Voltage regulators with improved wake-up response

A voltage regulation system, comprising:

• a regulator section, including:
• a power transistor connected between a supply level and an output of the voltage regulation system;
• a feedback path to receive feedback from the output of the voltage regulation system;
• an operational amplifier having first and second inputs and having an output connected to the gate of the power transistor, where the first input of the operational amplifier is connected to a reference level;
• and
• switching circuitry, whereby the second input of the operational amplifier is selectively connectable to either receive feedback from the feedback path or ground;
• and
• detection circuitry connected to the switching circuitry and to receive the output of the operational amplifier and an enable signal, whereby the second input of the operational amplifier is connected to ground when the enable signal is asserted and the voltage level on the output of the operational amplifier is above a first regulation level and is otherwise connected to receive the feedback,
• whereby when the second input of the operational amplifier is connected to ground, the full current level though the operational amplifier is discharging the output of the operational amplifier.

A method of resetting a voltage regulation circuit, the voltage regulation circuit including a power transistor connected between a supply level and the output node of the voltage regulation circuit, and an operational amplifier having first and second inputs and having an output connected to the gate of the power transistor, where the first input of the operational amplifier is connected to a reference level and wherein the voltage regulation circuit is part of a system including detection circuitry comprising:

• a first, p-type transistor connected between the supply level and an intermediate node, having a node connected to the output of the operational amplifier;
• and a second, n-type transistor connected between the intermediate node and ground, having a gate connected to receive an enable signal, wherein the second input of the operation amplifier is set based upon the level on the intermediate node, the method comprising:
• setting the output of the operational amplifier to the supply level;
• subsequently setting the second input of the operational amplifier to ground;
• while the second input of the operational amplifier is connected to ground, determining when the output voltage of the operational amplifier falls below a regulation level;
• and
• in response to the output voltage of the operation falling below the first regulation level, connecting the second input of the operation amplifier to receive feedback from the output of the voltage regulation circuit.

A method of operating a voltage regulation circuit forming a component of an integrated circuit, the voltage regulation circuit connected between a supply voltage and ground and connected to receive a reference voltage and generate therefrom a regulated output voltage at an output node, the method comprising:

• receiving a chip enable signal at the integrated circuit;
• in response to the chip enable signal being asserted, determining whether the voltage regulation circuit is active;
• in response to determining that the voltage regulation circuit is not active, activating the voltage regulation circuit;
• subsequently to the enable signal being asserted, receiving at the integrated circuit a command to perform an operation using the regulated output voltage;
• determining whether the command is received within a first interval after activating the voltage regulation circuit;
• and
• in response to the command being received within the first interval, shorting the output node to the supply voltage,
• wherein determining whether the voltage regulation circuit is active comprises determining whether, prior to chip enable signal being enabled, the chip enable signal had been de-asserted for a period greater than a second interval.