Voltage control circuit for a semiconductor apparatus capable of controlling an output voltage

• US 5,083,043 A
• Filed: 01/18/1991
• Issued: 01/21/1992
• Est. Priority Date: 01/18/1990
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Yoshida, Makoto
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): TRAN, TOAN V
• Application Number:
  US07/642,898
• Time in Patent Office: 368 Days
• Field of Search: 323/299, 323/303, 323/281, 307/296.8, 307/241, 307/242, 307/264, 307/296.6, 307/139, 307/125, 307/571
• US Class Current: 327/437
• CPC Class Codes: G05F 1/465 Internal voltage generators for integrated circuits, e.g. step down generators
• CPC Class Codes: G05F 3/24 wherein the transistors are of the field-effect type only G05F3/205, G05F3/26, G05F3/30 take precedence
• CPC Class Codes: G11C 5/147 Voltage reference generators, voltage or current regulators; Internally lowered supply levels; Compensation for voltage drops G11C5/141 takes precedence
• CPC Class Codes: H03K 17/04106 in field-effect transistor switches H03K17/0412, H03K17/0416 take precedence
• CPC Class Codes: H03K 17/12 Modifications for increasing the maximum permissible switched current
• CPC Class Codes: H03K 17/6871 the output circuit comprising more than one controlled field-effect transistor

Abstract

There is disclosed a voltage control circuit for a semiconductor apparatus for controlling an output voltage to be applied from an external voltage source to a load circuit of the semiconductor apparatus therethrough. A reference voltage generator generates a predetermined reference voltage according to a source voltage outputted from an external voltage source, and an error amplifier compares the output voltage with the reference voltage, and outputs a comparison signal for representing the comparison result thereof. A voltage controller controls the output voltage according to the comparison signal. Further, a diode circuit which is connected in parallel with the voltage controller applies the source voltage to the load circuit in a forward direction thereof. Furthermore, a first switching device enables the reference voltage generator, the error amplifier and the voltage controlled in response to a first control signal outputted from an external circuit, and for disabling the reference voltage generator, the error amplifier and the voltage controller in response to a second control signal outputted from the external circuit. Also, a second switching device enables the diode circuit in response to the second control signal, and for disabling the diode circuit in response to the first control signal.

Claims

1. A voltage control circuit for a semiconductor apparatus for controlling an output voltage to be applied from an external voltage source to a load circuit of said semiconductor apparatus therethrough, comprising:

reference voltage generating means for generating a predetermined reference voltage according to a source voltage outputted from an external voltage source;

comparing means for comparing said output voltage to be applied to said load circuit with said reference voltage generated by said reference voltage generating means, and outputting a comparison signal for representing said comparison result thereof;

voltage control means for controlling said output voltage to be applied to said load circuit according to said comparison signal outputted from said comparing means;

diode means for applying said source voltage outputted from said external voltage source to said load circuit in a forward direction thereof, said diode means being connected in parallel with said voltage control means;

first switching means for enabling said reference voltage generating means, said comparing means and said voltage control means in response to a first control signal outputted from an external circuit when said load circuit requires a relatively large current equal to or larger than a predetermined threshold current, and for disabling said reference voltage generating means, said comparing means and said voltage control means in response to a second control signal outputted from said external circuit when said load circuit requires a relatively small current smaller than said predetermined threshold current; and

second switching means for enabling said diode means in response to said second control signal, and for disabling said diode means in response to said first control signal.

2. The circuit as claimed in claim 1,

wherein said semiconductor apparatus is an integrated circuit to which a chip enable signal is inputted from said external circuit, said first control signal corresponds to said chip enable signal having a first level, and said second control signal corresponds to said chip enable signal having a second level which is different from said first level.

3. The circuit as claimed in claim 1,

wherein said first switching means comprises:

a first transistor for controlling the action of said reference signal generating means;

a second transistor for controlling the action of said comparing means; and

a third transistor for controlling the action of said voltage control means, and

said second switching means comprises a fourth transistor for controlling the action of said diode means.

4. The circuit as claimed in claim 3,

wherein said first transistor is an N type metal oxide semiconductor field effect transistor;

said second transistor is an N type metal oxide semiconductor field effect transistor;

said third transistor is a P type metal oxide semiconductor field effect transistor; and

said fourth transistor is a P type metal oxide semiconductor field effect transistor.

5. The circuit as claimed in claim 2,

wherein said first switching means comprises:

a first transistor for controlling the action of said reference signal generating means;

a second transistor for controlling the action of said comparing means; and

a third transistor for controlling the action of said voltage control means, and

said second switching means comprises a fourth transistor for controlling the action of said diode means.

6. The circuit as claimed in claim 5,

wherein said first transistor is an N type metal oxide semiconductor field effect transistor;

said second transistor is an N type metal oxide semiconductor field effect transistor;

said third transistor is a P type metal oxide semiconductor field effect transistor; and

said fourth transistor is a P type metal oxide semiconductor field effect transistor.

7. The circuit as claimed in claim 1,

wherein said comparing means is an error amplifier, and said voltage control means is a field effect transistor.

8. The circuit as claimed in claim 2,

wherein said comparing means is an error amplifier, and said voltage control means is a field effect transistor.