Level Detection Circuit With Over-Voltage Tolerant Threshold Biasing
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Solution Overview
Problem
Detection circuits in mobile electronic devices consume significant power and are susceptible to over-voltages when detecting accessory devices, which can reduce the device's usable interval between charging and require expensive high-voltage components to accommodate diverse accessories.
Innovation Solution
A detection circuit using a voltage divider, transistors, and a bias circuit to set a threshold, allowing the circuit to detect accessory devices without high voltage components, consuming minimal power when not in use and tolerating voltages up to four times the gate oxide rating, with adjustable setpoint resistance for non-linear threshold adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a detection circuit is implemented to detect accessory devices, then accessory detection capability is improved, but power consumption increases significantly
Solution Approach 1:
The detection circuit operates periodically rather than continuously. The transistor switches between active detection mode and sleep mode, enabling accessory detection only when needed while minimizing power consumption during idle periods.
Solution Approach 2:
The circuit uses the accessory device's own voltage to power the detection process. When an accessory is connected, its voltage supplies the detection circuit, eliminating the need for separate power consumption from the mobile device battery.
2Reliability
If high-voltage components are used to tolerate over-voltages, then over-voltage tolerance is improved, but device complexity and cost increase
Solution Approach 1:
The circuit changes the operating parameters of standard transistors by using them in a specific configuration with carefully selected resistors. This allows standard low-voltage transistors to tolerate over-voltages up to four times their gate oxide rating without requiring special high-voltage components.
Solution Approach 2:
Resistors are introduced as intermediary elements to divide and control the voltage distribution across the transistor. The voltage divider configuration with resistors R1 and R2 mediates the high voltage input, protecting the transistor while enabling over-voltage tolerance.
3Speed
If the detection circuit remains active to enable immediate detection, then detection speed is improved, but power consumption increases
Solution Approach 1:
The circuit performs preliminary preparation by keeping the transistor in a ready state with minimal power consumption. When an accessory is connected, the detection can proceed quickly because the circuit is pre-configured and only requires a small trigger to become fully active.
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 efficient detection of accessory devices with minimal power consumption and over-voltage tolerance, extending the device's usable interval and reducing component costs by avoiding the need for high-voltage components.
Implementation Method 1
a voltage divider configured to receive a first supply voltage from an external device coupled to the detection circuit
Implementation Method 2
first and second transistors configured to receive a control voltage from the voltage divider and to couple an output to ground when the control voltage exceeds a first threshold
Implementation Method 3
a bias circuit configured to bias the first transistor to set the first threshold
Data Source
AI summary
This document discusses, among other things, apparatus and methods for a detection circuit. In an example, the detection circuit can include a voltage divider configured to receive a first supply voltage from an external device coupled to the detection circuit, first and second transistors configured to receive a control voltage from the voltage divider and to couple an output to ground when the control voltage exceeds a first threshold, and a bias circuit configured to bias the first transistor to set the first threshold.