Boost converter with buck mode

Abstract

A boost converter includes an input terminal (102), an output terminal (106), a switch terminal (112), a low-side transistor (108), and a buck mode detection circuit (302). The low-side transistor (108) is coupled to the switch terminal (112). The buck mode detection circuit (302) is coupled to the low-side transistor (108). The buck mode detection circuit (302) is configured to detect that a voltage at the output terminal (106) is greater than a voltage at the input terminal (102) and turn off the low-side transistor (108) based on the voltage at the output terminal (106) being greater than the voltage at the input terminal (102).

Description

Background Art

[0001] A switched-mode power supply is an electronic circuit that converts an input direct current (DC) supply voltage into one or more DC output voltages with amplitudes higher or lower than the input DC supply voltage. Switched-mode power supplies that generate output voltages lower than the input voltage are called step-down converters or step-down converters. Switched-mode power supplies that generate output voltages higher than the input voltage are called step-up converters or step-up converters.

[0002] Some switch-mode power supply topologies include a driver / power transistor coupled to an energy storage inductor / transformer at the switch node. By alternately opening and closing the switch in response to a switching signal, electrical energy is delivered to the load through the energy storage inductor / transformer. The amount of electrical energy delivered to the load is a function of the on / off duty cycle of the switch and the frequency of the switching signal. Switch-mode power supplies are widely used in electronic devices, particularly battery-powered devices such as portable cellular phones, laptop computers, automobiles, industrial tools, and other electronic systems where efficient power usage is desired. Summary of the Invention

[0003] Disclosed herein is a boost converter that provides efficient operation when the boost converter input voltage exceeds the boost converter output voltage. In one example, a boost converter includes a switch terminal, a ground terminal, a buck mode detection circuit, a modulation circuit, a low-side transistor, and a switch. The buck mode detection circuit includes an output terminal. The modulation circuit includes an output terminal. The low-side transistor includes a first terminal, a second terminal, and a third terminal. The first terminal is coupled to the switch terminal. The second terminal is coupled to the ground terminal. The switch includes a first terminal, a second terminal, a third terminal, and a control terminal. The first terminal of the switch is coupled to the third terminal of the low-side transistor. The second terminal of the switch is coupled to the output terminal of the modulation circuit. The third terminal of the switch is coupled to the ground terminal. The control terminal of the switch is coupled to the output terminal of the buck mode detection circuit.

[0004] In another example, a boost converter includes an input terminal, an output terminal, a switch terminal, a low-side transistor, and a buck mode detection circuit. The low-side transistor is coupled to the switch terminal. The buck mode detection circuit is coupled to the low-side transistor. The buck mode detection circuit is configured to detect when a voltage at the output terminal is greater than a voltage at the input terminal and to turn off the low-side transistor based on the voltage at the output terminal being greater than the voltage at the input terminal.

[0005] In another example, a boost converter includes an input terminal, an output terminal, a switch terminal, a ground terminal, a high-side transistor, a first switch, a low-side transistor, and a second switch. The high-side transistor includes a first terminal, a second terminal, and a third terminal. The first terminal of the high-side transistor is coupled to the switch terminal. The second terminal of the high-side transistor is coupled to the output terminal. The first switch is coupled to the third terminal of the high-side transistor. The first switch is configured to modulate the voltage at the third terminal of the high-side transistor between a voltage at the ground terminal and a voltage at the input terminal in a buck mode. The low-side transistor includes a first terminal, a second terminal, and a third terminal. The first terminal of the low-side transistor is coupled to the switch terminal. The second terminal of the low-side transistor is coupled to the ground terminal. The second switch is coupled to the third terminal of the low-side transistor. The second switch is configured to maintain the third terminal of the low-side transistor at a voltage at the ground terminal in a buck mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] To describe various examples in detail, reference will now be made to the accompanying drawings, in which:

[0007] Figure 1A-1C illustrates an example of buck mode operation in a conventional boost converter;

[0008] Figure 2 Shows the Figure 1A-1C A graph showing the relationship between efficiency and input voltage for buck mode operation;

