PBL38570 Datasheet, PDF (1/12 Pages) Ericsson – Universal Speech Circuit

September 1997
PBL 385 70
Universal Speech Circuit
Description.
Key features.
PBL 38570 is a monolithic integrated speech transmission circuit for use in electronic • Minimum number of external
telephones. It is designed to accomodate either a low impedance dynamic or an electret
components, 7 capacitors and 11
microphone. A separate input for DTMF dialling tones that is controlled by a mute signal,
resistors.
and a signal summing point at the transmitter input, are available.
• Easy adaption to various market
An internally preset line length compensation can be adjusted with external resistors
needs.
to fit into different current feed systems as for ex. 48 V, 2 x 200 ohms, 48 V, 2 x 400 ohms • Mute control input for operation with
and 48 V, 2 x 800 ohms. The line length compensation can be shut off in either high or
DTMF - generator.
low gain mode. Application dependent parameters such as line balance, side tone level, • A separate input for DTMF tones
transmitter and receiver gains and frequency responces are set independently by
controlled by mute.
external components which means an easy adaption to various market needs.
• Transmitter and receiver gain
The setting of the parameters if carried out in certain order will counteract the
regulation for automatic loop loss
interaction between the settings.
compensation.
A number of different DC - supplies are provided to feed microphones and diallers. • Extended current and voltage range
5 - 130 mA, down to 2 V.
• Differential microphone input for
good balance to ground.
• Balanced receiver output stage.
• Stabilized DC - supplies for low
current CMOS diallers and electret
microphones.
• 18 - pin DIP and 20 - pin SO packa-
ges.
• Short start up time.
• Excellent RFI performance.
DTMF
input
Mic.
Mute
(active low)
DC-output for
external devices
10
AD
12
13
AM
DC-supply
89 7
6
Sense input
1
PBL 385 70
17
AT
AR
18
5 11 3
2
15
16 14 ⁺ 4
5
Gain
regulation
+
4
3
2
1
+
1. Line impedance and radio interference suppression.
2. Transmit gain and frequency response network.
3. Receive gain and frequency response network.
4. Side tone balance network.
5. DC-supply components.
Figure 1. Functional diagram. DIP package.
Telephone
line
PBL ³⁸⁵⁷⁰
PBL ³⁸⁵⁷⁰
20-pin plastic SO
18-pin plastic DIP
1