ILA1062A データシートの表示（PDF） - IK Semicon Co., Ltd
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ILA1062A Datasheet PDF : 11 Pages
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FUNCTIONAL DESCRIPTION
Supplies VCC, LN, SLPE, REG and STAB
Power for the IC and its peripheral circuits is usually
obtained from the telephone line. The supply voltage is
delivered from the line via a dropping resistor and
regulated by the IC. The supply voltage VCC may also
be used to supply external circuits e.g. dialing and
control circuits.
Decoupling of the supply voltage is performed by a
capacitor between VCC and VEE . The internal voltage
regulator is decoupled by a capacitor between REG and
VEE.
The DC current flowing into the set is determined by
the exchange supply voltage Vexch , the feeding bridge
resistance Rexch and the DC resistance of the telephone
line Rline .
The circuit has internal current stabilizer operating at a
level determined by a 3.6 kΩ resistor connected
between STAB and VEE (see Fig.6). When the line
current (Iline) is more than 0.5mA greater than the sum
of the IC supply current (ICC) and the current drawn by
the peripheral circuitry connected to VCC (Ip) the excess
current is shunted to VEE via LN.
The regulated voltage on the line terminal (VLN) can be
calculated as:
VLN = Vref + ISLPE x R9
VLN = Vref + {(Iline - ICC - 0.5 x 10-3A) - Ip} x R9
Vref is an internally generated temperature compensated
reference voltage of 3.7V and R9 is an external resistor
connected between SLPE and VEE.
In normal use the value of R9 would be 20Ω.
Changing the value of R9 will also affect microphone
gain, DTMF gain, gain control characteristics, sidetone
level, maximum output swing on LN and the DC
characteristics (especially at the lower voltages).
ILA1062/1062A
Under normal conditions, when ISLPE >>ICC + 0.5mA +
Ip, the static behaviour of the circuit is that of a 3.7V
regulator diode with an internal resistance equal to that
of R9. In the audio frequency range the dynamic
impedance is largely determined by R1. Fig.2 show the
equivalent impedance of the circuit.
At line currents below 9mA the internal reference
voltage is automatically adjusted to a lower value
(typically 1.6V at 1mA). This means that more sets can
be operated in parallel with DC line voltage (excluding
the polarity guard) down to an absolute minimum
voltage of 1.6V. At line currents below 9mA the circuit
has limited sending and receiving levels. The internal
reference voltage can be adjusted by means of an
external resistor (RVA). This resistor when connected
between LN and REG will decrease the internal
reference voltage and when connected between REG
and SLPE will increase the internal reference voltage.
Microphone inputs MIC+ and MIC- and gain pins
GAS1 and GAS2
The circuit has symmetrical microphone inputs. Its
input impedance is 64 kΩ (2 x 32kΩ) and its voltage
gain is typically 52 dB (when R7 = 68kΩ; see Fig.6).
Dynamic, magnetic, piezo-electric or electret (with
built-in FET source followers) can be used.
The gain of the microphone amplifier can be adjusted
between 44 dB and 52 dB to suit the sensitivity of the
transducer in use. The gain is proportional to the value
of R7 which is connected between GAS1 and GAS2.
Stability is ensured by two external capacitors, C6
connected between GAS1 and SLPE and C8 connected
between GAS1 and VEE. The value of C6 is 100pF but
this may be increased to obtain a first-order low-pass
filter. The value of C8 is 10 times the value of C6. The
cut-off frequency corresponds to the time constant R7 x
C6.
Input MUTE (ILA1062A)
When MUTE is LOW or open-circuit, the DTMF input
is enable and the microphone and receiving amplifier
inputs are inhibited. The reverse is true when MUTE is
HIGH.
MUTE switching causes only negligible clicking on the
line and earpiece output. If the number of parallel sets
in use causes a drop in line current to below 6 mA the
DTMF amplifier becomes active independent to the DC
level applied to the MUTE input.
Fig.2 Equivalent impedance circuit
2011, March, ver.01
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