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Page 23 of 50
IRAUDAMP5 REV 3.1
.
.
.
.
0V
0V
LP Filter
L1
C23A
R47
C25
Zobel Filter and Output filter demodulator
Fig 25
Output
Both outputs for the IRAUDAMP5 are single-ended and therefore have terminals labeled (+) and
(-), with the (-) terminal connected to power ground. Each channel is optimized for a 4-Ohm
speaker load for a maximum output power (120W), but is capable of operating with higher load
impedances (at reduced power), at which point the frequency response will have a small peak at
the corner frequency of the output LC low pass filter. The IRAUDAMP5 is stable with
capacitive-loading; however, it should be noted that the frequency response degrades with heavy
capacitive loading of more than 0.1
μ
F.
Gain Setting / Volume Control
The IRAUDAMP5 has an internal volume control (potentiometer R108 labeled, ”VOLUME”, Fig
26) for gain adjustment. Gain settings for both channels are tracked and controlled by the volume
control IC (U_2), setting the gain from the microcontroller IC (U_1). The maximum volume
setting (clockwise rotation) corresponds to a total gain of +37.9dB (78.8V/V). The total gain is a
product of the power-stage gain, which is constant (+23.2dB), and the input-stage gain that is
directly-controlled by the volume adjustment. The volume range is about 100dB, with minimum
volume setting to mute the system with an overall gain of less than -60dB. For best performance
in testing, the internal volume control should be set to a gain of 21.9V/V, such that 1Vrms input
will result in rated output power (120W into 4
Ω
), allowing for a >11dB overdrive.
J5
J6
R4
100R
ZCEN
CS
SDATAI
VD+
DGRD
SCLK
SDATAO
MUTE
AINL
AGNDR
AOUTL
VA-
VA+
AOUTR
AGNDL
AINR
U_1
CS3310
R3
100R
R1
100K
R2
100K
R7
47R
R8
47R
R9
10R
R10
47R
R11
47R
C1
10uF, 50V
MUTE
-5V
+5V
+5V
VSS
8
VR0
7
VR1
6
CLK
5
VDD
1
CS
2
SDATA
3
SIMUL
4
U_2
3310S06S
R108
CT2265-
N
D
C107
4.7uF, 16V
C108
10nF, 50V
SCLK
SDATAI
C109
4.7uF, 16V
CS
+5V
Control Volume
+5V
Audio in
Audio in
Level OUT 1
Level OUT 2
Fig 26
Digital volume Control
Summary of Contents for IRAUDAMP5
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