CYCLE BY CYCLE SYNCHRONOUS BUCK CONVERTER CONTROL BASED ON EXTERNAL CLOCK

• US 20080100278A1
• Filed: 10/22/2007
• Published: 05/01/2008
• Est. Priority Date: 10/27/2006
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Salato, Maurizio
• Granted Patent: US 8,587,269 B2
• Time in Patent Office: Days
• US Class Current: 323/318
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• 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 DC-DC voltage converter having a switching stage including high- and low-side switches connected in series at a switched node across a DC voltage bus; a control circuit; and a feedback loop connected between an output of the switching stage and an input of the control circuit, the control circuit having a clock signal input and including an error processing circuit coupled to the input for detecting an output of the feedback loop, the control circuit turning OFF the low-side switch and turning ON the high-side switch when the clock signal is detected. The control circuit operates in a cycle-by-cycle operation generating PWM modulation synchronous to the external clock source.

Claims

1. A DC-DC voltage converter comprising:

a switching stage including high- and low-side switches connected in series at a switched node across a DC voltage bus;

a control circuit; and

a feedback loop connected between an output of the switching stage and an input of the control circuit, the control circuit having a clock signal input and including an error processing circuit coupled to the input for detecting an output of the feedback loop, the control circuit turning OFF the low-side switch and turning ON the high-side switch when the clock signal is detected,

wherein the control circuit operates in a cycle-by-cycle operation generating PWM modulation synchronous to the external clock source.

2. The DC-DC voltage converter of claim 1, wherein the clock signal is provided from a clock source external to the DC-DC voltage converter.

3. The DC-DC voltage converter of claim 1, wherein the control circuit comprises a flip-flop circuit and a bridge logic circuit connected to gates of the high- and low-side switches, the control circuit directing the flip-flop circuit to signal the bridge logic circuit to turn OFF the low-side switch and turn ON the high-side switch when the control circuit detects one of falling and rising edges of the clock signal.

4. The DC-DC voltage converter of claim 1, wherein the feedback loop comprises a shunt regulator and the error processing circuit acts as an error amplifier generating an error signal thereby implementing PWM modulation based on the clock signal and the error signal.

5. The DC-DC voltage converter of claim 4, wherein the shunt regulator includes first and second compensation circuits and a shunt regulator component connected to a pin providing the error signal to the error processing circuit.

6. The DC-DC voltage converter of claim 1, wherein the error processing circuit comprises:

a capacitor;

a mirror current circuit for charging the capacitor;

a comparator circuit for comparing voltage on the capacitor with the voltage at the ERR feedback pin while the capacitor charges; and

a third switch for switching ON and forcing the control circuit to turn ON the low-side switch and to turn OFF the high-side switch, the third switch being triggered to turn ON when the voltage on the capacitor reaches the larger of the voltage at the error processing circuit and an internal reference,

wherein the third switch stays ON for the duration of time it takes the capacitor to discharge.

7. The DC-DC voltage converter of claim 6, wherein the third switch resets the flip-flop circuit to signal the bridge logic circuit to turn OFF the high-side switch and to turn ON the low-side switch.

8. The DC-DC voltage converter of claim 7, wherein the error processing circuit presents a resistive behavior and the shunt regulator drains a current inversely proportional to an output voltage error from the error processing circuit.