Electronic Components Datasheet Search
  English  ▼

Delete All
ON OFF
ALLDATASHEET.COM

X  

Preview PDF Download HTML

TEA1112 Datasheet(PDF) 6 Page - NXP Semiconductors

Part No. TEA1112
Description  Low voltage versatile telephone transmission circuits with dialler interface
Download  20 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Maker  PHILIPS [NXP Semiconductors]
Homepage  http://www.nxp.com
Logo 

TEA1112 Datasheet(HTML) 6 Page - NXP Semiconductors

Zoom Inzoom in Zoom Outzoom out
 6 / 20 page
background image
1997 Mar 26
6
Philips Semiconductors
Product specification
Low voltage versatile telephone
transmission circuits with dialler interface
TEA1112; TEA1112A
The DC line current flowing into the set is determined by
the exchange supply voltage (Vexch), the feeding bridge
resistance (Rexch), the DC resistance of the telephone line
(Rline) and the reference voltage (Vref). With line currents
below 7.5 mA, the internal reference voltage (generating
Vref) is automatically adjusted to a lower value. This means
that more sets can operate in parallel with DC line voltages
(excluding the polarity guard) down to an absolute
minimum voltage of 1.6 V. At currents below 7.5 mA, the
circuit has limited sending and receiving levels. This is
called the low voltage area.
Set impedance
In the audio frequency range, the dynamic impedance is
mainly determined by the RCC resistor. The equivalent
impedance of the circuits is illustrated in Fig.8.
LED supply (pin ILED)
The TEA1112; TEA1112A give an on-hook/off-hook status
indication. This is achieved by a current made available to
drive an LED connected between pins ILED and LN. In the
low voltage area, which corresponds to low line current
conditions, no current is available for this LED.
Fig.5 Reference voltage adjustment by RVA.
(1) Influence of RVA on Vref.
(2) Vref without influence of RVA.
handbook, halfpage
6.0
Vref
(V)
3.0
4.0
(1)
(2)
5.0
RVA (Ω)
MGD176
105
104
106
107
For line currents higher than a threshold, ILEDstart, the ILED
current increases proportionally to the line current (with a
ratio of one third). The ILED current is internally limited to
19.5 mA (see Fig.9). If no LED device is used in the
application, the ILED pin should be shorted to pin SLPE.
For 17 mA < Iline < 77 mA:
This LED driver is referenced to SLPE. Consequently, all
the ILED supply current will flow through the RSLPE resistor.
The AGC characteristics are not disturbed (see Fig.4).
Microphone amplifier (pins MIC+, MIC
− and GAS)
The TEA1112; TEA1112A have symmetrical microphone
inputs. The input impedance between pins MIC+ and
MIC
− is 64 kΩ (2 × 32 kΩ). The voltage gain from
pins MIC+/MIC
− to pin LN is set at 51.8 dB (typ). The gain
can be decreased by connecting an external resistor RGAS
between pins GAS and REG. The adjustment range is
13 dB. A capacitor CGAS connected between pins GAS
and REG can be used to provide a first-order low-pass
filter. The cut-off frequency corresponds to the time
constant CGAS × (RGASint // RGAS). RGASint is the internal
resistor which sets the gain with a typical value of 69 k
Ω.
Automatic gain control is provided on this amplifier for line
loss compensation.
Microphone mute (pin MMUTE; TEA1112)
The microphone amplifier can be disabled by activating
the microphone mute function. When MMUTE is LOW, the
normal speech mode is entered, depending on the level on
MUTE (see Table 1). When MMUTE is HIGH, the
microphone amplifier inputs are disabled while the DTMF
input is enabled (no confidence tone is provided).
The voltage gain between LN and MIC+/MIC
− is
attenuated; the gain reduction is 80 dB (typ).
Microphone mute (pin MMUTE; TEA1112A)
The microphone amplifier can be disabled by activating
the microphone mute function. When MMUTE is LOW, the
microphone amplifier inputs are disabled while the DTMF
input is enabled (no confidence tone is provided).
The voltage gain between LN and MIC+/MIC
− is
attenuated; the gain reduction is 80 dB (typ). When
MMUTE is HIGH, the normal speech mode is entered,
depending on the level on MUTE (see Table 1).
I
LED
I
line
17
3
----------------------
=


Html Pages

1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20 


Datasheet Download




Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ]  

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Alldatasheet API   |   Link Exchange   |   Manufacturer List
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn