Regulator control integrated circuit having COT and valley current modes
A voltage regulator control integrated circuit includes constituent parts including an error amplifier circuit, a comparator circuit, a compensation signal generator circuit, an oscillator/one-shot circuit, a latch, and a current sense circuit. In a first example, the integrated circuit is operable in a first mode and in a second mode. In the first mode, the various parts are configured and interconnected in such a way that they operate together as a valley current mode regulator control circuit. In the second mode, the various parts are configured and interconnected in such a way that they operate together as a current-mode constant on-time mode regulator control circuit. In another example, a voltage regulator control integrated circuit has the same basic constituent parts and is operable in a first mode as a peak current mode regulator control circuit, or in a second mode as a constant off-time time mode regulator control circuit.
1. A voltage regulator control integrated circuit having a peak current mode and a constant off-time mode, the voltage regulator control integrated circuit comprising:
a sequential logic element having a set input lead, a reset input lead, and an output lead;
a comparator circuit that supplies a reset signal RESET to the sequential logic element;
a osc/one-shot circuit that supplies a set signal SET to the sequential logic element, wherein in the constant off-time mode the set signal SET is a delayed one-shot pulse signal, and in the peak current mode the set signal SET is a free-running oscillating signal;
a compensation signal generator circuit that supplies a compensation voltage signal V C to the comparator circuit, wherein in the constant off-time mode the compensation voltage signal V C is an AC ground signal, and in the peak current mode the compensation voltage signal V C is a ramp signal;
a current sense circuit that outputs a voltage signal V CURRENT indicative of a magnitude of a current, wherein the current sense circuit supplies the voltage signal V CURRENT to the comparator circuit; and
an error amplifier circuit that supplies an error voltage signal V E to the comparator circuit.
2. The voltage regulator control integrated circuit of claim 1 , further comprising:
a mode control integrated circuit terminal MODE, wherein a signal received on the mode control integrated circuit terminal MODE determines whether the voltage regulator control integrated circuit operates in the constant off-time mode or in the peak current mode.
3. The voltage regulator control integrated circuit of claim 1 , wherein the voltage regulator control integrated circuit is hardwired so that it only operates in one of the constant off-time mode and the peak current mode.
4. The voltage regulator control integrated circuit of claim 1 , wherein:
the comparator circuit generates an error and compensated error voltage signal V E-C by summing the error voltage signal V E and the compensation voltage signal V C ;
the comparator circuit comprises a comparator;
the error and compensated error voltage signal V E-C is supplied onto a first input lead of the comparator; and
the voltage signal V CURRENT is supplied onto a second input lead of the comparator.
5. The voltage regulator control integrated circuit of claim 1 , wherein the current is a current flowing on the integrated circuit.
6. The voltage regulator control integrated circuit of claim 5 , wherein the current sense circuit comprises a circuit element taken from the group consisting of: a current sense resistor, a current mirror transistor, and a matched RC network.
7. The voltage regulator control integrated circuit of claim 1 , wherein:
the error amplifier circuit comprises a reference voltage generator, a differential transconductance amplifier, and a compensation resistor;
the reference voltage generator is coupled to a first input lead of the differential transconductance amplifier; and
the compensation resistor is coupled to an output lead of the differential transconductance amplifier.
8. The voltage regulator control integrated circuit of claim 7 , further comprising:
a feedback integrated circuit terminal FB, wherein a second input lead of the differential transconductance amplifier is coupled to receive a feedback signal from the feedback integrated circuit terminal FB.
9. The voltage regulator control integrated circuit of claim 1 , wherein the compensation signal generator circuit is coupled to receive the free-running oscillating signal from the osc/one-shot circuit.
10. The voltage regulator control integrated circuit of claim 1 , wherein:
the compensation signal generator circuit comprises a ramp signal generator and a switch;
in the peak current mode the switch is switched to receive the ramp signal from the ramp signal generator and to output the ramp signal onto a switch output node; and
in the constant off-time mode the switch is switched to couple the switch output node to an AC ground node.
