High-Voltage Output Driver with Bulk Control for Reverse Current Blocking
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Solution Overview
Problem
Existing high-voltage output drivers for sensor devices fail to prevent current flow into the output terminal in reverse polarity conditions, leading to inefficiencies and potential damage.
Innovation Solution
A high-voltage output driver with a bulk control circuit acting as an independent well-switch and a smart gate control circuit to manage the high-side driver transistor, preventing reverse current flow by controlling the bulk and gate nodes based on operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reverse polarity protection diode is added to the supply path, then reverse current blocking is improved, but the output terminal voltage is pulled up above the high-voltage supply causing the driver transistor to conduct in reverse
Solution Approach 1:
A bulk control circuit is introduced as an intermediary between the supply voltage and the bulk node of the driver transistor. This bulk control circuit applies a dynamically adjusted bulk control voltage to prevent the driver transistor from conducting in reverse when the output terminal voltage exceeds the supply voltage, thereby blocking reverse current without affecting normal operation
Solution Approach 2:
The bulk control voltage applied to the bulk node is dynamically changed based on the operating conditions. When reverse polarity is detected (output voltage exceeds supply voltage), the bulk control voltage is adjusted to raise the reverse conduction threshold of the driver transistor, effectively preventing reverse current flow
2Reliability
If the driver transistor reverse conduction threshold is increased to prevent reverse current, then reverse current blocking is improved, but the chip area increases due to additional circuits
Solution Approach 1:
The bulk control circuit serves multiple functions: it prevents reverse current conduction, provides voltage level shifting, and enables smart gate control. By making the bulk control circuit multi-functional, the patent avoids adding separate dedicated circuits for each function, thereby minimizing the increase in chip area while achieving reliable reverse current blocking
Solution Approach 2:
The gate control circuit and bulk control circuit are merged into a coordinated control system that jointly manages the driver transistor operation. The gate control voltage and bulk control voltage work together to achieve reverse current blocking, allowing the circuits to share control logic and reduce overall area consumption
3Reliability
If external diodes or charge pumps are used to prevent reverse current, then reverse current blocking is improved, but device complexity increases
Solution Approach 1:
The driver transistor's bulk node is used to actively control its own reverse conduction behavior. The bulk control circuit applies a voltage to the bulk node that dynamically adjusts the transistor's threshold characteristics, enabling the device to protect itself from reverse current without requiring external protection components
Solution Approach 2:
The patent extracts the reverse current blocking function from external components (diodes, charge pumps) and implements it internally using the driver transistor's own bulk control mechanism. This eliminates the need for separate external protection circuits and simplifies the overall device architecture
Data Source
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AI summary
A high-voltage output driver (1) for a sensor device (100) with reverse current blocking comprises a supply node (SN) to apply a supply voltage (VHV) and an output node (OP) to provide an output signal (OS) of the high-voltage output driver (1). The high-voltage output driver (1) comprises a driver transistor (MP0) being disposed between the supply node (SN) and the output node (OP). The high-voltage output driver (1) further comprises a bulk control circuit (20) to apply a bulk control voltage (Vwell) to a bulk node (BMP0) of the driver transistor (MP0), and a gate control circuit (30) to apply a gate control voltage (GCV) to the gate node (GMP0) of the driver transistor (MP0).