U4090B Datasheet, PDF (14/34 Pages) TEMIC Semiconductors – Monolithic Integrated Feature Phone Circuit

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
W ^{ohmic loudspeaker. Input impedance at VRING is fixed}
at 5 k and the efficiency of the step down converter is
approx. 65%.
7
R_DC=∞
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
m m ^{with hysteresis. Input voltage VRING is transformed into}
a current via RTHA. Thresholds are 8 A and 24 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.
6
W R_DC=130k
5
W R_DC=68k
4
3
10 12
14
16
18
20
94 9131
I_L ( mA )
W ^{= ILON}
= ILOFF
at line impedance = 600
W ^{= ILON} at line impedance = 900
= 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
Pin 17
Symbol
Value
Unit
I_L
140
mA
V_L
12
V
I_RING
15
mA
T_j
125
°C
T_amb
– 25 to + 75
°C
T_stg
– 55 to + 150
°C
P_tot
0.9
W
14 (34)
TELEFUNKEN Semiconductors
Preliminary Information
Rev. C1, 28-Oct-96