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Electronics => Projects, Designs, and Technical Stuff => Topic started by: cRash1001 on March 29, 2022, 12:38:02 am

Title: Choosing appropiate replacement for MOSFET
Post by: cRash1001 on March 29, 2022, 12:38:02 am

Hi,
I am having a bit of a problem choosing alternatives for a pair of MOSFETs on a Li-Ion charger based on LTC4006-4.

The MOSFET pair I am currently using is DMC4050SSD and I am trying to analyze if ZXMC3A16DN8 can be used as an alternative without modifying the switching characteristics of the current circuit. The problem is the datasheet of these components have their Gate-Charge Characteristics for different operating conditions.
DMC4050SSD's Gate-Charge Characteristics is given only for Vds=20V, Vgs=10V and Id=12A and
ZXMC3A16DN8's Gate-Charge Charactersitics is given only for Vds=15V, Vgs=5V and Id=3.5A.

I need to check against operating conditions with Vds=24V, Id=2.45A and Vgs=4.5V.

Could someone please help me with how do I get the Gate-Charge Characteristics of these MOSFETs at the desired operating conditions?

Some details of the circuit:
Input Voltage: 24V
Output Voltage: 16.8V
I pk-pk = 2.45A
Fsw = 300kHz

Thanks.

Title: Re: Choosing appropiate replacement for MOSFET
Post by: moffy on March 29, 2022, 01:00:22 am

The ZXMC3A16DN8 seem slightly better than the  DMC4050SSD except for the lower breakdown voltage of 30V vs 40V. With a 24V input I would look for something with at least 40V breakdown voltage, but it's your choice.