The integrated gate driver supports adjustable gate-drive strength to allow for the independent control of turn-on and turn-off slew rates. Turn-on rates range from 10 to 100 V/ns and turn-off rates extend from 10 V/ns to a maximum level based on the load-current magnitude. The independent adjustments can help optimize switching performance while minimizing electromagnetic interference (EMI).
The device determines the programmed slew rates on startup by sensing external resistor-capacitor networks connected to its drive-strength selection pin. After startup, that pin takes on the role of fault monitoring.
The gate driver also integrates an undervoltage lockout (UVLO) feature and overvoltage and overtemperature protection capability. On top of that, it includes, cycle-by-cycle, an overcurrent protection (OCP) function and a latched short-circuit protection (SCP) function that responds within 300 ns. The device can withstand a 720-V surge while switching.
Versions of the device are available with a zero-voltage detection (ZVD) feature, a zero-current detection (ZCD) feature, or a 5-V low-drop-out (LDO) regulator output that can power an external isolator. The different versions assign ground, the 5-V output, the ZVD signal, or the ZCD signal to the pin shown on the lower left of the Figure 3 block diagram.
Evaluation Module
To help you get started on designs based on the LMG3650R035, TI offers the LMG3650EVM-114 evaluation module, a daughtercard that can be part of a larger custom-designed system or paired with a TI GaN motherboard. Available motherboards include the LMG342X-BB-EVM, which is a DC-DC buck-boost converter that can support up to 4 kW, and the PFC23338EVM-107, an AC-DC totem-pole PFC stage that can support up to 3.6 kW.
The LMG3650EVM-114 card itself includes two LMG3650R035 GaN ICs in a half-bridge configuration, two digital isolators for the GaN IC fault signals, and isolated bias and bootstrap supplies. The card also incorporates two isolated gate drivers to enable layout compatibility with discrete GaN devices in TOLL packages (Fig. 4).