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TEA1097

Speech and loudspeaker amplifie IC with auxiliary inputs/outputs and analog multiplexer

Philips Electronics 

Philips Semiconductors

Speech and loudspeaker amplifier IC with

auxiliary inputs/outputs and analog multiplexer

Product specification

TEA1097

108

handbook, full pagewidth

IDD

(pA)

107

FCA050

106

105

104

103

102

10

1.0

1.5

2.0

2.5

3.0

VDD (V)

Fig.6 Current consumption on VDD.

SUPPLY FOR MICROPHONE (PINS MICS AND GNDTX)

The MICS output can be used as a supply for an electret

microphone. Its voltage is equal to 2 V; it can source

current up to 1 mA and has an output impedance equal to

200 Ω.

LOW VOLTAGE BEHAVIOUR

For line currents below 9 mA, the reference voltage is

automatically adjusted to a lower value; the VBB voltage

follows the SLPE voltage with 250 mV difference.

The excess current available for other purposes than DC

biasing of the IC becomes small. In this low voltage area,

the IC has limited performances.

When the VBB voltage reaches 2.7 V, the VBB detector of

the receive dynamic limiter on pin LSAO acts continuously,

discharging the capacitor at pin DLC. In the DC condition,

the loudspeaker is automatically disabled below this

voltage.

When VBB becomes lower than 2.5 V, the TEA1097 is

forced in a low voltage mode whatever the levels on the

logic inputs are. It is a speech mode with reduced

performances only enabling the microphone channel

(between the MIC inputs and LN) and the earpiece

amplifier. These two channels are able to deliver signals

for line currents as small as 3 mA. The HFC input is tied to

GND sinking a current equal to 300 µA (typ.).

POWER-DOWN MODE (PINS PD AND AUXC)

To reduce current consumption during dialling or register

recall (flash), the TEA1097 is provided with a power-down

input (PD). When the voltage on pins PD and AUXC is

LOW, the current consumption from VBB and VDD is

reduced to 460 µA (typ.). Therefore a capacitor of 470 µF

connected to pin VBB is sufficient to power the TEA1097

during pulse dialling or flash. The PD input has a pull-up

structure, while AUXC has a pull-down structure. In this

mode, the capacitor CREG is internally disconnected.

1999 Apr 08

10

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