DC-DC Converter High Side Switching Device for LDO Mode Control
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Solution Overview
Problem
Conventional low dropout (LDO) regulators require additional silicon area and extra circuitry for linear mode operation, leading to unwanted conduction during switching modes, and necessitate an extra power device for boost and LDO mode functionality.
Innovation Solution
The proposed solution involves using a high side switching device as the main driver in linear mode, eliminating the need for an additional power device and simplifying the circuit by incorporating an active device matched with the main active device of the boost type DC-to-DC regulator, including an error amplifier, programmable attenuation factor circuit, and a high side sense output stage element to regulate the output voltage in linear mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an extra power device is added for LDO linear mode operation, then linear mode functionality is achieved, but silicon area and device complexity increase
Solution Approach 1:
The high side switching device is designed to perform dual functions: serving as the main power switch during boost mode operation and as the linear mode driver during LDO operation. This eliminates the need for a separate power device, reducing silicon area while maintaining both boost and LDO functionality.
Solution Approach 2:
The patent merges the functions of the high side switching device into a single structure that can operate in both switching mode (for boost conversion) and linear mode (for LDO regulation). The device structure and control circuitry are integrated to allow seamless transition between modes without requiring additional power devices.
2Adaptability or versatility
If extra circuitry is added for LDO operation, then linear mode control is achieved, but unwanted conduction during switching modes occurs
Solution Approach 1:
The control circuitry dynamically adjusts its operation based on the working mode. During boost mode, the controller enables the high side switching device for switching operation while disabling linear mode control paths. During LDO mode, it switches to linear control. This dynamic reconfiguration prevents unwanted conduction by ensuring only the appropriate control path is active at any given time.
Solution Approach 2:
The system employs mode detection feedback mechanisms that monitor operating conditions and automatically switch between boost mode and LDO mode control schemes. This feedback ensures that the high side device is properly controlled in each mode, preventing unwanted conduction by activating the correct control logic based on real-time operating state.
3Area of stationary object
If the high side switching device is used as main driver in linear mode, then silicon area is reduced, but device matching characteristics must be optimized
Solution Approach 1:
The patent implements local quality optimization by carefully designing the high side switching device with specific structural characteristics that enhance matching. The device geometry, doping profiles, and layout are locally optimized to ensure consistent electrical characteristics across process variations, enabling reliable linear mode operation when the device serves dual purposes.
Data Source
AI summary
A low dropout (LDO) device with improved linear mode 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 electrically coupled to said high side (HS) pre-drive circuit, a low side (LS) output stage element electrically coupled to said low side (LS) pre-drive circuit, and a high side sense (HSENSE) output stage element whose gate is electrically coupled to said high side (HS) pre-drive circuit, and whose gate and source are electrically connected to the output of said error amplifier.