Digital control of switching voltage regulators

• US 20050116698A1
• Filed: 12/01/2003
• Published: 06/02/2005
• Est. Priority Date: 12/01/2003
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Semiconductor Corporation (ON Semiconductor Corporation)
• Inventors: Kotikalapoodi, Sridhar, Prinz, Francois X.
• Granted Patent: US 7,498,786 B2
• Time in Patent Office: Days
• US Class Current: 323/283
• CPC Class Codes: H02M 3/157 with digital control

Abstract

A digital control system and method for use in switching type voltage regulators measures the rate of the change and the magnitude of the output voltage to change not only the pulse width but also the frequency of the pulses. A voltage regulator according to the present invention creates a more stable output voltage and responds more quickly to sudden changes in current load than prior analog and digitally controlled systems.

Claims

1. A digital control system for voltage converters, comprising:

an oscillator that issues a pulse;

a duty cycle generator, wherein the pulse is used to load a numerical value stored in a memory of the system into the duty cycle generator;

a digital counter that stores and alters a duty cycle;

a first comparator that determines how the duty cycle must be modified; and

an algorithm generator producing an algorithm that determines the rate of change of the duty cycle.

2. The system of claim 1 wherein if the comparator detects that an output voltage is higher than a reference voltage, the comparator retards the issuance of the pulse in a cyclical fashion, thereby creating a burst of pulses with a desired duty cycle.

3. The system of claim 2 further comprising a second comparator having a reference different than the first comparator.

4. A method for producing a desired output voltage comprising:

storing in memory, an indication of a pulse duty cycle needed for a varying load;

monitoring the load;

altering the stored duty cycle at a first frequency to produce the desired output voltage based upon the indication; and

if a change in the load is detected, changing the frequency of alteration of the duty cycle.

5. The method of claim 4 wherein the indication comprises a digital counter, and wherein changing the frequency of alteration of the duty cycle comprises changing the frequency of updating the digital counter.

6. The method of claim 4 wherein monitoring the load comprises usage of two or more comparators.

7. The method of claim 4, wherein if the load increases, the frequency of alteration is increased, thereby minimizing a dip in the output voltage.

8. The method of claim 6, wherein the two or more comparators each have a different reference.

9. A voltage converter that produces an output voltage, comprising:

a digital controller that controls the output voltage of analog circuitry;

a numerical value stored in a memory of the converter;

a duty cycle generator that utilizes the numerical value to alter the duty cycle of the analog circuitry;

a first comparator that compares the output voltage to a reference voltage at a first rate; and

a second comparator that compares the output voltage to the reference voltage at a second rate,

wherein the numerical value is updated based upon a comparison at the first or second rate.

10. The voltage converter of claim 9 further comprising an algorithm generator that selects the speed that the numerical value is updated.

11. The voltage converter of claim 9 wherein the digital controller selects either the first or second rate.

12. The voltage converter of claim 9 wherein when either comparator detects that the output voltage is higher than the reference voltage it decreases the duty cycle.

13. The voltage converter of claim 9 wherein when either comparator detects that the output voltage is lower than the reference voltage it increases the duty cycle.

14. The voltage converter of claim 9 wherein the numerical value is stored in an up-down counter in the memory, and wherein if either comparator detects that the output is lower than the reference voltage it switches the up-down counter in up mode, and if the reference voltage is lower, it switches the up-down counter in down mode.

15. A method for bucking or boosting a voltage, comprising:

providing groups of pulses, each group comprising one or more pulses;

detecting the rate of change of an output voltage over time;

modifying the frequency of generation of the groups of pulses in response to said rate of change;

detecting the magnitude of the output voltage; and

changing a pulse width of the output voltage in response to the detected magnitude.

16. A digital controller of a voltage regulator, comprising:

an up/down counter that stores a numerical value used to alter a duty cycle of the controller driving a transistor/switch;

a duty cycle generator that utilizes the numerical value to alter the duty cycle; and

an algorithm generator that produces an algorithm that alters the rate of change of the duty cycle.