TS4974 datasheet(3/8 Pages) STMICROELECTRONICS

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Application Information

TS4974

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Application Information

Operation Mode

The TS4974 is a fully differential power amplifier which enables better performances in terms of noise

immunity and PSRR.

The TS4974 features a digital volume control with an internal gain range from -33dB up to +12dB, by

steps of 3dB. When the device is firstly biased, an initial gain of -12dB is internally fixed. When standby

mode is activated, the gain value is memorized and held until standby is released.

The volume is controlled by means of two pins UP and DOWN on which the application of a VIL voltage

will activate the increase or decrease in gain. The TS4974 integrates a debouncing system which does

not allow to take into account UP or DOWN pulse shorter than Tdebounce time. Moreover an autorepeat

function is implemented. When a continuous voltage is applied on UP or DOWN pin, the gain is

continuously increased or decreased after a certain time called Tautorepeat. The first period of each

autorepeat sequence is longer ( x1.5Tauto ) to avoid any parasitic activation. In this operational mode,

Trange time is necessary to cover the whole gain range of the device.

Figure 1: Typical application schematics

BIAS

DIGITAL VOLUME

CONTROL

GND

VCC

DOWN

Ω

TS4974

1µF

330nF

OUT1

STBY

STDBY

BYPASS

OUT2

DIFFERENTIAL

INPUT STAGE

Vin+

Vin-

1µF

BIAS

DIGITAL VOLUME

CONTROL

DIGITAL VOLUME

CONTROL

GND

VCC

DOWN

Ω

TS4974

1µF

330nF

OUT1

STBY

STDBY

BYPASS

OUT2

DIFFERENTIAL

INPUT STAGE

Vin+

Vin-

1µF

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