UBA1707TS Ver la hoja de datos (PDF) - Philips Electronics

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UBA1707TS

Cordless telephone, answering machine line interface

Philips Electronics 

Philips Semiconductors

Cordless telephone, answering machine

line interface

Product specification

UBA1707

Auxiliary amplifier (pins AXI and AXO; bit AXM)

The auxiliary amplifier (see Fig.12) has one input (AXI) and one output (AXO). The input impedance between pins AXI

and GND is 3.8 kΩ. The rail-to-rail output stage is designed to drive a 500 µA peak current. The output impedance at pin

AXO is approximately 100 Ω.

The output as well as the input are biased at 2 × Vd ≅ 1.4 V DC voltage. The voltage gain from pin AXI to pin AXO is set

at 31.8 dB.The amplifier can be muted by setting bit AXM at logic 1 via the serial interface. In this case, the input

impedance between pins AXI and GND is infinite.

handbook, full pagewidth

Bit names are given in italics.

AXI

UBA1707

AXM

2Vd

AXO

MGK712

Fig.12 Auxiliary amplifier.

Loudspeaker channel (see Fig.13)

LOUDSPEAKER AMPLIFIER (PINS LSAI1, LSAI2, LSAO AND

LSPGND; BITS LSPD, LSA1 AND LSA2)

The loudspeaker amplifier has two symmetrical inputs

LSAI1 and LSAI2 selectable independently by the bits

LSA1 and LSA2 respectively. The input impedance

between pins LSAI1or LSAI2 and GND is typically 21 kΩ.

Each of these two inputs stages can accommodate signals

up to 500 mV (RMS) at room temperature for less than 2%

of Total Harmonic Distortion (THD) at minimum voltage

gain.

The inputs are biased at 2 × Vd ≅ 1.4 V DC voltage

(whatever the state of bits LSA1 and LSA2).

The rail-to-rail output stage is designed to power a

loudspeaker connected as a single-ended load (between

pins LSAO and LSPGND). The output LSAO is able to

drive at least a 150 mA peak current.

As a result, it can drive loudspeaker loads down to 8 Ω at

VCC = 4.0 V and 16 Ω at VCC = 5.5 V. The output is biased

at 1⁄2VCC. Its output voltage capability is specified for

continuous wave drive and depends on the value of VCC.

In order to avoid crosstalk from the loudspeaker to other

amplifiers, the loudspeaker current flows via pin LSPGND.

This pin must be externally connected to pin GND.

The nominal value of the voltage gain for maximum

volume from pins LSAI1 or LSAI2 to pin LSAO is set at

28 dB.

This amplifier is no longer supplied by setting the LSPD bit

at logic 1 via the serial interface.

1999 Feb 17

14

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