U2090B
| Model | U2090B |
| Description | Monolithic Integrated Feature Phone Circuit |
| PDF file | Total 34 pages (File size: 675K) |
| Chip Manufacturer | ATMEL |
U4090B
The U4090B contains two identical series regulators,
which provide a supply voltage V
MP
of 3.3 V suitable for
a microprocessor. In speech mode both regulators are
active, because V
MPS
and V
B
are charged simultaneously
by the DC-line interface. Output current is 4 mA. The
capacitor at V
MPS
is used to provide the microcomputer
with sufficient power during long line interruptions. Thus
long flash pulses can be bridged or a LCD display can be
turned on for more than 2 seconds after going on hook.
When the system is in ringing mode, V
B
is charged by the
on chip ringing power converter. In this mode only one
regulator is used to supply V
MP
with max. 2 mA.
Supply structure of the chip
As a major benefit the chip uses a very flexible system
structure, which allows simple realization of numerous
applications such as:
group listening phone
handsfree phone
ringing with the built in speaker amplifier
answering machine with external supply
The special supply topology for the various functional
blocks is illustrated in figure 6.
V
RING
RPC
Voltage
regulator
V
B
7V
VMP
V
MPS
Voltage
regulator
VL
Power
supply
6.3 V
QS
PD
ES
IMPED
CONTR
IMPSEL
LIDET
LIDET
VLon
MIC, DTMF
AGA, RA1, RA2
TX MUTE
MUT REC, STBAL
RECATT
RFDO
RFD
TXA
TXACL
OFFSA
COMP
SAI,SA
SACL
AFS
94 8046
Figure 6. Supply of functional blocks is controlled by input voltages V
L
, V
B
, V
ring
and by logic inputs PD and IMPSEL
There are four major supply states:
1.
2.
3.
4.
Speech condition
Power down (pulse dialing)
Ringing
External supply
For line voltages below 1.9 V the switches remain in their
quiescent state as shown the diagram.
OFFSACOMP disables the group listening feature (SAI,
SA, SACL, AFS) below line currents of approximately
10 mA.
2. When the chip is put into Power-down mode
(PD = high), e.g. during pulse dialing, the internal
switch QS shorts the line and all amplifiers are
switched off. In this condition LIDET, voltage
regulators and IMPED CONTR are the only active
blocks.
1. In speech condition the system is supplied by the line
current. If the LIDET-block detects a line voltage
above the fixed threshold (1.9 V), the internal signal
VLON is activated, thus switching off RFD and RPC
and switching on all other blocks of the chip.
TELEFUNKEN Semiconductors
Rev. C1, 28-Oct-96
9 (34)
Preliminary Information
