resistor R53 and one end of the resistor R57 are both connected with a positive input end of the operational amplifier U4A, and the other end of the resistor R57 is connected with an SGND ground end;

[0019] The output end of the operational amplifier U4A is electrically connected with the controller, one end of the operational amplifier U4A is electrically connected with the resistor R65, and the other end of the resistor R65 and one end of the resistor R66 are electrically connected with the negative input end of the operational amplifier U4A, and the other end of the resistor R66 is connected with the SGND ground end.

[0020] Further, the first voltage division detection module comprises a resistor R52, a resistor R58 and a capacitor C23; one end of the resistor R52 is used for being electrically connected with the negative electrode of the output end of the dimming output module, and the other end of the resistor R52 is electrically connected with the controller;

[0021] The other end of the resistor R52 and one end of the resistor R58 are electrically connected with one end of the capacitor C23, and the other end of the resistor R58 and the other end of the capacitor C23 are connected with the SGND ground end.

[0022] Further, the circuit structure of the second voltage division detection module is same as that of the first voltage division detection module.

[0023] Further, the dimming output module is provided with an output common mode inductor LF1, a first winding of the output common mode inductor LF1 is connected in series with the positive electrode of the output end of the dimming output module, and a second winding of the output common mode inductor LF1 is connected in series with the negative electrode of the output end of the dimming output module.

[0024] The peripheral circuit of the dimming chip U1 comprises a resistor R10, a resistor R12 and a resistor R16; the resistor R12 is connected in series with the input side of the second winding of the output common mode inductor LF1, the resistor R10 and the resistor R16 are both connected in parallel with the two ends of the resistor R12, one end of the resistor R12 which is electrically connected with the output common mode inductor LF1 is connected with the current detection positive electrode end of the dimming chip U1, and the other end of the resistor R12 is connected with the current detection negative electrode end of the dimming chip U1.

[0025] The technical scheme provided by the application can have the following beneficial effects: the double dimming channels of the dimming chip U1 are simultaneously used in the dimming output module, after the analog dimming signal (DIM) is adjusted from 100% to 1% minimum, the analog dimming signal remains 1%, and the chopper dimming signal (PWM) is further adjusted from 100% to 1%, so that the one-thousandth dimming scale is realized, and finally the output voltage is expanded to a lower band. Since the analog dimming signal is unstable and the current precision is poor when the output current is small, the analog dimming signal is mainly responsible for high brightness dimming, and the chopper dimming signal is responsible for low brightness dimming.

[0026] In addition, in order to match the one ten thousandth dimming scale with the output voltage detection of the load, ensure that the controller (such as MCU) can accurately adjust the analog dimming signal and the chopping dimming signal output to the dimming chip U1, respectively set the amplification detection module for large load output voltage detection (because the detection point is at the negative output end of the dimming output module, the larger the load output voltage, the smaller the feedback, so signal amplification is needed) and the first voltage division detection module for small load output voltage detection (based on the rules of the detection point, the small load feedback is large, and the voltage division can be detected). On this basis, the controller will receive two detection data at the same time, and according to the comparison between the detection data read from the first voltage division detection module and the preset demarcation value (for example, 10V), it is determined which detection data should be selected as valid data by the timing controller; considering that the load output voltage will be relatively large most of the time (i.e. above 10V), the detection data of the amplification detection module is usually used as valid data, so the first voltage division detection module is more optimal, and the detection data of the first voltage division detection module is less than the preset demarcation value for a long time. If it is suddenly greater than the preset demarcation value, the controller can immediately sense the switching to use the detection data of the first voltage division detection module as valid data (the same as the switching from the first voltage division detection module to the amplification detection module); thereby ensuring the accuracy of the load output voltage detection. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a principle diagram of a dimming scale fine driving power supply according to one embodiment of the present application.

[0028] Figure 2 It is a circuit diagram of the subtracter detection module as shown in Figure 1 .

[0029] Figure 3 It is a circuit diagram of the second voltage division detection module and the ghost switch module as shown in Figure 1 .

[0030] Figure 4 It is a circuit diagram of the amplification detection module as shown in Figure 1 .

[0031] Figure 5 It is a circuit diagram of the first voltage division detection module as shown in Figure 1 .

