SIMO DC-DC Converter Topology for Simple NMOS Bidirectional Blocking
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Solution Overview
Problem
Existing single-input, multi-output (SIMO) DC-to-DC converters face challenges in providing multiple power supply rails efficiently due to high costs, space consumption, and complex gate drive schemes, particularly when using enhancement mode NMOS FETs for bidirectional current blocking, which often require multiple power supply rails and bootstrap domains.
Innovation Solution
A SIMO DC-to-DC converter design that uses a single power supply rail for each output switching block, employing NMOS FETs oriented to facilitate robust and simple gate drive without body switching, enabling bidirectional current blocking and scalable operation across various voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If enhancement mode NMOS FETs are used for bidirectional current blocking in SIMO DC-to-DC converters, then device performance and voltage handling capability are improved, but gate drive complexity and body switching requirements increase
Solution Approach 1:
The patent segments the current blocking function by using two NMOS FETs in series (first and second switching devices) with opposite body diode orientations. Each FET handles one polarity of bidirectional current blocking independently, eliminating the need for complex body switching schemes while maintaining reliable bidirectional blocking capability.
Solution Approach 2:
The patent merges the gate drive schemes by connecting the gates of both NMOS FETs to a common gate drive node, allowing both devices to be controlled by a single power supply rail. This integration simplifies the overall gate drive architecture while maintaining effective control of both switching devices.
2Reliability
If multiple power supply rails are provided for each output switching block, then bidirectional current blocking is achieved, but converter cost and size increase
Solution Approach 1:
The patent makes a single power supply rail serve multiple functions by using it to drive the gates of both NMOS FETs in series. This universal power supply approach eliminates the need for separate power supply rails for each switching device, reducing overall converter size and component count while maintaining full bidirectional current blocking functionality.
Data Source
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AI summary
A single-input, multiple-output (SIMO) direct-current-to-direct-current (DC-to-DC) converter includes a (i) power conversion stage electrically coupled between an input power node and a switching node and (ii) a plurality of output switching blocks. Each output switching block is electrically coupled between the switching node and a respective output power node. Each output switching block includes a respective input N-type metal oxide semiconductor field effect transistor (input NMOS FET) and a respective output N-type metal oxide semiconductor field effect transistor (output NMOS FET). The input NMOS FET is oriented in each output switching block such that a cathode of a body diode of the input NMOS FET is electrically coupled to the switching node. The output NMOS FET is oriented in each output switching block such that a cathode of a body diode of the output NMOS FET is electrically coupled to the output power node of the output switching block.