while looking a driver for my lovely mtg-2 emitter at fleabay, i stumbled a item from Russia Seller (most of you probably know it)
its quite cheap and what interest me is input voltage range is wide. perfect it for my motorcycle purpose
Order 5 piece for 3A version
Russia to Indonesia about a month, not bad.
hooked to my 6v mtg-2 and i hear inductor make a heavy buzz with current is moving up and down from 2.2-2.8A with clamp meter
Mosfet is very hot in few seconds. Somehing is not right,
Here close up picture of the driver
why the heck you scrubbed ic marking like other China seller?
its not hard to guess it
go to qxmd site, browse all the driver list, compare to pinout and got it (less than 5 minutes)
its QX5241, more or less MAX 16819/20 copycat
try hookit on my scope just to see what happened, and got an ugly gate mosfet input freq
its jumping around, try to move the trigger level did not change anything
followed a calculation in the datasheet, and my guess is the inductor value is too small. it will affect higher freq
Original using 6.8uH, replace it with 10uH Inductor and now works normal
freq value is wrong, its should be around 300kH
Try to run it 30 minutes, without any additional heatsink
after 15 minutes, i try to measure mosfet temp using a thermocouple probe
while touching its pads, those mosfet sliding.WHAT! solder starts to melt
im amazed its still works though
looked at AOD240 mosfet datasheet, its seem this one have to much gate charge which means higher switching loses
plus this QX5241 have a weak drive CMIIW
replace those mosfet with IPD135N03, and now works like a charm
after 30 minutes, temp on the metal pad was around 74 C
i think its ok for use after this mod
my guessing this driver is not good for 6V emitter, dont know for 3V or even 3*3V as seller claimed
i already test 3 of them, and have same behaviour