Low electrical consumption voltage regulator

• US 20010030530A1
• Filed: 04/04/2001
• Published: 10/18/2001
• Est. Priority Date: 04/12/2000
• Status: Active Grant

• Current Assignee: ST-Ericcson SA (Telefonaktiebolaget LM Ericsson)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Marty, Nicolas
• Granted Patent: US 6,501,253 B2
• Time in Patent Office: Days
• US Class Current: 323/280
• CPC Class Codes: G05F 1/565 sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor G05F1/563 takes precedence
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit

Abstract

A voltage regulator includes a regulation MOS transistor and an amplifier providing an output for driving a gate of the regulation MOS transistor. The amplifier drives the gate based upon a difference between a reference voltage and a feedback voltage. The voltage regulator may further include a circuit for making the amplifier switch to a standby mode with low current consumption when the difference between the supply voltage and the output voltage of the regulator is below a first threshold. This is done while maintaining, at the gate of the regulation transistor, a voltage that keeps the regulation transistor on. The present invention is particularly applicable to the management of power supplies in portable telephones.

Claims

1. A voltage regulator comprising a regulation MOS transistor and an amplifier whose output drives the gate of the regulation transistor as a function of the difference between a reference voltage and a feedback voltage, the regulator comprising means to make the amplifier change over into a standby mode with low current consumption when the difference between the supply voltage and the output voltage of the regulator is below a first threshold, while maintaining, at the gate of the regulation transistor, an electrical potential that keeps the regulation transistor on.

2. A regulator according to

claim 1

, comprising a comparator laid out to compare the supply voltage and the output voltage of the regulator and deliver a standby signal to the amplifier when the difference between the supply voltage and the output voltage of the regulator is below the first threshold.

3. A regulator according to

claim 2

, wherein the comparator shows a switch-over hysteresis and cancels the signal for putting the amplifier on standby when the difference between the supply voltage and the output voltage of the regulator is higher than a second threshold that is higher than the first threshold.

4. A regulator according to one of the

claims 1

to

3

, wherein the amplifier comprises a resistor connecting the output of the amplifier to the supply voltage, wherein a switch is series-connected with the resistor and wherein the switch series-connected with the register is open when the amplifier is put on standby, and closed if not.

5. A regulator according to one of the

claims 1

to

4

, wherein the amplifier comprises current sources changing over into low current mode when the amplifier is put on standby.

6. A regulator according to one of the

claims 1

to

5

, wherein the amplifier comprises a switch driven by a standby-setting signal to connect the gate of the regulation transistor to an electrical potential making the transistor on when the amplifier is put on standby.

7. A regulator according to one of the

claims 1

to

4

, wherein the amplifier comprises a stage to bias the gate of the regulation transistor, laid out for the application, to the gate of the regulation transistor when the amplifier is on standby, of a voltage that is determined so that the gate-source voltage of the regulation transistor is close to the threshold voltage of the regulation transistor.

8. A regulator according to one of the claims 6 and 8, wherein the electrical supply of the amplifier is eliminated in standby mode by a switch.

9. A mobile telephone comprising a battery and radio circuits powered by means of a regulator according to the one of the

claims 1

to

8

.

10. A method for the management of the power available in a battery powering a load by means of a voltage regulator, the regulator comprising a regulation MOS transistor and an amplifier whose output drives the gate of the regulation transistor as a function of the difference between the reference voltage and a feedback voltage, the method comprises a step consisting of the monitoring of the difference between the supply voltage and the output voltage of the regulator and a step in which the amplifier is made to change over into standby mode with low current consumption when the difference between the supply voltage and the output voltage of the regulator is below a first threshold, while keeping the gate of the regulation transistor at a potential enabling the regulation transistor to be kept in the on state.

11. A method according to

claim 10

, characterized in that the amplifier is reactivated when the difference between the supply voltage and the output voltage of the regulator is higher than a second threshold that is higher than the first threshold.

12. A method according to one of the claims 10 and 11, wherein the consumption of the amplifier in standby mode is reduced by disconnecting the output node of the amplifier from the supply voltage.

13. A method according to one of the

claims 10

to

12

, wherein the consumption of the amplifier in standby mode is reduced by diminishing the current delivered by current sources internal to the amplifier.

14. A method according to one of the claims 10 and 11, wherein the application of the supply voltage to the amplifier is eliminated.

15. A method according to one of the

claims 10

to

14

, wherein, when the amplifier is put on standby, there is applied, to the gate of the regulation transistor, a voltage determined so that the gate-source voltage of the regulation transistor is close to its threshold voltage.