ICM7101D IC MICROSYSTEMS, ICM7101D Datasheet - Page 3

• Manufacturer Part Number: ICM7101D
• Description: Low Cost Single Chip Telephone Ic
• Manufacturer: IC MICROSYSTEMS

FUNCTIONAL DESCRIPTION
SYSTEM STARTUP
ICM7101D generates internal power-on-reset
when VDD reaches around 1.5V. Power-on-
reset appropriately initiates the system to a
known initial state.
ICM7101D stays in shutdown mode so long as
HS/DPB pin stays LOW. However, the ringer
circuitry is activated in this mode to monitor the
incoming ringing signal.
OSCILATOR
All the timing of ICM7101D is based on a clock
frequency of 3.58 MHz. A Crystal or ceramic
resonator
connected to oscilator pins of ICM7101D. Care
has to be taken in selecting this components
since in practise minor deviations from the
nominal frequency may occur due to the
characteristics of the oscillator.
It is recommended to connect a small value
capcitors (≤ 47pF) in parallel with the oscillator
to ensure start-up and or operation at the
nominal frequency.
TONE RINGER
The tone ringer of ICM7101D consists of ring
detection circuit and melody generator circuit.
Ring Detection Circuit
Ring detection circuit will assures the signal
that present on RGD pin input is valid. The
signal is considered as a valid signal if the
signal has frequencies between 13Hz and
70Hz.
Melody Generator
Once the valid ring signal is detected on the
Ring Detection (RGD) pin and is present for
about 75 ms continously, the melody generator
will be actived, the ring signal will be monitored
continously and the melody generator will be
immediately turn on or off according to the
momentary presence of a valid or unvalid ring
signal respectively until next power on reset or
off-hook. The melody generator of ICM7101D
creates 2 frequencies of 874Hza and 1250Hz.
Rev. 2.4
of
ICmic reserves the right to change the specifications without prior notice
this
frequency
L
should
OW
C
be
OST
S
INGLE
SPEECH NETWORK
The speech network of ICM7101D consists of
a transmitter and a receiver path, side tone
cancellation and line loss compensation.
The speech network is activated as soon as
the phone goes off-hook (i.e. when HS/DPB
pin goes HIGH). At the same time the ringer
circuitry is deactivated.
Transmit
For 600 ohm termination, the transmit gain
from microphone input to the line voltage is
35dB.
Receive
Receive path gain is 3dB for 600 ohm
termination.
Side Tone Cancellation
As shown in the typical application circuit in
Appendix A, side tone cancellation can be
achieved best by balancing the Whitestone
bridge comprised of R11, R12, R13+R14//C6,
and the line impedance.
Line Loss Compensation
LLC input level is scanned as the phone goes
off-hook (i.e. as HD/DPB pin goes HIGH). At
the same time, the loop current level is sensed
and determined. If LLC=0, no compensation
scheme is in effect.
If LLC=AGND, “low” compensation scheme is
in effect. Transmit and receive gains are
reduced by as much as 6dB when the loop
current exceeds 50mA.
If LLC=VDD, “high” compensation scheme is in
effect. Transmit and receive gains are reduced
by as much as 6dB when the loop current
exceeds 75mA.
AC Impedance
Placing a resistor between CI and AGND pins
adjusts the AC impedance. If such resistor is
not present, the typical AC impedance is 1000
ohm.
C
HIP
ICM7101D
T
ELEPHONE
IC
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