HEMT Gate Driver Circuit With Integrated Under-Voltage Lockout
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Solution Overview
Problem
High voltage applications using silicon-based gate drivers for wide-bandgap semiconductor switching devices face challenges in protecting against under-voltage conditions, which can lead to uncontrolled switching and potential damage, and existing solutions are inefficient in manufacturing and prone to parasitic inductance issues.
Innovation Solution
A driver circuit based on n-type high electron mobility transistors (HEMTs) is designed to detect under-voltage conditions and implement an under-voltage lockout mode, using a protection circuit with a voltage divider and detection circuit to generate signals that disable high voltage device switching, thereby providing UVLO protection without requiring additional masks for p-type devices and reducing parasitic inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silicon-based gate drivers are used to drive wide-bandgap switching devices, then the switching devices can operate at high voltages, but the system becomes vulnerable to uncontrolled switching under under-voltage conditions
Solution Approach 1:
The driver circuit proactively detects under-voltage conditions before they can cause uncontrolled switching of the wide-bandgap device. By implementing UVLO detection that monitors the power supply voltage and preemptively disables the gate drive signal when voltage drops below a threshold, the system prevents harmful switching events before they occur.
Solution Approach 2:
An under-voltage lockout detection circuit serves as an intermediary between the power supply and the gate driver. This detection circuit monitors the power supply voltage and controls the gate drive enable signal, acting as a protective mediator that blocks harmful gate drive signals during under-voltage conditions while allowing normal operation when voltage is sufficient.
2Reliability
If additional p-type devices are added to implement UVLO protection, then under-voltage protection is achieved, but manufacturing complexity and parasitic inductance increase
Solution Approach 1:
The n-type HEMT-based driver circuit performs multiple functions: it drives the wide-bandgap switching device and simultaneously provides under-voltage lockout protection through integrated voltage detection. The same n-type HEMT structure and power supply connection serve dual purposes, eliminating the need for separate p-type protection devices and reducing overall circuit complexity.
Solution Approach 2:
The invention changes the transistor type parameter from traditional p-type devices for protection to n-type HEMTs that can perform both driving and protection functions. By utilizing the voltage-dependent characteristics of n-type HEMTs and configuring the gate drive circuitry appropriately, the system achieves UVLO protection through parameter-based control rather than additional device types.
3Productivity
If n-type HEMTs are used in the driver circuit, then manufacturing efficiency improves and parasitic inductance is reduced, but the circuit must handle both driving and protection functions
Solution Approach 1:
The n-type HEMT driver circuit is designed to universally perform both the primary function of driving the wide-bandgap switching device and the secondary function of providing under-voltage lockout protection. Through integrated voltage detection circuitry and appropriate configuration of the n-type HEMTs, a single circuit topology accomplishes multiple protective and driving functions that would traditionally require separate circuits.
Data Source
AI summary
A circuit includes power supply and reference nodes, a protection circuit including a first output terminal and first and second series of n-type HEMTs coupled between the power supply and reference nodes, and a gate driver including a second output terminal and third through fifth series of n-type HEMTs coupled between the power supply and reference nodes. The first HEMT series controls a first node voltage responsive to a power supply node voltage, the second HEMT series controls a first output terminal voltage responsive to the first node voltage, the third HEMT series controls an internal signal on a second node responsive to the first output terminal voltage and to an input signal, the fourth HEMT series controls a third node voltage responsive to the internal signal, and the fifth HEMT series controls a signal at the second output terminal responsive to the internal signal and the third node voltage.