Low-Power Power-On Control Circuit for Cross-Domain Voltage Detection
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Solution Overview
Problem
Conventional voltage detectors are unable to detect the state of the core voltage domain when the pad voltage domain is not powered, as they are either powered by the pad voltage domain or inoperable, leading to incomplete power-on control in electronic devices.
Innovation Solution
A low-power power-on control circuit is configured to detect the voltage state of a first voltage domain and provide an output to a second voltage domain, using a power detector circuit powered by the core voltage domain and a voltage level-shifting device to ensure proper reset signals during debugging procedures like JTAG boundary scan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage detectors are used to detect core voltage domain state, then the detection function is provided, but the detector becomes inoperable when pad voltage domain is not powered
Solution Approach 1:
The voltage detection function is segmented into two independent parts: a power detector circuit powered by the core voltage domain (independent of pad voltage) and a voltage level-shifting device that interfaces with the pad voltage domain. This segmentation allows the detection function to operate reliably regardless of the pad voltage state.
Solution Approach 2:
A voltage level-shifting device is introduced as an intermediary between the pad voltage domain and the core voltage domain. This intermediary translates voltage levels and allows the power detector circuit to receive test inputs from the pad domain without being directly powered by it, enabling operation in states where pad voltage is insufficient.
2Device complexity
If power detector circuit is powered by pad voltage domain, then simple power supply connection is achieved, but detection is impossible when pad voltage is insufficient
Solution Approach 1:
The power supply connection is segmented such that the power detector circuit is powered by the core voltage domain (VCCORE) rather than the pad voltage domain. This simple yet effective segmentation ensures the detector remains operational even when pad voltage is insufficient, while the voltage level-shifting device handles the interface with the pad domain.
3Adaptability or versatility
If voltage level-shifting device is added to enable detection during pad unpowered state, then adaptability is improved, but device complexity increases
Solution Approach 1:
A voltage level-shifting device is introduced as an intermediary between the pad voltage domain and the core voltage domain. This intermediary translates voltage levels and allows the power detector circuit to receive test inputs from the pad domain without being directly powered by it, enabling operation in states where pad voltage is insufficient.
Solution Approach 2:
The voltage level-shifting device serves multiple functions: it provides voltage level translation, enables test input delivery to the power detector, and allows the system to operate in multiple voltage domain states (both powered and unpowered pad states). This multi-functionality justifies the added complexity.
Data Source
AI summary
Methods and implementation of low-power power-on control circuits are disclosed. In a particular embodiment, an apparatus includes a power detector circuit powered by a first voltage supply. At least one voltage level-shifting device is coupled to a second voltage supply and a test input is provided to the power detector circuit. An optional leakage self-control device may reduce unwanted leakage currents associated with the first supply and the second supply.