U4091BM Datasheet, PDF (5/29 Pages) TEMIC Semiconductors – Programmable Telephone Audio Processor

U4091BM
For line voltages below 2 V, the switches remain in _{Ringing Frequency Detector (RFD)}
quiescent state as shown in the diagram.
The U4091BM provides an output signal for the
2. When the chip is in power-down mode (Bit ^{microcontroller. This output signal is always double the}
LOMAKE), e.g., during pulse dialing, all internal ^{value of the input signal (ringing frequency). It is}
blocks are disabled via the serial bus. In this condition, ^{generated by a current comparator with hysteresis. The}
the voltage regulators and their internal bandgap are ^{levels for the on-threshold are programmable in 16 steps;}
the only active blocks.
the off-level is fixed. Every change of the comparator
output generates a high level at the interrupt output INT.
3. During ringing, the supply for the system is fed into The information can then be read out by means of a serial
VB via the Ringing Power Converter (RPC). bus with either normal or fast read mode. The block RFD
Normally, the speaker amplifier in single-ended mode is always enabled.
is used for ringing. The frequency for the melody is
generated by the DTMF/Melody generator.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _{4. In an answering machine, the chip is powered by an}
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ external supply via Pin VB. The answering machine
connections can be directly put to U4091BM. The
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _{answering machine is connected to the Pin AMREC.}
RINGTH[0:3]
0
15
VRING
7V
22 V
step
1V
Clock Output Divider Adjustment
For the output AMREC, an AGC function is select-
able 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, and thus
enables the signal to be switched to every desired
output.
The Pin OSCOUT is a clock output which is derived from
the crystal oscillator. It can be used to drive a micro-
controller or another remote component and thereby
reduces the number of crystals required. The oscillator
frequency can be divided by 1, 8, 16, 32. During power-on
reset, the divider will be reset to 1 until it is changed by
setting the serial bus.
V_L R_SENSE
10 Ω
C
1 µF
+
IND
–
–
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _{5.5 V}
V_MPS
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _470µF
CLK[0:1]
0
1
2
3
Divider
1
8
16
32
Frequency
3.58 MHz
447 kHz
224 kHz
112 kHz
+ _{3.3 V VMP Serial Bus Interface}
R
R
300 kΩ
V
+
47 µF
–
5.5 V
V_B
220µF
14573
Figure 3. Supply generator
Ringing Power Converter (RPC)
The circuit is controlled by an external microcontroller
through the serial bus.
The serial bus is a bi-directional system consisting of a
one-directional clock line (SCL) which is always driven
by the microcontroller, and a bi-directional data-signal
line. It is driven by the microcontroller as well as from the
U4091BM (see fig. 23).
The serial bus requires external pull-up resistors as only
pull-down transistors (Pin SDA) are integrated.
WRITE: The data is a 12-bit word:
The RPC transforms the input power at VRING (high
voltage/ low current) into an equivalent output power at
VB (low voltage/ high current) which is capable of
driving the low-ohmic loudspeaker. The input impedance
W W at VRING is adjustable from 3 k to 12 k by RIMPA
(ZRING = RIMPA / 100) and the efficiency of the step-
down converter is approximately 65%.
A0 – A3: address of the destination register (0 to 15)
D0 – D7: content of the register
The data line must be stable when the clock is high. Data
must be shifted serially.
After 12 clock periods, the write indication is sent. Then,
the transfer to the destination register is (internally)
generated by a strobe signal transition of the data line
when the clock is high.
Rev. A1, 02-Jun-98
5 (29)
Target Specification