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High Performance Two-Channel 120 W Solution Saves 50 % PCB Space
International Rectifier has introduced
the IRAUDAMP4 Class D audio power
amplifier reference design. Based on IR´s
IRS20955 digital audio driver IC, this
extremely compact high performance
two-channel solution delivers an output
power of 120 W.
Compared to typical circuit designs, the new
reference design illustrates how designers
can reduce PCB board space by 50 percent
for Class D audio amplifiers for the entire
mid-voltage range of mid- and high-power
amplifiers for home theatre applications,
professional amplifiers, musical instruments
and car entertainment systems.
Two-Channel Half-Bridge Design using a Digital Audio Driver and DirectFET MOSFETs
Showcasing IR’s IRS20955 200 V digital
audio driver IC and the IRF6645 DirectFET® digital audio MOSFETs, the IRAUDAMP4 reference design is a two-channel, 120 W half-bridge design offering 96 % efficiency
at 120 W, four ohms.
The design incorporates critical protection
features such as over-current protection,
over-voltage protection, under-voltage protection,
DC-protection, and over-temperature
protection, in addition to housekeeping
functions such as a ±5 V supply for analog
signal processing for the pre-amplifier and a
+12 V supply (VCC) referenced to -B for the Class D gate driver stage. The two-channel
design is scalable (power and a number of
channels) and requires no heatsink under
normal operating conditions.
IRS20955 Driver IC
The IRS20955 digital audio driver IC, on
which the reference design is based, features
a floating PWM input designed specifically for Class D audio amplifier applications.
Bi-directional current sensing detects
over-current conditions during positive and
negative load currents without any external
shunt resistors. A built-in protection control
block provides a secure protection sequence
against over-current conditions and a programmable
reset timer.
The internal dead-time generation block enables
accurate gate switching and optimum dead-time setting for better audio performance,
such as lower total harmonic distortion
(THD) and lower audio noise floor.
IRF6645 Power MOSFETs
The companion IRF6645 power MOSFETs are
part of IR’s DirectFET® family of MOSFETs.
The innovative DirectFET® packaging technology enhances performance in Class D
audio amplifier circuits by reducing lead
inductance to improve switching performance
and reduce EMI noise.
The higher thermal efficiency enables 120 W
operation into four ohms, eliminating the
need for a heatsink to shrink circuit size,
provide greater layout flexibility and reduce
overall amplifier system cost.
Key specifications of the IRAUDAMP4
reference design include a supply voltage of
±35 V, a load impedance of 4 Ω, a frequency
of 400 kHz and a gain setting of 26.8 dB.
Additional Information
For additional information regarding the
IRS20955 digital audio driver IC, please
contact your local SPOERLE Branch Office.
Data sheets for the reference design and the
featured IR devices are available at
www.irf.com
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