Low drop-out voltage regulator having split power device
AssigneeTexas Instruments Incorporated
InventorXiaoyu Xi
Life of this patent
Estimating the term…
Abstract
The present invention provides a low drop-out voltage regulator (200) that reduces gate capacitance and simplifies the compensation needed to maintain stability, without requiring additional and/or larger Miller capacitors (108), by splitting the output (220, 221) of the driver (112A) for different operational modes, selectively driving a small power device (206), a large power device (214) or both based on the mode.
Claims25
A low drop-out voltage regulator, comprising:
- an input error amplifier stage;
- a unity gain amplifier stage having a first output, a second output, a first input coupled to said input error amplifier stage and a second input coupled to said first output;
- a first power transistor having a gate coupled to said first output, said first power transistor also coupled to a node where voltage is to be regulated;
- a second power transistor having a gate coupled to said second output, said second power transistor also coupled to said node;
- and
- a compensating capacitor coupled between said node and said input error amplifier stage.
A low drop-out voltage regulator comprising:
- a supply voltage node;
- an output voltage node;
- a first power transistor having a source connected to the supply voltage node, a drain connected to the output voltage node and a gate;
- a second power transistor having a source connected to the supply voltage node, a drain connected to the output voltage node and a gate;
- a unity gain amplifier having a first output connected to the gate of the first power transistor, a second output connected to the gate of the second power transistor, an inverting input connected to the first output of the unity gain amplifier, and a non-inverting input;
- a variable gain amplifier having an output connected to the unity gain amplifier non-inverting input;
- a differential amplifier having an output connected to an input of the variable gain amplifier;
- a voltage divider network having a first node connected to the output voltage node, a second node connected to ground and a third node connected to an input of the differential amplifier, providing thereto a feedback voltage;
- and
- a compensation capacitor connected between said output voltage node and the differential amplifier output.
A low drop-out voltage regulator, comprising:
- an input error amplifier stage;
- a unity gain amplifier stage having a first output, a second output, a first input coupled to said input error amplifier stage, and a second input coupled to said first output;
- and
- a power circuit having first and second inputs respectively coupled to said first and second outputs, said power circuit having first and second outputs coupled to a node where voltage is to be regulated.
A method for maintaining the stability of a low drop-out voltage regulator, the method comprising:
- providing a current flow capability through the low drop-out voltage regulator to drive a load;
- and
- based on conditions at the load, selectively activating first and second power devices to pass current to the load.
Dependencies are inferred from the claim text.