Safety Isolated IC with Internal Voltage Regulator
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Solution Overview
Problem
Current integrated circuit chip designs for safety areas in vehicles require large die area for isolating supply lines, which is not desirable for certain applications, and existing solutions do not effectively protect against shorts in high voltage input signals.
Innovation Solution
An integrated circuit chip with a safety area isolated by deep trench isolation, featuring an internal voltage regulator that generates a protected internal voltage and a protection circuit using level shifters and avalanche diodes to protect against shorts, allowing safety circuits to detect faults in main logic operation and initiate appropriate responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If supply lines are fully isolated from the rest of the integrated circuit chip to achieve independent isolated voltage for the safety area, then safety and independence are improved, but die area increases significantly
Solution Approach 1:
An internal voltage regulator is introduced as an intermediary component within the safety area that generates the isolated internal voltage from the external supply voltage. This regulator acts as a mediator that provides electrical isolation between the safety area and the rest of the chip, eliminating the need for extensive physical isolation structures while maintaining safety independence.
Solution Approach 2:
The voltage regulator changes the voltage parameter from the external supply voltage to an internal regulated voltage, creating an isolated power domain within the safety area. This parameter transformation enables electrical isolation without requiring large physical separation, as the voltage conversion process itself provides the isolation barrier.
2Reliability
If protection circuitry is added to protect against shorts in external supply voltage line and analog input lines, then reliability is improved, but device complexity increases
Solution Approach 1:
Protection circuits are implemented that proactively detect and respond to fault conditions before they can affect the safety area. The protection circuitry monitors external supply voltage and analog input lines for short conditions and takes preliminary protective action, preventing faults from propagating into the safety area.
Solution Approach 2:
The protection circuits provide a cushioning effect by absorbing and containing fault conditions on external lines before they can impact the safety area. The isolation mechanisms and protection circuitry act as a buffer that cushions the safety area against external faults, allowing the system to maintain reliability without requiring overly complex protection schemes.
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
The solution effectively isolates safety circuits from external faults, reduces die area requirements, and ensures reliable fault detection and response, meeting ASIL-D standards for safety-critical vehicle components.
Implementation Method 1
an avalanche diode coupled between the internal node and ground, the avalanche diode configured to protect the internal voltage regulator from shorts of the external supply voltage line to other voltages
Implementation Method 2
a protection circuit configured to receive at least one analog signal over an external analog input line and to generate at least one analog fault signal from the at least one analog signal by level shifting the at least one analog signal downward in voltage
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Disclosed herein is a single integrated circuit chip with a main logic (11) that operates a vehicle component such as a valve driver. Isolated from the main logic (11) within the chip is a safety area (12') that operates to verify proper operation of the main logic. The safety area (12') is internally powered by an internal regulated voltage (VREG) generated by an internal voltage regulator that generates the internal regulated voltage from an external voltage (PWR_IN) while protecting against shorts of the external line delivering the external voltage. The safety area (12') includes protection circuits (25) that level shift external analog signals downward in voltage for monitoring within the safety area, the protection circuits (25) serving to protect against shorts of the external line delivering the external analog signals.