An embodiment of a power supply includes a supply output node, phase paths, and sensor circuits. The supply output node is operable to provide a regulated output voltage, and each phase path has a respective phase-path non-output node, has a respective phase-path output node coupled to the supply output node, and is operable to carry a respective phase-path current. And each sensor circuit has a respective sensor node coupled to the phase-path non-output nodes and is operable to generate a respective sense signal that represents the phase current flowing through a respective one of the phase paths.
For example, where the phase paths are magnetically coupled to one another (e.g., the phase paths include magnetically coupled windings), the sensor circuits are able to account for the portions of the phase currents induced by the magnetic couplings between phase paths, and this accounting allows the sensor circuits to generate sense signals that more accurately represent the phase currents as compared to conventional sensor circuits. The sense signals may be fed back to the power-supply controller, which regulates the output voltage at least partly in response to the fed-back sense signals.
The current sensors 141-14n respectively generate sense signals IFB1-IFBn, which respectively represent the phase currents i1-in. For example, each of the signals IFB1-IFBn may be a respective voltage that has substantially the same signal phase as the corresponding phase current i and that has an amplitude that is substantially proportional to the amplitude of the corresponding phase current.
In addition to the current sensors 141-14n, the converter 10 includes a coupled-inductor assembly 16 having windings 181-18n, which are wound about a common core (not shown in
The controller 20 may be any type of controller suitable for use in a multiphase CI power supply, is supplied by voltages VDDcontroller and VSScontroller, and receives the regulated output voltage Vout, a reference voltage Vref, and the sense signals IFB1-IFBn, which are fed back to the controller from the current sensors 141-14n, respectively. The controller 20 may use Vref and the fed back Vout and IFB1-IFBn to conventionally regulate Vout to a desired value.
The high-side transistors 221-22n, which are each switched “on” and “off” by the controller 20, are power NMOS transistors that are respectively coupled between input voltages VIN1-VINn and the nodes INT1-INTn. Alternatively, the transistors 221-22n may be other than power NMOS transistors, and may be coupled to a common input voltage. Moreover, the transistors 221-22n may be integrated on the same die as the controller 20, may be integrated on a same die that is separate from the die on which the controller is integrated, or may be discrete components.
Similarly, the low-side transistors 241-24n, which are each switched on and off by the controller 20, are power NMOS transistors that are respectively coupled between low-side voltages VL1-VLn and the nodes INT1-INTn of the phase windings 181-18n. Alternatively, the transistors 241-24n may be other than power NMOS transistors, and may be coupled to a common low-side voltage such as ground. Moreover, the transistors 241-24n may be integrated on the same die as the controller 20, may be integrated on a same die that is separate from the die on which the controller is integrated, may be integrated on a same die as the high-side transistors 221-22n, may be integrated on respective dies with the corresponding high-side transistors 221-22n (e.g., transistors 221 and 241 on a first die, transistors 222 and 242 on a second die, and so on), or may be discrete components.
The filter capacitor 26 is coupled between the regulated output voltage Vout and a voltage VSScap, and works in concert with the windings 181-18n and an optional filter inductor 28 (if present) to maintain the amplitude of the steady-state ripple-voltage component of Vout within a desired range which may be on the order of hundreds of microvolts (μV) to tens of millivolts (mV). Although only one filter capacitor 26 is shown, the converter 10 may include multiple filter capacitors coupled in electrical parallel. Furthermore, VSScap may be equal to VSScontroller and to VL1-VLn; for example, all of these voltages may equal ground.
As further discussed below, the filter inductor 28 may be omitted if the leakage inductances Llk1-Llkn (discussed below) of the windings 181-18n are sufficient to perform the desired inductive filtering function. In some applications, the filter inductor 28 may be omitted to reduce the size and component count of the converter 10.
Each of the windings 181-18n of the coupled-inductor assembly 16 may be modeled as a self inductance L and a resistance DCR. For purposes of discussion, only the model components of the winding 181 are discussed, it being understood that the model components of the other windings 182-18n are similar, except for possibly their values.
