MC34216A Datasheet, PDF (9/20 Pages) Motorola, Inc – PROGRAMMABLE TELEPHONE LINE INTERFACE CIRCUIT WITH LOUDSPEAKER AMPLIFIER

MC34216A
Figure 2. Block Diagram of the MC34216A with Essential Components
Line +
C20
Handset
Earpiece
R6
R9
Handset _C24
Microphone
R30
Speaker
R28
To IMP
Z1
C17 _R20
HYN
10
To IMP To SAI
C16 C12
Z0
Z21
CM NDC SAO
LAI
12
11 14
9
R12
IMP ^Iref
13 20
RXO1
26
RXO2
27
RXI
C5
25
TXI
6
Mic
7
LPO ₂₃
Ear
Mute, AGC
Mute, AGC
Mic
Volume
LSP
LPI
DC Mask Generation
AC Termination
2–4 Wire Conversion
Line Length AGC
Protection
MC34216A
Anti–Howling
Microphone Threshold
Supply–
Stabilizer
References
Ring–
Regulator
Line
Driver
DTMF/Tone
and Ring
Generator
Micro–
Interface
Clock
Hook–Detect
24
C21
AGC
28
C25
AHO1 AHO2 MTF MTC SAI
1
2
3
4
15
C26 C27 C28 C29
Osc
16
X1
Line –
To IMP
VCC
21
AGnd
5
Gnd
22
LAO
8
RS
19
Clk
18
D/HS
17
T2
C7
T3
To
Micro–
controller
R1
DC CHARACTERISTICS AND STARTUP
Figure 3. General Form of the
DC Mask of the MC34216A
Vline
4
VLP
3
VLK
2
VLC
1
0
ILC
Iline
ILP ILK IVLP
Region 1: Startup, Low Line Current, High Slope
Region 2: Mid Range Line Current, Small Slope
Region 3: High Line Current, High Slope
Region 4: Overload Protection
adjustments. The software adjustments make it possible to
program the 4 different basic masks: France, United Kingdom,
Low Voltage and Startup. The hardware adjustments can be
used for fine–tuning. The adjustment possibilities will be
discussed below with the aid of the block diagram of Figure 4.
In Region 1, the transfer of the amplifier G at the HYN input
equals zero. The voltage difference between SAO and SAI
will equal VO1. The slope RE1 of the Vline, Iline characteristic
will equal:
ǒ Ǔ + ) RE1
R1 x 1
Z0
Z21
In Region 2, the output current of the amplifier G will be
proportional to the input current. As a result, the voltage
between SAO and SAI will increase with the line voltage.
Speech signals on the line are of no influence on this
because they are filtered out via capacitor C16. The slope
RE2 of the Vline, Iline characteristic will equal:
+ _ȧȡȢ ) _{) ȧȣȤ} RE2
R1 x 1
1
Ri Z21
Z1 Z0
The MC34216A offers the possibility to adjust the dc
characteristics of all 4 regions via both software and hardware
In Region 3, the output current of the amplifier G is kept
constant. As a result, the slope in Region 3 will equal the
slope of Region 1.
MOTOROLA ANALOG IC DEVICE DATA
9