Switching voltage converter

Abstract

The invention provides a switch type voltage converter. A control circuit of a switch is powered by an adaptive stabilized voltage. A voltage stabilizer for providing the adaptive stabilized voltage is provided with a first receiving end coupled with an input end of the switch type voltage converter, a second receiving end coupled with an output end of the switch type voltage converter, and a stabilized voltage output end coupled with the control circuit; therefore, the adaptive stabilized voltage is provided to supply power to the control circuit to form a load current. The voltage stabilizer controls whether to generate the adaptive stabilized voltage based on the output voltage based on the load current.

Description

Technical Field

[0001] The present invention relates to a switching DC-DC converter. Background Art

[0002] A switching DC-DC converter generally uses a switch to adjust its output voltage. The control circuit driving the switch needs to have sufficient power supply.

[0003] However, with the advancement of technology, the voltage design of electronic products is getting lower and lower. How to provide a stable and high enough power supply to the control circuit in a power-saving manner is an important issue in the technical field. Summary of the invention

[0004] The present invention is a control circuit for a switch of a switching DC-DC converter, providing an adaptive regulated voltage.

[0005] A switching voltage converter implemented according to one embodiment of the present invention receives an input voltage at an input terminal, converts the input voltage into an output voltage, and outputs it at an output terminal. The switching voltage converter comprises a switch, a control circuit, and a voltage regulator. The switch is used to adjust the output voltage. The control circuit is used to control the switch. The voltage regulator has a first receiving terminal coupled to the input terminal of the switching voltage converter, and a second receiving terminal coupled to the output terminal of the switching voltage converter, and has a regulated output terminal coupled to the control circuit to provide an adaptive regulated voltage to power the control circuit, forming a load current. In particular, the voltage regulator controls whether to generate the adaptive regulated voltage based on the output voltage based on the load current.

[0006] In one embodiment, the load current determines a first threshold voltage. In response to the input voltage being lower than the first threshold voltage, the voltage regulator includes supporting the generation of the adaptive regulated voltage based on the output voltage. In response to the input voltage not being lower than the first threshold voltage, the voltage regulator generates the adaptive regulated voltage based on the input voltage, but does not support the generation of the adaptive regulated voltage based on the output voltage.

[0007] In one embodiment, a second threshold voltage is lower than the first threshold voltage. In response to the input voltage being lower than the second threshold voltage, the voltage regulator does not generate the adaptive regulated voltage based on the input voltage, but generates the adaptive regulated voltage based on the output voltage. In addition, in response to the input voltage not being lower than the second threshold voltage but lower than the first threshold voltage, the voltage regulator generates the adaptive regulated voltage based on the input voltage, and also supports the generation of the adaptive regulated voltage based on the output voltage.

[0008] In one embodiment, the voltage regulator includes a first voltage stabilizing subcircuit and a second voltage stabilizing subcircuit. The first voltage stabilizing subcircuit compares a first feedback voltage with a reference voltage to couple the input voltage to the voltage stabilizing output terminal. The second voltage stabilizing subcircuit compares a second feedback voltage with the reference voltage to couple the output voltage to the voltage stabilizing output terminal. The first feedback voltage and the second feedback voltage are divided from two different potentials of the adaptive voltage stabilizing voltage, so that the first voltage stabilizing subcircuit takes precedence over the second voltage stabilizing subcircuit.

[0009] In one embodiment, the first voltage stabilizing subcircuit includes a first transistor of a P-type channel, a first operational amplifier, and a first diode. The first transistor has a source coupled to the input voltage, and a drain coupled to an anode of the first diode. The first operational amplifier has a positive input terminal coupled to the first feedback voltage, a negative input terminal coupled to the reference voltage, and an output terminal coupled to a gate of the first transistor. A cathode of the first diode is coupled to the voltage stabilizing output terminal. The second voltage stabilizing subcircuit may be designed accordingly. In one embodiment, the second voltage stabilizing subcircuit includes a second transistor of a P-type channel, a second operational amplifier, and a second diode. The second transistor has a source coupled to the output voltage, and a drain coupled to an anode of the second diode. The second operational amplifier has a positive input terminal coupled to the second feedback voltage, a negative input terminal coupled to the reference voltage, and an output terminal coupled to a gate of the second transistor. A cathode of the second diode is coupled to the voltage stabilizing output terminal. Under such a design, the first feedback voltage is lower than the second feedback voltage.