The self inductance L1 of the winding 181 may be modeled as two zero-resistance inductances: a magnetic-coupling inductance LC1, and a leakage inductance Llk1. When a phase current i1 flows through the winding 181, the current generates a magnetic flux. The value of the coupling inductance LC1 is proportional to the amount of this flux that is coupled to other windings 182-18n, and the value of the leakage inductance Llk1 is proportional to the amount of the remaining flux, which is not coupled to the other windings 182-18n. In one embodiment, LC1=LC2= . . . =LCn, and Llk1=Llk2= . . . =Llkn, although inequality among the coupling inductances LC, the leakage inductances Llk, or both LC and Llk, is contemplated. Furthermore, in an embodiment, the respective magnetic-coupling coefficients between pairs of coupling inductances Lc are equal (i.e., a current through LC1 magnetically induces respective equal currents in LC2, . . . LCn), although unequal coupling coefficients are contemplated.
The resistance DCR1 is the resistance of the winding 181 when a constant voltage V1 is applied across the winding and causes a constant current I1 to flow through the winding. That is, DCR1=V1/I1.
The power supply 10 may provide the regulated voltage Vout to a load 30, such as a microprocessor.
Still referring to
The sensor 141 includes a capacitor C1 across which the sense signal IFB1 (here a voltage signal) is generated, an optional scaling resistor RC1 coupled across C1, and resistors R11-Rn1, which are respectively coupled between the nodes INT1-INTn and C1.
The resistor R11 couples to C1 a signal (a current in this embodiment) that represents the portion of the phase current i1 that the switching transistors 221 and 241 (
And the resistors R21-Rn1 each couple to C1 a respective signal (a current in this embodiment) that represents the respective portion of i1 that a respective phase current i2-in magnetically induces in the winding 181. That is, the resistor R21 couples to C1 a current that is proportional to the portion of i1 that the phase current i2 magnetically induces in the winding 181. Similarly, the resistor R31 couples to C1 a current that is proportional to the portion of i1 that the phase current i3 magnetically induces in the winding 181, and so on.
C1 generates from the sum of the signals from R11-Rn1 the sense voltage IFB1, which has the same phase as i1 and which has an amplitude that is proportional to the amplitude of i1.
Therefore, a power-supply controller, such as the controller 20 of
In a similar manner, the capacitors C2-Cn respectively generate the sense voltages IFB2-IFBn, from which a power-supply controller, such as the controller 20 of
Referring to
Still referring to
V
1
=s·(Llk+LC)·i1−s·LC·i2+DCR·i1 (1)
V
2
=s·(Llk+LC)·i2−s·LC·i1+DCR·i2 and (2)
where V1 and V2 are the voltages at nodes INT1 and INT2, respectively.
From equations (1)-(3), one may derive the following equation for i1:
Furthermore, where R11=R1 and R21=R2 are the resistors coupled to the capacitor C1, one may derive the following equation for the voltage IFB1 across C1:
Because the voltage VDCR1 across DCR1 equals i1·DCR1, VDCR1 has the same phase as i1, and has an amplitude that is proportional (by a factor DCR1) to the amplitude of i1; as discussed above in conjunction with
Unfortunately, DCR1 is a modeled component, and one does not have physical access to the voltage VDCR1 across it.
But, one can set IFB1=VDCR1=i1·DCR1 according to the following equation, which is derived from equations (4) and (5):
From equation (6), one can derive the following two equations:
Referring to
From equations (9) and (10), one may derive the following design equations for the sensor circuit 141 of
Therefore, by selecting the components R11=R1, R21=R2, and C1 (LC1=LC, Llk1=Llk, and DCR1=DCR are assumed to be known quantities for purposes of this disclosure) of the sensor circuit 141 such that they satisfy the design equations (11)-(13), the results are that IFB1≈i1·DCR1, and therefore, that IFB1 has approximately the same phase as i1, and has an amplitude that is approximately proportional to (i.e., that has approximately the same amplitude profile as) the amplitude of i1. Furthermore, because at least in some applications the design equation (12) may be redundant, one may design the sensor circuit 141 by selection component values that satisfy only the equations (11) and (13).
