Voltage regulator having boost and charge pump functionality

The present application claims the benefit of U.S. Provisional Patent Application No. 62/432,108, filed on Dec. 9, 2016, which is incorporated herein by reference.

As is known in the art, voltage regulators can automatically maintain a constant voltage level for proper circuit operation. Conventional voltage regulators can be configured as a so-called feed-forward type regulator, for example. Other known regulators can utilize negative feedback control loops. Electronic voltage regulators can be used in wide variety of devices in which a reliable and constant voltage is desirable.

Embodiments of the present invention provide methods and apparatus for a voltage regulator having boost DC-DC and charge pump mode functionality. In some embodiments, the charge pump mode can have multiple operating modes which may correspond to the presence of, or lack thereof, an external voltage supply. In embodiments, a voltage regulator can generate first and second voltage rails, where the first voltage rail is referenced to the positive rail and the second voltage rail is referenced to the negative rail. In the boost mode, an inductor, which may be external to an IC embodiment, is employed, and in the charge pump mode, an external power supply may be referenced to the negative rail.

In one aspect, a voltage regulator system comprises: a boost module to boost an input voltage signal and provide an output voltage signal on a first output node; and a charge pump module coupled to the boost module to provide the output signal on the first output node.

A voltage regulator system can further include one or more of the following features: the charge pump module and the boost module share a circuit component, the charge pump module and the boost module share a capacitor coupled to the first output node, the charge pump module has a first mode to provide the output signal in combination with the boost module and a second mode to provide the output signal independently from the boost module, the charge pump module is configured to receive an external supply voltage to generate the output signal, the charge pump module includes a capacitor current that flows in one direction during the first mode and the opposite direction during the second mode, the second mode is configured to operate without an inductor, the boost module and charge pump module are provided as part of an IC package, the system is configured to drive a load comprising a bootstrap circuit, the boost module comprises an inductor switching element provided in an IC package configured for connection to an external inductor, a diode, a first capacitor, and the charge pump module comprises switching elements provided in the IC package to control charge and pump phases in first and second modes, the boost module and the charge pump module share the first capacitor, the charge pump module comprises first and second charge pump switching elements coupled to the first capacitor, wherein the first and second charge pump switching elements are conductive during a charge phase of a first mode and non-conductive during a pump phase of the first mode, the first and second charge pump switching elements are non-conductive during a charge phase of a second mode and conductive during a pump phase of the second mode, the second mode corresponds to an external voltage supply coupled to the charge pump module to charge a second capacitor that pumps charge to the first capacitor during the pump phase of the second mode, and/or the charge pump module comprises first and second charge pump switching elements coupled to a first capacitor, and at least one regulator switching element coupled between a second capacitor and a third capacitor, wherein the first and second charge pump switching elements are conductive during a charge phase of a first mode to charge the second capacitor, and non-conductive during a pump phase of the first mode, wherein the at least one regulator switching element is non-conductive during the charge phase of the first mode and conductive during the pump phase to charge the third capacitor for providing an output voltage at the third capacitor.

In another aspect, a method for providing a voltage regulator comprises: employing a boost module to boost an input voltage signal and provide an output voltage signal on a first output node; and employing a charge pump module coupled to the boost module to provide the output signal on the first output node.

