DC-DC Digital Controller Timing for Lower Inductor Peak Current
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Solution Overview
Problem
DC-DC converters face inefficiencies due to the rise in inductor current during supply awareness measurements, which are currently performed at the beginning of the inductor charging phase, leading to higher power consumption and material costs.
Innovation Solution
Decouple the supply awareness measurement from the inductor charging phase by triggering it at regular intervals and using lookup tables to determine charging cycles based on latched measurement values, independent of the charging operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If supply awareness measurement is performed at the beginning of the inductor charging phase, then the measurement can be completed before charging starts, but the inductor current rises during the measurement time causing higher power consumption
Solution Approach 1:
The supply awareness measurement is triggered at regular intervals independent of the charging phase, allowing the measurement to be completed beforehand. The measurement result is latched and stored, so when charging is needed, the controller can immediately read the latched value without waiting for measurement completion, eliminating the delay and reducing power consumption during charging.
Solution Approach 2:
The measurement and charging operations are decoupled into separate independent processes. The measurement operates on its own timing schedule while charging operates independently, allowing them to proceed without interfering with each other. This segmentation eliminates the harmful interaction where measurement timing affects charging efficiency.
2Productivity
If supply awareness measurement is performed during the inductor charging phase, then the measurement time affects the charging duration, but decoupling them requires additional lookup tables and control logic
Solution Approach 1:
The measurement results are latched and stored in advance in memory structures. When charging is initiated, the controller simply reads the pre-st latched measurement value and uses it to determine charging parameters, eliminating the need for complex real-time measurement-charging coordination logic.
Solution Approach 2:
Lookup tables serve as intermediaries between the latched measurement values and the charging control decisions. The tables map measurement results to appropriate charging durations and parameters, simplifying the controller logic while maintaining optimal charging efficiency based on supply voltage conditions.
3Reliability
If the inductor charging phase waits for supply awareness measurement to complete, then accurate voltage information is available for charging control, but the charging time increases leading to higher active power consumption
Solution Approach 1:
Supply voltage measurements are performed and latched in advance at regular intervals, so when charging is needed, the controller already has accurate voltage information available immediately. This eliminates waiting time during charging while maintaining reliable voltage-based control decisions through the use of pre-captured measurement data.
Data Source
AI summary
In an example, a voltage converter includes a pulse generator. The voltage converter also includes a high-side transistor having a gate coupled to the pulse generator, a source coupled to a first voltage terminal, and a drain coupled to an output node. The voltage converter includes a low-side transistor having a gate coupled to the pulse generator, a source coupled to a second voltage terminal, and a drain coupled to the output node. The voltage converter includes a charge lookup table coupled to the pulse generator, where the charge lookup table is configured to provide a charge duration. The voltage converter includes a discharge lookup table coupled to the pulse generator, where the discharge lookup table is configured to provide a discharge duration. The voltage converter also includes a latch coupled to the charge lookup table, where the latch is configured to store an indication of a supply voltage.