TS2007FC

Application information

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4.10

Output filter considerations

The TS2007 is designed to operate without an output filter. However, due to very sharp

transients on the TS2007 output, EMI radiated emissions may cause some standard

compliance issues.

These EMI standard compliance issues can appear if the distance between the TS2007

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

directions). 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 TS2007 output pins and the

speaker terminals.

●

Use a ground plane for shielding sensitive wires.

●

Place, as close as possible to the TS2007 and in series with each output, a ferrite bead

with a rated current of minimum 2.5 A and impedance greater than 50

Ω at frequencies

above 30 MHz.

●

Allow extra footprint to place, if necessary, a capacitor to short perturbations to ground

(Figure 45).

Figure 45.

Ferrite chip bead placement

In the case where the distance between the TS2007 output and the speaker terminals is too

long, it is possible to have low frequency EMI issues due to the fact that the typical operating

PWM frequency is 280 kHz and fall and rise time of the output signal is less than or equal to

5 ns. In this configuration, it is necessary to use the output filter represented in Figure 46 on

page 24, that consists of L1, C1, L2 and C2 as close as possible to the TS2007 outputs.

When an output filter is used and there exists a possibility to disconnect a load, it is

recommended to use an RC network that consists of C3 and R as shown in Figure 46 on

page 24. In this case, when the output filter is connected without any load, the filter acts like

a short circuit for input frequencies above 10 kHz. The RC network corrects frequency

response of the output filter and compensates this limitation.

to speaker

about 100pF

gnd

Ferrite chip bead

From TS2007 output