GENERAL DESCRIPTION

The TDA1074A is a monolithic integrated circuit designed for use as volume and tone control circuit in stereo amplifiers. This dual tandem potentiometer IC consists of two ganged pairs of electronic potentiometers with the eight inputs connected via impedance converters, and the four outputs driving individual operational amplifiers. The setting of each electronic potentiometer pair is controlled by an individual d.c. control voltage. The potentiometers operate by current division between the arms of cross-coupled long-tailed pairs. The current division factor is determined by the level and polarity of the d.c. control voltage with respect to an externally available reference level of half the supply voltage. Since the electronic potentiometers are adjusted by a d.c. control voltage, each pair can be controlled by single linear potentiometers which can be located in any position dictated by the equipment styling. Since the input feedback impedances around the operational amplifier gain blocks are external, the TDA1074A can perform bass/treble and volume/loudness control. It also can be used as a low-level fader to control the sound distribution between the front and rear loudspeakers in car radio installations.

Features

• High impedance inputs to both ‘ends’ of each electronic potentiometer

• Ganged potentiometers track within 0,5 dB

• Electronic rejection of supply ripple

• Internally generated reference level available externally so that the control voltage can be made to swing positively

and negatively around a well-defined 0 V level

• The operational amplifiers have push-pull outputs for wide voltage swing and low current consumption

• The operational amplifier outputs are current limited to provide output short-circuit protection

• Although designed to operate from a 20 V supply (giving a maximum input and output signal level of 6 V), the

TDA1074A can work from a supply as low as 7,5 V with reduced input and output signal levels.