Voltage Converting LED Circuit with Switched Capacitor Network
AssigneeAdvanced Analogic Technologies, Inc.
InventorsBruno Ferrario, Yun Tung Sien
Life of this patent
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Abstract
A Voltage Converting LED Circuit with Switched Capacitor Network contains a 2-way MOSFET switch that connects a capacitor network to the output of an error amplifier, thereby enabling the error amplifier to resume operation quickly after the off-time segment of a PWM cycle. The switch is controlled synchronously with current sinks controlling brightness and color levels. In a preferred embodiment, multiple serially connected strings of LED's can be controlled simultaneously via one switch.
Claims14
A circuit that comprises:
- a DC-to-DC voltage converter that comprises an inductor, wherein the DC-to-DC voltage converter is said to be in an active state while it supplies a variable output voltage to the monitored sub-circuits, and is said to be in an inactive state otherwise;
- an operational amplifier that comprises an input coupled to a voltage reference, one or more inputs configured to be representative of voltages within the monitored sub-circuits, and an output;
- a current mode PWM loop sub-circuit configured to control the DC-to-DC voltage converter based on the output of the operational amplifier and one or more measurements taken from within the DC-to-DC voltage converter;
- a compensation RC network that comprises a resistor and a capacitor;
- a transmission gate that is configured to allow a connection between the compensation RC network and the output of the operational amplifier when the DC-to-DC voltage converter is in the active state, and to prevent a connection between the compensation RC network and the output of the operational amplifier when the DC-to-DC voltage converter is in the inactive state.
A method of regulating the output voltage of a DC-to-DC voltage converter that comprises an inductor, the method comprising:
- monitoring one or more voltages within one or more monitored sub-circuits, each monitored sub-circuit connected to the output of the DC-to-DC converter;
- using an operational amplifier to amplify the difference between a reference voltage and one or more voltages that are representative of the monitored voltages;
- regulating the output voltage of the DC-to-DC converter in response to the output of the operational amplifier;
- connecting the output of the operational amplifier to a network that comprises a resistor and a capacitor when the DC-to-DC converter is supplying a variable output voltage to the monitored sub-circuits, and preventing said connection otherwise.
Dependencies are inferred from the claim text.