Multi-Phase COT Buck Controller with Ripple Injection Interleaving
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Solution Overview
Problem
Existing multiphase and parallelable constant on-time (COT) step-down switching regulators face challenges in achieving precise phasing and interleaving, particularly with variable frequency and duty cycles greater than 50%, limiting their ability to efficiently deliver high output currents and manage thermal performance.
Innovation Solution
A daisy chain ring configuration using memory bits and constant TON generators, with external calibrated ripple injection, allows sequential TON request sensing and delivery across phases, enabling precise interleaving and parallel operation independent of input voltage, output voltage, or duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional multiphase regulators use fixed frequency control with master-slave architecture to achieve precise phasing, then phasing precision is improved, but device complexity and inability to scale to more phases worsen
Solution Approach 1:
The system segments the phasing control function by giving each phase its own independent constant on-time generator and phase detector, eliminating the need for a complex master-slave architecture. Each phase operates autonomously while maintaining synchronization through the shared ripple signal on the FBS node.
Solution Approach 2:
The FBS node serves multiple functions: it is the feedback node for voltage regulation, the ripple injection point for phase synchronization, and the common reference for all phase detectors. This multi-functionality eliminates the need for separate synchronization circuits in each phase.
2Measurement precision
If ripple injection is used to achieve phase synchronization in COT controllers, then phase interleaving is improved, but duty cycle limitation to less than 50% worsens
Solution Approach 1:
The system uses dynamic sampling of the ripple signal at the FBS node, where each phase detector captures the ripple at its specific phase offset. This dynamic approach allows the system to maintain synchronization across the full duty cycle range by continuously adapting to the instantaneous ripple waveform regardless of duty cycle magnitude.
3Speed
If each phase operates independently with variable TON in COT control, then transient response is improved, but phase interleaving precision worsens
Solution Approach 1:
Each phase incorporates a phase detector that continuously monitors the ripple signal at the FBS node and adjusts its switching timing based on the detected phase error. This feedback mechanism ensures that even with variable TON for transient response, each phase maintains its precise interleaved positioning relative to the others.
Data Source
AI summary
A multiple-phase parallelable constant on time (COT) buck controller, a first phase containing a first memory bit and a second phase containing a second memory bit. The COT buck controller includes a first converter comprising a first constant TON generator configured to sense and deliver a first TON request when the first memory bit is in a logic one state, and a second converter connected in parallel with the first converter, the second converter comprising a second constant TON generator configured to sense and deliver a second TON request when the second memory bit is in the logic one state, only one of the first memory bit and the second memory bit being in the logic one state thus generating activity in a daisy chain ring where each of the first converter and the second converter senses and delivers a corresponding TON request in a sequential manner.