Switching power source apparatus

• US 20070210776A1
• Filed: 02/08/2007
• Published: 09/13/2007
• Est. Priority Date: 02/09/2006
• Status: Abandoned Application

• Current Assignee: Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Oka, Tomohiro
• Application Number:
  US11/704,679
• Publication Number:
  US 20070210776A1
• Time in Patent Office: Days
• US Class Current: 323/283
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

There is provided a switching power supply device which is capable of reducing an influence of noises and also reducing a consumption current of a control circuit. A pseudo-random number generator circuit (12) generates random number data for determining frequencies of switching signals of MOS transistors (M1) and (M2). A chopping wave oscillation frequency (a frequency of a switching signal) of a chopping wave oscillator (3) randomly changes according to the random number data that is generated by the pseudo-random number generator circuit (12). A current control circuit (1) and a current control circuit (2) control consumption currents that flow in the chopping wave oscillator (3) and an error amplifier (8) according to a change (a change in the frequency of the switching signal) in the random number data that is generated by the pseudo-random number generator circuit (12).

Claims

1. A switching power supply device, which has means for controlling an on/off operation of a switching element that is connected to a DC power supply to output a DC voltage of a given voltage value, and randomly changing a frequency of a switching signal that allows the switching element to turn on/off, the switching power supply device comprising:

a pseudo-random number generator circuit for generating random number data for randomly determining the frequency of the switching signal that allows the switching element to turn on/off; and

a current control circuit for controlling a magnitude of a supply current to a given circuit section whose response speed depends on a consumption current according to the random number data that is generated by the pseudo-random number generator circuit.

2. A switching power supply device according to claim 1, wherein in a case where the frequency of the switching signal changes at random, the current control circuit controls a magnitude of the consumption current so that the response speed of the given circuit section becomes a response speed necessary and sufficient to accept the frequency of the switching signal.

3. A switching power supply device according to claim 1, wherein the pseudo-random number generator circuit includes n-stage feedback shift registers for generating the random number data.

4. A switching power supply device according to claim 1, further comprising:

a chopping wave oscillator having an oscillation frequency controlled according to the random number data which is generated by the pseudo-random number generator circuit;

an error amplifier for comparing a feedback voltage of the output DC voltage with a given reference voltage;

a PWM comparator for comparing a chopping wave signal that is output from the chopping wave oscillator with an output signal of the error amplifier to generate a PWM pulse signal for controlling the on/off operation of the switching element;

a first current control circuit for determining a supply current to the PWM comparator in correspondence with the random number data that is generated by the pseudo-random number generator circuit; and

a second current control circuit for determining a supply current to the error amplifier in correspondence with the random number data that is generated by the pseudo-random number generator circuit.