Multi-Phase DC-DC PWM Sequencing for Latch-Up Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Latch-up conditions in multi-phase DC-DC converters can occur due to parasitic structures interacting, leading to high currents that disrupt normal operation and cause damage, particularly when transitioning from a high-impedance state to an active state in the power stage circuitry.
Innovation Solution
Incorporation of a latch-up pre-detection circuit that monitors PWM signals and overrides the control sequence to briefly pulse the low-side transistor ON when a transition from high-impedance to active state is detected, redirecting residual current through the transistor channel to prevent the formation of a low impedance path and reduce the likelihood of latch-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the high-side transistor is enabled directly from high-impedance state, then the power stage responds quickly to control signals, but latch-up may occur due to parasitic structure interactions
Solution Approach 1:
The low-side transistor is pulsed ON briefly before the high-side transistor is enabled, preparing the current path in advance. This preliminary action ensures that when the high-side transistor switches on, current flows through the controlled low-side path rather than creating unintended parasitic paths that could cause latch-up.
Solution Approach 2:
The latch-up pre-detection circuit detects the high-impedance to active state transition and preemptively activates the low-side transistor to counteract the potential latch-up condition before it can occur. This anti-action prevents the harmful parasitic structure interactions by establishing a safe current path beforehand.
2Reliability
If a latch-up pre-detection circuit is added to monitor PWM signals and prevent latch-up, then reliability improves, but device complexity increases
Solution Approach 1:
The latch-up pre-detection circuit is integrated into the existing PWM control path, allowing the same monitoring infrastructure to serve both normal control operations and latch-up detection. The circuit leverages existing PWM signal paths and transistor control mechanisms, adding latch-up prevention functionality without requiring entirely separate control systems.
Solution Approach 2:
The latch-up pre-detection circuit acts as an intermediary between the PWM controller and the power stage transistors. It monitors the control signals and intervenes by adjusting transistor switching sequences when latch-up conditions are detected, providing a simple mediation layer that adds protection without fundamentally redesigning the power stage.
3Reliability
If the low-side transistor is pulsed ON to redirect current and prevent latch-up, then latch-up risk reduces, but switching losses increase due to additional transitions
Solution Approach 1:
The low-side transistor is pulsed ON for only the minimum duration necessary to establish the safe current path, rather than remaining ON continuously. This partial action provides just enough protection against latch-up while minimizing the time during which additional switching losses occur, balancing reliability improvement with energy efficiency.
Data Source
AI summary
The techniques and circuits, described herein, include solutions for latch-up prevention in multi-phase direct current (DC) to DC converters by ensuring safe pulse width modulation (PWM) control sequencing. In some aspects a latch-up pre-detection circuit has first and second detection inputs configured to receive high-side and low-side PWM signals respectively. The latch-up pre-detection circuit is configured to monitor for a transition from a first state to a second state based on the first and second detection inputs. The transition from the first state to the second state may be associated with condition(s) favorable for latch-up. Upon detecting the transition from the first state to the second state, the latch-up pre-detection circuit can output a pulse signal to temporarily override the unsafe PWM control sequence and reduce the possibility of latch-up.