A method for providing a voltage regulator can further include one or more of the following features: the charge pump module and the boost module share a circuit component, the charge pump module and the boost module share a capacitor coupled to the first output node, the charge pump module has a first mode to provide the output signal in combination with the boost module and a second mode to provide the output signal independently from the boost module, the charge pump module is configured to receive an external supply voltage to generate the output signal, the charge pump module includes a capacitor current that flows in one direction during the first mode and the opposite direction during the second mode, the second mode is configured to operate without an inductor, the boost module and charge pump module are provided as part of an IC package, the system is configured to drive a load comprising a bootstrap circuit, the boost module comprises an inductor switching element provided in an IC package configured for connection to an external inductor, a diode, a first capacitor, and the charge pump module comprises switching elements provided in the IC package to control charge and pump phases in first and second modes, the boost module and the charge pump module share the first capacitor, the charge pump module comprises first and second charge pump switching elements coupled to the first capacitor, wherein the first and second charge pump switching elements are conductive during a charge phase of a first mode and non-conductive during a pump phase of the first mode, the first and second charge pump switching elements are non-conductive during a charge phase of a second mode and conductive during a pump phase of the second mode, the second mode corresponds to an external voltage supply coupled to the charge pump module to charge a second capacitor that pumps charge to the first capacitor during the pump phase of the second mode, and/or the charge pump module comprises first and second charge pump switching elements coupled to a first capacitor, and at least one regulator switching element coupled between a second capacitor and a third capacitor, wherein the first and second charge pump switching elements are conductive during a charge phase of a first mode to charge the second capacitor, and non-conductive during a pump phase of the first mode, wherein the at least one regulator switching element is non-conductive during the charge phase of the first mode and conductive during the pump phase to charge the third capacitor for providing an output voltage at the third capacitor.

In a further aspect, a voltage regulator system comprises: a boost means for boosting an input voltage signal and providing an output voltage signal on a first output node; and a charge pump means coupled to the boost module for providing the output signal on the first output node.

The foregoing features of this invention, as well as the invention itself, may be more fully understood from the following description of the drawings in which:

FIG. 1 is a schematic representation of a voltage regulator having a boost module and a charge pump module in accordance with illustrative embodiments of the invention;

FIG. 2 is a circuit diagram of an example implementation of the voltage regulator of FIG. 1 ;

FIG. 3A is an example circuit implementation of the boost module of FIG. 1 in a first phase and FIG. 3B is an example circuit implementation the boost module of FIG. 1 in a second phase;

FIG. 4 is a circuit diagram of an example implementation of the voltage regulator of FIG. 1 showing external component connection for an illustrative IC embodiment, FIG. 4A is an example circuit implementation showing a charge pump module in a boost mode in a charge phase, and FIG. 4B shows the charge pump module in the boost mode in a pump phase;

FIG. 5 is a circuit diagram of an example implementation of the voltage regulator of FIG. 1 showing external component connection for an illustrative IC embodiment, FIG. 5A is an example circuit implementation showing a charge pump module in a mode coupled to an external power supply in a charge phase and FIG. 5B shows the charge pump module in a mode coupled to the external power supply in a pump phase;

FIG. 6 is a schematic representation of an example integrated circuit package implementation of the voltage regulator of FIG. 1 having a boost module and a charge pump module with a protection/isolation circuit in accordance with illustrative embodiments of the invention.

FIG. 1 shows an illustrative voltage regulator 100 having a boost DC-DC module 102 and a charge pump module 104 in accordance with illustrative embodiments of the invention. In embodiments, the voltage regulator 100 can be provided in an integrated circuit (IC) package configured for connection to external components, such as inductors, capacitors, diodes and the like. In some embodiments, one or more internal or external components can be common to the boost module 102 and the charge pump module 104 . The voltage regulator 100 can be configured to power a load 106 . In embodiments, the charge pump module 104 can operate in a first mode when an external voltage supply signal is connected to the charge pump module and in a second mode when an external voltage supply is not connected the charge pump module. In embodiments, the charge pump module 104 can include current flow in opposite directions for charge and pump phases depending upon whether the external voltage supply is connected.

In general, embodiments of the voltage regulator 100 are useful in a variety of applications. While example embodiments of the voltage regulator are shown and described in conjunction a bootstrap circuit for a floating gate MOS driver, it is understood that embodiments of the voltage regulator shown and described herein are applicable to circuits, devices, and systems in general in which it is desirable to provide boost and charge pump functionality and flexibility.

It is further understood that example components and impedance values are shown so as to facilitate understanding of embodiments of the invention. It is readily understood by one of ordinary skill in the art that components and impedance values can vary to meet the needs of a particular application without departing from the scope of the invention.

FIG. 2 shows an example circuit implementation of the voltage regulator 100 of FIG. 1 . In general, the boost module 102 provides a step-up DC-to-DC power converter that steps up voltage while stepping down current from a supply voltage to voltage output. In embodiments, the boost module 102 includes at least one diode and a switching element, such as a transistor, and at least one energy storage element, such as an inductor and/or and a capacitor.