[0032] Wherein: dimming output module 1, amplification detection module 2, first voltage division detection module 3, subtracter detection module 5, second voltage division detection module 6, ghost fire switch module 4, resistance R44, resistance R37, triode Q4, triode Q5, module closing unit 51, operational amplifier U4B, resistance R50, resistance R56, resistance R62, resistance R69, resistance R70, resistance R63, resistance R67, resistance R71, diode D11, resistance R49, resistance R46, triode Q6, triode Q7, operational amplifier U4A, resistance R65, resistance R66, resistance R51, resistance R53, resistance R57, resistance R52, resistance R58, capacitor C23, output common mode inductor LF1, resistance R10, resistance R12, resistance R16. DETAILED DESCRIPTION

[0033] Embodiments of the present application are described below in detail with reference to the accompanying drawings, wherein the same or similar components are denoted by the same or similar reference numerals throughout the drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are for the purpose of explanation only, and should not be understood as limiting the present application.

[0034] In the description of the embodiments of the present application, the terms "first", "second" are used only for the purpose of description, and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0035] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0036] The embodiments of the present application are described below in combination with Figures 1 to 5 , a driving power supply with fine dimming scale.

[0037] The application discloses a driving power supply with fine dimming scale, which comprises a dimming output module 1 and a controller; the dimming output module 1 is integrated with a dimming chip U1 with double dimming channels and peripheral circuits of the dimming chip U1, further comprises an amplification detection module 2 and a first voltage division detection module 3; the controller is electrically connected with the dimming chip U1, and outputs an analog dimming signal and a chopping dimming signal to the dimming chip U1; when the analog dimming signal is adjusted to the lowest, the chopping dimming signal is used for dimming.

[0038] The negative output end of the dimming output module 1 is electrically connected with the controller through the amplification detection module 2, and is also electrically connected with the controller through the first voltage division detection module 3; the amplification detection module 2 is used for detecting the output voltage of a large load, and the first voltage division detection module 3 is used for detecting the output voltage of a small load.

[0039] The controller compares the detection data read from the first voltage division detection module 3 with a preset boundary value; when the detection data is greater than the preset boundary value, the controller selects the data read from the first voltage division detection module 3; when the detection data is less than or equal to the preset boundary value, the controller selects the data read from the amplification detection module 2.

[0040] As shown in the preferred embodiment of the driving power supply with fine dimming scale, Figure 1 the double dimming channels (for example, the DIM and PWM dimming pins of the Hi5010Q chip) of the dimming chip U1 are simultaneously used in the dimming output module 1; after the analog dimming signal (DIM) is adjusted from 100% to 1%, the lowest, the analog dimming signal remains 1%, and the chopping dimming signal (PWM) is further adjusted from 100% to 1%, so that the dimming scale of one ten-thousandth is realized; the dimming current Iout can be obtained by Iout=Imax·D1·D2, wherein Imax is the maximum dimming current, D1 is the duty ratio of the analog dimming signal, and D2 is the duty ratio of the chopping dimming signal (D1 and D2 refer to the PWM signal sent by the controller to the dimming chip U1, and the dimming chip U1 converts the PWM signal into the analog dimming signal and the chopping dimming signal respectively after recognizing the PWM signal); finally, the output voltage range of the load is 2.5V~49V (the range is only for reference) under the condition that the output Vbus of the front-stage flyback module is 60V, and the output voltage range of the load is further expanded to a lower value; wherein the analog dimming signal is mainly responsible for high-brightness dimming because the analog dimming signal is unstable and the current precision is poor when the output current is small, and the chopping dimming signal is responsible for low-brightness dimming.

[0041] In addition, in order to match the one-tenth dimming scale with the output voltage detection of the load, to ensure that the controller (such as MCU) can accurately adjust the analog dimming signal and the chopping dimming signal output to the dimming chip U1, the amplification detection module 2 is arranged for large load output voltage detection (because the detection point is at the negative output end of the dimming output module 1, the larger the load output voltage, the smaller the feedback, so signal amplification is needed), and the first voltage division detection module 3 is arranged for small load output voltage detection (based on the rule of the detection point, the feedback of the small load is large, and the voltage division can be detected). On this basis, the controller will receive the two detection data at the same time, and determine which detection data should be selected as valid data by the controller according to the comparison between the detection data read from the first voltage division detection module 3 and the preset demarcation value (for example, 10V); considering that the load output voltage is usually large (for example, more than 10V) most of the time, the detection data of the amplification detection module 2 is usually used as valid data, so the judgment right falls on the first voltage division detection module 3, and the detection data of the first voltage division detection module 3 is less than the preset demarcation value for a long time. If it suddenly exceeds the preset demarcation value, the controller can immediately switch to use the detection data of the first voltage division detection module 3 as valid data (the same for switching from the first voltage division detection module 3 to the amplification detection module 2); thereby ensuring the accuracy of the load output voltage detection.

