Multi-Chip Power Module With Segmented High-Side Drivers
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Solution Overview
Problem
Conventional microcontroller motor drive circuits face challenges in efficiently managing ultra-high voltage applications, particularly in ensuring safe and reliable operation of high-side and low-side drivers, and in providing effective fault protection without processor execution delays.
Innovation Solution
A multi-chip module configuration with a first die containing a processor, timer, high-side drivers, and low-side drivers, and a second die with ultra-high voltage high-side drivers, where the dies are coupled through a package with specially spaced terminals, enabling direct control of external high-side and low-side power transistors and incorporating a fault protection circuit that generates disable signals independently of processor execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional microcontroller motor drive circuit is used, then the system can operate with standard components, but the fault protection response is delayed due to processor execution time
Solution Approach 1:
The system is divided into two separate die: the first die contains the processor and control logic, while the second die contains only the ultra-high voltage high-side drivers. This segmentation allows the fault protection circuitry to be physically closer to the power transistors, enabling faster response times independent of processor execution delays.
Solution Approach 2:
A dedicated fault protection circuit is introduced as an intermediary between the processor and the high-side drivers. This circuit can independently detect faults and generate disable signals without waiting for processor intervention, thereby reducing the overall fault response time.
2Reliability
If all drivers are integrated on a single die, then the device complexity is reduced, but the ultra-high voltage high-side drivers cannot be properly isolated from low-side drivers
Solution Approach 1:
The driver circuitry is segmented into two separate die: the first die contains the processor, timer, high-side drivers, low-side drivers, and fault protection circuit, while the second die contains only the ultra-high voltage high-side drivers. This physical separation ensures proper voltage isolation and prevents interference between low-voltage and ultra-high voltage circuits.
Solution Approach 2:
The ultra-high voltage high-side drivers are extracted from the main control die and placed on a separate second die. This extraction allows for specialized packaging and terminal spacing that is optimized for ultra-high voltage applications, while the first die maintains its focus on control and protection functions.
3Reliability
If package terminals are closely spaced, then the package size is reduced, but the voltage differences between terminals cause safety and reliability issues
Solution Approach 1:
The package terminals are configured with different spacing based on their function: terminals associated with ultra-high voltage high-side drivers are spaced at least one millimeter apart to handle voltage differences of more than eighty volts, while other terminals can be more closely spaced. This local differentiation of terminal spacing optimizes both safety and package size.
4Reliability
If a separate second die with ultra-high voltage high-side drivers is added, then the voltage isolation and reliability are improved, but the device complexity increases
Solution Approach 1:
The first die integrates multiple functions including the processor, timer, high-side drivers, low-side drivers, and fault protection circuitry into a single control unit. This merging of control functions on the first die reduces the overall system complexity compared to having completely separate components for each function.
Data Source
AI summary
A packaged device includes a first die, a second die, and specially spaced and positioned sets of package terminals. The first die includes a pulse-width modulator (PWM), a processor, a timer, high-side drivers, low-side drivers, and a fault protection circuit. The second die includes ultra-high voltage high-side drivers. In an ultra-high voltage application, the PWM and external circuitry together form a switching power supply that generates a high voltage. The high voltage powers external high-side transistors. The processor and timer control the ultra-high voltage high-side drivers, that in turn supply drive signals to the external high-side transistors through the package terminals. External low-side transistors are driven directly by low-side drivers of the first die. If the fault protection circuit detects an excessive current, then the fault protection circuit supplies a disable signal to high-side and low-side drivers of both dice. The disable signal is generated without execution of processor instructions.