In the illustrated embodiment, the boost DC-DC module 102 includes a first boost switch SL 1 coupled between ground and a first diode D 1 . A first capacitor C 1 is coupled to the cathode of the first diode D 1 , such that the first diode D 1 , the first capacitor C 1 , and a first inductor L 1 form a circuit loop coupled to the first boost switch SL 1 . The node formed by the cathode of the first diode D 1 and the first capacitor C 1 provides an output voltage of the boost module 102 . In the illustrated embodiment, the output voltage is shown as VCP. A voltage supply VBB, for example 12V, is provided at a node between the first capacitor C 1 and the first inductor L 1 . It is understood that voltage is boosted to VCP relative to voltage VBB.

In general, charge pump module 104 uses energy-storage elements to create a higher or lower voltage power source by using a switching element to control the connection of voltages to the capacitor. For example, a two-stage cycle can be used to generate a higher pulsed voltage from a lower-voltage supply, such that in the first stage, a capacitor is connected across the voltage supply to charge the capacitor to the voltage supply. In the second stage, the circuit connects the capacitor in series with the supply to the load so as to effectively double the supply voltage to the load (the sum of the original supply voltage and the voltage on the capacitor). The voltage level can be smoothed with an output capacitor, for example.

In the illustrative embodiment of FIG. 2 , the charge pump module 104 includes first and second charge pump switching elements SC 1 , SC 2 . In one embodiment, the first charge pump switching element SC 1 is coupled between VCP and one terminal of a second capacitor C 2 and the second charge pump switching element SC 2 is coupled between VBB and the second capacitor C 2 .

First and second first regulator switching elements SR 1 , SR 2 are coupled end-to-end between the first charge pump switching element SC 1 and the third capacitor C 3 . A VREG node is located between the second regulator switching element SR 2 and the third capacitor C 3 , which can be coupled to ground. In the illustrated embodiment, a load 106 includes first and second bootstrap switching elements SB 1 , SB 2 coupled end-to-end between VCP and the third capacitor C 3 . Second and third diodes D 2 , D 3 can be coupled to the first and second bootstrap switching elements SB 1 , SB 2 , as shown, as well as a bootstrap capacitor. In embodiments, outputs CA and SA can be configured to provide a gate drive signals for a MOS device.

It is understood that the voltage regulator 100 can be used in a variety of applications in which it is desirable to provide boost and charge pump functionality in a single IC, for example. In the illustrated embodiment, first and second bootstrap switching elements SB 1 , SB 2 are used where power rails provide the supplies for high-side and low-side MOSFETs for n-n half-bridge configurations.

As noted above, in embodiments, a voltage regulator 100 has a boost inductor voltage rail generation mode provided by the boost DC-DC module 102 and an external supply voltage rail generation mode provided by the charge pump module 104 . In embodiments, as shown and described more fully below, capacitors and inductors can be provided as external components coupled to an IC having the boost and charge pump circuitry.

In the boost mode of the charge pump module, external inductor L 1 is configured in boost mode to generate output voltage VCP. During a first phase, the first and second charge pump switching elements SC 1 , SC 2 are closed, i.e., conductive. During a second phase of boost mode, the first, second, and third regulator switching elements SR 1 , SR 2 , SR 3 are closed.

In the charge pump mode, an external supply voltage, such as 12 or 15 volts, for example, is boosted to provide VREG. During a first phase, the charge pump switching elements SC 1 , SC 2 are closed, and during a second phase, the regulator switching elements SR 1 , SR 2 , SR 3 are closed.

In the illustrated embodiment, VREG and GND provide the power rails for a load comprising a low-side MOSFET gate charging and the VCP rail sources the current for the CA-SA high-side MOSFET gate charging.

Embodiments of the invention provide advantages over conventional regulators. For example, by using switched-mode-power-supply (SMPS) techniques to generate the rails, IC power dissipation is reduced. As voltage levels increase, e.g., 48V for automotive applications, reducing power dissipation becomes increasingly desirable. In addition, the VREG rail can be generated using SMPS techniques without having to use complicated Buck-boost topologies. Also, user flexibility is increased as some users may not be able to use inductors (e.g., for boost mode), while other users may not have an external 12V-15V power supply for connect to VREG.

