CN116647124A

CN116647124A - Switching Converter with Drive Strength Control

Info

Publication number: CN116647124A
Application number: CN202310142263.5A
Authority: CN
Inventors: 张亮
Original assignee: Texas Instruments Inc
Current assignee: Texas Instruments Inc
Priority date: 2022-02-22
Filing date: 2023-02-20
Publication date: 2023-08-25

Abstract

Embodiments of the present disclosure relate to a switching converter with drive strength control. An electronic system (100) includes a switching converter (102). The switching converter (102) includes a switch (111) having a control terminal, drive stage circuitry (108A) coupled to the control terminal of the switch (111) and configured to provide one of first and second drive signals to the switch (111), and a controller (103) coupled to the drive stage circuitry (108A). The controller (103) is configured to operate the drive stage circuitry (108A) in one of a first drive mode and a second drive mode based on a temperature of the switching converter (102), wherein in the first drive mode the controller (103) is configured to control the drive stage circuitry (108A) to provide the first drive signal to the switch (111), and wherein in the second drive mode the controller (103) is configured to control the drive stage circuitry (108A) to provide a second drive signal to the switch (111).

Description

Switching converter with drive strength control

Cross reference to related applications

The present application claims priority to U.S. provisional patent application No. 63/312,475, 22 nd month 2022, which is incorporated herein by reference.

Technical Field

The present description relates generally to integrated circuits, and more particularly to a switching converter system with drive strength control.

Background

Power supplies and power converters are used in a variety of electronic systems. Electrical power is typically transmitted over long distances as Alternating Current (AC) signals. AC signals are divided and metered as needed for each commercial or home location and are typically converted to Direct Current (DC) for use with individual electronic devices or components. Modern electronic systems (e.g., mobile phones, personal computers, automobiles, lighting systems, industrial equipment) typically employ devices or components that operate at different DC voltages. Thus, the system benefits from a different DC-DC converter or a DC-DC converter supporting a wide range of output voltages.

The various DC-DC converters differ with respect to their components, the amount of power processed, the input voltage(s), the output voltage(s), efficiency, reliability, size, and/or other characteristics. Example topologies include buck converters, boost converters, buck-boost converters, flyback converters, and the like.

The DC-DC converter should survive at room temperature, at high temperatures, e.g. 125 c, and at low temperatures, e.g. -40 c. Typically, the driver strength of the switch provided by the driver to the DC-DC converter has a negative temperature coefficient, such that when the junction temperature of the switch of the DC-DC converter becomes lower, the driver becomes faster, which results in a larger bounce at low temperatures, e.g. -40 ℃, and thus increases the risk of possible damage at low temperatures.

For example, to protect the device in a low temperature (e.g., -40 ℃) hard short circuit test, the driver of the switch (high side switch or low side switch) of the DC-DC device should be relatively slow. But under heavy load conditions where the junction temperature of the high-side or low-side switch (which is a power FET) is high (e.g., 80 ℃), slower drivers can lead to undesirable inefficiencies.

Disclosure of Invention

In a switching converter, a controller has a controller input and a controller output. The controller is configured to: providing a first mode signal at the controller output in response to a first temperature signal at the controller input; and providing a second mode signal at the controller output in response to a second temperature signal at the controller input. The driving circuitry has a driving input and a driving output. The drive input is coupled to the controller output. The drive circuitry is configured to: providing a first drive signal at a drive output in response to the first mode signal; and providing a second drive signal at the drive output in response to the second mode signal. The switch has a control terminal coupled to the drive output.

Drawings

Fig. 1 is a block diagram of an electronic system in some examples.

Fig. 2A and 2B are example circuit diagrams of a bandgap voltage generator.

Fig. 3 is a graph of the change in the sensing voltage with temperature change.

Fig. 4 is a diagram of ringing at the switching terminal at different temperatures.

Fig. 5 is a graph showing thermal performance of the DC-DC converter when in a full load condition.

Fig. 6A and 6B are timing diagrams of voltage waveforms at a switch terminal in some examples.

Fig. 7 is a schematic diagram of an electronic system in some examples.

Fig. 8 is a graph of comparison of drive strengths in the case of temperature detection and in the case of no temperature detection.

Fig. 9 is a graph of efficiency as a function of load in some examples.

Fig. 10 is a flow chart of a method of controlling a switching converter in some examples.

Detailed Description

A switching converter topology having multiple drive stages and drive modes is described herein. The switching converter includes switching circuitry and a plurality of driver stages coupled to the switching circuitry, wherein the switching circuitry includes at least one switch and a switching terminal. In one example, with the described switching converter topology, the switching converter adjusts its operation based on its temperature. The switching converter is typically in the form of a semiconductor device. If the semiconductor device is sufficiently small in size, the temperature of the semiconductor device is substantially equal to the junction temperature of the at least one switch of the switching converter.

