u4091bm-r ATMEL Corporation, u4091bm-r Datasheet - Page 7

• Manufacturer Part Number: u4091bm-r
• Description: Programmable Telephone Audio Processor
• Manufacturer: ATMEL Corporation

5. Ringing Power Converter (RPC)
6. Ringing Frequency Detector (RFD)
4872A–CORD–08/05
Figure 4-1.
The RPC transforms the input power at VRING (high voltage/low current) into an equivalent out-
put power at VB (low voltage/high current) which is capable of driving the low-ohmic
loudspeaker. The input impedance at VRING is adjustable from 3 k
(Z
The U4091BM-R provides an output signal for the microcontroller. This output signal is always
double the value of the input signal (ringing frequency). It is generated by a current comparator
with hysteresis. The levels for the on-threshold are programmable in 16 steps, the off-level is
fixed. Every change of the comparator output generates a high level at the interrupt output INT.
The information can then be read out by means of a serial bus with either normal or fast read
mode. The block RFD is always enabled.
2. Power down (pulse dialing)
3. Ringing
4. External supply
RING
When the chip is in power-down mode (bit LOMAKE), for example, during pulse dialing,
all internal blocks are disabled via the serial bus. In this condition, the voltage regula-
tors and their internal band gap are the only active blocks.
During ringing, the supply for the system is fed into VB via the Ringing Power Converter
(RPC). Normally, the speaker amplifier in single-ended mode is used for ringing. The
frequency for the melody is generated by the DTMF/Melody generator.
In an answering machine, the chip is powered by an external supply via pin VB. The
answering machine connections can be directly made to U4091BM-R. The answering
machine is connected to the pin AMREC. For the output AMREC, an AGC function is
selectable via the serial bus. The output of the answering machine will be connected to
the pin AMPB, which is directly connected to the switching matrix. This enables the sig-
nal to be switched to every desired output.
= R
IMPA
Supply Generator
/ 100) and the efficiency of the step-down converter is approximately 65%.
V
L
R
C
SENSE
R
10
1 µF
IND
300 k
R
+
-
V
+
+
-
-
3.3V
5.5V
5.5V
V
220 µF
V
47 µF
470 µF
MPS
MP
V
B
U4091BM-R
to 12 k
by R
IMPA
7