[0042] Further, the subtracter detection module 5 and the second voltage division detection module 6 are further included; the negative output end of the dimming output module 1 is further electrically connected with the dimming chip U1 through the subtracter detection module 5, and the negative output end of the dimming output module 1 is further electrically connected with the controller through the second voltage division detection module 6.

[0043] In the embodiment, the change of the dimming scale also affects the fault detection of the driving power supply, for which the original fault detection circuit is modified to be provided with the subtracter detection module 5 and the second voltage division detection module 6. Among them, the subtracter detection module 5 is mainly used to feed back the fault to the dimming chip U1, so that the dimming chip U1 can dynamically adjust the working state according to the detection data, and is closed in the fault state and automatically opened after the fault disappears, and is suitable for faults with small influence (such as floating overvoltage), so the subtracter function is used to subtract the reference voltage (such as VREF in Figure 2 ) and the detection point voltage (such as LED- in Figure 1 or VLED- in Figure 2 ) to obtain dynamic data; and the second voltage division detection module 6 is mainly used to feed back the fault to the controller, so as to cope with faults with large influence (such as serious overvoltage, short circuit, etc.), and the detection data is provided to the preset fault threshold of the controller for comparison (that is, it does not need to be very accurate, and the detection data will change obviously), and the global protection is realized by the controller.

[0044] Further, the ghost fire switch module 4 is further included; the negative output end of the dimming output module 1 first passes through the ghost fire switch module 4, and then passes through the amplification detection module 2, and is electrically connected with the controller; the negative output end of the dimming output module 1 first passes through the ghost fire switch module 4, and then passes through the first voltage division detection module 3, and is electrically connected with the controller.

[0045] The negative output end of the dimming output module 1 first passes through the ghost fire switch module 4, and then passes through the subtracter detection module 5, and is electrically connected with the dimming chip U1; the negative output end of the dimming output module 1 first passes through the ghost fire switch module 4, and then passes through the second voltage division detection module 6, and is electrically connected with the controller.

[0046] The ghost fire switch module 4 is electrically connected with the controller; the ghost fire switch module 4 is used for being controlled by the controller to cut off the loop passing through the ghost fire switch module 4 when the driving power supply is in standby.

[0047] In the embodiment, the driving power supply integrates the amplification detection module 2, the first voltage division detection module 3, the subtracter detection module 5 and the second voltage division detection module 6 and the like, and the detection points are all located at the negative output end of the dimming output module 1; when the driving power supply is dimmed to the lowest standby, these branches are extremely easy to provide a discharge loop for the electrolytic capacitor CE1 of the dimming output module 1 (especially the voltage division detection branch, the voltage division resistor is used as a discharge resistor), and the leakage current flows from the output end of the dimming output module 1 to the connected load lamps (such as LED lamps and the like, the parasitic capacitor exists), so that the parasitic capacitor of the load is divided, and the load lamps are re-lit, and the ghost fire phenomenon is generated; therefore, the ghost fire switch module 4 is provided, so that all the detection branches need to pass through the ghost fire switch module 4, thereby cutting off all the detection branches by using the ghost fire switch module 4 when the driving power supply is in standby, and the ghost fire problem is effectively solved.

[0048] Further, the ghost fire switch module 4 includes the resistor R44, the resistor R37, the triode Q4 and the triode Q5; one end of the resistor R44 is electrically connected with the controller, the other end of the resistor R44 is electrically connected with the base of the triode Q5, the emitter of the triode Q5 is connected with the SGND ground end, the collector of the triode Q5 is electrically connected with the base of the triode Q4 through the resistor R37, the emitter of the triode Q4 is electrically connected with the negative output end of the dimming output module 1, and the amplification detection module 2, the first voltage division detection module 3, the subtracter detection module 5 and the second voltage division detection module 6 are all electrically connected with the collector of the triode Q4.

[0049] In the embodiment, as shown in Figure 3 The ghost fire switch module 4 is preferably composed of double triodes, wherein the triode Q4 is used for cutting off the loop, and the triode Q5 is used for accelerating the driving; the specific principle is as follows:

[0050] (1) When the driving power supply is in normal working state, the CHECK-EN2 signal is controlled to be high level by the controller.

