UBA2050 データシートの表示（PDF） - Philips Electronics

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UBA2050

One-chip telephone ICs with speech, dialler and ringer functions

Philips Electronics 

Philips Semiconductors

One-chip telephone ICs with speech,

dialler and ringer functions

Product specification

UBA2050(A); UBA2051(A;C)

handbook, halfpage

LN 1

SLPE 2

28 VCC

27 MIC−

REG 3

26 MIC+

IR 4

25 RX

AGC 5

24 GAR

DTMF 6

VDD 7

XTAL 8

23 QR

22 GND

UBA2051CT

21 R1

DP/FL 9

20 R2

KT 10

19 R3

CE/CSI 11

18 R4

CE/FDI 12

17 C1

MDY/TONE 13

16 C2

C4 14

15 C3

FCA128

Fig.6 Pin configuration (UBA2051CT).

FUNCTIONAL DESCRIPTION

The values given in the functional description are typical

values unless otherwise specified.

For numbering of components, refer to Figs 7, 37 and 38.

Voltage levels are referenced to the negative line terminal

GND, except when otherwise specified.

Speech/transmission part

SUPPLY

The supply for the IC and its peripheral circuits is obtained

from the telephone line (see Fig.7).

Line interface (pins LN, SLPE and REG)

The IC generates a stabilized reference voltage Vref

between pins LN and SLPE. This reference voltage is

4.15 V, is temperature compensated and can be adjusted

by means of an external resistor RVA.

The reference voltage can be increased by connecting the

resistor RVA between pins REG and SLPE or decreased by

connecting the resistor RVA between pins REG and LN.

The voltage at pin REG is used by the internal regulator to

generate Vref and is decoupled by capacitor CREG

connected between pins REG and GND. This capacitor,

converted into an equivalent inductance (see Section “Set

impedance”), realizes the set impedance conversion from

its DC value (RSLPE) to its AC value (RCC in the audio

frequency range).

The voltage at pin SLPE is proportional to the line current,

and the voltage VLN at pin LN can be calculated as follows:

VLN = Vref + RSLPE × ISLPE

ISLPE = Iline − ICC − IP − ISUP

where:

Iline = line current

ICC = internal current consumption

IP = supply current for peripheral circuits

ISUP = current consumed by the VDD regulator from

pin LN.

Resistor RSLPE is an external resistor connected between

pins SLPE and GND. The preferred value for RSLPE is

20 Ω. Changing the value of RSLPE will affect more than

the DC characteristics: it also influences the microphone

and DTMF gains, the gain control characteristics, the

sidetone level and the maximum output swing on the line.

The DC 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 excess current

is shunted via pin LN to pin SLPE when the line current

(Iline) is greater than the sum of the supply current of the

speech/transmission part (ICC), the current drawn by the

peripheral circuitry connected to VCC (IP) and the input

current of the VDD regulator (ISUP). With line currents below

Ilow (9 mA), the internal reference voltage (generating Vref)

is automatically adjusted to a lower value.

This means that more sets can operate in parallel with

DC line voltages (excluding the polarity guard) down to an

absolute minimum voltage of 1.45 V. At line currents

below Ilow, the circuit has limited sending and receiving

levels. This is called the low voltage area.

2000 May 19

8

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