u4090b-p ATMEL Corporation, u4090b-p Datasheet - Page 8

• Manufacturer Part Number: u4090b-p
• Description: U4090b-p Monolithic Integrated Feature Phone Circuit Emi Improved
• Manufacturer: ATMEL Corporation

Figure 3-3.
3.1
8
Supply Structure of the Chip
U4090B-P
LIDET
VRING
RFDO
PD
VL
Supply of Functional Blocks Controlled by Input Voltages V
QS
LIDET
The U4090B-P contains two identical series regulators which provide a supply voltage V
3.3V suitable for a microprocessor. In speech mode, both regulators are active because V
and V
itor at V
interruptions. Thus, long flash pulses can be bridged or an LCD display can be turned on for
more than 2 seconds after going on hook. When the system is in ringing mode, V
the on-chip ringing power converter. In this mode only one regulator is used to supply V
maximum of 2 mA.
A major benefit of the chip is that it uses a very flexible supply structure which allows simple real-
ization of numerous applications such as:
The special supply topology for the various functional blocks is illustrated in
• Group listening phone
• Hands-free phone
• Ringing with the built in speaker amplifier
• Answering machine with external supply
V
LON
B
RFD
are charged simultaneously by the DC-line interface. Output current is 4 mA. The capac-
MPS
supply
Power
RPC
is used to provide the microcomputer with sufficient power during long-line
TXACL
TXA
OFFSA
COMP
regulator
regulator
Voltage
Voltage
SAI,SA
SACL
L
, V
AFS
B
, V
RING
6.3V
7V
MUT REC, STBAL
and by Logic Inputs PD and IMPSEL
AGA, RA1, RA2
MIC, DTMF
TX MUTE
RECATT
ES
CONTR
IMPED
Figure
VMP
VB
IMPSEL
VMPS
B
4741C–CORD–11/05
is charged by
3-3.
MP
with a
MP
MPS
of