U209B
| Model | U209B |
| Description | Monolithic Integrated Feature Phone Circuit |
| PDF file | Total 34 pages (File size: 675K) |
| Chip Manufacturer | ATMEL |
U4090B
Pin
17
18
19
20
21
Symbol
Function
VRING Input for ringing signal protected by
internal zener diode
THA Threshold adjustment for ringing
frequency detector
RFDO Output of ringing frequency detector
LIDET Line detect; output is low when the
line current is more than 15 mA
IMP- Control input for selection of line
SEL
impedance
1. 600
Ω
2. 900
Ω
3. Mute of second transmit stage
(TXA); also used for indication of
external supply (answering machine);
last chosen impedance is stored
TSACL Time constant of anti-clipping of
speaker amplifier
GSA Current input for setting the gain of
the speaker amplifier,
adjustment characteristic is
logarithmical,
or RGSA > 2 MΩ, the speaker
amplifier is switched off
SA I
Speaker amplifier input (for
loudspeaker, tone ringer and
handsfree use)
MUTX Three state input of transmit mute:
1) Speech condition; inputs MIC1 /
MIC2 active
2) DTMF condition; input DTMF
active
a part of the input signal is
passed to the receiving amplifier
as a confidence signal during
dialing
3) Input DTMF used for answering
machine and handsfree use;
receive branch not affected
ATAFS Attenuation of acoustical feedback
suppression,
maximum attenuation of AFS circuit
is set by a resistor at this pin,
without the resistor, AFS is switched
off
INLDT Input of transmit level detector
INLDR Input of receive level detector
Pin
29
30
31
Symbol
Function
TLDT Time constant of transmit level
detector
TLDR Time constant of receive level
detector
AGA Automatic gain adjustment with line
current
a resistor connected from this pin to
GND sets the starting point
max. gain change: 6 dB.
IREF
STO
Internal reference current generation;
RREF = 62 kΩ; IREF = 20
µA
Side tone reduction output
output resistance is approx. 300
Ω,
maximum load impedance: 10 kΩ.
Reference node for microphone-
earphone and loudspeaker amplifier,
supply for electret microphone
(IM
≤
700
m
A)
Three state mute input
1. Normal operation
2. Mute of ear piece
3. Mute of RECIN signal
Condition of earpiece mute is stored
32
33
34
V
M
22
23
35
MUTR
24
36
37
38
39
40
41
25
RECO 2 Inverting output of receiving
amplifier
STI S Input for side tone network (short
loop) or for answering machine
STI L Input for side tone network (long
loop)
RAC Input of receiving amplifier for ac
coupling in feedback path
RECO 1 Output of receiving amplifier
G
R
A resistor connected from this pin to
GND sets the receiving amplification
of the circuit; amplifier RA1 can be
muted by applying VMP to GR
Time constant of anticlipping in
transmit path
RECIN Input of receiving path; input
impedance is typically 80 k
W
TXIN Input of intermediate transmit stage,
input resistance is typically 20 kΩ
TTXA
26
42
43
44
27
28
TELEFUNKEN Semiconductors
Rev. C1, 28-Oct-96
7 (34)
Preliminary Information