FIGS. 3A and 3B show operation of the boost DC-DC module 102 of FIG. 1 . In the first phase shown in FIG. 3A , the first inductor switching element SL 1 is conductive, and in the second phase shown in FIG. 3B the first inductor switching element SL 1 is non-conductive, i.e., open. It is understood that voltage VCP is boosted relative to voltage VBB. That is, the voltage on the first capacitor C 1 charges to a level corresponding to VCP-VBB. When the first inductor switching element SL 1 is conductive, current flows from VBB through the first inductor L 1 storing energy by generating a magnetic field. When the first inductor switching element SL 1 opens, the energy stored in the first inductor L 1 maintains a current toward the load via the first diode D 1 as the first capacitor C 1 receives charge.

FIGS. 4, 4A and 4B show operation of the charge pump module 104 in the boost mode. FIG. 4 shows an example embodiment having an IC with I/O pins LX, VCP, VBB, CP 1 , CP 2 , VREG, C, and S. For example, the boost module 102 includes external components L 1 , D 1 , and C 1 . The second capacitor C 2 is coupled across pins CP 1 , and CP 2 and the third capacitor C 3 is coupled to the VREG pin (no external supply voltage is connected in this mode). In this mode, the boost circuit 102 operates to charge the first capacitor C 1 independently of the charge pump circuit 104 . In embodiments, the first inductor switching element SL 1 may have a different, e.g., higher, switching frequency than the frequency of the first and second charge pump switching elements SC 1 , SC 2 .

As shown FIG. 4A , in the first phase (charge), the first and second charge pump switching elements SC 1 , SC 2 are closed so that the second capacitor C 2 charges. In FIG. 4B , the first and second charge pump switching elements SC 1 , SC 2 are open and the regulator switching elements SR 1 , SR 2 , SR 3 are closed so that the second capacitor C 2 pumps charge to the third capacitor C 3 . In embodiments, there is no external supply connection to VREG in this mode.

FIGS. 5, 5A and 5B show operation of the charge pump module 104 when an external voltage supply is supplied at VREG with an external third capacitor C 3 coupled as shown. In example embodiments, external VREG can range from about 12 to 15 Volts, however, any suitable voltage can be used to meet the needs of a particular application. In embodiments, the boost module is not used so that no boost inductor is connected. As shown, an external first capacitor C 1 can be connected between pin VCP and a first voltage supply +V, which can also be coupled to pin VBB.

FIG. 5A shows a charge phase and FIG. 5B shows a pump phase. In the charge phase, the regulator switching elements SR 1 , SR 2 , SR 3 are closed so that VREG charges the second capacitor C 2 . In the pump phase shown in FIG. 5B , the first and second charge pump switching elements SC 1 , SC 2 are closed so that the second capacitor C 2 pumps charge to the first capacitor C 1 , which is coupled to VCP.

It should be noted that the current flow direction in the charge pump circuit when external supply is coupled to VREG is the opposite of when no external supply is coupled to VREG. That is, in FIG. 4B the direction of current flow through SR 1 , SR 2 (when closed) is in the opposite direction from FIG. 5A . In embodiments, first and second regulator switching elements SR 1 , SR 2 are coupled in series to enable oppositely oriented blocking diodes to be provided since the voltage can be less than or greater than VBB.

FIG. 6 shows an example protection and isolation circuit coupled between the IC and a supply voltage +V.

Having described exemplary embodiments of the invention, it will now become apparent to one of ordinary skill in the art that other embodiments incorporating their concepts may also be used. The embodiments contained herein should not be limited to disclosed embodiments but rather should be limited only by the spirit and scope of the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.

Elements of different embodiments described herein may be combined to form other embodiments not specifically set forth above. Various elements, which are described in the context of a single embodiment, may also be provided separately or in any suitable subcombination. Other embodiments not specifically described herein are also within the scope of the following claims.