[0051] For the NPN transistor Q5, the base voltage Vb>Ve, and the collector voltage Vc>Vb, so the Q5 is in the on state, and the current flows from the collector to the emitter. At this time, for the PNP transistor Q4, the base is pulled down to the ground through the resistor R37, the emitter voltage Ve>Vb, and the base voltage Vb>Vc, so the Q4 is also in the on state.

[0052] Therefore, when the driving power supply is in normal working state, the transistor Q4 and the transistor Q5 are normally on, and all detection branches can normally operate.

[0053] (2) When the driving power supply is in standby state, the CHECK-EN2 signal is controlled to be low level by the controller.

[0054] For the transistor Q5, the base voltage Vb≈Ve, and the transistor Q5 is not on; for the transistor Q4, the base is equivalent to be suspended, and the emitter Ve≈Vb, so the transistor Q4 is also not on.

[0055] Therefore, when the driving power supply is in standby state, the transistor Q4 and the transistor Q5 jointly act to cut off the discharge circuit, and the load lamp will not have a leakage current flowing through, effectively solving the ghost fire problem.

[0056] Further, the subtracter detection module 5 includes a module closing unit 51, an operational amplifier U4B, a resistor R50, a resistor R56, a resistor R62, a resistor R69, a resistor R70, a resistor R63, a resistor R67, a resistor R71, and a diode D11; one end of the resistor R63 and the negative output end of the dimming output module 1 are electrically connected, the other end of the resistor R63 and one end of the resistor R67 are electrically connected, the other end of the resistor R67 and one end of the resistor R71 are electrically connected with one end of the resistor R70, the other end of the resistor R71 is connected with the SGND ground end, the other end of the resistor R70 and one end of the resistor R69 are electrically connected with the negative input end of the operational amplifier U4B, the other end of the resistor R69 and the anode of the diode D11 are electrically connected with the output end of the operational amplifier U4B, and the cathode of the diode D11 is electrically connected with the dimming chip U1;

[0057] The power supply voltage is electrically connected with one end of the resistor R50 through the module closing unit 51, and the other end of the resistor R50 and one end of the resistor R56 are electrically connected; the other end of the resistor R56 and one end of the resistor R62 are electrically connected with the positive input end of the operational amplifier U4B, and the other end of the resistor R62 is connected with the SGND ground end;

[0058] The module closing unit 51 is electrically connected with the controller; and the module closing unit 51 is used for being controlled by the controller to disconnect the loop passing through the module closing unit 51 when the driving power supply is in standby.

[0059] In this embodiment, according to the specification of the general dimming chip U1, it can be used as a BUCK step-down topology or a BOOST step-up topology, and the VFB pin of the dimming chip U1 is usually used for overvoltage protection. Taking the Hi5010Q chip as an example, when the VFB voltage is higher than 1.2V, the chip closes the output, and when the VFB voltage is lower than 1.1V, the chip restarts the output. Based on this, the circuit structure of the subtracter detection module 5 is designed as shown in Figure 2 The specific working principle is as follows. Figure 2 The identification of VREF and VLED- in the dashed box is only used as a reference point for the calculation process, and does not represent the connection relationship.

[0060] Using the subtracter of the operational amplifier U4B, the voltage of LED- (i.e. VLED-) is the inverting input terminal of the subtracter, and then there is a reference voltage point VLED1-=(LED-·R71) / (R63+R67+R71); wherein LED- is the corresponding voltage value, and R71, R63, R67 and R71 are the corresponding resistance values. A reference voltage VREF=[power supply voltage·(R56+R62)] / (R50+R56+R62) is given to the non-inverting input terminal; wherein R50, R56 and R62 are the corresponding resistance values.

[0061] By setting R69=R62 and R70=R56, the following can be obtained: VFB=VREF-(VLED1-)·R69 / R70; wherein R69 and R70 are the corresponding resistance values.

[0062] As can be seen from the calculation formula of VFB, VREF is a fixed value, and VLED1- decreases with the increase of the output voltage Vout, so VFB increases with the increase of Vout (precise dynamic detection data). By reasonably allocating the resistance R69 and the resistance R70 of the subtracter, VFB reaches 1.2V when Vout approaches 60V (i.e. triggering the overvoltage protection of the dimming chip U1), so that the dimming chip U1 triggers the overvoltage protection, and Vout is limited below 60V, realizing the overvoltage protection.

