TEA1110AL-S14-R datasheet(7/9 Pages) UTC

7 / 9 page

TEA1110A

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

7 of 9

www.unisonic.com.tw

QW-R108-014.C

FUNCTIONAL DESCRIPTION(Cont.)

6.0

3.0

5.0

4.0

104

105

106

107

(1) Influence of RVA on VREF

(2) VREF without influence of RVA

Fig.2 Reference voltage adjustment by RVA

(1)

(2)

RVA (Ω)

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

0.5

1.5

(1)

(2)

Vcc (V)

(1) With RVA resistor.

(2) Without RVA resistorl

Vcc

VEE

Rccint

Vcco

Irec

PERIPHERAL

CIRCUIT

Fig.3 Typical current IP available from VCC for peripheral

circuits at ILINE=15mA.

Fig.4

VCC supply voltage for peripherals

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