Supply Voltage Level Detector Circuit for Latch-Up Prevention
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Solution Overview
Problem
Conventional supply voltage level detector circuits in semiconductor integrated circuits (ICs) face variations in trigger voltage due to temperature changes and semiconductor processing, leading to premature enablement of internal circuits, which can result in latch up or improper functioning when power supplies ramp up at different rates.
Innovation Solution
A supply voltage level detector circuit is designed with a configuration of transistors, resistors, and an inverter to detect trigger voltage and provide an enable signal, with parameters such as transistor size, gain, and resistor values selected to minimize temperature-induced variations, ensuring that internal voltage generators are enabled only when the higher specified power supply voltage is greater than the lower, thus preventing latch up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional supply voltage level detector circuits are used, then the circuit can detect trigger voltage, but temperature changes and semiconductor processing cause variations in trigger voltage leading to premature enablement of internal circuits
Solution Approach 1:
The patent applies parameter changes by carefully selecting transistor sizes (e.g., first transistor size vs. second transistor size), gain values, and resistor values to minimize temperature-induced variations in trigger voltage. The circuit parameters are optimized so that the trigger voltage remains stable across temperature changes and manufacturing variations, preventing premature enablement of internal circuits while maintaining reliable detection functionality
2Speed
If multiple power supplies ramp from zero volts at different rates, then each power supply can reach its specified voltage, but the IC may power up at a time when voltages are at undesirable values causing improper operation
Solution Approach 1:
The patent implements preliminary action by using the supply voltage level detector circuit to monitor and detect when the higher specified power supply voltage has reached a safe level relative to the lower specified power supply voltage before enabling internal circuits. This preliminary detection ensures that internal circuits are only enabled when voltage conditions are appropriate, preventing improper operation during power-up even when power supplies ramp at different rates
Data Source
AI summary
Example apparatuses and methods may detect when one or more supply voltage levels have reached a trigger voltage. An example apparatus may include a terminal, a voltage reference circuit and a voltage detector circuit. The terminal may be configured to receive a first voltage, and the voltage reference circuit may be coupled to the terminal. The voltage reference circuit may be configured to receive the first voltage and provide a second voltage responsive, at least in part, to the first voltage. The voltage detector circuit may be configured to respond, at least in part, to the first and second voltages, and further configured to produce an output signal when the first voltage reaches a target level. The voltage detector circuit may include a first transistor including a gate configured to receive the second voltage, and a first resistor coupled in series between the terminal and the transistor.