PBL 388 14
24
23
22
-Txin
1
2
CTR
+Txin
F2out
LSPin
24
23
22
21
-Txin
1
2
3
4
5
6
7
8
9
CTR
3
VA
+Txin
F2out
LSP in
4
21 VOL
20 LL
Txout
TxDetin
TxDetout
Ref.
V
A
5
Txout
TxDetin
TxDetout
Ref.
VOL
20 LL
6
19 LSP
18 GND
19 LSP
7
A
18
GND
A
GND
V+
8
17
16
N Det
N Det
17 GND
16 V+
CMP
9
CMP
10
15 -Rxin
+Rxin
RxDetout
15
14
-Rxin
RxDetout 10
RxDetin 11
Rxout 12
14
13 F5out
RxDetin
Rxout
+Rxin
F5out
11
12
13
24 pin DIP
24 pin SO
Figure 4. Pin configuration.
Pin Descriptions
Refer to figure 6. (24 pin DIP and 24 pin SO package)
Pin
Symbol
Description
Pin
Symbol
Description
1
2
3
4
5
6
-Txin
+Txin
F2out
Txout
Transmitter channel negative input.
Input impedance 3.16 kohm.
11
12
13
14
15
16
RxDetin Input of the receiver channel signal
detector. Input impedance 13 kohm.
Transmitter channel positive input.
Input impedance 100 kohm.
Rxout
F5out
+Rxin
-Rxin
V+
Receiver channel output. Min. ac load
impedance 10 kohm.
Output of the second amplifier in the
transmitter channel.
Output of the second amplifier in the
receiver channel.
Transmitter channel output. Min. ac
load impedance 10 kohm.
Receiver channel positive input. Input
impedance 140 kohm.
TxDetin Input of the transmitter channel signal
detector. Input impedance 13 kohm.
Receiver channel negative input. Input
impedance 20 kohm.
TxDetout Output of the transmitter channel signal
detector. Goes nagative referred to the
internal ref. voltage of appx. 2V when a
transmitter signal is present.
Supply of the speech switching circuitry.
A shunt regulator, voltage apprx. 3.3V at
1.0mA.
17
18
GND
System ground.
7
8
Ref.
Internal reference app. 2V.
GNDA
Power amplifier ground. Can lie positive
relative to GND, otherways connected
externally to GND.
NDet
Background noise detector output.
Goes positive referred to the internal ref.
voltage of app. 2V when a background
noise signal is present
19
20
21
LSP
LL
Loudspeaker power amplifier output.
Feedback loop input
9
CMP
Comparator input. External resistance
to this point should not be less than
50 kohm. Summing point to the different
detector outputs.
VOL
Volume control input. By sourcing a
current of appx. 0-40 µA into this pin the
gain can be reduced.
22
23
24
VA
Positive supply for the loudspeaker
amplifier.
10
RxDetout Output of the receiver channel signal
detector. Goes positive referred to the
internal ref. voltage of appx. 2V when a
receiver signal is present
LSPin
CTR
Loudspeaker amplifier signal input. Input
impedance 30 kohm.
Control input for gain dynamics
(25 or 50dB), mute and disable.
5
ERICSSON [ ERICSSON ]
