Active transient response circuits, system and method for digital multiphase pulse width modulated regulators
View Patent ↗Disclosed is a multi-phase pulse width modulated voltage regulator and method in which transient voltage excursions or deviations that exceed the load line voltage by more than a pre-determined amount are detected by an ATR circuit and a correction signal is applied. The correction signal is in the form of asynchronous pulses and the number of such pulses is a function of the magnitude of the voltage excursion as determined by the number of thresholds that are exceeded. Also disclosed is an adaptive voltage positioning (AVP) circuit and method for early detection of a transient event by sensing voltage changes at the load and adjusting the target voltage with pre-determined current values prior to the time that ATR event changes in the current at the load are detected. The AVP load line is pre-positioned for more precise current control. Also disclosed is an adaptive filter with adjustable frequency characteristics in response to an ATR event. Also disclosed is a pulse limiting circuit. Also disclosed is a tri-state implementation. Response to transient events is further improved with an external ATR circuit coupled to the load.
1. A multiphase power regulator for supplying a load comprising:
a multiphase pulse width modulator;
an output stage comprising a high side FET, a low side FET and an inductor coupled to the multiphase pulse width modulator;
an active transient response circuit coupled between the output stage and the multiphase pulse width modulator and configured to detect a voltage level at the output stage and providing a signal to the multiphase pulse width modulator that is a function of an amplitude of a deviation of the detected voltage level from a target voltage; and
an external active transient response circuit coupled to the active transient response circuit and coupled directly to the load and configured to adjust the voltage level at the load only in response to the amplitude of the deviation crossing a selected threshold.
2. A multiphase power regulator as in claim 1 wherein said active transient response circuit comprises:
a circuit for setting discrete voltage levels representing deviations from the target voltage; and
a plurality of comparators configured to provide an output when a sensed voltage exceeds the set discrete voltage.
3. A multiphase power regulator as in claim 2 wherein the plurality of comparators comprises:
three comparators to detect three discrete voltage levels representing deviations from the target voltage.
4. A multiphase power regulator as in claim 1 wherein the target voltage is determined by adaptive voltage positioning.
5. A multiphase power regulator as in claim 1 , further comprising:
an adaptive voltage positioning circuit for setting the target voltage in accordance with a load line, said load line being pre-positioned.
6. A multiphase power regulator as in claim 2 , wherein the circuit for setting discrete voltage levels comprises:
a digital to analog converter; and
a voltage divider.
7. A multiphase power regulator as in claim 6 , wherein said digital to analog converter is configured to receive a digital input signal representing a desired deviation from the target voltage and said voltage divider comprises:
a plurality of series connected resistors.
8. A multiphase power regulator as in claim 7 , wherein said digital to analog converter is configured to receive a programmable digital input signal representing a desired deviation from the target voltage.
9. A multiphase power regulator as in claim 1 , further comprising:
a gating circuit having inputs connected to the output of said multiphase pulse width modulator and said active transient response circuit for blocking synchronous pulse width modulated pulses on all phases.
10. A multiphase power regulator as in claim 1 , wherein said pulse width modulator is configured to provide compensation pulses on at least one phase in addition to the synchronous phase output of the pulse width modulator.
11. A multiphase power regulator as in claim 10 , wherein said active transient response circuit comprises: a circuit for setting discrete voltage levels representing deviations from the target voltage and a plurality of comparators configured to provide an output when a sensed voltage exceeds the set discrete voltage, further comprising:
a gating circuit having a first input for receiving said output asynchronously and a second input for receiving a phase signal, said gating circuit providing a gated output during said received phase signal.
12. A multiphase power regulator as in claim 1 , further comprising;
an adaptive voltage positioning circuit (AVP) for determining the target voltage.
13. A multiphase power regulator as in claim 12 , wherein the adaptive voltage positioning circuit comprises:
a first circuit for receiving a signal indicative of an ATR event;
a second circuit for sensing the current at the output stage; and
an adaptive filter circuit coupled to the output of the first and second circuits, the bandwidth of the filter circuit being changed in response to a signal from the first circuit when a signal indicative of an ATR event is received.
14. A multiphase power regulator as in claim 13 , wherein the adaptive voltage regulator further comprises:
an output circuit for receiving the output of the filter circuit and the VID set point value to provide a digital output value that is the target voltage.
15. A multiphase power regulator as in claim 14 , wherein the adaptive voltage positioning circuit further comprises:
a pre-positioning circuit for receiving pre-determined current values for different level of ATRH events and providing such pre-determining current values to the filter circuit when a ATRH event is detected.
16. A multi-phase power regulator as in claim 1 , wherein a tri-state mode of operation results from turning off both the high side FET and the low side FET.
17. A multi-phase power regulator as in claim 1 , further comprising:
a Schottky diode coupled in parallel with said low side FET.