[0009] Figure 3 A block diagram illustrating an example boost converter including high-efficiency buck mode operation;

[0010] Figure 4 Show comparison Figure 2 and Figure 1A-1C A graph showing the efficiency of a boost converter in buck mode operation;

[0011] Figure 5A and Figure 5B An example of high-efficiency buck-mode operation in a boost converter is shown;

[0012] Figure 6 shows example signals generated in a boost converter with high-efficiency buck mode operation;

[0013] Figure 7 A block diagram illustrating an example boost converter including high-efficiency buck mode operation is shown; and

[0014] Figure 8 Show Figure 7 Example signals generated when the boost converter of FIG1 is operated in buck mode. DETAILED DESCRIPTION

[0015] A boost converter uses an inductor to generate an output voltage greater than the input voltage. However, in various boost converter operating scenarios, the input voltage may exceed the output voltage. For example, during startup or when the output load changes, the boost converter input voltage may exceed the converter output voltage. Some boost converters include circuitry to provide output voltage regulation when the input voltage exceeds the output voltage. This type of operation is referred to as "buck mode."

[0016] Figure 1A-1C An example of buck mode operation in a conventional boost converter is shown. Figure 1A-1C In the embodiment of the present invention, the input voltage provided to the boost converter 100 is greater than the output voltage of the boost converter 100. That is, the boost converter 100 is illustrated as operating in the buck mode. The boost converter 100 includes an input terminal 102, an inductor 104, an output terminal 106, a low-side transistor 108, and a high-side transistor 110. The low-side transistor 108 can be an N-channel metal oxide semiconductor field effect transistor (MOSFET) and the high-side transistor 110 can be a P-channel MOSFET. When the boost converter 100 operates in the buck mode (similar to its operation in the non-buck mode), the low-side transistor 108 is turned on and off by a modulation circuit (not shown) to charge the inductor 104. In the non-buck mode operation, the high-side transistor 110 is controlled by the modulation circuit (not shown) so that when the low-side transistor 108 is turned on, the high-side transistor 110 is turned off, and when the low-side transistor 108 is turned off, the high-side transistor 110 is turned on. In buck mode, gate terminal 110G of high-side transistor 110 is coupled to input terminal 102. With gate terminal 110G maintained at the voltage (VIN) at input terminal 102, conduction of high-side transistor 110 is controlled by the voltage at source terminal 110S of high-side transistor 110.

[0017] exist Figure 1B In the , low-side transistor 108 is turned on to charge the inductor 104, the switch terminal 112 is pulled to ground, and the high-side transistor 110 is turned off (and thus in Figure 1B not shown).

[0018] exist Figure 1C , the low-side transistor 108 is off (and thus Figure 1C not shown). Figure 1B The charging of the inductor 104 in the boost mode generates a gate-to-source voltage across the high-side transistor 110 that is sufficient to place the high-side transistor 110 in the linear region and operate the high-side transistor 110 as a pass transistor. When the high-side transistor 110 operates as a pass transistor, its power consumption can be considerable and the efficiency of the boost converter 100 is relatively poor. The efficiency of the boost converter 100 in the buck mode can be expressed as:

[0019]

[0020] in:

[0021] V IN >V OUT ;

[0022] V t is the threshold voltage of the high-side transistor 110 (approximately 1 volt for a 7 volt P-channel MOSFET); and

[0023] Eff is the efficiency of the boost converter 100 , neglecting switching and control power losses.

[0024] Figure 2 A graph showing the relationship between efficiency and input voltage for the boost converter 100 is shown. At an input voltage of approximately 3.9 volts and an output voltage of 3.3 volts, the efficiency of the boost converter 100 is approximately 65%. Figure 2 As shown, the efficiency of the boost converter 100 is much higher when not operating in buck mode (when the input voltage is lower than the output voltage).

