Operational transconductance amplifier feedback mechanism for fixed feedback voltage regulators

摘要

An operational transconductance amplifier used in conjunction with a multiple chip voltage feedback technique allows multiple strings of LEDs and current sinks to be efficiently powered by a simple feedback oriented voltage regulator within an appliance. A connected series of differential amplifiers or multiplexors are used to monitor the voltages between the connected LEDs and the current sinks, in order to progressively determine the lowest voltage. The operational transconductance amplifier compares this voltage to a reference voltage and injects or removes current from the feedback node of a voltage regulator, thereby altering the voltage present at the feedback node. This causes the voltage regulator to adjust its output, ensuring that the current sinks of the LED strings have adequate voltage with which to function, even as the LEDs have different forward voltages and the strings are asynchronously enabled and disabled.

主权项

1. A voltage regulation circuit comprising:
a plurality of controllers connected in a series, the plurality of controllers including a first controller and a last controller, the first controller in the series being configured to provide a summary voltage equal to one of a first set of voltages monitored by the first controller, each respective controller other than the first controller being configured to provide a respective summary voltage equal to one of the respective summary voltage provided by a preceding controller in the series and one of a second set of voltages monitored by the respective controller; an amplifier having a first input coupled to the last controller in the series, a second input to receive a reference voltage, and an output, the amplifier being configured to generate an output current in proportion to a difference between the respective summary voltage provided by the last controller and the reference voltage; and a DC-to-DC voltage regulator having an input and an output, the input being coupled to the output of the amplifier, the voltage regulator providing a regulated output voltage based on the output current of the amplifier.