ZXLD1370Q

Document number: DS37117 Rev. 4 - 2

22 of 39

www.diodes.com

February 2018

© Diodes Incorporated

ZXLD1370Q

Matching the MOSFET with the controller is primarily based on the rise and fall time of the gate voltage. The best rise/fall time in the application is

based on many requirements, such as EMI (conducted and radiated), switching losses, lead/circuit inductance, switching frequency, etc. How fast

a MOSFET can be turned on and off is related to how fast the gate capacitance of the MOSFET can be charged and discharged. The relationship

I

Qg

I

C

dV

dt







Where

dt = turn-on/turn-off time

dV = gate voltage

I = drive current

– constant current source (for the given voltage value)

Here the constant current source

“I” usually is approximated with the peak drive current at a given driver input voltage.

(Example 1)

ns

35

mA

300

nC

3

.

10

I

Q

dt

PEAK

g







Assuming that cumulatively the rise time and fall time can account for a maximum of 10% of the period, the maximum frequency allowed in this

condition is:



This frequency is well above the max frequency the device can handle, therefore the DNM6068 can be used with the ZXLD1370Q in the whole

spectrum of frequencies recommended for the device (from 300kHz to 1MHz).

(Example 2)

ns

97

mA

300

nC

29

I

Q

dt

PEAK

g







Assuming that cumulatively the rise time and fall time can account for a maximum of 10% of the period, the maximum frequency allowed in this

condition is:



This frequency is within the recommended frequency range the device can handle, therefore the ZXMN6A09K is recommended to be used with

the ZXLD1370Q for frequencies from 300kHz to 500kHz.

The recommended total gate charge for the MOSFET used in conjunction with the ZXLD1370Q is less than 30nC.