Switching voltage regulator employing current pre-adjust based on power mode
View Patent ↗A switching voltage regulator is disclosed including a charging element operable to generate an output voltage. The charging element is configured during a cycle, including to charge the charging element for an on-time, discharge the charging element for a discharge time, and tristate the charging element for a tristate time. Prior to a power mode changing which increases the current demand of the load, the on-time is increased.
1. A switching voltage regulator operable to regulate a supply voltage to a load, the switching voltage regulator comprising:
(a) a charging element operable to generate an output voltage;
(b) switching circuitry coupled to the charging element; and
(c) switch control circuitry operable to control the switching circuitry to configure the charging element during a cycle, including to charge the charging element for an on-time, discharge the charging element for a discharge time, and tristate the charging element for a tristate time, and further operable to:
initialize the on-time to a first on-time;
measure a first switch time comprising the first on-time and a first discharge time of a first cycle;
measure a first tristate time of the first cycle;
determine a first ratio of the first tristate time to the first switch time;
compare the first ratio to a first ratio threshold;
decrease the on-time to a second on-time when the first ratio exceeds the first ratio threshold; and
prior to a power mode changing which increases the current demand of the load, increase the on-time.
2. The switching voltage regulator as recited in claim 1 , wherein the control circuitry is further operable to increase the on-time to the first on-time.
3. The switching voltage regulator as recited in claim 1 , wherein the control circuitry is further operable to increase the on-time one cycle before the power mode changes.
4. The switching voltage regulator as recited in claim 1 , wherein prior to a power mode changing which decreases the current demand of the load the control circuitry is further operable to decrease the on-time to the second on-time.
5. The switching voltage regulator as recited in claim 4 , wherein the control circuitry is further operable to decrease the on-time to the second on-time one cycle before the power mode changes.
6. A switching voltage regulator operable to regulate a supply voltage to system circuitry, the switching voltage regulator comprising:
a ring oscillator operable to generate an oscillator signal representing a gate speed of a reference circuit in the system circuitry, wherein the ring oscillator comprises a plurality of delay elements connected in series;
a frequency generator operable to generate a reference signal representing a target gate speed of the reference circuit, wherein a frequency of the reference signal is based on a divider value;
a comparator operable to compare the oscillator signal to the reference signal;
switching circuitry operable to charge a charging element in response to the comparison; and
control circuitry operable to:
adjust the number of delay elements in the ring oscillator and the divider value of the frequency generator to generate hysteresis in the comparison; and
prior to a power mode of the system circuitry changing, adjust a hysteresis threshold for controlling a level of the hysteresis.
7. The switching voltage regulator as recited in claim 6 , wherein the control circuitry is further operable to adjust the hysteresis threshold by adjusting the comparator.
8. The switching voltage regulator as recited in claim 7 , wherein the control circuitry is further operable to adjust the hysteresis threshold by adjusting a counter clocked by the oscillator signal.
9. The switching voltage regulator as recited in claim 7 , wherein the control circuitry is further operable to adjust the hysteresis threshold by adjusting a counter clocked by the reference signal.
10. The switching voltage regulator as recited in claim 7 , wherein the control circuitry is further operable to adjust the hysteresis threshold by adjusting a first counter clocked by the oscillator signal and a second counter clocked by the reference signal.
11. A method of operating a switching voltage regulator operable to regulate a supply voltage to a load, the switching voltage regulator comprising a charging element operable to generate an output voltage, the method comprising:
initializing an on-time of the charging element to a first on-time;
measuring a first switch time comprising the first on-time and a first discharge time of a first cycle;
measuring a first tristate time of the first cycle;
determining a first ratio of the first tristate time to the first switch time;
comparing the first ratio to a first ratio threshold;
decreasing the on-time to a second on-time when the first ratio exceeds the first ratio threshold; and
prior to a power mode changing which increases the current demand of the load, increasing the on-time.
12. The method as recited in claim 11 , further comprising increasing the on-time to the first on-time one.
13. The method as recited in claim 11 , further comprising increasing the on-time one cycle before the power mode changes.
14. The method as recited in claim 11 , wherein prior to a power mode changing which decreases the current demand further comprising decreasing the on-time to the second on-time.
15. The method as recited in claim 14 , further comprising decreasing the on-time to the second on-time one cycle before the power mode changes.
16. A method of operating a switching voltage regulator operable to regulate a supply voltage to system circuitry, the switching voltage regulator comprising:
a ring oscillator operable to generate an oscillator signal representing a gate speed of a reference circuit in the system circuitry, wherein the ring oscillator comprises a plurality of delay elements connected in series;
a frequency generator operable to generate a reference signal representing a target gate speed of the reference circuit, wherein a frequency of the reference signal is based on a divider value;
a comparator operable to compare the oscillator signal to the reference signal;
switching circuitry operable to charge a charging element in response to the comparison; and
the method comprising:
adjusting the number of delay elements in the ring oscillator and the divider value of the frequency generator to generate hysteresis in the comparison; and
prior to a power mode of the system circuitry changing, adjusting a hysteresis threshold for controlling a level of the hysteresis.
17. The method as recited in claim 16 , further comprising adjusting the hysteresis threshold by adjusting the comparator.
18. The method as recited in claim 17 , further comprising adjusting the hysteresis threshold by adjusting a counter clocked by the oscillator signal.
19. The method as recited in claim 17 , further comprising adjusting the hysteresis threshold by adjusting a counter clocked by the reference signal.
20. The method as recited in claim 17 , further comprising adjusting the hysteresis threshold by adjusting a first counter clocked by the oscillator signal and a second counter clocked by the reference signal.