In one example, if the voltage representative of the device temperature provided by the temperature sensor is greater than a reference voltage representative of a threshold temperature level, a first set of the plurality of drive stages provides a first drive signal to the switching circuitry to drive the high-side switch or the low-side switch. The threshold temperature level is set based on a breakdown voltage of the at least one switch. When a first number of the plurality of drive stages provides a first drive signal to the switching circuitry, the switching slew rate of the at least one switch increases, which increases the efficiency of the switching converter and increases ringing at the switching terminals. Because the device temperature is greater than or equal to the threshold temperature level, the increase in switching slew rate is temperature limited and this ringing does not exceed the maximum voltage target (e.g., the breakdown voltage of at least one transistor of the switching converter). In contrast, if the voltage representative of the device temperature is less than the reference voltage, a second number of the plurality of drive stages provides a second drive signal to the switching circuitry to drive the high-side switch or the low-side switch, wherein the second number is less than the first number. When the second number of drive stages provides the second drive signal to the switching circuitry, the switching slew rate decreases, which decreases the efficiency of the switching converter and decreases ringing at the switching terminals.

In some examples, the switching converter includes a controller that supports a plurality of modes, wherein a mode is selected based on a voltage representative of a switching converter temperature. For example, if the output of the temperature sensor indicates that the temperature of the switching converter is below a threshold temperature level, the controller is configured to select a first drive mode that uses only one of the first drive stage and the second drive stage to provide the first drive signal to the switching circuitry. In contrast, if the output of the temperature sensor indicates that the temperature of the switching converter is greater than or equal to the threshold temperature level, the controller is configured to select a second drive mode that uses both the first drive stage and the second drive stage to provide a second drive signal to the switching circuitry. In some examples, the controller includes a temperature sensor circuit and a level shifter, wherein the level shifter is coupled between the supply voltage detector circuit and the second drive stage.

In some examples, the first drive stage is configured to provide a first drive signal contribution to the switching circuitry and the second drive stage is configured to provide a second drive signal contribution to the switching circuitry. The second drive signal contribution is larger than the first drive signal contribution. The controller may support additional modes (e.g., use only the first drive stage, use only the second drive stage, use both the first and second drive stages). Also, in some examples, more than two drive stages are possible. With the switching converter topology described herein, switching converter efficiency and ringing management is performed based on temperature sensor circuitry and threshold temperature levels. Various switching converter options and current monitoring circuit options are described herein.

Fig. 1 is a block diagram of an electronic system 100 in some examples. The system 100 represents an Integrated Circuit (IC), a multi-die module (MDM), discrete components, or a combination thereof. In some examples, the ICs, MDMs, and/or discrete components are coupled together using a Printed Circuit Board (PCB). In one example, the electronic system 100 may be a mobile phone, personal computer, automobile, lighting system, industrial equipment, etc., employing devices or components that operate at different DC voltages. As shown, the system 100 includes a switching converter 102 having drive stages 108A-108N coupled to switching circuitry 110. The switching circuitry 110 includes one or more switches and a switch terminal SW. In one example, the drive stages 108A-108N are coupled to a first switch (e.g., the high-side switch 111) of the switching circuitry 112, wherein each of the drive stages 108A-108N is configured to provide a respective drive signal contribution to the high-side switch 111. When the switching converter is a buck converter, the high side switch 111 is coupled between the input voltage supply and the switching terminal SW. In another example, the drive stages 108A-108N are coupled to a second switch (e.g., the low-side switch 112) of the switching circuitry 110, wherein each of the drive stages 108A-108N is configured to provide a respective drive signal contribution to the low-side switch 112. The low side switch 112 may be coupled between the switching terminal SW and ground. In some examples, the drive signal contributions of each of the drive stages 108A-108N are equal to each other (e.g., two drive signal contributions 50%, four drive signal contributions 25%, etc.). In other examples, each drive signal contribution is different from each other (e.g., two drive signal contributions 60% and 40%, etc.). In some examples, some of the drive stages 108A-108N are coupled to the high-side switch 111, while other of the drive stages 108A-108N are coupled to the low-side switch 112.

In the example of fig. 1, the driver stages 108A-108N are coupled to the controller 103. The controller 103 is configured to control the driving stages 108A to 108N based on the temperature of the switching converter 102. As shown, the controller 103 includes: a temperature detector 104 configured to detect a temperature of the switching converter 102 relative to a threshold temperature and generate a detection signal DS; and control circuitry 113 configured to control the drive stages 108A to 108N based on the detection signal DS. In some examples, the temperature detector 104 includes: a temperature sensor 1041 configured to generate a signal Vptat representing the temperature of the switching converter 102; and one or more comparators configured to perform temperature detection based on the signal Vptat and a reference voltage VREF representing a threshold temperature. In other examples, temperature sensor 1041 is configured to measure the temperature of switching converter 102.