[0025] The present disclosure describes embodiments of a boost converter that provides efficient buck mode operation. In efficient buck mode operation, the high-side transistor switches while the low-side transistor remains off. Therefore, the conduction losses and switching losses of the boost converter are reduced in buck mode, and efficiency is improved. In addition, because the low-side transistor is turned off and the current flowing through the high-side transistor is continuous, the embodiments reduce switching noise when operating in buck mode relative to conventional implementations. The boost converter of the present disclosure is suitable for use in a variety of applications that require an increased power supply voltage, including battery-powered devices such as mobile phones, gaming systems, and other portable electronic devices.

[0026] Figure 3 A block diagram of an example boost converter 300 including efficient buck mode operation is shown. In the boost converter 300, when operating in buck mode, the low-side transistor 108 is kept off and the high-side transistor 110 is modulated to regulate the output voltage. Since the low-side transistor 108 is always off when operating in buck mode, the current output of the boost converter 300 is equal to the current input of the boost converter 300. The boost converter 300 provides , which is much higher than the efficiency of the boost converter 100.

[0027] The boost converter 300 includes the input terminal 102, the inductor 104, the output terminal 106, the low-side transistor 108, the high-side transistor 110, and the switch terminal 112. The boost converter 300 also includes a buck mode detection circuit 302, a modulation circuit 304, a switch 306, a switch 308, a driver 310, and a driver 312. The buck mode detection circuit 302 compares VIN and VOUT to detect a buck mode. If VIN is greater than VOUT, the buck mode detection circuit 302 activates a signal DOWN-MODE at an output terminal 302A to indicate that the boost converter 300 is operating in a buck mode. The buck mode detection circuit 302 can include a comparator for comparing VIN and VOUT.

[0028] The buck mode detection circuit 302 is coupled to the switch 306 and the switch 308 to control operation of the low-side transistor 108 and the high-side transistor 110 based on whether the boost converter 300 is operating in a buck mode. The switch 306 turns off the low-side transistor 108 when the boost converter 300 is operating in a buck mode and modulates the low-side transistor 108 when the boost converter 300 is not operating in a buck mode (operating in a boost mode). The switch 306 includes a terminal 306A coupled to the gate terminal 108G of the low-side transistor 108, a terminal 306B coupled to a ground terminal 320, a terminal 306C coupled to the modulator circuit 304, and a control terminal 306D coupled to the output terminal 302A of the buck mode detection circuit 302. When the DOWN-MODE signal is active, the switch 306 routes a ground signal to the low-side transistor 108 by connecting the gate terminal 108G of the low-side transistor 108 to ground, thereby turning off the transistor 108 if the transistor 108 is implemented with an n-type transistor, such as an n-channel MOSFET. When the DOWN-MODE signal is inactive, the switch 306 routes a modulation signal to the low-side transistor by connecting the gate terminal 108G of the low-side transistor 108 to the output terminal 304A of the modulation circuit 304.

[0029] The modulation circuit 304 generates a modulation signal to turn on and off the low-side transistor 108 and the high-side transistor 110. In the boost converter 300, the modulation circuit 304 includes a pulse width modulation control circuit 314, an error amplifier 316, and a reference voltage circuit 318. The error amplifier 316 generates an error signal representing a difference between VOUT and a reference voltage provided by the reference voltage circuit 318. The pulse width modulation control circuit 314 compares the error signal generated by the error amplifier 316 with a scaled value of the current (I S )(sensed at the output terminal 106) to generate the modulation signal. The modulation signal is provided to the low-side transistor 108 and the high-side transistor 110 to turn on and off the transistors 108, 110 based on the modulation signal. The current flowing through the high-side transistor 110 (the current at the output terminal 106 ) can be sensed and scaled using a current mirror circuit.

[0030] The switch 308 controls the operation of the high-side transistor 110 based on the DOWN-MODE signal. When operating in buck mode, the switch 308 drives the gate terminal 110G of the high-side transistor 110 with a drive signal that swings between ground and VIN (e.g., an inverted version of the modulation signal generated by the modulation circuit 304). When not operating in buck mode, the switch 308 drives the gate terminal 110G of the high-side transistor 110 with a drive signal that swings between ground and VOUT (e.g., the modulation signal generated by the modulation circuit 304). The switch 308 includes a terminal 308A coupled to the gate terminal 110G of the high-side transistor 110, a terminal 308B coupled to the output terminal 312B of the driver 312, a terminal 308C coupled to the output terminal 310B of the driver 310, and a control terminal 308D coupled to the output terminal 302A of the buck mode detection circuit 302.

