JP4416516B2 - Power supply voltage control system - Google Patents

Description

  The present invention relates to a power supply voltage system for controlling a power supply voltage to be applied to a data processing device built in a mobile device.

  In recent years, mobile devices such as mobile phones are required to have a large amount of data processing capability due to camera functions and various applications, and accordingly, consumption of a central processing unit (hereinafter referred to as CPU) as a data processing device is required. Electricity tends to increase significantly. This is a big problem for portable devices using batteries as a power supply source.

  Therefore, a technique for actively changing the power supply voltage of the CPU in accordance with the operation state of the CPU is proposed in (Patent Document 1) and the like. This type of CPU power supply voltage control method will be described with reference to FIG.

The conventional power supply voltage system shown in FIG. 4 is configured to control the power supply voltage applied to the CPU 10 based on serial data DATA.
Here, in addition to the CPU 10, a smoothing circuit 8 including an inductance L1, a diode D1, and a capacitor C1 is provided outside the substrate 11 having the pads P1 to P6.

  In addition to the DC / DC converter 7 that converts the pre-conversion voltage Vcc applied to the pad P6 into the pulse voltage 7a, the substrate 11 includes a serial control circuit 1 and a D / A conversion circuit 5.

  A clock CLK and serial data DATA synchronized with the clock CLK are supplied to the pads P2 and P1 of the substrate 11, and an output 1a converted in parallel by the serial control circuit 1 is input to the D / A conversion circuit 5. Yes.

  On the other hand, in the DC / DC converter 7, the pre-conversion voltage Vcc is converted into a pulse voltage 7a by an internal reference oscillation signal and generated between the pads P4 and P5. The voltage OUTPUT is converted. The DC voltage OUTPUT is supplied to the D / A conversion circuit 5 through the pad P3. The D / A conversion circuit 5 converts the analog signal 5a into the DC / DC converter 7 so that the DC voltage OUTPUT approaches the output 1a. Have feedback.

In this way, the occasional DC voltage OUTPUT applied as the power supply voltage to the CPU 10 is determined by the contents of the serial data DATA. Therefore, the power consumption can be optimized by detecting the load state of the data processing of the CPU 10 and inputting the serial signal DATA so that the power supply voltage becomes the optimum voltage.
JP-A-1-157269

  The recent CPU 10 has been miniaturized and the breakdown voltage tends to decrease, so that the damage to the CPU 10 due to overshoot has increased. If the contents of the serial data DATA are changed in a single transfer so that the power supply voltage to the CPU 10 is changed from the current power supply voltage to the final target voltage value at a stretch because the load state of data processing has increased rapidly, DC / In the power supply voltage control system using the DC converter 7, an overshoot or undershoot occurs due to a rapid voltage fluctuation, causing a problem that causes destruction or malfunction of the CPU 10.

  When serial data transfer is performed in several times so that such an overshoot or undershoot does not occur, it takes time to reach the target voltage, and the reaction speed decreases.

  In the present invention, when the load state of data processing changes drastically and the power supply voltage to the data processing device changes greatly, the number of serial data transfers in order to minimize the delay time until the target voltage is reached. It is an object of the present invention to provide a power supply voltage control system that can realize a smooth voltage change that does not cause overshoot and undershoot as in the prior art even if the number is reduced.

A power supply voltage control system according to claim 1 of the present invention is a power supply voltage control system that varies a power supply voltage applied to a data processing device, and a waveform memory circuit that stores a plurality of step data corresponding to a variable slope of the power supply voltage. And a selector circuit that reads out appropriate step data from the waveform memory circuit according to data specifying a variable slope of the power supply voltage, and step data read out from the selector circuit is repeatedly added or subtracted as time elapses. An arithmetic circuit that forms a control signal that changes stepwise, and a voltage conversion circuit that varies a power supply voltage applied to the data processing device based on a control signal generated at the output of the arithmetic circuit is provided. .

The power supply voltage control system according to claim 2 of the present invention is the power supply voltage control system according to claim 1 , wherein the voltage conversion circuit includes a DC / DC converter that converts a pre-conversion voltage into a pulse voltage by an internal reference oscillation signal, and the calculation The circuit is configured to repeatedly add or subtract step data read from the selector circuit in synchronization with the timing of the reference oscillation signal of the voltage conversion circuit.

