TDA4390-2X Datasheet, PDF (9/39 Pages) Siemens Semiconductor Group – Audioprocessor

TDA 4390-2X
2
Circuit Description
2.1 Signal Processing
1. The selection of the AF inputs happens in the input switch. There are four stereo
inputs available. An input level switch circuitry behind the input switch realizes the
adaption of different signal source levels. A gain of 0 dB or 6 dB is possible. After this
section a stereo output/input is placed for connecting external circuits like an
equalizer.
2. In the following signalpath there is tone control, consisting of bass and treble control.
Bass control offers a control range of + 18 dB to – 12 dB with a stepwidth of 2 dB.
Frequency characteristic, 1st order or 2nd order (resonance type) is fixed by external
components. Treble control offers a control range of ± 12 dB with a stepwidth of 2 dB.
The treble control corner frequency is fixed by an external capacitor. Last stage in
signalpath is volume control which can be adjusted independent for left, right, rear and
front. 57 steps with an increment of 1.25 dB give a setting range of 70 dB, the 57th
step activates muting.
2.2 Controlpart
All functions are controlled via an I²C Bus interface. All data is stored into a latch circuit.
The telegram structure is built as follows:
Startcondition – chipaddress – any number of databytes – stopcondition.
For the databytes the following conditions must be fulfilled:
Before transmitting a databyte a subaddress byte must first be placed in the data
telegram.
Semiconductor Group
9
02.96