U4092B Datasheet, PDF (9/32 Pages) TEMIC Semiconductors – Monolithic Integrated Feature Phone Circuit

TELEFUNKEN Semiconductors
U4092B
The U4092B contains two identical series regulators,
which provide a supply voltage V_MP of 3.3 V at 2 mA
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. 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_MPS.
VRING
RPC
Voltage
regulator
VL
QS
PD
Power
supply
Voltage
regulator
RFDO
LIDET
VLon
RFD
TXA
TXACL
OFFSA
COMP
SAI,SA
SACL
7V
6.3 V
VB
VMP
VMPS
ES _IMPED
CONTR
IMPSEL
MIC, DTMF
AFS
AGA, RA1, RA2
TX MUTE
MUT REC, STBAL
RECATT
Figure 6 Supply of functional blocks is controlled by input voltages V_L, V_B, V_ring
and by logic inputs PD and IMPSEL
95 9628
There are four major supply states:
1. Speech condition
2. Power down (pulse dialing)
3. Ringing
4. External supply
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.
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.
Rev. A1: 24.01.1995
Preliminary Information
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