A power supply voltage control system according to a third aspect of the present invention is the power supply voltage control system according to the first aspect , wherein the voltage conversion circuit includes a DC / DC converter that converts a pre-conversion voltage into a pulse voltage by an internal reference oscillation signal, and the selector The arithmetic circuit that repeatedly adds or subtracts step data read from the circuit repeatedly adds or subtracts step data read from the selector circuit, and a serial data clock that specifies a variable slope of the power supply voltage. It is characterized in that it is configured to execute in synchronization with the above timing.

  According to this configuration, by changing the voltage stepwise every unit time, it is possible to control the time change (slew rate) of the voltage and realize a smooth voltage change without occurrence of a transient voltage abnormality. .

Hereinafter, each embodiment of the present invention will be described with reference to FIGS.
(First embodiment)
1 and 2 show the first embodiment of the present invention.

  The power supply voltage system of the first embodiment shown in FIG. 1 is configured to control changes in the power supply voltage applied to the CPU 10 based on serial data DATA that specifies a voltage variable slope.

  Here, in addition to the CPU 10, a smoothing circuit 8 including an inductance L1, a diode D1, and a capacitor C1 is provided outside the substrate 11 having the pads P1 to P6.

  In addition to the DC / DC converter 7 that converts the pre-conversion voltage Vcc applied to the pad P6 to the pulse voltage 7a, the substrate 11 includes a serial control circuit 1, a selector circuit 2, a waveform memory circuit 3, an addition circuit 4, and a D. The / A conversion circuit 5 and the like are configured.

  The DC / DC converter 7 shown in FIG. 1 is configured to convert the pre-conversion voltage Vcc into a pulse voltage 7a by the reference oscillation signal 6a generated at the output of the oscillator 6 and generate it between the pads P4 and P5. Has been.

  A clock CLK and serial data DATA synchronized with the clock CLK are supplied to the pads P 2 and P 1 of the substrate 11, and an output 1 a converted in parallel by the serial control circuit 1 is input to the selector circuit 2.

  The selector circuit 2 a reads out data matching the variable voltage gradient input from the output 1 a of the serial control circuit 1 from the inside of the waveform memory circuit 3 and uses it as the output 2 a of the selector circuit 2. This will be specifically described.

Step data V1, V2, and V3 are set in the waveform memory circuit 3 in accordance with the degree of inclination of the power supply voltage to be applied to the CPU 10, and the voltage level is V1>V2> V3.
It is. When the serial data DATA has a content indicating that the variable slope is “large”, the selector circuit 2 reads the step-up data V1 from the waveform memory circuit 3 and outputs it as the output 2a. When the serial data DATA has a content indicating that the variable slope is “medium”, the selector circuit 2 reads the step-up data V2 from the waveform memory circuit 3 and outputs it as the output 2a. If the serial data DATA has a variable slope representing “small”, the selector circuit 2 reads the step-up data V3 from the waveform memory circuit 3 and outputs it as the output 2a.

The adder circuit 4 repeats the addition of the output 2a of the selector circuit 2 with the period T of the reference oscillation signal 6a, and outputs an occasional added value 4a.
On the other hand, in the DC / DC converter 7, the pre-conversion voltage Vcc is converted into a pulse voltage 7a by the reference oscillation signal 6a and is generated between the pads P4 and P5. The voltage OUTPUT is converted. The DC voltage OUTPUT is applied to the D / A conversion circuit 5 via the pad P3, and the D / A conversion circuit 5 converts the analog signal 5a to the DC / DC so that the DC voltage OUTPUT approaches the output 4a from time to time. Feedback is provided to the converter 7.

  In this way, the DC voltage OUTPUT that is sometimes applied as the power supply voltage to the CPU 10 has the waveform A shown in FIG. 2 when the slope of the variable voltage indicated by the serial data DATA is “large”. As described above, the voltage v1 is stepped up every period T and automatically increased to the target voltage. When the slope of the variable voltage indicated by the serial data DATA is “medium”, as shown in the waveform B shown in FIG. To rise. When the slope of the voltage variable instructed by the serial data DATA is “small”, as shown in the waveform C shown in FIG. To rise. Note that v1> v2> v3.