[0063] As described above, by reasonably allocating the power supply voltage, the resistance R69 and the resistance R70, the subtracter detection module 5 can adapt to the upper limit of different output voltage ranges (solve the problem that the output voltage range cannot be detected and overvoltage protected after being expanded) and adapt to the trigger threshold of different dimming chips U1.

[0064] Based on the circuit structure of the subtracter detection module 5 and the ghost switch module 4, the driving power supply is in the standby state, the ghost switch module 4 cuts off the loop, at this time VLED-constant is 0, this state is the same as the no-load, when the no-load, VLED- is 0, because the no-load will trigger the over-voltage protection of the dimming chip U1, so it means that the over-voltage protection of the dimming chip U1 will also be triggered in the standby state, which belongs to false protection. In order to prevent false triggering of the over-voltage protection in the standby state, the module closing unit 5 is provided to cut off VREF in the standby state, then the positive input of the operational amplifier U4B is 0, the negative input is also 0, then VFB is also 0 according to the formula, so the over-voltage protection will not be triggered.

[0065] Further, the module closing unit 51 includes resistors R49, R46, a transistor Q6 and a transistor Q7; one end of the resistor R49 is electrically connected with the controller, the other end of the resistor R49 is electrically connected with the base of the transistor Q7, the emitter of the transistor Q7 is connected with the SGND ground end, the collector of the transistor Q7 is electrically connected with the base of the transistor Q6 through the resistor R46, the emitter of the transistor Q6 is connected with the power supply voltage, and the collector of the transistor Q6 is electrically connected with one end of the resistor R50.

[0066] In the embodiment, the module closing unit 51 and the ghost switch module 4 are the same, wherein the transistor Q6 is used to cut off the loop, and the transistor Q7 is used to accelerate the driving, the controller sends a low-level CHECK-EN1 signal to drive the transistor Q6 and the transistor Q7 to cut off VREF in the standby state, then the positive input of the operational amplifier U4B is 0, the negative input is also 0, then VFB is also 0 according to the formula, so the over-voltage protection will not be triggered.

[0067] It should be noted that there are many ways to configure the CHECK-EN1 signal and the CHECK-EN2 signal, which can be two different signals or the same signal (because they are both cut off in the standby state).

[0068] Further, the amplification detection module 2 includes an operational amplifier U4A, resistors R65, R66, R51, R53 and R57; one end of the resistor R51 is electrically connected with the negative output end of the dimming output module 1, the other end of the resistor R51 and one end of the resistor R53 are electrically connected, the other end of the resistor R53 and one end of the resistor R57 are electrically connected with the positive input end of the operational amplifier U4A, and the other end of the resistor R57 is connected with the SGND ground end.

[0069] The output end of the operational amplifier U4A is electrically connected with the controller, the output end of the operational amplifier U4A and one end of the resistor R65 are electrically connected, the other end of the resistor R65 and one end of the resistor R66 are electrically connected with the negative input end of the operational amplifier U4A, and the other end of the resistor R66 is connected with the SGND ground end.

[0070] As shown in the embodiment, the amplification detection module 2 is mainly composed of an operational amplifier U4A and its peripheral circuit to form a differential amplifier. Figure 4 After the controller reads the output of the differential amplifier, the reverse operation can be performed to obtain the output voltage under load, thereby ensuring the accuracy of detection under large load.

[0071] Further, the first voltage division detection module 3 comprises a resistor R52, a resistor R58 and a capacitor C23; one end of the resistor R52 is electrically connected to the negative output end of the dimming output module 1, and the other end of the resistor R52 is electrically connected to the controller.

[0072] The other end of the resistor R52 and one end of the resistor R58 are electrically connected to one end of the capacitor C23, and the other end of the resistor R58 and the other end of the capacitor C23 are both connected to the SGND ground end.

[0073] Further, the circuit structure of the second voltage division detection module 6 is the same as that of the first voltage division detection module 3.

[0074] As shown in the embodiment, the first voltage division detection module 3 and the second voltage division detection module 6 both preferably adopt a resistor to form a voltage division circuit. Figure 3 Figure 5 As shown in the embodiment, the first voltage division detection module 3 and the second voltage division detection module 6 both preferably adopt a resistor to form a voltage division circuit.

