U2090B
| Model | U2090B |
| Description | Monolithic Integrated Feature Phone Circuit |
| PDF file | Total 34 pages (File size: 675K) |
| Chip Manufacturer | ATMEL |
U4090B
Ringing power converter (RPC)
RPC transforms the input power at VRING (high voltage/
low current) into an equivalent output power at V
B
(low
voltage/ high current), which is capable of driving the low
ohmic loudspeaker. Input impedance at VRING is fixed
at 5 k
W
and the efficiency of the step down converter is
approx. 65%.
7
R
DC
=∞
6
V
L
( V )
R
DC
=130k
W
5
R
DC
=68k
W
Ringing frequency detector (RFD)
The U4090B offers an output signal for the micro-
controller, which is a digital representation of the double
ringing frequency. It is generated by a current comparator
with hysteresis. Input voltage VRING is transformed into
a current via RTHA. Thresholds are 8
m
A and 24
m
A.
RFDO and VRING are in phase. A second comparator
with hysteresis is used to enable the output RFDO, as long
as the supply voltage for the microprocessor VMP is
above 2.0 V.
4
3
10
94 9131
12
14
16
18
20
I
L
( mA )
= ILON
at line impedance = 600
W
= ILOFF
= ILON
at line impedance = 900
W
= ILOFF
Figure 11. Comparator thresholds depend on dc mask and line
impedance
Absolute Maximum Ratings
Parameters
Line current
DC line voltage
Maximum input current
Junction temperature
Ambient temperature
Storage temperature
Total power dissipation, T
amb
= 60°C
Symbol
I
L
V
L
I
RING
T
j
T
amb
T
stg
P
tot
Value
140
12
15
125
– 25 to + 75
– 55 to + 150
0.9
Unit
mA
V
mA
°C
°C
°C
W
Pin 17
14 (34)
Preliminary Information
TELEFUNKEN Semiconductors
Rev. C1, 28-Oct-96
