SWITCHED MODE POWER SUPPLY

• US 20110095730A1
• Filed: 01/05/2006
• Published: 04/28/2011
• Est. Priority Date: 01/07/2005
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Langeslag, Wilhemus H. M., Strijker, Arjan, Terpstra, Gerrit
• Granted Patent: US 8,278,900 B2
• Time in Patent Office: Days
• US Class Current: 323/205
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A power supply includes a PFC stage 6 and an SMPS stage 8. The power supply can operate in a normal mode in which the PFC stage supplies a voltage to the SMPS stage. In a standby mode, the PFC stage is operated in bursts to supply a lower voltage to the SMPS stage that is high enough that the SMPS stage can rapidly respond when it needs to supply a load.

Claims

1. A power supply, comprising:

a power factor correction stage having power inputs for receiving input power and power outputs for outputting output power at the power factor output stage voltage;

wherein the power factor correction stage can be switched between an operating mode and an off mode;

a switched mode power stage having output terminals for supplying output power to a load at a supply voltage and input terminals connected to the power outputs of the power factor correction stage for receiving power at the power factor output stage voltage;

wherein the power factor correction stage (6) can be switched between an operating mode and an off mode;

wherein the power supply is arranged to be switchable between a normal mode and a standby mode;

the power supply further comprising a controller (64) for controlling the power factor correction stage to supply in the normal mode a normal power factor output stage voltage to the switched mode power stage and to operate in the standby mode in a burst mode to supply power in a voltage range below the normal power factor output stage voltage.

2. A power supply according to claim 1, wherein the power factor correction stage is a switched mode boost circuit

3. A power supply according to claim 1, wherein the controller is arranged in the standby mode to switch on the power factor correction stage for a burst when the power factor output stage voltage falls below a low burst level and to switch off the power factor correction stage to end the burst when the power factor output stage voltage rises above a high burst level higher than the low burst level, the high and low burst levels both being below the normal power factor output stage voltage.

4. A power supply according to claim 3, wherein the controller includes:

a bistable device having an output connected to the power factor correction stage to control whether the power factor connection stage is in a burst mode or not;

a first comparator for comparing the power factor output stage voltage with the low burst level, the first comparator being connected to the bistable device to switch the bistable device to the burst mode when the power factor output stage voltage falls below the low burst level; and

a second comparator for comparing the power factor output stage voltage with the high burst level, the second comparator being connected to the bistable device to switch the bistable device out of the burst mode when the power factor output stage voltage rises above the high burst level.

5. A switching controller for a power supply having a power factor correction stage and a switched mode power stage, the input of the switched mode power stage being connected to the output of the power factor correction stage on a connection line, the switching controller comprising:

an input for connection, directly or indirectly, to the connection line to input the power factor output stage voltage on the connection line to the switching controller;

a controller output for switching the power factor correction stage; and

a control stage arranged to operate in a normal mode to control the power factor correction stage to supply a normal power factor output stage voltage to the switched mode power stage and to control the power factor correction stage to operate in the standby mode in a burst mode to supply power in a voltage range below the normal power factor output stage voltage.

6. A switching controller according to claim 5, wherein the control stage comprises:

a bistable device having an output for controlling whether the power factor correction stage is in a burst mode or not;

a first comparator for comparing the power factor output stage voltage with the low burst level, the first comparator being connected to the bistable device to switch the bistable device to the burst mode when the power factor output stage voltage falls below the low burst level; and

a second comparator for comparing the power factor output stage voltage with the high burst level, the second comparator being connected to the bistable device to switch the bistable device out of the burst mode when the power factor output stage voltage rises above the high burst level.

7. A method of operating a power supply having a switched mode power stage having as an input the output of a power factor correction stage, the method comprising:

switching the power supply between a normal mode and a standby mode;

operating the power factor correction stage in the normal mode to supply a normal power factor output stage voltage to the switched mode power stage; and

operating the power factor correction stage in the standby mode in a burst mode, including supplying a voltage range below the normal power factor output stage voltage to the switched mode power stage.

8. A method according to claim 7, including turning on the power factor correction stage for a burst when the power factor output stage voltage falls below a low burst level;

and

turning off the power factor correction stage to end the burst when the power factor output stage voltage rises above a high burst level higher than the low burst level, the high and low burst levels both being between the normal power factor output stage voltage and the nominal input voltage.