High-Side Driver Reverse Current Protection Circuit
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Solution Overview
Problem
Current high-side driver circuits in automotive applications require separate current sense loops for short to ground and short to battery protection, leading to increased area and power consumption.
Innovation Solution
A single current sense path is implemented to provide protection against both short to ground and short to battery conditions, eliminating the need for multiple current sense loops and incorporating a switch circuit, forward current sensing circuit, reverse current switching circuit, and forward current protection circuit to manage bus pin protection efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate current sense loops are used for short to ground and short to battery protection, then protection reliability is improved, but circuit area and power consumption increase
Solution Approach 1:
The patent merges two separate current sense loops into a single current sense path that serves both short-to-ground and short-to-battery protection functions. The single sense path shares common components including current sense resistors, operational amplifiers, and switching transistors, eliminating the need for duplicate circuitry while maintaining protection reliability for both fault conditions.
Solution Approach 2:
The single current sense circuit is designed to perform multiple protection functions universally. By using bidirectional current sensing capability and configurable switching elements, the same circuit path can detect and respond to both forward current faults (short to ground) and reverse current faults (short to battery), making the circuit multi-functional rather than requiring separate dedicated paths for each protection type.
2Reliability
If two separate current sense loops are used for short to ground and short to battery protection, then protection reliability is improved, but power consumption increases
Solution Approach 1:
The patent merges two separate current sense loops into a single current sense path that serves both short-to-ground and short-to-battery protection functions. The single sense path shares common components including current sense resistors, operational amplifiers, and switching transistors, eliminating the need for duplicate circuitry while maintaining protection reliability for both fault conditions.
Solution Approach 2:
The single current sense circuit is designed to perform multiple protection functions universally. By using bidirectional current sensing capability and configurable switching elements, the same circuit path can detect and respond to both forward current faults (short to ground) and reverse current faults (short to battery), making the circuit multi-functional rather than requiring separate dedicated paths for each protection type.
3Area of stationary object
If a single current sense path is used for both protections, then circuit area and power consumption are reduced, but protection coverage may be compromised
Solution Approach 1:
The patent employs dynamic switching elements (transistors Q16, Q17, Q18, Q19) that can change the circuit configuration based on the type of fault detected. The switching network can reconfigure the single current sense path to optimize sensing for either forward current faults or reverse current faults, maintaining full protection coverage while using shared components. This dynamic reconfiguration ensures that protection coverage is not compromised despite using a single sense path.
Solution Approach 2:
The patent introduces intermediary switching transistors and control logic that act as mediators between the single current sense path and the two different protection functions. These intermediary elements route and condition the sensed current appropriately for each protection type, ensuring that the single sense path can accurately detect both short-to-ground and short-to-battery conditions without compromising protection coverage.
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
An electronic control unit (ECU) (400) operates between first and second voltage rails (VDD_HV and VDD_MV) and includes an amplifier circuit (304') and a single current sense circuit (402, 404, 406, 408) coupled to carry a signal to a bus pin (OUTx) and to protect the bus pin from both a short to ground and a short to battery. The single current sense circuit includes: a switch circuit (402) that passes the signal to the bus pin; and a forward current sensing circuit (404) that provides a second current (IMrev) that is proportional to an output current at the bus pin. The forward current sensing circuit (404) causes the second current to be substantially zero when voltage on the bus pin (OUTx) is above a given value. The single current sense circuit also includes a forward current protection circuit (406) and a reverse current switching circuit (408) that receives the second current and closes a connection to the second voltage when the second current is zero.