APPLICATION SUGGESTIONS (see Test and Application Circuits of the Fig. 1)
The recommended values of the external components are those shown on the application circuit of Fig-
ure 1. Different values can be used; the following table can help the designer.
COMPONENTS
SUGGESTED VALUE
PURPOSE
LARGER THAN
SUGGESTED
SMALLER THAN
SUGGESTED
R1 (*)
22k
INPUT RESISTANCE
INCREASE INPUT
IMPEDANCE
DECREASE INPUT
IMPEDANCE
R2
680
Ω
CLOSED LOOP GAIN
SET TO 30dB (**)
DECREASE OF GAIN INCREASE OF GAIN
R3 (*)
22k
INCREASE OF GAIN
DECREASE OF GAIN
R4
22k
ST-BY TIME
CONSTANT
LARGER ST-BY
ON/OFF TIME
SMALLER ST-BY
ON/OFF TIME;
POP NOISE
R5
10k
MUTE TIME
CONSTANT
LARGER MUTE
ON/OFF TIME
SMALLER MUTE
ON/OFF TIME
C1
0.47
µ
F
INPUT DC
DECOUPLING
HIGHER LOW
FREQUENCY
CUTOFF
C2
22
µ
F
FEEDBACK DC
DECOUPLING
HIGHER LOW
FREQUENCY
CUTOFF
C3
10
µ
F
MUTE TIME
CONSTANT
LARGER MUTE
ON/OFF TIME
SMALLER MUTE
ON/OFF TIME
C4
10
µ
F
ST-BY TIME
CONSTANT
LARGER ST-BY
ON/OFF TIME
SMALLER ST-BY
ON/OFF TIME;
POP NOISE
C5
22
µ
FXN (***)
BOOTSTRAPPING
SIGNAL
DEGRADATION AT
LOW FREQUENCY
C6, C8
1000
µ
F
SUPPLY VOLTAGE
BYPASS
C7, C9
0.1
µ
F
SUPPLY VOLTAGE
BYPASS
DANGER OF
OSCILLATION
(*) R1 = R3 for pop optimization
(**) Closed Loop Gain has to be
(***) Multiplay this value for the number of modular part connected
MASTER
UNDEFINED
SLAVE
-V
S
+1V
-V
S
D98AU821
Slave function: pin 4 (Ref to pin 8 -V
S
)
Note:
If in the application, the speakers are connected
via long wires, it is a good rule to add between
the output and GND, a Boucherot Cell, in order to
avoid dangerous spurious oscillations when the
speakers terminal are shorted.
The suggested Boucherot Resistor is 3.9
Ω
/2W
and the capacitor is 1
µ
F.
TDA7293
5/15
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