Regardless of the particular temperature sensing mechanism, the temperature detector 104 is configured to provide a Detection Signal (DS) to indicate whether the temperature of the switching converter 102 is greater than or equal to a threshold temperature.

In one example, the temperature sensor 1041 is part of a bandgap voltage generator of the switching converter 102 that generates a bandgap voltage of the switching converter 102.

Fig. 2A shows an example of a circuit diagram of a bandgap voltage generator 200. The bandgap voltage generator 200 is configured to generate a bandgap voltage VBG of the switching converter 102. In the example of fig. 2A, the bandgap voltage generator 200 includes an amplifier 202, a first resistor 204 coupled between a first input of the amplifier 202 and an output of the amplifier 202, a second resistor 206 coupled between a second input and an output of the amplifier 202, a first transistor Q1 208 coupled between the first input and ground, a third resistor R3 210 and a second transistor Q2 212 coupled in series between the second input and ground. The output of amplifier 202 is configured to provide a bandgap voltage VBG.

In one example, the first and second transistors 208 and 212 are Bipolar Junction Transistors (BJTs) and have negative temperature coefficients in the linear region. However, the first and second transistors 208 and 212 may also be Field Effect Transistors (FETs). In one example, the signal Vptat is the voltage across the third resistor R3 210, representing the difference between: the voltage between the base and emitter of the first transistor Q1 208; and the voltage between the base and emitter of the second transistor Q2 212, which increases with increasing temperature. In another example, a voltage Vntat (which is proportional to the voltage between the base and emitter of the first transistor Q1 208 or the voltage between the base and emitter of the second transistor Q2 212, and which increases with decreasing temperature) may also be provided for temperature detection.

Fig. 2B shows another example of a circuit diagram of the bandgap voltage generator 220. The bandgap voltage generator 220 is configured to generate a bandgap voltage VBG of the switching converter 102. In the example of fig. 2B, the bandgap voltage generator 220 includes an amplifier 222, a first resistor 224 having a first terminal coupled to a first input of the amplifier 222 and having a second terminal, a second resistor 226 having a second terminal coupled to the first resistor 224 and having a second terminal coupled to ground, a third resistor 228 coupled between the second input of the amplifier 222 and the first terminal of the second resistor 226, and a fourth resistor 230 having a first terminal coupled to the first input of the amplifier 222 and having a second terminal. The bandgap voltage generator 220 further includes a first transistor Q1 232 and a second transistor Q2 234. The first transistor 232 includes a first current terminal coupled to the second input of the amplifier 222, a second current terminal coupled to the voltage supply terminal, and a control terminal coupled to the output of the amplifier 222. The second transistor 234 includes a first current terminal coupled to the second terminal of the fourth resistor 230, a second current terminal coupled to the voltage supply terminal, and a control terminal coupled to the output of the amplifier 222. The output of amplifier 222 is configured to provide a bandgap voltage VBG.

In one example, the first and second transistors 232 and 234 are Bipolar Junction Transistors (BJTs) and have negative temperature coefficients in the linear region. However, the first and second transistors 232 and 234 may also be FETs. In one example, the signal Vptat is the voltage across the second resistor 226, representing the difference between: a voltage between the base and the emitter of the first transistor 232; and the voltage between the base and emitter of the second transistor 234, which increases with increasing temperature. In the example of fig. 2B, the signal Vptat is the voltage at the first terminal of the second resistor 226.

Referring again to fig. 1, the temperature detector 104 generates a detection signal DS based on the signal Vptat. Other topologies providing a Vptat or Vntat bandgap generator that is proportional to temperature are also suitable. By using the bandgap generator 200 to sense the temperature of the switching converter 102, no additional temperature sensor is required for temperature sensing.

Fig. 3 is a graph 300 illustrating the increase in the signal Vptat with increasing temperature TEMP. In one example, the threshold temperature is set to 40 ℃, and when the temperature is 40 ℃, the reference voltage VREF 304 is set based on the level of the signal Vptat 302. In one example, the temperature detector 104 includes a comparator to compare the signal Vptat with a reference voltage VREF and generate a detection signal DS.

