Programmable shunt regulator
AssigneeCypress Semiconductor Corporation
InventorPavan Kumar Kuchipudi
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Abstract
A device and method that includes a shunt regulator of a universal serial bus (USB) compatible power supply device is disclosed. The shunt regulator includes an amplifier with an output, a first input, and a second input. The shunt regulator also includes a current digital-to-analog converter (DAC) that is coupled to the first input of the amplifier and a voltage bus node. The current DAC adjusts a sink or a source current delivered at the first input of the amplifier to regulate a programmable output voltage (Vbus) in the USB-compatible power supply device. The current delivered by the DAC is responsive to receipt of a digital code indicative of a programmable power supply command specifying the Vbus to be delivered by the USB-compatible power supply device on the voltage bus node.
Claims15
A device comprising:
- a shunt regulator of a universal serial bus (USB) compatible power supply device, the shunt regulator comprising:
- an amplifier comprising an output, a first input, and a second input;
- a first resistor comprising a first terminal and a second terminal, wherein the first terminal is coupled to the first input of the amplifier and the second terminal is to couple to a ground potential;
- a current digital-to-analog converter (DAC), coupled to the first input of the amplifier, the first terminal of the first resistor, and a voltage bus node, to adjust at least a sink current applied at the first input of the amplifier to control a programmable output voltage (Vbus) in the USB-compatible power supply device, wherein the sink current applied by the DAC is responsive to receipt of a digital code indicative of a programmable power supply command specifying the Vbus to be delivered by the USB-compatible power supply device on the voltage bus node;
- and
- a current generator comprising a resistor that is proportional to an input voltage of the current generator with respect to a current delivered to and from the current DAC, wherein the resistor is matched to a second resistor of a resistor network of the shunt regulator, wherein a bandgap voltage is shared between an input of the current generator and the second input of the amplifier, and wherein an output of the current generator is coupled to the current DAC.
A universal serial bus (USB) compatible power supply device, comprising:
- a controller to receive a programmable power supply command specifying a programmable output voltage (Vbus) to be delivered by the USB-compatible power supply device;
- and
- a shunt regulator coupled to the controller, the shunt regulator comprising:
- an amplifier comprising an output, a first input, and a second input;
- a first resistor comprising a first terminal and a second terminal, wherein the first terminal is coupled to the first input of the amplifier and the second terminal is to couple to a ground potential;
- a current digital-to-analog converter (DAC) comprising an input and an output, wherein the output of the current DAC is coupled to the first input of the amplifier, the first terminal of the first resistor, and a voltage bus node, wherein the input of the current DAC is coupled to the controller, wherein the current DAC to adjust at least a sink current delivered at the first input of the amplifier from the output of the current DAC to control the Vbus in the USB-compatible power supply device, wherein the sink current delivered by the DAC is responsive to receipt of a digital code from the controller indicative of the programmable power supply command specifying the Vbus to be delivered by the USB-compatible power supply device, wherein the programmable output voltage is programmable in a plurality of predefined increments within a voltage range;
- and
- a current generator comprising a resistor that is proportional to an input voltage of the current generator with respect to a current delivered to and from the current DAC, wherein the resistor is matched to a second resistor of a resistor network of the shunt regulator, wherein a bandgap voltage is shared between an input of the current generator and the second input of the amplifier, and wherein an output of the current generator is coupled to the current DAC.
A method comprising:
- receiving, by a current digital-to-analog converter (DAC) of a shunt regulator, a first digital code indicative of a first programmable power supply command specifying a first programmable output voltage (Vbus) to be delivered to a voltage bus of USB-compatible device;
- and
- responsive to receiving the first digital code, adjusting, by the current DAC, a sink current delivered to a feedback node to adjust an output voltage to the first Vbus for dynamic programmability, wherein the feedback node is coupled to a first input of an amplifier of the shunt regulator, wherein the first programmable output voltage is programmable from 3 volts to 22 volts within 2% tolerance in increments of 20 millivolts (mV).
Dependencies are inferred from the claim text.