UBA1706 查看數據表（PDF） - Philips Electronics

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UBA1706

Cordless telephone line interface

Philips Electronics 

Philips Semiconductors

Cordless telephone line interface

Objective specification

UBA1706

FUNCTIONAL DESCRIPTION

All data given in this chapter consists of typical values,

except when otherwise specified.

Supply (pins VCC and GND; bit PD)

The UBA1706 must be supplied with an external stabilized

voltage source across pins VCC and GND.

Without any signal and without any general purpose switch

selected, the internal current consumption is 2.2 mA at

VCC = 3.3 V. Each selected switch (pins SWI1 or SWI2)

increases the current consumption by 600 µA.

To drastically reduce current consumption, the UBA1706

is provided with a power-down mode controlled by bit PD.

When bit PD is at logic 1, the current consumption from

VCC becomes 110 µA. In the power-down mode, the serial

interface is the only function which remains active.

Line interface

DC CHARACTERISTICS (PINS LN, SLPE, REG, CST, LVI,

LCC, RGL AND GND; BIT CRC)

The IC generates a stabilized reference voltage (Vref)

across pins LN and SLPE. This reference voltage is equal

to 2.9 V, is temperature compensated and can be adjusted

by means of an external resistor (RVA). The reference

voltage can be increased by connecting the RVA resistor

between pins REG and SLPE (see Fig.3).

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

generate the stabilized reference voltage and is decoupled

by a capacitor (CREG) which is connected to GND. This

capacitor, converted to an equivalent inductance

(see Section “Set impedance”) realizes the set impedance

conversion from its DC value (RSLPE) to its AC value

(ZSET in the audio frequency range). Figure 4 illustrates

the reference voltage supply configuration. As can be seen

from Fig.4, part of the line current flows into the ZSET

impedance network and is not sensed by the UBA1706.

Therefore, using the RVA resistor to change the value of

the reference voltage will also modify all parameters

related to the line current such as:

• The AGC

• The DC mask management

• The low voltage area characteristics.

In the same way, changing the value of ZSET also affects

the characteristics. The IC has been optimized for

Vref = 2.9 V and ZSET = 619 Ω.

8.5

handVboreokf, halfpage

(V)

7.5

6.5

5.5

4.5

3.5

2.5

103

(1)

(2)

104

MGK706

105 RVA (Ω) 106

(1) Influence of RVA on Vref.

(2) Vref without influence of RVA.

Fig.3 Reference voltage adjustment with RVA.

The IC regulates the line voltage at pin LN, which can be

calculated as follows:

VLN = Vref + RSLPE × ISLPE

ISLPE = Iline – IZSET – I* ≅ Iline – IZSET

Where:

Iline = line current

IZSET = current flowing through ZSET

I* = current consumed between LN and GND

(approximately 100 µA).

The preferred value for RSLPE is 10 Ω. Changing RSLPE will

affect more than the DC characteristics; it also influences

the transmit gain, the gain control characteristics, the

sidetone level and the maximum output swing on the line.

Nevertheless, for compliance with CTR21, 8.66 Ω is the

optimum value for RSLPE.

1999 Jun 04

6

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