ASK.. MOSFET DRIVER

[tiotepe]

Anyone have use LT1160/LT1162 as a MOSFET driver for class D amp?
from datasheet say that PWM freq is 100kHz but when try to use 100kHz PWM ,the result that sound quality is bad..(MOSFET get warm)
i try to increase the PWM freq until about 200kHz the sound quality is good..(MOSFET is not warm at all)
i want to ask why this happen?
anyone can give me reference/schematic to use this IC?
thanks for attention,sorry for my bad eng..

regards,

 

[SemperFi]

that driver is too slow for audio.
What are you using as audio-to-pwm converter?

 

[solar1366]

A lower switching frequency also increases the ripple current flowing through the output filter inductor. The conduction and switching losses of this higher current can be the reason for the higher dissipation in your MOSFET's.

 

[tiotepe]

that driver is too slow for audio.
What are you using as audio-to-pwm converter?

i use unipolar PWM or it can say as BD Modulation. that get 3-level output.
until now nothing happen with the IC and MOSFET. but i little confused about the switch.freq.
I try to use feedback to improve THD until 0.1%. now My Class D have 1% THD for 1W output.
thanx SemperFi.. 🙂

 

[tiotepe]

A lower switching frequency also increases the ripple current flowing through the output filter inductor. The conduction and switching losses of this higher current can be the reason for the higher dissipation in your MOSFET's.

which is true increasing switching losses because higher switching freq or lower switching freq?
thanx solar1366 🙂