[0031] The driver 310 generates a drive signal that is applied to the gate terminal 110G of the high-side transistor 110 when not operating in the buck mode. The driver 310 receives the modulation signal generated by the modulation circuit 304 and swings the drive signal between VOUT and ground to turn on the high-side transistor 110 when the low-side transistor is off, and to turn off the high-side transistor 110 when the low-side transistor is on. The driver 310 includes an input terminal 310A coupled to the output terminal 304A of the modulation circuit 304 and an output terminal 310B coupled to the terminal 308C of the switch 308.

[0032] Driver 312 generates a drive signal applied to gate terminal 110G of high-side transistor 110 when operating in buck mode. Driver 312 inverts the modulation signal generated by modulation circuit 304 and swings the drive signal between VIN and ground. Driver 312 includes an input terminal 312A coupled to output terminal 304A of modulation circuit 304 and an output terminal 312B coupled to terminal 308B of switch 308.

[0033] Figure 4 A graph comparing the efficiency of boost converter 300 and boost converter 100 in buck mode operation is shown. Curve 402 shows the efficiency of boost converter 300 over a range of VIN values ​​greater than VOUT (e.g., VOUT is 3.3 volts). Curve 404 shows the efficiency of boost converter 100 under the same conditions. At the illustrated input voltage, boost converter 300 is significantly more efficient than boost converter 100.

[0034] Figure 5A and Figure 5B The diagram shows the high efficiency buck mode operation of the boost converter 300. Figure 5A and Figure 5B In both cases, the low-side transistor 108 (where transistor 108 is an n-channel MOSFET) is turned off by connecting the gate terminal 108G to ground. Figure 3 ), terminal 308A is connected to terminal 308B to connect driver 312 ( Figure 3 ) is transmitted to the high-side transistor 110. Figure 5A and Figure 5B The switch 502 in FIG represents a switch within the driver 312. When the modulation signal provided by the modulation circuit 304 is logic high, the driver 312 inverts the modulation signal to turn on the high-side transistor 110. Accordingly, Figure 5A In the first part of the modulation period (the first logic level of the modulation signal), the switch 502 connects the gate terminal 110G of the high-side transistor 110 to ground to fully turn on the high-side transistor 110 (where the high-side transistor 110 is a p-type MOS transistor, such as a p-channel MOSFET). When VIN is greater than VOUT, the current in the inductor 104 increases.

[0035] When the modulation circuit 304 ( Figure 3 ) is logic low, the driver 312 ( Figure 3 ) inverts the modulation signal to provide VIN to the high-side transistor 110. Figure 5A In the second part of the modulation cycle (the second logic level of the modulation signal), the switch 502 connects VIN to the gate terminal 110G of the high-side transistor 110, causing the high-side transistor 110 to operate in saturation mode. The voltage across the inductor 104 is V t , and the current in the inductor 104 decreases.

[0036] Figure 6 1 shows example signals of the boost converter 300 during buck mode operation. When the gate terminal 110G of the high-side transistor 110 is at ground voltage, the high-side transistor 110 is fully turned on (when it is implemented as a p-channel MOSFET), the voltage across the inductor 104 is VIN-VOUT, and the current in the inductor 104 increases. When the gate terminal 110G of the high-side transistor 110 is at VIN, the high-side transistor 110 is saturated and the voltage across the inductor 104 is VOUT. t , and the current in the inductor 104 decreases (the inductor 104 discharges).

[0037] Figure 7A block diagram of an example boost converter 700 that provides efficient buck mode operation is shown. Boost converter 700 includes input terminal 102, inductor 104, output terminal 106, low-side transistor 108, high-side transistor 110, switch terminal 112, buck mode detection circuit 302, and switch 306. Boost converter 700 also includes switch 702, modulation circuit 704, and driver circuit 706.

