IR continues to improve the performance capabilities of Class D audio amplifiers by offering Audio DirectFET® MOSFETs. IR’s benchmark DirectFET® package technology plus the latest MOSFET process maximizes performance in class D audio amplifier applications.

The DirectFET® package enables system benefits such as reduced footprint, improved PCB layout, reduced EMI, and improved thermal characteristics over other plastic package devices. The device electrical parameters are tuned specifically for improved audio performance. In addition, class D audio application critical parameter such as internal Gate Resistance, RG(int), has a guaranteed maximum value for improved dead time control. This is an important factor to reduce system THD level. This innovative solution enables customers to provide high performance audio systems with better reliability and higher amplifier output power.

A Class D Audio DirectFET® MOSFET, with its improved electrical and thermal characteristics, delivers up to 120W Pout into 4 Ohms load without a heatsink.

Class D amplifier applications range from battery-powered portable products to high-end professional amplifiers, musical instruments and home multimedia systems. Amplifiers above 50 W per channel can benefit from IR’s product.

Package Designed Specifically for Power Applications
DirectFET MOSFET has a uniquely simple construction that provides breakthroughs in die-free package resistance and heat dissipation capabilities, increasing efficiency and current carrying capacity of the device in a given footprint for optimal performance.

SPECIFICATIONS

Part Number	Package	BVDSS	RDS(on) typ. @ 10V	ID @ Tc=25°C	QG typ.	QSW typ.	Package	Qualification Level
IRF6665	DirectFET	100V	53mOhms	19A	8.4nC	3.4nC	DirectFET SH (Small Can)	Consumer
IRF6645	DirectFET	100V	28mOhms	25A	14nC	5.6nC	DirectFET SJ (Small Can)	Consumer
IRF6775M	DirectFET	150V	47mOhms	28A	25nC	8.0nC	DirectFET MZ (Medium Can)	Consumer
IRF6785M	DirectFET	200V	85mOhms	19A	26nC	8.2nC	DirectFET MZ (Medium Can)	Consumer

DirectFET for After-market Automotive Audio

RMS Power	4 Ohms	Heatsink required?
50W - 100W	IRF6665	yes
100W - 200W	IRF6645	yes
200W - 250W	IRF6775M	yes

DirectFET for Home Audio

Clipping Power	Without Heatsink		With Heatsink
	4 Ohms	8 Ohms	4 Ohms	8 Ohms
50W - 100W	IRF6645	IRF6665	IRF6665	IRF6665
100W - 120W	IRF6645	-	IRF6645	IRF6775M
120W - 200W	-	-	IRF6645	IRF6775M
200W - 250W	-	-	IRF6775M	IRF6785M

Conditions:
Single half-bridge configuration
Switching frequency = 400 kHz, Modulation Index = 90%, Vpeak factor = 10%
For more info, read AN-1070: Class D Audio Amplifier Performance Relationship to MOSFET Parameters