  Therefore, it is possible to change the voltage with a desired inclination by simply detecting the load state of the data processing of the CPU 10 and designating a variable voltage inclination by one update of the serial data DATA, which is a problem in the conventional system. Overshoot and undershoot due to sudden voltage change can be greatly reduced.

  In general, the frequency of the reference oscillation signal 6a for operating the DC / DC converter 7 is several hundred kHz to several MHz, and can be changed at a higher speed than changing the output voltage every time by serial control. Moreover, since the voltage can be changed by sending data only once, the load on the host side can be reduced.

  In this embodiment, assuming that the power supply voltage applied to the CPU 10 is variable to a target voltage with a predetermined slope, an output 4a that rises stepwise is created by using the adder circuit 4 as an arithmetic circuit to create a direct current. Although the voltage OUTPUT is controlled, depending on the configuration of the D / A conversion circuit 5 and the DC / DC converter 7 as the voltage conversion circuit, a subtraction circuit is employed as an arithmetic circuit in place of the addition circuit 4, and is synchronized with the reference oscillation signal 6a. Thus, the subtracting operation is repeatedly performed to generate the output 4a that drops in a stepwise manner, and the DC voltage OUTPUT that increases the DC voltage OUTPUT with the slopes of the waveforms A, B, and C in FIG.

Furthermore, the case where the power supply voltage applied to the CPU 10 is varied up and down with a predetermined gradient has been described. However, the present invention can be similarly implemented when the power supply voltage is varied down with a predetermined inclination.
(Second Embodiment)
FIG. 3 shows a (second embodiment) of the present invention.

  In the first embodiment, the addition circuit 4 repeatedly performs the addition operation or subtraction operation in synchronization with the reference oscillation signal 6a for operating the DC / DC converter 7, so that the addition operation or subtraction is performed from the outside of the substrate 11. Although the cycle of repeating the operation could not be changed, in this (second embodiment), the cycle of repeating the addition operation or the subtraction operation from the outside of the substrate 11 can be realized by changing the clock CLK.

  FIG. 3 is different from the first embodiment only in that the addition circuit 4 is configured to repeatedly perform the addition operation in synchronization with the clock CLK of the serial data DATA.

  The power supply voltage control system of the present invention can be used for various mobile devices that need to control the power supply voltage of the data processing apparatus.

Configuration diagram of power supply voltage control system in (first embodiment) of the present invention Output waveform diagram of the same embodiment Configuration diagram of power supply voltage control system according to (second embodiment) of the present invention Configuration diagram of conventional power supply voltage control system

Explanation of symbols

1 Serial control circuit 2 Selector circuit 3 Waveform memory circuit 4 Adder circuit (arithmetic circuit)
5 D / A conversion circuit 6 Oscillator 6a Reference oscillation signal 7 DC / DC converter circuit (voltage conversion circuit)
8 Smoothing circuit 10 CPU (data processing device)
DATA Serial data CLK clock

Claims (3)

In a power supply voltage control system that varies the power supply voltage applied to the data processing device,
A waveform memory circuit for storing a plurality of step data corresponding to the variable slope of the power supply voltage;
A selector circuit for reading out appropriate step data from the waveform memory circuit according to data designating a variable slope of the power supply voltage;
An arithmetic circuit that repeatedly adds or subtracts step data read from the selector circuit to form a control signal that changes stepwise with time; and
A power supply voltage control system provided with a voltage conversion circuit that varies a power supply voltage applied to the data processing device based on a control signal generated at the output of the arithmetic circuit. The voltage conversion circuit is constituted by a DC / DC converter that converts a voltage before conversion into a pulse voltage by an internal reference oscillation signal,
The arithmetic circuit is configured to repeatedly add or subtract step data read from the selector circuit in synchronization with the timing of the reference oscillation signal of the voltage conversion circuit.
The power supply voltage control system according to claim 1 . The voltage conversion circuit is constituted by a DC / DC converter that converts a voltage before conversion into a pulse voltage by an internal reference oscillation signal,
The arithmetic circuit for repeatedly adding or subtracting the step data read from the selector circuit repeatedly adds or subtracts the step data read from the selector circuit, serial data designating a variable slope of the power supply voltage Configured to run in sync with the clock timing of
The power supply voltage control system according to claim 1 .

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