[0075] Further, the dimming output module 1 is provided with an output common-mode inductor LF1, and a first winding of the output common-mode inductor LF1 is connected in series to the positive output end of the dimming output module 1, and a second winding of the output common-mode inductor LF1 is connected in series to the negative output end of the dimming output module 1.

[0076] The peripheral circuit of the dimming chip U1 comprises a resistor R10, a resistor R12 and a resistor R16; the resistor R12 is connected in series to the input side of the second winding of the output common-mode inductor LF1, the resistor R10 and the resistor R16 are both connected in parallel to the two ends of the resistor R12, one end of the resistor R12 which is electrically connected to the output common-mode inductor LF1 is connected to the current detection positive end of the dimming chip U1, and the other end of the resistor R12 is connected to the current detection negative end of the dimming chip U1.

[0077] ​In this embodiment, because the dimming scale is small, the dimming range is large, and the load range is also large, the dimming chip U1 is prone to poor self-load adjustment rate. Therefore, the resistor R10, the resistor R12 and the resistor R16 (sampling resistor) are placed on the input side of the output common mode inductor LF, and then the current detection positive terminal (isenP) and the current detection negative terminal (isenN) of the dimming chip U1 are used to detect the voltage (current is converted into voltage for easy chip recognition) across the sampling resistor; in this way, in the BUCK dimming output module, whether the MOS tube Q2 is in the on stage (also referred to as the Ton stage) or the off stage (also referred to as the Toff freewheeling stage), the current output can be detected (usually referred to as full cycle detection), and then the Ton time is adjusted in real time according to the output current; thereby based on the characteristic that the output current is less affected by the load, the poor adjustment rate problem can be effectively improved.

[0078] Other configurations and operations of the dimming scale fine driving power supply according to the embodiments of the present application are known to those skilled in the art, and will not be described in detail here.

[0079] In the description of the present specification, the description referring to the terms "embodiment", "example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0080] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A dimming scale fine driving power supply, comprising a dimming output module and a controller; characterized in that: The dimming output module is integrated with a dimming chip U1 with double dimming channels and its peripheral circuit, and further comprises an amplification detection module and a first voltage division detection module; the controller is electrically connected with the dimming chip U1 to output an analog dimming signal and a chopping dimming signal to the dimming chip U1; when the analog dimming signal is adjusted to the lowest, the chopping dimming signal intervenes in dimming; The output negative pole of the dimming output module is electrically connected with the controller through the amplification detection module, and is also electrically connected with the controller through the first voltage division detection module; the amplification detection module is used for large load output voltage detection, and the first voltage division detection module is used for small load output voltage detection; The controller compares the detection data read from the first voltage division detection module with a preset demarcation value; when the detection data is greater than the preset demarcation value, the controller selects the data read from the first voltage division detection module; when the detection data is less than or equal to the preset demarcation value, the controller selects the data read from the amplification detection module.

2. The driving power supply with fine dimming scale according to claim 1, characterized in that: Further comprising a subtractor detection module and a second voltage division detection module; the output negative pole of the dimming output module is also electrically connected with the dimming chip U1 through the subtractor detection module, and is also electrically connected with the controller through the second voltage division detection module.

3. The driving power supply with fine dimming scale according to claim 2, characterized in that: Further comprising a ghost fire switch module; the output negative pole of the dimming output module first passes through the ghost fire switch module, and then passes through the amplification detection module, and is electrically connected with the controller; the output negative pole of the dimming output module first passes through the ghost fire switch module, and then passes through the first voltage division detection module, and is electrically connected with the controller; The output negative pole of the dimming output module first passes through the ghost fire switch module, and then passes through the subtractor detection module, and is electrically connected with the dimming chip U1; the output negative pole of the dimming output module first passes through the ghost fire switch module, and then passes through the second voltage division detection module, and is electrically connected with the controller; The ghost fire switch module is electrically connected with the controller; the ghost fire switch module is used for being controlled by the controller to disconnect the loop passing through the ghost fire switch module when the driving power supply is in standby.

4. The driving power supply with fine dimming scale according to claim 3, characterized in that: The ghost fire switch module comprises a resistor R44, a resistor R37, a triode Q4 and a triode Q5; one end of the resistor R44 is electrically connected with the controller, the other end of the resistor R44 is electrically connected with the base of the triode Q5, the emitter of the triode Q5 is connected with an SGND ground end, the collector of the triode Q5 is electrically connected with the base of the triode Q4 through the resistor R37, the emitter of the triode Q4 is electrically connected with the output negative pole of the dimming output module, and the amplification detection module, the first voltage division detection module, the subtractor detection module and the second voltage division detection module are all electrically connected with the collector of the triode Q4.

