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TEA1110A View Datasheet(PDF) - Unisonic Technologies

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TEA1110A Datasheet PDF : 9 Pages
1 2 3 4 5 6 7 8 9
TEA1110A
LINEAR INTEGRATED CIRCUIT
„ FUNCTIONAL DESCRIPTION(Cont.)
Fig.2 Reference voltage adjustment by RVA
6.0
5.0
4.0
(1)
(2)
3.0
104
105
106
107
RVA (Ω)
(1) Influence of RVA on VREF
(2) VREF without influence of RVA
The internal circuitry of the UTC TEA1110A is supplied from pin VCC which can be used to supply peripheral
circuits such as dialling or control circuits. This voltage supply is derived from the line voltage by means of a resistor
(RCC) and it must be decoupled by a capacitor CVCC. The VCC voltage depends on the current consumed by the IC
and the peripheral circuits as shown by the formula :( RCCint is the internal equivalent resistance of the voltage
supply, and Irec is the current consumed by the output stage of the earpiece amplifier))
VCC= VCC0 - RCCint × (IP-IREC)
V CC0= VLN-RCC × ICC (see also Figs 3 and 4).
The DC line current flowing into the set is determined by the exchange supply voltage (Vexch), the feeding
bridge resistance (Rexch), the DC resistance of the telephone line (Rline) and the reference voltage (VREF). The
internal reference voltage (generating VREF) would be automatically adjusted to a lower value when the line currents
drop below 7.5mA. Therefore, more sets can work in parallel with DC line voltages (excluding the polarity guard)
down to 1.6V (absolute minimum voltage). At currents below 7.5mA, the circuit has limited sending and receiving
levels. This is called the low voltage area.
2.5
2
1.5
1
(2)
0.5
(1) With RVA resistor.
(2) Without RVA resistorl
0
0
1
2
Vcc (V)
(1)
3
4
Fig.3 Typical current IP available from VCC for peripheral
circuits at ILINE=15mA.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
Rccint Vcc
+
Vcco
Irec
PERIPHERAL Ip
CIRCUIT
VEE
Fig.4 VCC supply voltage for peripherals
7 of 9
QW-R108-014.C
 

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