Referring again to
Referring again to
And K1 is given by the following equation:
The modified design equations for the components of the sensor circuits 142-14n and the equations for the scale factors K2-Kn may be respectively similar to equations (14)-(16). Furthermore, equations (14)-(16) may be modified where LC, Llk, and DCR are not the same for each winding 181-18n.
The sensor 141 includes a capacitor C1 across which the sense signal IFB1 (here a voltage signal) is generated, an optional scaling resistor RC1 across the capacitor C1, a resistor R1 coupled to the capacitor C1, and a resistor R11, which is coupled between the phase intermediate node INT1 and the resistor R1. The resistors R11 and R1 couple to C1 a signal (a current in this embodiment) that represents the portion of the phase current i1 that the switching transistors 221 and 241 (
Similarly, the sensor circuit 142 includes a capacitor C2 across which the sense signal IFB2 (here a voltage signal) is generated, an optional scaling resistor RC2 across the capacitor C2, a resistor R2 coupled to the capacitor C2, and a resistor R22, which is coupled between the phase intermediate node INT2 and the resistor R2. The resistors R22 and R2 couple to C2 a signal (a current in this embodiment) that represents the portion of the phase current i2 that the switching transistors 222 and 242 (
The sensor circuits 141 and 142 also “share” a resistor R12, which is coupled between the resistors R1 and R2 and also between the resistors R11 and R22. The resistors R22, R12, and R1 couple to C1 a signal (a current in this embodiment) that represents the portion of the phase current i1 that the phase current i2 magnetically induces in the winding 181. That is, the resistors R22, R12, and R1 couple to C1 a current that is proportional to the portion of i1 that i2 magnetically induces in the winding 181. Similarly, the resistors R11, R12, and R2 couple to C2 a signal (a current in this embodiment) that represents the portion of the phase current i2 that the phase current i1 magnetically induces in the winding 182.
One may extrapolate the sensor circuit 141 for use in the power supply 10 (
One may extrapolate the sensor circuit 142 for use in the power supply 10 (
Still referring to
Referring again to
The system 40 includes computer circuitry 44 for performing computer functions, such as executing software to perform desired calculations and tasks. The circuitry 44 typically includes a controller, processor, or one or more other integrated circuits (ICs) 46, and the power supply 42, which provides power to the IC(s) 46—these IC(s) compose(s) the load of the power supply. The power supply 42, or a portion thereof, may be disposed on the same IC die as one or more of the ICs 46, or may be disposed on a different IC die.
One or more input devices 48, such as a keyboard or a mouse, are coupled to the computer circuitry 44 and allow an operator (not shown) to manually input data thereto.
One or more output devices 100 are coupled to the computer circuitry 44 to provide to the operator data generated by the computer circuitry. Examples of such output devices 50 include a printer and a video display unit.
One or more data-storage devices 52 are coupled to the computer circuitry 44 to store data on or retrieve data from external storage media (not shown). Examples of the storage devices 52 and the corresponding storage media include drives that accept hard and floppy disks, tape cassettes, compact disk read-only memories (CD-ROMs), and digital-versatile disks (DVDs).
From the foregoing it will be appreciated that, although specific embodiments have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of this disclosure. Furthermore, where an alternative is disclosed for a particular embodiment, this alternative may also apply to other embodiments even if not specifically stated.
This application claims priority to U.S. Provisional Application Ser. No. 60/964,792 filed on Aug. 14, 2007 and U.S. Provisional Application Ser. No. 61/072,287 filed on Mar. 27, 2008, which are incorporated by reference.
Number | Date | Country | |
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60964792 | Aug 2007 | US | |
61072287 | Mar 2008 | US |