Method and apparatus for low standby current switching regulator

A method capable of operating a controller of a switching regulator which regulates an output voltage, said method comprising:

• receiving a sense signal indicative of the output voltage;
• enabling a switching regulator when operating in a normal mode and a dual mode and enabling a low dropout regulator when operating in the dual mode and in an LDO only mode;
• developing, by the switching regulator when enabled, a pulse control signal for regulating the output voltage;
• controlling, by the low dropout regulator when enabled, a power device for regulating the output voltage;
• sensing output current of the low dropout regulator when the low dropout regulator is enabled and providing a current sense signal indicative thereof;
• detecting a load condition based on the pulse control signal and the current sense signal, wherein said detecting a load condition comprises detecting at least one skipped pulse on the pulse control signal and providing a low load indication;
• and
• switching modes of operation between the normal, the dual, and the LDO only modes of operation based on the detected load condition, wherein said switching modes of operation comprises switching from the normal mode to one of the dual mode and the LDO only mode when the low load indication is provided during the normal mode.

An electronic device, comprising:

• device circuitry receiving a supply voltage;
• and
• a voltage regulator providing said supply voltage, comprising:
• a switching circuit which converts an input voltage to said supply voltage based on a pulse control signal;
• a switching regulator which receives a voltage sense signal indicative of a level of said supply voltage and which develops said pulse control signal to regulate said supply voltage to a first voltage level when enabled;
• a low dropout regulator which receives said voltage sense signal and which operates to regulate said supply voltage to a second voltage level when enabled, wherein said second voltage level is greater than said first voltage level;
• wherein said low dropout regulator includes a current limiter which limits said output current of said low dropout regulator to a first current level when said switching regulator and said low dropout regulator are both enabled, and which limits said output current of said low dropout regulator to a second current level which is greater than said first current level when said switching regulator is disabled and said low dropout regulator is enabled;
• a current sensor which senses output current of said low dropout regulator and which provides a current sense signal indicative thereof;
• and
• a mode controller which receives said pulse control signal and said current sense signal and which enables and disables said switching regulator and said low dropout regulator based on said pulse control signal and said current sense signal.