[0038] Buck mode detection circuit 302 is coupled to switch 306 and switch 702 to control the operation of low-side transistor 108 and high-side transistor 110 based on whether boost converter 700 is operating in buck mode. Switch 306 turns off low-side transistor 108 (by connecting terminal 306A to 306B) when boost converter 700 is operating in buck mode, and modulates low-side transistor 108 (by connecting terminal 306A to 306C) when boost converter 700 is not operating in buck mode.

[0039] Modulation circuit 704 generates a modulation signal to turn on and off low-side transistor 108 and high-side transistor 110 to generate VOUT based on VIN. Modulation circuit 704 includes output terminal 304A, output terminal 704A, trigger 708, comparator 710, error amplifier 712, and timer circuit 716. Error amplifier 712 generates an error signal representing the difference between VOUT and a reference voltage provided by reference voltage circuit 318. The error signal is converted into a current by current source 714. Resistor 718 and capacitor 720 form a low-pass filter and filter the error signal generated by error amplifier 712. Error amplifier 712 includes input terminal 712A coupled to output terminal 106, input terminal 712B coupled to reference voltage circuit 318, and output terminal 712C coupled to current source 714.

[0040] The error current provided by the current source 714 is compared to the current sensed at the output terminal 106 (proportional value) by the comparator 710. When the current (I S ) is less than the error current (I C), comparator 710 sets flip-flop 708. Comparator 710 includes an input terminal 710A coupled to output terminal 106, an input terminal 710B coupled to current source 714, and an output terminal 710C coupled to input terminal 708A of flip-flop 708. Setting flip-flop 708 triggers timer circuit 716 to time a predetermined interval. When the predetermined interval expires, timer circuit 716 resets flip-flop 708. Timer circuit 716 includes an input terminal 716A coupled to an inverting output terminal 708D of flip-flop 708, and an output terminal 716B coupled to a reset input 708B of flip-flop 708. The output of flip-flop 708 is an inverted version of the modulation signal applied to control low-side transistor 108 and the modulation signal applied to control high-side transistor 110 during buck mode operation.

[0041] Flip-flop 708 includes an output terminal 708C and an output terminal 708D. Output terminal 708C is coupled to output terminal 304A of modulation circuit 704, and output terminal 708D is coupled to output terminal 704A of modulation circuit 704. Modulation signal 722 is output at output terminal 708C, and inverted modulation signal 724 is output at 708D. Output terminal 708C is coupled to terminal 306C of switch 306 and terminal 702C of switch 702. Output terminal 708D of flip-flop 708 is coupled to terminal 702B of switch 702. Switch 702 controls whether modulation signal 722 or inverted modulation signal 724 is applied to high-side transistor 110. Switch 702 includes a control terminal 702D coupled to output terminal 302A of buck mode detection circuit 302, and a terminal 702A coupled to input terminal 706B of driver circuit 706. When boost converter 700 operates in buck mode, switch 702 routes the inverted modulation signal 724 to high-side transistor 110. When boost converter 700 does not operate in buck mode, switch 702 routes the modulation signal 722 to high-side transistor 110.

[0042] Driver circuit 706 drives high-side transistor 110 and sets the voltage of the drive signal provided to high-side transistor 110 based on which of VIN or VOUT is greater. When operating in buck mode, VIN is greater than VOUT, and the drive signal provided by driver circuit 706 transitions between VIN and ground. When not operating in buck mode, VOUT is greater than VIN, and the drive signal provided by driver circuit 706 transitions between VOUT and ground. Driver circuit 706 includes an input terminal 706B coupled to terminal 702A, an output terminal 706A coupled to gate terminal 110G of high-side transistor 110, a power supply terminal 706C coupled to output terminal 106, a power supply terminal 706D coupled to input terminal 102, and a terminal 706E coupled to ground terminal 320.

