TS4962 datasheet(34/44 Pages) STMICROELECTRONICS

34 / 44 page

Application information

TS4962

34/44

DocID10968 Rev 9

We have the following equations.

In general, for mixed situations (single-ended and differential inputs) it is best to use the

same rule, that is, equalize impedance on both TS4962 inputs.

4.10

Output filter considerations

The TS4962 is designed to operate without an output filter. However, due to very sharp

transients on the TS4962 output, EMI-radiated emissions may cause some standard

compliance issues.

These EMI standard compliance issues can appear if the distance between the TS4962

outputs and the loudspeaker terminal is long (typically more than 50 mm, or 100 mm in both

directions, to the speaker terminals). As the PCB layout and internal equipment device are

different for each configuration, it is difficult to provide a one-size-fits-all solution.

However, to decrease the probability of EMI issues, there are several simple rules to follow.

•

Reduce, as much as possible, the distance between the TS4962 output pins and the

speaker terminals.

•

Use ground planes for "shielding" sensitive wires.

•

Place, as close as possible to the TS4962 and in series with each output, a ferrite bead

with a rated current of at least 2.5 A and an impedance greater than 50

Ω at

frequencies above 30 MHz. If, after testing, these ferrite beads are not necessary,

replace them by a short-circuit.

•

Allow enough footprint to place, if necessary, a capacitor to short perturbations to

ground (see Figure 63).

Figure 63. Method for shorting perturbations to ground

Out

–

300

in1

-------------

… V

300

ink

-------------

(V)

e q

j 1

ini

π R

ini

----------------------------------------------------- (F)

ini

----------

j 1



-------------------

Ferrite chip bead

about 100pF

Gnd

From TS4962 output

To speaker

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