Referring again to fig. 1, in some examples, the controller 103 also includes a level shifter 106 configured to receive the detection signal DS from the temperature detector 104. The level shifter 106 is configured to adjust the detection signal DS to another voltage domain to enable the selection logic 107 to control at least one of the driver stages 108A to 108N. In the example of fig. 1, the controller 103 supports a plurality of modes, wherein a mode is selected based on the detection signal DS. For example, if the detection signal DS indicates that the temperature of the switching converter 102 is below a threshold temperature, the controller 103 is configured to select a first drive mode using a first number of the drive stages 108A to 108N to provide a first drive signal to the switching circuitry 112. In contrast, if the detection signal DS indicates that the temperature of the switching converter 102 is greater than or equal to the threshold temperature, the controller 103 is configured to select a second drive mode that uses a second number of the drive stages 108A-108N to provide a second drive signal to the switching circuitry 110, wherein the second number is greater than the first number.

In one example, the switching converter 102 includes first and second driver stages. When the temperature is lower than the threshold temperature, the detection signal DS output from the temperature detector 104 is in a first state (e.g., logic low); and in response, control circuitry 113 enables only a first one of the two drive stages to provide a first drive signal to switching circuitry 110. When the temperature is higher than or equal to the threshold temperature, the detection signal DS output from the temperature detector 104 is in a second state (e.g., logic high); and in response, control circuitry 113 enables both the first and second drive stages to provide a second drive signal to switching circuitry 110.

In the buck converter example, the switching terminal SW is adapted to be coupled to an output inductor (e.g., one of the output components 114 of the system 100). In this example, the output component 114 also includes an output capacitor, wherein the charge stored by the output capacitor is provided to the load 116. In some examples, the controller 103 directs the drive stages 108A-108N using different modes to provide drive signals to the high-side switches based on temperature. In other examples, the controller 103 directs the drive stages 108A-108N using different modes to provide drive signals to the low side switches based on the input supply voltage level. In some examples, the first set of drive stages provides a high-side drive signal to the high-side switch based on temperature, and the second set of drive stages provides a low-side drive signal to the low-side switch based on temperature.

Fig. 4 is a graph 400 of ringing of a switching terminal of a switching converter with respect to ground at different temperatures caused by the same drive signal. Waveform 402 depicts the inductor current IL when the temperature is-40 ℃ and waveform 404 depicts ringing at the switching terminal SW in response to the high side switch being turned on at T1 when the temperature is-40 ℃. Waveform 406 depicts the inductor current IL when the temperature is 0 ℃, and waveform 408 depicts ringing at the switching terminal SW in response to the high side switch being turned on at T2 when the temperature is 0 ℃. Waveform 410 depicts inductor current IL when the temperature is 40 ℃ and waveform 412 depicts ringing at switching terminal SW in response to the high side switch being turned on at T3 when the temperature is 40 ℃. Waveform 414 depicts the inductor current IL when the temperature is 80 ℃, and waveform 416 depicts ringing at the switching terminal SW in response to the high side switch being turned on at T4 when the temperature is 80 ℃. Fig. 4 shows that when the corresponding high side switch indicated by the change in inductor current from decreasing to increasing changes from off to on, the lower temperature results in more ringing at the switching terminal.

Fig. 5 is a thermal diagram 500 of the device 502 switching the converter after 15 minutes of operation under heavy load conditions. The input voltage Vin of the switching converter is 12V, the output voltage of the switching converter is 5V, and the output current of the switching converter is 6A. After 15 minutes of operation, the temperature of the device 502 may be raised above 80 ℃. In one example, for a switching converter with an output current of 3A, the threshold temperature is set between 50 ℃ and 60 ℃. The threshold temperature may be obtained through testing to ensure that ringing caused by the corresponding drive mode does not exceed the breakdown voltage of the high-side or low-side switch of switching converter 102.

Fig. 6A and 6B are timing diagrams of switching terminal voltage waveforms in some examples. In the timing chart 600 of fig. 6A, a switching terminal voltage waveform 602 is shown. As shown, the switch terminal voltage waveform 602 shows a falling edge scenario, where the switch terminal voltage drops from a high level 604 to a low level 610. In the example of FIG. 6A, the slew rate of the falling edge is measured as the voltage change/time change (dv/dt) from point 606 to 608. The switch terminal voltage waveform 602 also shows that the switch terminal voltage reaches a minimum 614, and there is an offset 612 between the minimum 614 and the low 610. In the example of FIG. 6A, the slew rate of the switch terminal voltage is approximately 3V/ns. This slew rate reduces ringing problems but results in inefficient switching operations (switching losses are greater compared to faster slew rates).

In the timing diagram 620 of fig. 6B, another switch terminal voltage waveform 622 is shown. As shown, the switch terminal voltage waveform 622 shows a falling edge scenario, where the switch terminal voltage drops from a high level 625 to a low level 630. In the example of FIG. 6B, the slew rate of the falling edge is measured as the voltage change/time change (dv/dt) from point 624 to 626. The switch terminal voltage waveform 620 also shows that the switch terminal voltage reaches a minimum value 632, with an offset 628 between the minimum value 632 and a low level 630. In the example of FIG. 6B, the slew rate of the switch terminal voltage is approximately 10V/ns. This slew rate is more efficient (compared to the slew rate of the switch node voltage waveform 302), but increases ringing problems. For example, offset 628 shown in fig. 6B is greater than offset 612 shown in fig. 6A.

