DC-DC converter having feedback type switching voltage converting circuit

• US 4,633,379 A
• Filed: 09/17/1984
• Issued: 12/30/1986
• Est. Priority Date: 09/30/1983
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Mori, Toshihiro, Oda, Takashi, Ohyagi, Takashi
• Primary Examiner(s): BEHA JR, WILLIAM
• Application Number:
  US06/651,413
• Time in Patent Office: 834 Days
• Field of Search: 363/19, 363/23, 363/97, 323/226, 323/280, 323/281, 323/234, 323/222
• US Class Current: 363/19
• CPC Class Codes: H02M 3/155 using semiconductor devices only
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A DC-DC converter having a high conversion efficiency and stable output voltage. A constant current supply circuit, located between the output terminals of the converter, make it possible for the source current to decrease as a function of battery output voltage, resulting in lower current requirements for a lower required voltage boost and hence increased efficiency.

Claims

1. A DC-DC comprising:

feedback type switching voltage converting means for converting a DC input voltage to an output voltage in accordance with a control voltage provided at a feedback input thereof;

constant current supply means responsive to the output of said switching voltage oonverting means for producing a constant current;

voltage stabilizing and picking-up means responsive to said constant current for stabilizing the output voltage of said switching voltage converting means and pickup up the output voltage to provide a feedback voltage; and

feedback means for providing said feedback voltage to said feedback input as said control signal.

2. A DC-DC converter, as claimed in claim 1,

wherein said constant current supply means comprises a first resistor having first and second ends, said first end being connected to one output end of said voltage converting means;

a first transistor having a base and an emitter which are respectively connected to said second end of said first resistor and a second output end of said voltage converting means;

a second resistor connected between a base and a collector of said first transistor; and

a second transistor having a base, a collector and an emitter which are respectively connected to the collector of said first transistor, one end of said voltage stabilizing and picking-up means and the second output end of said voltage converting means, and wherein

said feedback means comprises a third transistor having a base, a collector and an emitter which are respectively connected to the collector of said second transistor, said feedback input and the second output end of said voltage converting means.

3. A DC-DC converter, as claimed in claim 2, wherein

said voltage stabilizing and picking-up means comprises a resistor connected between the collector of said second transistor and said one output end of said switching voltage converting means.

4. A DC-DC converter as claimed in claim 2, further comprising a temperature compensating element, connected in series to said voltage stabilizing and picking-up means, for compensating for fluctuations in the output voltage of said switching voltage converting means resulting from temperature changes.

5. A DC-DC converter as claimed in claim 4, wherein

said element comprises a diode-connected transistor connected between one end of said voltage stabilizing and picking-up means and the collector of said second transistor.