PCA1070T データシートの表示（PDF） - Philips Electronics
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PCA1070T Datasheet PDF : 36 Pages
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Philips Semiconductors
Multistandard programmable analog
CMOS transmission IC
Product specification
PCA1070
Speech condition
After hook-off, line current will be applied to the line input
LN and the supply capacitor connected to VDD and VMC
will be charged.
The internal reset signal will change from logic 1 to logic 0
when VDD passes the threshold level (1.2 V) and the circuit
becomes partly active [the line interface part is kept in
power-down mode, so that all of the line current is
available to charge the supply capacitor(s)];
The PCA1070 can receive data via the I2C-bus (standard
I2C specifications are fulfilled for VDD ≥ 2.5 V; relaxed
performance for VDD = 1.8 to 2.5 V).
When VVMC passes the microcontroller reset level of 2 V
(2.1 V in standby mode) the output RMC changes from
logic 1 to logic 0 and the circuit is switched to the normal
operating mode.
After hook-on VVMC decreases and the output RMC will
change from logic 0 to logic 1 when VVMC passes the
threshold level, however the PCA1070 will stay in the
normal operating mode until the internal reset at 1.2 V
takes place.
By decreasing VDD the internal reset signal will change
from logic 0 to logic 1 when VDD passes 1.2 V and the
circuit will go into the reset mode (line interface part in
power-down and all programmable parameters reset to
default values).
Ringer condition
In this condition the supply capacitor connected to VDD and
VMC is charged by the rectified ringer signal; no line
current is applied to pin LN.
VDD and VVMC are increasing and when VDD passes the
internal reset threshold level (1.2 V), the internal
ring/speech-detector will be activated and the circuit will
switch to the standby condition (IDD < 5 µA; IVMC < 5 µA)
before the voltage at VMC reaches the threshold level for
microcontroller reset. When VVMC passes this threshold
level (2.1 V) output RMC changes from logic 1 to logic 0
and the circuit will stay in the standby mode until line
current is applied to pin LN. By setting the ‘Reset Ring’
control bit (RRG) to logic 1 via the I2C-bus interface, the
ring/speech detector will be disabled.
DIAL PULSE INPUT (DPI)
The DPI bit controls output DOC (open-drain) that drives
the gate of an external MOS interrupter transistor. DPI is
controlled via the I2C-bus interface.
If DPI is set to logic 1, pin DOC will be pulled down to
switch-off the MOSFET to generate a line break. If DPI = 0
pin DOC is high-ohmic and the interrupter transistor will
conduct the line current.
Sending channel
The PCA1070 has symmetrical microphone inputs and
accepts input signals of maximum 70 mV (peak) for
THD = 2% (VDD ≥ 2.5 V). Its input impedance is 100 kΩ
and its gain is default 41 dB. Dynamic, magnetic,
piezoelectric and electret (with built-in FET source
follower) microphones can be used. Some possible
microphone arrangements are shown in Fig.5.
The gain of the sending channel can be programmed
between 30 dB and 51 dB in 1 dB steps using bit code
GMAx (6 bits). The gain of the microphone preamplifier is
20 dB (with dynamic limiter not active) and GMAx sets the
gain of the ‘sending prog-amp’ (allowed range
Gma = 4 to 25 dB). The gain of the line interface is 6 dB.
Thus the total gain of the sending channel (GM) is as
follows:
GM = 20 + Gma + 6 (dB)
Default: GM = 20 + 15 + 6 = 41 dB
Where Gma = ‘gain sending prog-amp’.
Programming the gain of the ‘sending prog-amp’ is given
in Table 13.
1997 Jun 20
7
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