Power-On Reset Circuit With dV/dt-Independent Threshold Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power on reset (POR) circuits either consume high power due to constant current consumption or have ill-defined detection levels and are sensitive to power supply dV/dt.
Innovation Solution
A POR circuit that includes a power supply input, a capacitor, a resistor divider with tap points, a comparator with a voltage-dependent threshold, and a feedback loop of transistors to generate a stable reference signal and POR pulse during power supply ramp-up, independent of dV/dt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a POR circuit uses constant current consumption to ensure detection, then the detection reliability is improved, but the power consumption increases
Solution Approach 1:
The POR circuit uses periodic action by implementing detection only during the power-up ramp phase rather than continuous constant current consumption. The circuit activates detection functionality when needed (during voltage transitions) and remains inactive otherwise, achieving reliable detection without continuous power draw.
Solution Approach 2:
The circuit changes its operational parameters dynamically - using variable current consumption based on the power supply voltage state. During power-up, the circuit draws current to perform detection, but during normal operation, it consumes minimal or zero current, adapting its parameters to the system state.
2Device complexity
If a POR circuit uses simple voltage threshold detection, then the device complexity is reduced, but the detection precision becomes ill-defined and sensitive to dV/dt
Solution Approach 1:
The POR circuit implements feedback by monitoring the power supply voltage and using it to control the detection threshold and activation. The circuit feeds back the voltage state to adjust its detection behavior, ensuring precise detection levels that adapt to the actual power supply conditions rather than using fixed simple thresholds.
Solution Approach 2:
The circuit transitions from static simple threshold detection to dynamic detection where the threshold and activation conditions change based on the power supply voltage waveform. The detection mechanism becomes dynamic, responding to voltage transitions and state changes, which improves precision while maintaining reasonable complexity.
Data Source
AI summary
One example discloses a power on reset (POR) circuit, wherein a first circuit is configured to un-couple a power supply input from a resistor divider when the voltage on a second end of the capacitor is above a first circuit threshold; a second circuit configured to couple the second end of the capacitor to the power supply input when a voltage on at least one tap point of the resistor divider is above a second circuit threshold; wherein the comparator is coupled to at least one of the tap points, the reference potential, and a POR output; and wherein the comparator is configured to ramp-up a POR signal on the POR output when a voltage on the at least one of the tap points is greater than the comparator threshold.