[0010] The following is a detailed description of the present invention with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A switching voltage converter 100 according to one embodiment of the present invention is illustrated;

[0012] Figure 2 The voltage regulator 108 is illustrated according to one embodiment of the present invention;

[0013] Figure 3 Assuming that the load current Io is a constant, the diagram shows that as the input voltage Vin changes, the adaptive regulated voltage Vcc switches between the voltage Vcc1 and the voltage Vcc2.

[0014] Reference numerals:

[0015] 100: Switching voltage converter

[0016] 102: A string of light emitting diodes

[0017] 104: Switch

[0018] 106: Control circuit

[0019] 108: Voltage regulator

[0020] 110: Voltage conversion diode

[0021] 112: Inductor

[0022] 114: Capacitor

[0023] 202, 204: first and second voltage stabilizing sub-circuits

[0024] D1, D2: first and second diodes

[0025] Io: load current

[0026] MP1, MP2: first and second transistors

[0027] OP1, OP2: first and second operational amplifiers

[0028] R1, R2, R3: first, second, third resistor

[0029] TH1, TH2: first and second threshold voltages

[0030] Vfb1, Vfb2: first and second feedback voltages

[0031] Vcc: Adaptable regulated voltage

[0032] Vcc1, Vcc2: Two voltage values ​​of the adaptive regulated voltage Vcc

[0033] Vin: input voltage / input terminal of the switching voltage converter 100

[0034] Vo: output voltage / output terminal of the switching voltage converter 100

[0035] Vref: reference voltage DETAILED DESCRIPTION

[0036] The following description lists various embodiments of the present invention, but is not intended to limit the content of the present invention. The actual scope of the invention should be defined in accordance with the scope of the patent application.

[0037] Driving an electronic component often requires a voltage converter to convert an input voltage into an output voltage matching the operating potential of the electronic component, and then drive the electronic component with the output voltage.

[0038] A switching DC-DC converter is a common voltage conversion solution, which generally uses a switch to adjust its output voltage. In particular, a control circuit that drives the switch needs to have sufficient power supply. The present invention designs a voltage regulator in a switching voltage converter to generate an adaptive regulated voltage to power the control circuit. The voltage regulator disclosed in the present invention has a first receiving end coupled to an input end of the switching voltage converter to receive the input voltage, and a second receiving end coupled to an output end of the switching voltage converter to receive the output voltage, and provides the adaptive regulated voltage to power the control circuit to form a load current through a regulated output end. The voltage regulator controls whether to generate the adaptive regulated voltage based on the output voltage based on the load current.

[0039] Figure 1 A switching voltage converter 100 implemented according to an embodiment of the present invention is illustrated, which is used to drive a string of light-emitting diodes 102. The operating voltage required by the string of light-emitting diodes 102 may be as high as 30V. The switching voltage converter 100 may be a boosting design, receiving an input voltage Vin at an input terminal, and boosting the input voltage Vin to an output voltage Vo, which is output from an output terminal (also labeled as Vo below) to drive the string of light-emitting diodes 102.

[0040] As shown in the figure, the switching voltage converter 100 includes a switch 104, a control circuit 106, and a voltage regulator 108. The voltage regulator 108 has a first receiving terminal coupled to the input terminal (hereinafter also labeled as Vin) of the switching voltage converter 100, and a second receiving terminal coupled to the output terminal Vo of the switching voltage converter 100, and generates an adaptive regulated voltage Vcc and a regulated output terminal (hereinafter also labeled as Vcc) coupled to the control circuit 106. The adaptive regulated voltage Vcc supplies power to the control circuit 106 to form a load current (hereinafter referred to as Io). The voltage regulator 108 controls whether to support the generation of the adaptive regulated voltage Vcc based on the output voltage Vo based on the load current Io.

[0041] With such a design, if the input voltage Vin is too low, the regulator 108 will use the high voltage output voltage Vo to help generate the adaptive regulated voltage Vcc, ensuring that the adaptive regulated voltage Vcc is sufficient to drive the control circuit 106 .

[0042] In particular, the voltage regulator 108 does not simply determine whether to generate the adaptive regulated output Vcc based on the output voltage Vo support based on whether the input voltage Vin exceeds a fixed voltage. When the control circuit 106 is lightly loaded and the load current Io is low, even if the input voltage Vin is not high, the voltage regulator 108 can disable the assistance of the output voltage Vo and generate the adaptive regulated output Vcc not based on the high voltage output voltage Vo, but simply based on the input voltage Vin. In this way, the power consumption of the voltage regulator 108 is reduced, and the adaptive regulated output Vcc will not overshoot or undershoot due to the change of the input voltage Vin.

