Buck-boost switch mode power supply with burst topology

• US 5,528,125 A
• Filed: 04/05/1995
• Issued: 06/18/1996
• Est. Priority Date: 04/05/1995
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Marshall, Andrew, Schmidt, Thomas A.
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US08/416,663
• Time in Patent Office: 440 Days
• Field of Search: 323/222, 323/223, 323/268, 323/271, 323/282, 323/283, 323/284, 323/285, 363/22, 363/23, 363/24, 363/25, 363/133, 363/134
• US Class Current: 323/222
• CPC Class Codes: G05F 3/242 with compensation for device parameters, e.g. channel width modulation, threshold voltage, processing, or external variations, e.g. temperature, loading, supply voltage
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence

Abstract

A buck-boost switch mode regulated power supply using a burst circuit topology includes a detection circuit to sense overcurrent in the high side connected power transistor. This causes the flip flop to flip which turns off the transistor. A comparator connected to the output voltage detects when the output voltage falls below the threshold value of the comparator and sends a signal to the flip flop which is reset upon the next pulse of a pulsed reset signal. When the flip flop is reset, the high side power transistor is turned back on.

Claims

1. A buck-boost burst power supply with burst comprising:

a first power transistor coupled through an inductor to a load in high side configuration to provide an output voltage;

a second power transistor coupled through the inductor to the load in low side configuration to provide the output voltage;

a first means for detecting current level through the first power transistor;

a second means for turning the first power transistor "off" in response to the first means for detecting;

a comparator coupled to the output voltage;

a flip flop coupled to the output of the comparator and connected to a pulsed reset signal to turn the first power transistor "on" once the output voltage falls below a threshold voltage of the comparator; and

a voltage feedback control system comprising at least;

a) said second means for turning the first power transistor "off";

b) said comparator; and

c) said flip flop, said feedback control system being selectively operable to maintain said output voltage within prescribed limits through selective activation and deactivation of said first and second power transistors.

2. The buck-boost burst power supply of claim 1 wherein the first means for detecting comprises a resistor coupled between a supply voltage and the first power transistor.

3. A buck-boost burst power supply with burst comprising:

a first power transistor coupled through an inductor to a load in high side configuration to provide an output voltage;

a second power transistor coupled through the inductor to the load in low side configuration to provide the output voltage;

a first means for detecting the current level through the first power transistor, said first means for detecting comprising a resistor coupled between a supply voltage and the first power transistor;

a second means for turning the first power transistor off in response to the first means for detecting, said second means for turning the first power transistor off comprising logic circuitry connected across the resistor, connected to the output of the comparator and connected to the flip flop;

a comparator coupled to the output voltage; and

a flip flop coupled to the output of the comparator and connected to a pulsed reset signal to turn the first power transistor on once the output voltage falls below the threshold voltage of the comparator.