Multi-Channel Light Source Power Supply Protection Circuit
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Solution Overview
Problem
Multiple channel power supplies face challenges in meeting UL1310 Class 2 standards when a single output channel faults, as the front end stage's power limit is set higher than 100 Watts, potentially leading to excessive power delivery, which is not addressed effectively by existing protection circuitry without increasing component count and efficiency costs.
Innovation Solution
A protection circuit is implemented between the front end and output stages, featuring a current sense circuit and controller to decouple the front end stage from voltage converter circuits if excessive current is detected, preventing excessive power delivery by disabling all output channels and reducing inefficiency through a bypass switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the front end stage power limit is set higher than 100 Watts to support multiple channel outputs, then the power supply can deliver adequate total power across channels, but a single faulty channel may deliver excessive power greater than 100 Watts violating UL1310 Class 2 standards
Solution Approach 1:
A current sense circuit is introduced as an intermediary between the front end stage and the output stage to monitor current on each channel. When excessive current is detected, the circuit activates a protection mechanism that decouples the front end stage from the faulty channel, preventing excessive power delivery while allowing the power supply to maintain high total power capability across multiple channels
Solution Approach 2:
The current sense circuit provides real-time feedback about current conditions on each output channel. This feedback enables the protection circuit to detect faulty conditions and activate appropriate protection measures, ensuring that a single channel fault cannot cause excessive power delivery while maintaining normal operation of other channels
2Reliability
If additional protection circuitry is added to each output channel to prevent excessive power delivery, then fault protection is improved, but component count and space requirements increase
Solution Approach 1:
The protection function is merged into a centralized current sense circuit that monitors all channels through a shared sensing mechanism. Instead of duplicating protection circuitry on each channel, the invention combines the sensing and protection logic into a single integrated circuit that can detect and respond to faults on any channel, reducing overall component count while maintaining comprehensive protection
Solution Approach 2:
The current sense circuit is designed as a universal protection mechanism that can detect and respond to faults on any output channel regardless of which specific channel is faulty. This multi-functional approach allows a single protection circuit to serve all channels, eliminating the need for channel-specific protection components
3Loss of energy
If a bypass switch is used to shunt current around the current sensor during normal operation, then efficiency is improved by reducing resistive losses, but the circuit complexity increases
Solution Approach 1:
The bypass switch is designed to dynamically change its state based on operating conditions. During normal operation, the bypass switch is closed to shunt current around the current sensor, minimizing resistive losses. When a fault is detected, the bypass switch opens to allow current sensing for protection. This dynamic switching optimizes efficiency during normal operation while maintaining protection capability when needed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides effective protection against excessive power delivery in multiple channel power supplies without additional circuitry on each channel, offering size, cost, and efficiency advantages while maintaining low power consumption during standby mode.
Implementation Method 1
a current sensor and a bypass switch coupled in parallel with the current sensor. When the bypass switch is in a non-conducting state, a voltage across the current sensor establishes a current sense output representative of current through at least one of the voltage converter circuits
Implementation Method 2
a bypass switch coupled in parallel with the current sensor, the bypass switch having a conducting state to shunt current around the current sensor
Implementation Method 3
the controller circuit provides an output to a protection switch for decoupling the output of the front end stage from the voltage converter circuits
Data Source
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AI summary
Multiple output channel light source power supply circuits (100), and methods for protecting, are provided. A front end circuit (102) receives an input voltage and provides a regulated front end DC voltage (FEDC). Voltage converter circuits (VCCs) (106-1,106-2,... 106-N) receive the FEDC and provide a separate associated DC output for each associated output channel. A protection switch (112) is coupled between. In its conducting state, the FEDC is coupled to the VCCs (106-1, 106-2,...106-N). In its nonconducting state, the FEDC is decoupled. A current sense circuit (116) of a current sensor in parallel with a bypass switch is coupled to the VCCs (106-1,106-2,... 106-N) to provide a current sense output representing current through at least one VCC (106-1, 106-2, ... 106-N). A controller circuit (114) places the protection switch (112) in the nonconducting state in response to the current sense output. The bypass switch may be placed in a conducting state to shunt current around the current sensor during normal operation to reduce or eliminate inefficiency.