[0043] This section describes other components of the switch-mode voltage converter 100. The switch-mode voltage converter 100 further includes a voltage conversion diode 110, an inductor 112, and a capacitor 114. The voltage conversion diode 110 has a cathode coupled to the output terminal Vo of the switch-mode voltage converter 100. The inductor 112 is coupled between the input terminal Vin of the switch-mode voltage converter 100 and an anode of the voltage conversion diode 110. The capacitor 114 is coupled between the output terminal Vo of the switch-mode voltage converter 100 and a ground terminal. The switch 104 is an N-type channel transistor (NMOS) having a drain coupled to the anode of the voltage conversion diode 110, a source coupled to the ground terminal, and a gate controlled by the control circuit 106. Based on the special design of the voltage regulator 108 of the present invention, the control circuit 106 is appropriately driven by the adaptive voltage regulator voltage Vcc to accurately control the switch 104 to achieve a step-up conversion from the input voltage Vin to the output voltage Vo.

[0044] Figure 2The voltage regulator 108 is illustrated according to an embodiment of the present invention. The voltage regulator 108 includes a first voltage regulator subcircuit 202 and a second voltage regulator subcircuit 204. The first voltage regulator subcircuit 202 compares a first feedback voltage Vfb1 with a reference voltage Vref to couple the input voltage Vin to the voltage regulator output terminal Vcc. The second voltage regulator subcircuit 204 compares a second feedback voltage Vfb2 with the reference voltage Vref to couple the output voltage Vo to the voltage regulator output terminal Vcc. The first feedback voltage Vfb1 and the second feedback voltage Vfb2 are two different potentials divided from the adaptive voltage regulator Vcc, so that the first voltage regulator subcircuit 202 takes precedence over the second voltage regulator subcircuit 204. Since the first voltage regulator subcircuit 202 operates based on the input voltage Vin, which is much lower than the output voltage Vo used by the second voltage regulator subcircuit 204, energy saving is achieved. In particular, the sub-circuits 202 and 204 are designed with the same structure, so that the voltage regulator 108 does not switch between the input voltage Vin and the output voltage Vo by a simple switch. The input voltage Vin and the output voltage Vo may be used as the regulated input at the same time.

[0045] As shown in the figure, the first voltage stabilizing sub-circuit 202 includes a first transistor MP1 (PMOS) of a P-type channel, a first operational amplifier OP1, and a first diode D1. The first transistor MP1 has a source coupled to the input voltage Vin, and a drain coupled to an anode of the first diode D1. The first operational amplifier OP1 has a positive input terminal '+' coupled to the first feedback voltage Vfb1, a negative input terminal '-' coupled to the reference voltage Vref, and an output terminal coupled to a gate of the first transistor MP1. A cathode of the first diode D1 is coupled to the regulated output terminal Vcc.

[0046] The second voltage stabilizing sub-circuit 204 includes a second transistor MP2 of a P-type channel, a second operational amplifier OP2, and a second diode D2. The second transistor MP2 has a source coupled to the output voltage Vo, and a drain coupled to an anode of the second diode D2. The second operational amplifier OP2 has a positive input terminal '+' coupled to the second feedback voltage Vfb2, a negative input terminal '-' coupled to the reference voltage Vref, and an output terminal coupled to a gate of the second transistor MP2. A cathode of the second diode D2 is coupled to the regulated output terminal Vcc.

[0047] The voltage regulator 108 further includes a first resistor R1, a second resistor R2, and a third resistor R3 connected in series to the voltage stabilization output terminal Vcc and a ground terminal. The second feedback voltage Vfb2 is obtained from the connection point of the first resistor R1 and the second resistor R2. The first feedback voltage Vfb1 is obtained from the connection point of the second resistor R2 and the third resistor R3. In this way, the first feedback voltage Vfb1 is lower than the second feedback voltage Vfb2. Compared with the second operational amplifier OP2, the first operational amplifier OP1 is easier to turn on the coupled transistor (MP1). The first voltage stabilization sub-circuit 202 takes precedence over the second voltage stabilization sub-circuit 204, which is more power-saving.

[0048] Figure 3 Assuming that the load current Io is a constant value, the diagram shows that as the input voltage Vin changes, the adaptive regulated voltage Vcc switches between voltage Vcc1 and voltage Vcc2. Figure 2 According to the voltage regulator 108 architecture, the load current Io will determine a first threshold voltage TH1, which is Vcc2+Io*R_MP1+VD1. There is also a second threshold voltage TH2, which is Vcc2+VD1, lower than the first threshold voltage TH1. R_MP1 is the resistance of the first transistor MP1. VD1 is the voltage across the first diode D1.

