Fan Detection Chip Using Current Sensing for Noise-Free Type Identification
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Solution Overview
Problem
Conventional fan detection methods require transmitting a PWM control signal to rotate the fan and using a tachometer to determine the type of fan, resulting in noise and inefficiency.
Innovation Solution
A fan detection chip with a power supply module, PWM signal generating module, current sensing module, and control module that differentiates between DC and PWM fans by sensing currents generated by distinct PWM signals, allowing for accurate fan type determination without noise and complex hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fan detection methods use PWM control signal and tachometer to detect fan type, then fan type can be determined, but noise is generated and detection efficiency is reduced
Solution Approach 1:
The patent extracts the tachometer component from the detection system and replaces it with a current sensing module. By taking out the noise-generating tachometer and using only current sensing to detect fan type, the solution eliminates noise while maintaining detection accuracy. The current sensing module detects current characteristics during PWM signal transmission to determine whether the fan is DC or PWM type without requiring mechanical tachometer feedback.
Solution Approach 2:
The patent replaces the mechanical tachometer system with an electrical current sensing system. Instead of using mechanical rotation detection, the invention uses electrical current characteristics to infer fan type. This substitution eliminates mechanical noise and improves detection efficiency by using electrical field interactions rather than mechanical feedback.
2Measurement precision
If conventional fan detection methods transmit PWM control signal first to rotate fan, then detect revolving speed, then detection time is extended and efficiency is reduced
Solution Approach 1:
The patent applies preliminary action by transmitting the PWM detection signal before attempting to measure fan speed. This allows the system to detect current characteristics that indicate fan type during the signal transmission phase itself, rather than waiting for the fan to rotate and then measuring speed. The current sensing occurs during the PWM signal application, enabling parallel detection of both signal compatibility and fan type.
Solution Approach 2:
The patent uses partial action by applying PWM signals at a fixed duty cycle (50%) specifically for detection purposes, rather than using the full range of PWM control. This partial PWM application is sufficient to elicit detectable current responses that reveal fan type, without requiring full fan rotation or complex speed measurement sequences. The excessive PWM signal strength ensures reliable current detection regardless of fan state.
3Device complexity
If conventional fan detection methods use tachometer to detect revolving speed, then device complexity is reduced, but noise is generated
Solution Approach 1:
The patent makes the power supply module multi-functional by having it serve both as the power source for the fan and as the signal transmission medium for detection. The same power supply circuit that drives the fan also carries the PWM detection signals, and the current sensing module uses the existing power supply current path to detect fan type. This eliminates the need for separate tachometer hardware while maintaining detection capability, reducing overall device complexity.
Solution Approach 2:
The patent merges the power supply function and detection signal transmission function into a single integrated system. Instead of having separate power supply and tachometer circuits, the invention combines these functions by using the power supply current path for both powering the fan and carrying detection signals. The current sensing module monitors the same power lines that supply the fan, merging multiple functions into unified hardware that reduces complexity and eliminates noise.
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
Enables quick, noise-free, and efficient fan type detection, allowing for correct control of fan speed through either PWM or voltage signals, supporting plug-and-play functionality and reducing detection and setup procedures.
Implementation Method 1
The current sensing module is disposed between the power supply module and the first pin, and configured to sense, in the fan type detection mode, a first current flowing from the power supply module
Data Source
AI summary
A fan detection chip, a fan detection method and a fan detection system are disclosed. In the fan detection system, a fan includes a power terminal and a speed signal terminal, and optionally includes a PWM signal terminal; a power supply module provides a driving voltage to the fan, a PWM signal generating module provides a first PWM signal and a second PWM signal which respectively have different duty cycles, a current sensing module respectively senses a first current and a second current flowing from the power supply module, and a control module compares the first current and the second current. The control module determines the fan to be a PWM fan when the first current is different from the second current, and the control module determines the fan to be a DC fan when the first current is the same as the second current.