Fig. 7 is a schematic diagram of an electronic system 700 in some examples. As shown, the system 700 includes a switching converter 702 (an example of the switching converter 102 of fig. 1) having switching circuitry 704 (an example of the switching circuitry 110 of fig. 1), first and second driver stages 706 and 708 (examples of the driver stages 108A-108N of fig. 1), a level shifter 710 (an example of the level shifter 106 of fig. 1), selection logic 711 (an example of the selection logic 107 of fig. 1), and a temperature detector 712 (an example of the temperature detector 104 of fig. 1).

As shown in fig. 7, the switching circuitry 704 includes a high side switch 714 and a low side switch 716 coupled at a switching terminal SW. In the example of fig. 7, the high-side switch 714 includes control terminals coupled to the first driver stage 706 and the second driver stage 708. A first current terminal of the high side switch 714 is coupled to an input supply terminal 720 (e.g., the input voltage supply of fig. 1) via a first inductor L1, and a second current terminal of the high side switch 714 and a first current terminal of the low side switch 716 are coupled at a switching terminal SW. Also, the control terminal of the low-side switch 716 is coupled to a low-side drive signal (XDRVL) terminal 722 via a buffer 724. A second current terminal of the low side switch 716 is coupled to a ground terminal 726 via a second inductor L2. In the example of fig. 7, the first inductor L1 and the second inductor L2 represent parasitic inductances (e.g., from a Printed Circuit Board (PCB)), which are considerations for the driver design. The first inductor L1 and the second inductor L2 are not actual inductor components.

As shown, the switch terminal SW is also coupled to a first end of the output inductor 728. A second end of the output inductor 728 is coupled to an output terminal 730. As shown, output terminal 730 is also coupled to a first terminal of output capacitor 732. A second terminal of the output capacitor 732 is coupled to the ground terminal 726. In the example of fig. 7, a load 734 is coupled between the output terminal 730 and the ground terminal 726, where the load 734 is powered by the output voltage VOUT at the output terminal 730. Comparing fig. 1 and 7, the output inductor 728 and the output capacitor 732 of fig. 7 are examples of the output component 114, and the load 734 of fig. 7 is an example of the load 116 of fig. 1.

In operation, the first driver stage 706 is configured to provide a first drive signal 736 to a control terminal of the high-side switch 714 in response to a high-side drive signal XDRVH of a high-side drive signal (XDRVH) terminal 738. More specifically, the first driver stage 706 includes first and second transistors 740 and 742 having control terminals coupled to a high-side drive signal terminal 738 via respective buffers 744 and 746. Also, a first current terminal of the first transistor 740 is coupled to an input supply BST terminal 748. In some examples, BST is a power supply approximately 5V higher than the switch terminal SW. In one example, the voltage level of the BST is obtained by placing a capacitor 750 between the BST terminal 748 and the switch terminal SW. More specifically, a first (e.g., top) plate of capacitor 750 is coupled to BST terminal 748 and a second (e.g., bottom) plate of capacitor 750 is coupled to switch terminal SW.

A second current terminal of the first transistor 740 is coupled to a first current terminal of the second transistor 742, and a second current terminal of the second transistor 742 is coupled to the switching terminal SW. In response to the output voltage VOUT falling below a threshold or another flip-flop, the high-side drive signal XDRVH transitions from a logic high to a logic low, which causes the first and second transistors 740 and 742 to provide the first drive signal 736 to turn on the high-side transistor 714 to increase the output voltage VOUT. After the output voltage VOUT reaches a threshold or another trigger occurs, the high-side drive signal XDRVH transitions from logic low to logic high, which causes the first and second transistors 740 and 742 to cease providing the first drive signal 736 and causes the high-side switch 714 to be turned off. In some examples, the first driver stage 706 is used in multiple drive modes.