[0049] From time 0 to t1, before the input voltage Vin drops below the first threshold voltage TH1, the first voltage stabilizing sub-circuit 202 is enabled ("on"), and the second voltage stabilizing sub-circuit 204 is disabled ("off"). The adaptive regulated voltage Vcc is at voltage Vcc1. Figure 2 Circuit, Vcc1 = Vref*[1+(R1+R2) / R3].

[0050] During time t1-t2, the input voltage Vin is lower than the first threshold voltage TH1 but not lower than the second threshold voltage TH2, and the second voltage stabilizing sub-circuit 204 is also enabled to assist the first voltage stabilizing sub-circuit 202. The adaptive regulated voltage Vcc is switched to voltage Vcc2. Figure 2 circuit, Vcc2 = Vref*[1+R1 / (R2+R3)], which is lower than the voltage Vcc1.

[0051] During time t2-t3, the input voltage Vin is too low (lower than the second threshold voltage TH2), the first voltage stabilizing sub-circuit 202 is disabled, and the second voltage stabilizing sub-circuit 204 is fully responsible for generating the adaptive regulated voltage Vcc (= Vcc2).

[0052] During time t3-t4, the input voltage Vin rises to a level not lower than the second threshold voltage TH2 but still lower than the first threshold voltage TH1, and the first voltage stabilizing sub-circuit 202 and the second voltage stabilizing sub-circuit 204 are both enabled. The adaptive stabilizing voltage Vcc maintains the voltage Vcc2.

[0053] After time t4, the input voltage Vin is not lower than the first threshold voltage TH1, and the second voltage stabilizing sub-circuit 204 is no longer needed. The first voltage stabilizing sub-circuit 202 switches the adaptive regulated voltage Vcc to the voltage Vcc1.

[0054] Figure 3 In the embodiment, the first voltage stabilizing subcircuit 202 and the second voltage stabilizing subcircuit 204 are switched gradually, and the adaptive regulated voltage Vcc does not have an overshoot or undershoot condition. The first threshold TH1 (=Vcc2+Io*R_MP1+VD1) that determines whether the second voltage stabilizing subcircuit 204 is enabled or not depends on the load current Io, and the voltage regulator 108 will adjust with the load, which is more flexible. If the input voltage Vin is really too low, the fixed second threshold voltage TH2 (=Vcc2+VD1) is used to determine whether to disable the first voltage stabilizing subcircuit 202 and ignore the too low input voltage Vin.

[0055] In summary, corresponding to the input voltage Vin lower than the first threshold voltage TH1, the voltage regulator 108 includes supporting the generation of the adaptive regulated voltage Vcc based on the output voltage Vo. Corresponding to the input voltage Vin not lower than the first threshold voltage TH1, the voltage regulator 108 generates the adaptive regulated voltage Vcc based on the input voltage Vo, but does not generate the adaptive regulated voltage Vcc based on the output voltage Vo. Corresponding to the input voltage Vin lower than the second threshold voltage TH2, the voltage regulator 108 does not generate the adaptive regulated voltage Vcc based on the input voltage Vin, but generates the adaptive regulated voltage Vcc based on the output voltage Vo. Corresponding to the input voltage Vin not lower than the second threshold voltage TH2 but lower than the first threshold voltage TH1, the voltage regulator 108 generates the adaptive regulated voltage Vcc based on the input voltage Vin, and also supports the generation of the adaptive regulated voltage Vcc based on the output voltage Vo.

[0056] Under such a design, when the load is light (the load current Io is low), the first threshold TH1 (=Vcc2+Io*R_MP1+VD1) is low. Even if the input voltage Vin is not high, the second voltage regulator subcircuit 204 is not needed, and the first voltage regulator subcircuit 202 alone is sufficient to power the control circuit 106 .

[0057] In other implementations, the voltage stabilization subcircuit may have various variations. Any two similar voltage stabilization circuits that use the input voltage Vin and the output voltage Vo as the voltage stabilization basis can be used to implement the voltage stabilizer 108 of the present invention.

[0058] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims.

Claims

1. A switching voltage converter, characterized in that: An input voltage is received at an input terminal, and the input voltage is converted into an output voltage, which is outputted at an output terminal, including: a switch for adjusting the output voltage; a control circuit to control the switch; and A voltage regulator having a first receiving end coupled to the input end of the switching voltage converter, a second receiving end coupled to the output end of the switching voltage converter, and a regulated output end coupled to the control circuit to provide an adaptive regulated voltage to power the control circuit: in: The adaptive regulated voltage supplies power to the control circuit to form a load current; The voltage regulator controls whether to generate the adaptive regulated voltage based on the output voltage based on the load current.