[0043] Figure 8 1 shows example signals of the boost converter 700 during buck mode operation. Figure 8 804. In the embodiment of the present invention, VIN 802 is 3.6 volts and the boost converter 700 is configured to generate a VOUT 804 of 3.3 volts. The driver circuit 706 provides a drive signal 810 at the gate terminal 110G of the high-side transistor 110 to modulate the high-side transistor 110. The drive signal 810 is a version of the inverted modulation signal 724 generated by the modulation circuit 704, which is converted from 3.6 volts (VIN) to ground. During the charging interval 812, the drive signal 810 is at or near ground to fully turn on the high-side transistor 110, and the timer circuit 716 is effective to time the charging interval. During the charging interval 812, the current 808 in the inductor 104 increases and the voltage 806 across the inductor 104 increases at the edge 816. When the timer circuit 716 reaches a predetermined value, the trigger 708 is reset, the charging interval 812 ends and the discharge interval 814 begins. During the discharge interval 814, the drive signal 810 is at approximately 3.6 volts (VIN), and the high-side transistor 110 is in saturation mode. The current 808 in the inductor 104 decreases and the voltage 806 across the inductor 104 is -V t When the current flowing through the high-side transistor 110 to the output terminal 106 decreases and the sensed current I S Descend to I C When , comparator 710 sets flip-flop 708 to turn on high-side transistor 110 and initiate the next charging interval. In this example, voltage 806 across inductor 104 varies by approximately 1.3 volts (compared to approximately 4.6 volts when boost converter 100 operates in buck mode under similar conditions) to reduce circuit-generated noise. VOUT 804 is nominally 3.3 volts with a ripple of approximately 5 millivolts.

[0044] The term "coupled" is used throughout this specification. This term can encompass any connection, communication, or signal path that achieves a functional relationship consistent with the description of this disclosure. For example, if device A generates a signal to control device B to perform an action, then in the first example, device A is coupled to device B. Alternatively, in the second example, if the intermediate component C does not substantially change the functional relationship between devices A and B, then device A is coupled to device B through the intermediate component C such that device B is controlled by device A via the control signal generated by device A.

[0045] Modifications to the described embodiments are possible within the scope of the claims, and other embodiments are possible.

Claims

1. A boost converter comprising: a buck mode detection circuit having a detection output; a modulation circuit having a modulation output; a low-side transistor coupled between the switch terminal and the ground terminal and having a low-side control terminal; a first switch having first, second, and third switch terminals and a first switch control terminal, wherein the first switch terminal is coupled to the low-side control terminal, the second switch terminal is coupled to the modulation output, the third switch terminal is coupled to the ground terminal, and the first switch control terminal is coupled to the detection output; a high-side transistor coupled between the switch terminal and the converter output terminal and having a high-side control terminal; and a second switch having a fourth switch terminal, a fifth switch terminal, and a sixth switch terminal and a second switch control terminal, wherein the fourth switch terminal is coupled to the high-side control terminal, the fifth switch terminal is coupled to the modulation output, the sixth switch terminal is coupled to the modulation output through an inverter, and the second switch control terminal is coupled to the detection output. 2 . The boost converter of claim 1 , wherein the modulation output is a first modulation output, and the modulation circuit further comprises a second modulation output.

3. The boost converter of claim 1 , further comprising a driver circuit having a driver input and a driver output, wherein the driver input is coupled to the modulation output, and the driver output is coupled to the fifth switch terminal or the sixth switch terminal.

4. The boost converter of claim 1 , wherein the modulation circuit comprises an error amplifier having a first error input, a second error input, and an error output, wherein: The first error input is coupled to the converter output terminal, and the second error input is coupled to a reference voltage terminal.

5. The boost converter of claim 4 , wherein the modulation circuit further comprises a comparator having a first comparator input, a second comparator input, and a comparator output, wherein: The first comparator input is coupled to the error output, and the second comparator input is coupled to the converter output terminal.

6. The boost converter according to claim 5, wherein the modulation circuit further comprises: a flip-flop having first and second flip-flop inputs and first and second flip-flop outputs, wherein the first flip-flop input is coupled to the comparator output and the first flip-flop output is coupled to the modulation output; and A timer circuit has a timer input and a timer output, wherein the timer input is coupled to the second flip-flop output and the timer output is coupled to the second flip-flop input.