In operation, the second drive stage 708 is configured to provide a second drive signal 752 to the control terminal of the high-side switch 714 in response to the detection signal DS from the temperature sensor 712 indicating that the temperature is above a threshold. In one example, the temperature detector 712 includes: a comparator 760; and a temperature sensor 756 that is part of the bandgap voltage generator 754 of the switching converter 702 that generates the bandgap voltage VBG. The temperature sensor 756 includes an output 758 that provides a voltage signal Vptat representative of the temperature of the switching converter 702. An output 758 of the temperature sensor 756 is coupled to one of the input terminals of the comparator 760. The other input terminal of comparator 760 is configured to receive a reference voltage VREF, such as the reference voltage VREF of fig. 3. In one example, the reference voltage VREF is generated based on the bandgap voltage VBG and represents a threshold temperature. When the voltage Vptat is less than the reference voltage VREF, the detection signal DS at the output of the comparator 760 is logic low. Thus, when the high-side drive signal XDRVH is low, and if the temperature of the switching converter 702 is below the threshold temperature, the second drive stage 708 is not used, and only the first drive stage 706 drives the high-side switch 714. In contrast, when the voltage Vptat is greater than or equal to the reference voltage VREF, the detection signal DS at the output of the comparator 760 is logic high. Thus, when the high-side drive signal XDRVH is logic low, and if the temperature of the switching converter 702 is greater than or equal to the threshold temperature, both the first driver stage 706 and the second driver stage 708 drive the high-side switch 714.

As shown in fig. 7, the output of comparator 760 provides a control signal to level shifter 710, level shifter 710 includes a fourth resistor 762, a control switch 764, and a fifth resistor R5 coupled in series between BST terminal 748 and ground terminal 726. The control terminal of the control switch 764 is coupled to the output of the comparator 760, a fifth resistor R5 is coupled between the BST terminal 748 and the first current terminal of the control switch 764, and a fifth resistor 766 is coupled between the second current terminal of the control switch 764 and the ground terminal 726. In the example of fig. 7, a component 768, such as a schmitt comparator, adjusts the voltage level at the first current terminal of the control switch 764 to another voltage level.

As shown in fig. 7, the second driver stage 708 includes third and fourth transistors 770 and 772, and the output of the component 768 is provided to the input terminal of an or gate 774, with the output terminal of the or gate coupled to the control terminal of the third transistor 770. The other input terminal of the or gate 774 is coupled to a high side drive signal (XDRVH) terminal 738. The output of component 768 is also coupled to the input of inverter 776. An output of the inverter 776 is coupled to an input terminal of an and gate 778. The other input terminal of the and gate 778 is coupled to a high side drive signal (XDRVH) terminal 738. An output terminal of the and gate 778 is coupled to a control terminal of the fourth transistor 772.

In the first drive mode, only the first drive stage 706 is used. In some examples, the control of the first and second transistors 740 and 742 in the first drive mode varies with the high-side drive signal XDRVH. More specifically, in the first drive mode (where only the first drive stage 706 is used), when the high-side drive signal XDRVH is logic low, the second transistor 742 is turned off, the first transistor 740 is turned on, and the high-side switch 714 is turned on. In the first drive mode, if the output of component 768 is a logic high (which indicates that the temperature of switching converter 702 is below the threshold temperature), then third transistor MP2 will not be conductive. In contrast, in the first driving mode, when the high-side driving signal XDRVH is logic high, the second transistor 742 is on, the first transistor 740 is off, and the high-side switch 714 is off. In the first drive mode, if the output of component 768 is a logic high (which indicates that the temperature is below the threshold temperature level), then the fourth transistor 772 will not conduct.

In the second drive mode (where both the first and second drive stages 706 and 708 are used), the control of the first through fourth transistors 740, 742, 770, and 772 varies with the high side drive signal XDRVH. More specifically, in the second drive mode, when the high side drive signal XDRVH is logic low, if the output of component 768 is logic low (which indicates that the temperature is greater than or equal to the threshold temperature), then the first transistor 740 is turned on and the third transistor 770 is turned on. Turning on the third transistor 770 turns on the high-side switch 714 faster, which improves the efficiency of the switching converter 702. In the second driving mode, when the high-side driving signal XDRVH is logic high, the second transistor 742 is turned on, and the high-side switch 714 is turned off. The fourth transistor 772 is also turned on, which causes the high side switch 714 to turn off faster.

In the example of fig. 7, the operation of the switching converter 702 is adjusted based on temperature. If the temperature is greater than or equal to the threshold temperature (detected by temperature detector 712), then both the first and second driver stages 706 and 708 provide a drive signal to the high-side transistor 714. When both the first and second driver stages 706 and 708 provide drive signals to the high-side transistor 714, the switching slew rate increases, which increases the efficiency of the switching converter 702 and increases the switching terminal ringing. In contrast, if the temperature is below the threshold temperature, only the first drive stage 706 provides a drive signal to the high side switch 714. When only the first driver stage 706 provides a drive signal to the high side switch 714, the switching slew rate decreases, which decreases the efficiency of the switching converter 702 and also decreases the switching terminal ringing. In one example, for a switching converter with a target output voltage of 17V, the threshold temperature is set to about 40 ℃ to ensure that ringing does not exceed the breakdown voltage of at least one of the high side and low side switches of the switching converter.

