US 9,871,446 B2Granted

Current mode control regulator with load resistor emulation

AssigneeIntersil Americas Inc.

InventorsM. Jason Houston, Eric M. Solie

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Abstract

A current mode control regulator including a control circuit and a current generator. The control circuit regulates an output voltage based on a reference voltage using current mode control. The current generator applies an adjust current to a feedback current signal, in which the adjust current is proportional to a difference between a voltage indicative of the output voltage and the reference voltage to emulate an AC load resistance at an output of the current mode regulator. A load resistor emulator emulates an AC load resistor to increase the phase margin of current mode control regulator when operating without a battery coupled to the output, such as when the battery is physically removed or otherwise electrically disconnected. Operation is not substantially changed when the battery is connected, so that the desired phase margin is achieve with or without the battery.

Claims9

Dependent claims

An electronic device comprising a regulator that provides a regulated output voltage to a load, wherein said regulator comprises:

a converter that uses a pulse-width modulation signal to switch voltage applied to an output inductor to convert an input voltage to the regulated output voltage;
a current detector that provides a current sense signal indicative of current through said output inductor;
an error amplifier that receives a voltage indicative of the regulated output voltage, that receives a reference voltage indicative of a target level of the regulated output voltage, and that provides a control signal;
a comparator circuit that uses said control signal and said current sense signal to develop said pulse-width modulation signal;
and
a load emulator that adjusts said current sense signal based on a difference between said voltage indicative of the regulated output voltage and said reference voltage,
wherein said current detector comprises:
a ramp capacitor coupled to a ramp node developing a ramp voltage;
a first current generator that applies a current proportional to the regulated output voltage to said ramp node;
a switch having a first switch terminal coupled to said ramp node, having a second switch terminal, and having a control terminal receiving said pulse-width modulation signal;
and
a second current generator that applies a current proportional said input voltage to said second switch terminal of said switch,
and wherein said load emulator comprises a transconductance amplifier having a first input receiving said reference voltage, having a second input receiving said voltage indicative of the regulated output voltage, and having an output that applies an adjust current to said ramp node.

10 more elements

A method of regulating an output voltage, comprising:

converting an input voltage to the output voltage using a pulse-width modulation signal to switch voltage applied to an output inductor;
detecting a current through the output inductor and providing a current sense signal;
providing a control signal indicative of a difference between a target level of the output voltage and a voltage indicative of the output voltage;
comparing the control signal with the current sense signal to develop a compare signal and using the compare signal to develop the pulse-width modulation signal;
and adjusting the current sense signal based on a difference between the voltage indicative of the output voltage and the reference voltage, wherein said detecting a current through the output inductor comprises developing a ramp voltage on a ramp node that simulates current through the output inductor, and wherein said adjusting comprises converting the difference between the reference voltage and the voltage indicative of the output voltage to an adjust current and applying the adjust current to the ramp node, wherein said developing a ramp voltage that simulates current through the output inductor comprises:
discharging a ramp capacitor coupled to the ramp node with a current that is proportional to the output voltage;
and charging the ramp capacitor with a current that is proportional to the input voltage only when the pulse-width modulation signal is in an active state.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/062,387Filed 7 Mar 2016 · us provisional application
Priority: 1 Jun 2015
Published: US 2016/0352227 A11 Dec 2016
Granted: 16 Jan 2018
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

H02M 3/158
With automatic control of output voltage or current, e.g. switching regulators: including plural semiconductor devices as final control devices…
G06F 1/26
Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00: power supply means, e.g. regulation thereof
H02M 1/08
Details of apparatus for conversion: circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in…
H02J 7/02
Circuit arrangements for charging or discharging batteries or for supplying loads from batteries: for charging batteries from AC mains by converters