7. A boost converter comprising: a low-side transistor coupled between the switch terminal and the ground terminal and having a low-side control terminal; a buck mode detection circuit having a detection output coupled to the low-side control terminal and configured to turn off the low-side transistor in response to a voltage at the converter output terminal being greater than a voltage at the converter input terminal; a modulation circuit having a modulation output, wherein the modulation circuit is configured to provide a modulation signal at the modulation output; and a first switch having a first switch path and a second switch path, wherein the first switch path of the first switch is configured to couple the modulation output to the low-side control terminal in response to the voltage at the converter output terminal being greater than the voltage at the converter input terminal, and the second switch path of the first switch is configured to couple a ground terminal to the low-side control terminal in response to the voltage at the converter output terminal being less than the voltage at the converter input terminal.

8. The boost converter according to claim 7, further comprising: a high-side transistor coupled between the switch terminal and the converter output terminal and having a high-side control terminal; and a second switch having a first switching path and a second switching path, wherein the first switching path of the second switch selectively couples the modulation output to the high-side control terminal in response to the voltage at the converter output terminal being less than the voltage at the converter input terminal, and the second switching path of the second switch selectively provides an inverted modulation signal to the high-side control terminal in response to the voltage at the converter output terminal being greater than the voltage at the converter input terminal.

9. The boost converter of claim 8 , further comprising a driver circuit having a driver input and a driver output, wherein the driver input is coupled to the modulation output, and the driver output is selectively coupled to the high-side control terminal in response to a voltage at the converter output terminal being less than the voltage at the converter input terminal, or the driver output is selectively coupled to the inverted modulation signal in response to the voltage at the converter output terminal being greater than the voltage at the converter input terminal.

10. The boost converter according to claim 8, wherein In response to the voltage at the converter output terminal being less than the voltage at the converter input terminal, the switch is configured to: connecting the ground terminal to the high-side transistor in response to the modulation signal having a first logic level; and In response to the modulation signal having a second logic level different from the first logic level, the converter input terminal is connected to the high-side transistor.

11. The boost converter according to claim 10, wherein: In response to the voltage at the converter output terminal being greater than the voltage at the converter input terminal, the switch is configured to: connecting the converter output terminal to the high-side transistor in response to the modulation signal having the first logic level; and In response to the modulation signal having the second logic level, the ground terminal is connected to the high-side transistor.

12. The boost converter according to claim 10, wherein the modulation circuit comprises: a flip-flop configured to provide the modulation signal and an inverted modulation signal; an error amplifier having an error amplifier output, wherein the error amplifier is configured to provide an error signal at the error amplifier output, the error signal being a difference between a reference voltage and the voltage at the converter output terminal; a comparator configured to set the flip-flop in response to a comparison of the error signal and a current sensed at an output terminal of the converter; as well as A timer circuit is configured to reset the flip-flop.

13. A boost converter comprising: a high-side transistor coupled between the switch terminal and the converter output terminal and having a high-side control terminal; a first switch coupled to the high-side control terminal and configured to modulate a voltage at the high-side control terminal between ground and a voltage at a converter input terminal in a buck mode; a low-side transistor coupled between the switch terminal and a ground terminal and having a low-side control terminal; a second switch coupled to the low-side control terminal and configured to, in the buck mode, maintain the voltage at the low-side control terminal at ground; and A buck mode detection circuit is coupled to the first switch and the second switch and is configured to detect the buck mode in response to a voltage at the converter output terminal being greater than a voltage at the converter input terminal. 14 . The boost converter of claim 13 , further comprising a modulation circuit having a modulation output, wherein the modulation circuit is configured to provide a modulation signal at the modulation output.

15. The boost converter of claim 14 , wherein the first switch is coupled to the modulation circuit and is configured to: In boost mode, applying a modulation signal to modulate the voltage at the high-side control terminal between ground and the voltage at the converter output terminal; and In the buck mode, an anti-phase modulation signal is applied to the high-side control terminal. 16 . The boost converter of claim 14 , wherein the second switch is coupled to the modulation circuit and configured to provide the modulation signal to the low-side control terminal in a boost mode.

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