DC-DC converter circuit for preventing beat interference

• US 6,522,107 B1
• Filed: 09/29/2000
• Issued: 02/18/2003
• Est. Priority Date: 09/30/1999
• Status: Expired due to Term

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Sasaki, Fumihiro
• Primary Examiner(s): Sherry, Michael
• Assistant Examiner(s): Laxton, Gary L.
• Application Number:
  US09/675,624
• Time in Patent Office: 872 Days
• Field of Search: 323/222, 323/259, 323/265, 323/223, 323/282, 323/349, 323/351, 455/255, 455/296
• US Class Current: 323/222
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A transistor (48) is switched on or off to thereby cause a counter electromotive force on a coil (42) so that a high voltage is charged to a capacitor (46) via a zener diode (44). As a breakdown current of the zener diode (44) flows to the ground via the transistor (48), a voltage lower than a predetermined voltage is applied to the transistor (48). In addition, as the breakdown current of the zener diode (44) does not flow directly to the ground, variance of a boosted voltage can be prevented.

Claims

1. A DC-DC converter circuit for converting a voltage of a battery into a higher voltage for output, comprising:

a coil, one end thereof being connected to the battery;

a transistor, one end thereof being connected to other end of the coil and the other end thereof being connected to a ground, for being switched on or off in response to a predetermined clock signal;

a zener diode connected, at an anode thereof, to the other end of the coil, for outputting via a cathode thereof a boosted voltage; and

a capacitor connected to the cathode of the zener diode, for maintaining the boosted voltage;

wherein

the boosted voltage is used as a power source voltage for adjusting a local frequency of a radio receiver; and

the predetermined clock signal for switching on or off the transistor is a clock obtained by dividing the local frequency for receiving AM broadcasting.

2. A DC-DC converter circuit for converting a voltage of a battery into a higher voltage for output, comprising:

a coil, one end thereof being connected to the battery;

a transistor, one end thereof being connected to other end of the coil and the other end thereof being connected to a ground, for being switched on or off in response to a predetermined clock signal;

a zener diode connected, at an anode thereof, to the other end of the coil, for outputting via a cathode thereof a boosted voltage; and

a capacitor connected to the cathode of the zener diode, for maintaining the boosted voltage;

wherein

the boosted voltage is used as a power source voltage for adjusting a local frequency of a radio receiver; and

the predetermined clock signal for switching on or off the transistor is a circuit operation main clock or a clock obtained by dividing a circuit operation main clock for receiving FM broadcasting.

3. A DC-DC converter circuit for converting a voltage of a battery into a higher voltage for output, comprising:

a coil, one end thereof being connected to the battery;

a transistor, one end thereof being connected to other end of the coil and the other end thereof being connected to a ground, for being switched on or off in response to a predetermined clock signal;

a zener diode connected, at an anode thereof, to the other end of the coil, for outputting via a cathode thereof a boosted voltage; and

a capacitor connected to the cathode of the zener diode, for maintaining the boosted voltage;

wherein

the boosted voltage is used as a power source voltage for adjusting a local frequency of a radio receiver; and

the predetermined clock signal for switching on or off the transistor is a clock obtained by dividing the local frequency for receiving AM broadcasting, and, a circuit operation main clock or a clock obtained by dividing a circuit operation main clock for receiving FM broadcasting.

4. A DC-DC converter circuit for converting a voltage of a battery into a higher voltage for output, comprising:

a coil, one end thereof being connected to the battery;

a transistor, one end thereof being connected to other end of the coil and the other end thereof being connected to a ground, for being switched on or off in response to a predetermined clock signal;

a zener diode connected, at an anode thereof, to the other end of the coil, for outputting via a cathode thereof a boosted voltage; and

a capacitor connected to the cathode of the zener diode, for maintaining the boosted voltage;

wherein

the boosted voltage is used as a power source voltage for adjusting a local frequency of a radio receiver; and

the predetermined clock signal for switching on or off the transistor is a clock obtained by dividing the local frequency for receiving FM broadcasting.

5. A DC-DC converter circuit for converting a voltage of a battery into a higher voltage for output, comprising:

a coil, one end thereof being connected to the battery;

a transistor, one end thereof being connected to other end of the coil and the other end thereof being connected to a ground, for being switched on or off in response to a predetermined clock signal;

a zener diode connected, at an anode thereof, to the other end of the coil, for outputting via a cathode thereof a boosted voltage; and

a capacitor connected to the cathode of the zener diode, for maintaining the boosted voltage;

wherein

the boosted voltage is used as a power source voltage for adjusting a local frequency of a radio receiver; and

the predetermined clock signal for switching on or off the transistor is a circuit operation main clock or a clock obtained by dividing a circuit operation main clock for receiving FM broadcasting, and, a clock obtained by dividing the local frequency in a case where the power source voltage drops below a predetermined value in receiving FM broadcasting.