Fig. 8 is a graph 800 of a comparison of drive strength with and without temperature detection. Waveform 802 depicts the inductor current IL of the switching converter with a conventional driver and the switching converter of fig. 7 in the same drive mode when the temperature is-40 ℃. Waveform 804 depicts ringing at the switch terminal SW turned on at T1 in response to the high side switch when the temperature is-40 ℃. Waveform 806 depicts the inductor current IL of the switching converter of fig. 7 when the temperature is 40 ℃. Waveform 808 depicts ringing at the switch terminal SW that is turned on at T2 in response to the high side switch 714 when the temperature is 40 ℃. Waveform 810 depicts the inductor current IL of a switching converter with a conventional driver when the temperature is 40 ℃. Waveform 812 depicts ringing at the switch terminal SW that is turned on at T3 in response to the high-side switch 714 when the temperature is 40 ℃.

In fig. 8, when the temperature is-40 ℃, both the switching converter with conventional driver and the modified switching converter 702 of fig. 7 operate in the same driving mode, so the ringing amplitude is the same when the inductor current is changed from decreasing to increasing, and it does not exceed the breakdown voltage. When the temperature is 40 ℃, the switching converter with the conventional driver continues to use the same driving mode, and the ringing amplitude becomes smaller compared to the ringing amplitude when the temperature is-40 ℃. However, when the temperature is 40 ℃, the improved switching converter 702 of fig. 7 switches to the second drive mode, wherein the additional drive stage increases the slew rate while maintaining the ringing amplitude below the breakdown voltage. Thus, the efficiency of the switching converter 702 is improved.

Fig. 9 is a graph 900 showing a comparison of efficiency as a function of load between a conventional drive strategy and an improved drive strategy of the switching converter 702 of fig. 7. In graph 900, line 902 corresponds to a conventional drive strategy, where the efficiency reaches about 90% before dropping to about 84% with load. Meanwhile, line 904 corresponds to an improved drive strategy in which the efficiency reaches about 90% before the load drops to about 87% at a load current of about 5A and increases to almost 89% as the load current increases to about 6A and drops to about 86% with the load. In graph 900, assume that the values include vin=12v, vout=1v, and l=1μh.

Fig. 10 is a flow chart of a method 1000 of controlling a switching converter in some examples with reference to the system 700 of fig. 7. In step 1002, a temperature detector 712 monitors a signal Vptat representing the temperature of the switching converter 702. If Vpt is less than the reference voltage VREF representing the threshold temperature determined at step 1004, then one of the first and second drive stages (e.g., the first drive stage 706 of FIG. 7) provides a first drive signal at step 1006. In contrast, if Vtat is greater than or equal to the reference voltage VREF determined at step 1004, then both the first and second driver stages 706 and 708 of FIG. 7 provide a second drive signal at step 1008. In some examples, method 1000 controls switching the high-side switch 714 of the converter 702. In other examples, method 1000 controls a low-side switch 716 of switching converter 702.

In some examples, one or more of the described switching converters (e.g., switching converter 102 of fig. 1 or switching converter 702 of fig. 7) may be used in a battery powered device, such as a laptop computer or tablet computer. For example, the switching converter may be used in a battery-powered device, where the VIN for the switching converter is provided by a battery or an AC/DC adapter. The switching converter drops VIN to VOUT (e.g., VIN of 6V or greater and VOUT of 3.3V or 5V) for powering the electronic components of the battery-powered device. In other examples, the switching converter increases VIN to VOUT (e.g., VIN of 5V and VOUT of 12V).

In this description, the term "couple" means an indirect or direct wired or wireless connection. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect connection via other devices and connections.

In this description, the statement "based on" means "based at least in part on". Thus, if X is based on Y, X may vary with Y and any number of other factors.

In this description, unless otherwise stated, "about," "about," or "substantially" preceding a parameter means within +/-10% of the parameter.

In the described embodiments, modifications are possible and other embodiments are possible within the scope of the claims.

Claims

1. A switching converter, comprising:

a controller having a controller input and a controller output, the controller configured to: providing a first mode signal at the controller output in response to a first temperature signal at the controller input indicating that the temperature of the switching converter is below a threshold temperature; and providing a second mode signal at the controller output in response to a second temperature signal at the controller input indicating that the temperature of the switching converter is greater than or equal to the threshold temperature;

drive circuitry having a drive input and a drive output, the drive input coupled to the controller output, and the drive circuitry configured to provide a first drive signal at the drive output in response to the first mode signal; and providing a second drive signal at the drive output in response to the second mode signal; a kind of electronic device with high-pressure air-conditioning system

A switch having a control terminal coupled to the drive output.