11. The voltage regulator control integrated circuit of claim 1 , wherein:
the osc/one-shot circuit comprises a one-shot circuit, an oscillator, and a switch;
in the peak current mode the switch is switched to receive the free-running oscillating signal from the oscillator and to output the free-running oscillating signal onto a switch output node; and
in the constant off-time mode the switch is switched to receive a delayed one-shot pulse signal from the one-shot circuit and to output the delayed one-shot pulse signal onto the switch output node.
12. The voltage regulator control integrated circuit of claim 1 , further comprising:
a high side switch HSS, wherein the high side switch HSS is operable to close and to supply a high side voltage onto a switching node SW; and
a low side switch LSS, wherein the low side switch LSS is operable to close and to supply a low side voltage onto the switching node SW.
13. The voltage regulator control integrated circuit of claim 12 , further comprising:
a switching output integrated circuit terminal SW, wherein the switching output integrated circuit terminal SW is a part of the switching node SW.
14. The voltage regulator control integrated circuit of claim 1 , further comprising:
a switching output integrated circuit terminal SW, wherein the sequential logic element outputs a switching output signal from the voltage regulator control integrated circuit via the switching output integrated circuit terminal SW.
15. An integrated circuit having a peak current mode and a constant off-time mode, the integrated circuit comprising:
an error amplifier circuit adapted to receive a feedback signal FB;
a compensation signal generator circuit adapted to output a compensation voltage signal V C , wherein the compensation voltage signal V C is one of a ramp signal and an AC ground signal;
a comparator circuit adapted to receive an error voltage signal V E from the error amplifier circuit, and adapted to receive the compensation voltage signal V C from the compensation signal generator circuit;
a osc/one-shot circuit adapted to output a set signal SET, wherein the set signal SET is one of a free-running oscillating signal and a delayed one-shot pulse signal; and
a sequential logic element adapted to receive a reset signal RESET from the comparator circuit and adapted to receive the set signal SET from the osc/one-shot circuit;
wherein:
the sequential logic element outputs a switch control signal SWC;
in the constant off-time mode the error amplifier circuit, the compensation signal generator circuit, the comparator circuit, the osc/one-shot circuit, and the sequential logic element are configured to operate together as a constant-off time mode regulator control circuit; and
in the peak current mode the error amplifier circuit, the compensation signal generator circuit, the comparator circuit, the osc/one-shot circuit, and the sequential logic element are configured to operate together as a peak current mode regulator control circuit.
16. The integrated circuit of claim 15 , further comprising:
a mode control integrated circuit terminal MODE, wherein a signal received on the mode control integrated circuit terminal MODE determines whether the integrated circuit operates in the constant off-time mode or in the peak current mode.
17. The integrated circuit of claim 15 , wherein the integrated circuit is hardwired so that it only operates in one of the constant off-time mode and the peak current mode.
18. The integrated circuit of claim 15 , wherein the set signal SET is the free-running oscillating signal if the integrated circuit is operating in the peak current mode, and the set signal SET is the delayed one-shot pulse signal if the integrated circuit is operating in the constant off-time mode.
19. The integrated circuit of claim 15 , wherein:
the integrated circuit is hardwired to operate in the constant off-time mode; and
a ramp signal generator of the compensation signal generator circuit is disabled.
20. The integrated circuit of claim 15 , wherein:
the integrated circuit is hardwired to operate in the peak current mode; and
a one-shot circuit of the osc/one-shot circuit is disabled.
21. A voltage regulator control circuit having a peak current mode and a constant off-time mode, the voltage regulator control circuit comprising:
a sequential logic element that has a set state and a reset state;
a comparator circuit that supplies a reset signal RESET to the sequential logic element;
a osc/one-shot circuit that supplies a set signal SET to the sequential logic element, wherein in the constant off-time mode the set signal SET is a delayed one-shot pulse signal, and in the peak current mode the set signal SET is a free-running oscillating signal;
a compensation signal generator circuit that supplies a compensation voltage signal V C to the comparator circuit, wherein in the constant off-time mode the compensation voltage signal V C is an AC ground signal, and in the peak current mode the compensation voltage signal V C is a ramp signal;
a current sense circuit that outputs a voltage signal V CURRENT indicative of a magnitude of a current, wherein the current sense circuit supplies the voltage signal V CURRENT to the comparator circuit; and
an error amplifier circuit that supplies an error voltage signal V E to the comparator circuit.