2. The switching voltage converter according to claim 1, wherein: The load current determines a first threshold voltage; and In response to the input voltage being lower than the first threshold voltage, the regulator includes supporting generation of the adaptive regulated voltage based on the output voltage.

3. The switching voltage converter according to claim 2, wherein: In response to the input voltage being not lower than the first threshold voltage, the regulator generates the adaptive regulated voltage based on the input voltage, but does not support the generation of the adaptive regulated voltage based on the output voltage.

4. The switching voltage converter according to claim 3, wherein: a second threshold voltage lower than the first threshold voltage; and In response to the input voltage being lower than the second threshold voltage, the regulator does not generate the adaptive regulated voltage based on the input voltage, but generates the adaptive regulated voltage based on the output voltage.

5. The switching voltage converter according to claim 4, wherein: Corresponding to the input voltage not lower than the second threshold voltage but lower than the first threshold voltage, the regulator generates the adaptive regulated voltage based on the input voltage and also supports the generation of the adaptive regulated voltage based on the output voltage.

6. The switching voltage converter according to claim 1, wherein: The regulator includes: a first voltage stabilizing sub-circuit, comparing a first feedback voltage with a reference voltage to couple the input voltage to the voltage stabilizing output terminal; and a second voltage stabilizing sub-circuit, comparing a second feedback voltage with the reference voltage to couple the output voltage to the voltage stabilizing output terminal; in: The first feedback voltage and the second feedback voltage are divided from the adaptive voltage regulation voltage, so that the first voltage regulation sub-circuit takes precedence over the second voltage regulation sub-circuit.

7. The switching voltage converter according to claim 6, wherein: The first voltage stabilizing subcircuit includes a first transistor of a P-type channel, a first operational amplifier, and a first diode; The first transistor has a source coupled to the input voltage and a drain coupled to an anode of the first diode; The first operational amplifier has a positive input terminal coupled to the first feedback voltage, a negative input terminal coupled to the reference voltage, and an output terminal coupled to a gate of the first transistor; and A cathode of the first diode is coupled to the voltage-stabilizing output terminal.

8. The switching voltage converter according to claim 7, wherein: The second voltage stabilizing subcircuit includes a second transistor of a P-type channel, a second operational amplifier, and a second diode; The second transistor has a source coupled to the output voltage and a drain coupled to an anode of the second diode; The second operational amplifier has a positive input terminal coupled to the second feedback voltage, a negative input terminal coupled to the reference voltage, and an output terminal coupled to a gate of the second transistor; and A cathode of the second diode is coupled to the voltage-stabilizing output terminal.

9. The switching voltage converter according to claim 8, wherein: The first feedback voltage is lower than the second feedback voltage.

10. The switching voltage converter according to claim 9, wherein: The voltage stabilizer further includes a first resistor, a second resistor, and a third resistor connected in series from the voltage stabilizer output terminal to a ground terminal; The second feedback voltage is obtained from the connection point between the first resistor and the second resistor; and The first feedback voltage is obtained from a connection point between the second resistor and the third resistor.

11. The switching voltage converter of claim 10, wherein: The first resistor, the second resistor, and the third resistor determine a first ratio; The first ratio is R1 / (R2+R3), R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, and R3 is the resistance value of the third resistor; and The reference voltage and the first ratio are designed based on the power supply tolerance of the control circuit to determine the voltage lower limit of the adaptive regulated voltage.

12. The switching voltage converter of claim 10, wherein: The first resistor, the second resistor, and the third resistor determine a second ratio; The second ratio is (R1+R2) / R3, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, and R3 is the resistance value of the third resistor; and The reference voltage and the second ratio are designed based on the power tolerance of the control circuit to determine the voltage upper limit of the adaptive regulated voltage.

13. The switching voltage converter of claim 1, wherein: Also includes: a voltage conversion diode having a cathode coupled to the output terminal of the switch-mode voltage converter; an inductor coupled between the input terminal of the switch-mode voltage converter and an anode of the voltage conversion diode; and A capacitor coupled between the output terminal of the switch-mode voltage converter and a ground terminal; in: The switch is an N-type channel transistor having a drain coupled to the anode of the voltage conversion diode, a source coupled to the ground, and a gate controlled by the control circuit.

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