Method and Apparatus for DC-DC Converter with Boost/Low Dropout (LDO) Mode Control

A low dropout device with improved linear mode operation, the device comprising:

• an error amplifier;
• a programmable attenuation factor circuit coupled to said error amplifier;
• a feedback network whose input is electrically connected to said programmable attenuation factor circuit and whose output is electrically coupled to the negative input of said error amplifier;
• a high side (HS) pre-drive circuit whose input is a high impedance (HiZ) mode signal;
• a low side (LS) pre-drive circuit whose input is a low pull-down input mode signal;
• a high side (HS) output stage element which is an n-channel MOSFET device electrically coupled to said high side (HS) pre-drive circuit;
• a low side (LS) output stage element which is an n-channel MOSFET device electrically coupled to said low side (LS) pre-drive circuit;
• and
• a high side sense (HSENSE) output stage element which is an n-channel MOSFET device whose gate is electrically coupled to said high side (HS) pre-drive circuit, and whose gate is electrically connected to the output of said error amplifier.

A low dropout (LDO) device comprising:

• an error amplifier;
• a programmable attenuation factor circuit coupled to said error amplifier;
• a feedback network whose input is electrically connected to said programmable attenuation factor circuit and whose output is electrically coupled to the negative input of said error amplifier;
• a low side (LS) MOSFET element whose input is said error amplifier;
• a high side (HSENSE) MOSFET element whose gate is electrically coupled to said low side (LS) MOSFET;
• a high side (HS) element which is a MOSFET device whose gate and well are electrically coupled to said high side (HSENSE) device.

A low dropout (LDO) device comprising:

• an error amplifier;
• a programmable attenuation factor circuit coupled to said error amplifier;
• a feedback network whose input is electrically connected to said programmable attenuation factor circuit and whose output is electrically coupled to the negative input of said error amplifier;
• a first low side (LS) MOSFET element whose input is said error amplifier;
• a second low side (LS) MOSFET element whose gate is electrically connected to said first low side (LS) MOSFET;
• a current mirror network electrically coupled to the drain of said first low side (LS) MOSFET element and to the drain of said second low side (LS) MOSFET element;
• a high side (HSENSE) MOSFET element whose gate is electrically coupled to said first low side (LS) MOSFET and whose drain is electrically coupled to said current mirror network;
• and,
• a high side (HS) element which is a MOSFET device whose gate and well are electrically coupled to said high side (HSENSE) device and whose well and drain are electrically coupled to said current mirror.

A method of improved linear mode in a low dropout circuit comprising of the following steps:

• providing a low dropout (LDO) regulator comprising a low side (LS) pre-driver circuit, a low side (LS) output driver circuit, a high side (HS) pre-driver circuit, a high side (HS) output driver circuit, and a feedback loop error amplifier;
• providing a high side sense (HSENSE) circuit;
• matching said high side (HS) output driver circuit design layout and said high side sense (HSENSE) circuit design layout;
• feeding the output signal to said feedback loop error amplifier;
• feeding said feedback loop error amplifier output signal to said a high side sense (HSENSE) circuit;
• and,
• regulating the output voltage in linear mode.