HEMT (GaN) Forum Discussions
I have a question regarding the Infineon GaN HEMT IGOT60R070D1:
- In the datasheet, sometimes I_GS is used. What is I_GS? Where can I find out, what acronyms in datasheets mean?
I_G is the gate current, which average needs to be lower than 20mA.
I got the EVAL_2500W_PFC_GaN_A and in the start-up procedure is stated that the recommended way is to use an electronic load in constant current mode and a programmed sink current of 100mA.
Can be instead of the electronic load a load resistor be used with 3.9kOhm?
Best regardsShow Less
Hello: Looking for a robust GaN with 150V or higher breakdown voltage.
Came across this peculiar device IGO60R070D1.
Its Vgs is NEGATIVE WITH CURRENT CONTROEL of the gate?
We cannot use it but is there an equivalent GaN with + Vgs?
Hello, I have some doubts about Infineon's 12V 3KW server POWER SUPPLY. According to the document, the DC/DC isolation converter uses 4 transformers, using half-bridge LLC for power conversion, each transformer is responsible for a quarter For all the output power, the synchronous rectifier MOS used is Rds_on 0.5mΩ, I want to seek this model and his layout.
I'm currently learning about the LLC converter. But a few questions popped up.
Q1: Uncertainties about the body diode Primary Side
Some sources state, that the LLC to be able to gurantee ZVS operation an intrinsic body diode is necessary.
Resonant inductor current must be high enough to discharge the voltage of effective capacitance (Coss) appearing in parallel with drain-sources of the power MOSFETs. Additionally the converter must work in the inductive region to achieve ZVS.
When the FET switches during body diode conduction (leading to zero), a ZVS transition happens.
Incomplete body diode reverse recovery can damage the power FET due to large current caused by the high reverse recovery charge. This happens mainly during startup. This can be prevented by using the FETs with fast body diode because its low reverse recovery charge as well as the short recovery time. There are multiple approaches to get rid of this problem. 
Some LLC converter designs use GaN HEMTs, which have low equivalent capacitance, which shortens the charging/discharging time Co(tr). But it they do not have an intrinsic body diode and therefore zero reverse recovery charge.
So does the body diode not affect the ZVS behavior and GaN can be used?
Q2: Uncertainties about the body diode Secondary Side
When GaN is used, it is mostly used only on the primary side, and not on the secondary side.
In one Abstract is written that "[...] reverse recovery and junction capacitance (C j ) of secondary-side diode critically affect the ZVS condition of primary-side switches." 
Is this maybe the main reason why mostly Si or SiC is used?
Can't one just use GaN HEMTs here as well?
Additionally on the secondary side are often multiple FETs used in parallel. Is this only to split the current?
 Primary Side MOSFET Selection for LLC Topology (infineon)
 Analysis of Diode Reverse Recovery Effect on ZVS Condition for GaN-Based LLC Resonant Converter
The pulsed current capability at Vds=600V is also in that case basically null.
May I know the phenomenon root cause? it's material or horizontal structure of power device limitation?