5. The driving power supply with fine dimming scale according to claim 3, characterized in that: The subtraction detector module includes a module closing unit, an operational amplifier U4B, a resistor R50, a resistor R56, a resistor R62, a resistor R69, a resistor R70, a resistor R63, a resistor R67, a resistor R71 and a diode D11; one end of the resistor R63 is negatively connected with the output end of the dimming output module, the other end of the resistor R63 is connected with one end of the resistor R67, the other end of the resistor R67 and one end of the resistor R71 are both connected with one end of the resistor R70, the other end of the resistor R71 is connected with an SGND ground end, the other end of the resistor R70 and one end of the resistor R69 are both connected with a negative input end of the operational amplifier U4B, the other end of the resistor R69 and an anode of the diode D11 are both connected with an output end of the operational amplifier U4B, a cathode of the diode D11 is connected with the dimming chip U1. A power supply voltage is connected with one end of the resistor R50 through the module closing unit, and the other end of the resistor R50 is connected with one end of the resistor R56; the other end of the resistor R56 and one end of the resistor R62 are both connected with a positive input end of the operational amplifier U4B, and the other end of the resistor R62 is connected with an SGND ground end. The module closing unit is connected with the controller, and the module closing unit is used for being controlled by the controller to disconnect a loop passing through the module closing unit when a driving power supply is on standby.

6. The driving power supply with fine dimming scale according to claim 5, characterized in that: The module closing unit includes a resistor R49, a resistor R46, a triode Q6 and a triode Q7; one end of the resistor R49 is connected with the controller, the other end of the resistor R49 is connected with a base of the triode Q7, an emitter of the triode Q7 is connected with an SGND ground end, a collector of the triode Q7 is connected with a base of the triode Q6 through the resistor R46, an emitter of the triode Q6 is connected with a power supply voltage, and a collector of the triode Q6 is connected with one end of the resistor R50.

7. The driving power supply with fine dimming scale according to claim 1, characterized in that: The amplification detection module includes an operational amplifier U4A, a resistor R65, a resistor R66, a resistor R51, a resistor R53 and a resistor R57; one end of the resistor R51 is used for being connected with a negative output end of the dimming output module, the other end of the resistor R51 is connected with one end of the resistor R53, the other end of the resistor R53 and one end of the resistor R57 are both connected with a positive input end of the operational amplifier U4A, and the other end of the resistor R57 is connected with an SGND ground end; An output end of the operational amplifier U4A is connected with the controller and one end of the resistor R65, the other end of the resistor R65 and one end of the resistor R66 are both connected with a negative input end of the operational amplifier U4A, and the other end of the resistor R66 is connected with an SGND ground end.

8. The driving power supply with fine dimming scale according to claim 1, characterized in that: The first voltage division detection module comprises a resistor R52, a resistor R58 and a capacitor C23; one end of the resistor R52 is electrically connected with the negative output end of the dimming output module, and the other end of the resistor R52 is electrically connected with the controller; The other end of the resistor R52 and one end of the resistor R58 are electrically connected with one end of the capacitor C23, and the other end of the resistor R58 and the other end of the capacitor C23 are both connected with the SGND ground end.

9. The driving power supply with fine dimming scale according to claim 2, characterized in that: The circuit structure of the second voltage division detection module is the same as that of the first voltage division detection module.

10. The driving power supply with fine dimming scale according to claim 1, characterized in that: The dimming output module is provided with an output common mode inductor LF1, a first winding of the output common mode inductor LF1 is connected in series with the positive output end of the dimming output module, and a second winding of the output common mode inductor LF1 is connected in series with the negative output end of the dimming output module. The peripheral circuit of the dimming chip U1 comprises a resistor R10, a resistor R12 and a resistor R16; the resistor R12 is connected in series with the input side of the second winding of the output common mode inductor LF1, the resistor R10 and the resistor R16 are both connected in parallel with the resistor R12, one end of the resistor R12 which is electrically connected with the output common mode inductor LF1 is connected with the current detection positive end of the dimming chip U1, and the other end of the resistor R12 is connected with the current detection negative end of the dimming chip U1.

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