2. The switching converter of claim 1, wherein the drive circuitry includes a first drive stage and a second drive stage, the first drive stage configured to provide the first drive signal having a first intensity, and the second drive stage configured to provide the second drive signal having a second intensity greater than the first intensity.

3. The switching converter of claim 2, wherein the controller comprises a level shifter coupled between the controller input and the second drive stage, wherein the level shifter is configured to enable the second drive stage in response to the second temperature signal at the controller input.

4. The switching converter of claim 1, wherein the drive circuitry includes a first drive stage configured to provide the first drive signal having a first intensity and a second drive stage having a second intensity and being a combination of the first drive signal and a third drive signal, and the second drive stage is configured to provide the third drive signal having a third intensity.

5. The switching converter of claim 4, wherein the controller comprises a level shifter coupled between the controller input and the second drive stage, wherein the level shifter is configured to enable the second drive stage in response to the second temperature signal at the controller input.

6. The switching converter of claim 1, further comprising a temperature sensor having a temperature output coupled to the controller input, the temperature sensor configured to: providing the first temperature signal at the temperature output in response to the temperature of the switching converter being below the threshold temperature; and providing the second temperature signal at the temperature output in response to the temperature of the switching converter being greater than or equal to the threshold temperature.

7. The switching converter of claim 6, wherein the temperature sensor comprises:

a comparator having a comparator output and first and second comparator inputs, wherein the comparator output is the temperature output, and the comparator is configured to: providing the first temperature signal at the comparator output in response to a signal at the first comparator input indicating that the temperature of the switching converter is below the threshold temperature, wherein the threshold temperature is indicated by a threshold signal at the second comparator input; and providing the second temperature signal at the comparator output in response to the signal at the first comparator input indicating that the temperature of the switching converter is greater than or equal to the threshold temperature.

8. The switching converter of claim 6, further comprising a bandgap voltage generator configured to generate a bandgap voltage, wherein the bandgap voltage generator includes the temperature sensor, and the bandgap voltage generator is configured to generate a voltage proportional to a signal at the temperature output.

9. A system, comprising:

a temperature sensor having a temperature output, the temperature sensor configured to: providing a first temperature signal at the temperature output in response to a first temperature at the temperature sensor; and providing a second temperature signal at the temperature output in response to a second temperature at the temperature sensor;

a controller having a controller input and a controller output, the controller input coupled to the temperature output, and the controller configured to: providing a first mode signal at the controller output in response to the first temperature signal; and providing a second mode signal at the controller output in response to the second temperature signal;

drive circuitry having a drive input and a drive output, the drive input coupled to the controller output, and the drive circuitry configured to: providing a first drive signal at the drive output in response to the first mode signal; and providing a second drive signal at the drive output in response to the second mode signal; a kind of electronic device with high-pressure air-conditioning system

A switch having a control terminal coupled to the drive output.

10. The system of claim 9, wherein the drive circuitry includes first and second drive stages, the first drive stage configured to provide the first drive signal having a first intensity, and the second drive stage configured to provide the second drive signal having a second intensity greater than the first intensity.

11. The system of claim 10, wherein the controller comprises a level shifter coupled between the controller input and the second drive stage, wherein the level shifter is configured to enable the second drive stage in response to a signal at the controller input indicating any temperature greater than or equal to a threshold temperature.

12. The system of claim 9, wherein the drive circuitry includes first and second drive stages, the first drive stage configured to provide the first drive signal having a first intensity, the second drive signal having a second intensity and being a combination of the first and third drive signals, and the second drive stage configured to provide the third drive signal having a third intensity.

13. The system of claim 12, wherein the controller comprises a level shifter coupled between the controller input and the second drive stage, wherein the level shifter is configured to enable the second drive stage in response to the signal at the controller input indicating that any temperature of the switching converter is greater than or equal to the threshold temperature.

14. The system of claim 9, wherein the first temperature is any temperature below a threshold temperature and the second temperature is any temperature greater than or equal to the threshold temperature.

15. The system of claim 9, wherein the temperature sensor comprises:

a comparator having a comparator output and first and second comparator inputs, wherein the comparator output is the temperature output, and the comparator is configured to: providing the first temperature signal at the comparator output in response to a signal at the first comparator input indicating that any temperature is below a threshold temperature, wherein the threshold temperature is indicated by a threshold signal at the second comparator input; and providing the second temperature signal at the comparator output in response to the signal at the first comparator input indicating any temperature greater than or equal to the threshold temperature.

16. The system of claim 9, further comprising a bandgap voltage generator configured to generate a bandgap voltage, wherein the bandgap voltage generator includes the temperature sensor, and the bandgap voltage generator is configured to generate a voltage proportional to a signal at the temperature output.