TS2007FC datasheet(28/33 Pages) STMICROELECTRONICS

28 / 33 page

Application information

TS2007FC

28/33

DocID14937 Rev 4

Figure 46. Ferrite chip bead placement

In the case where the distance between the TS2007FC 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 the 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 shown in

Figure 47, that consists of L1, C1, L2, and C2 as close as possible to the TS2007FC

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 47. 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 the frequency response

of the output filter and compensates this limitation.

Figure 47. LC output filter with RC network

Table 12. Example of component choice

Component

RL = 4 Ω

RL = 8 Ω

μH/1.4 A

μH/0.7 A

μF/10 V

R22

Ω/0.25 W

to speaker

about 100pF

gnd

Ferrite chip bead

From TS2007FC output

from TS2007FC

LCOutput Filter

OUT+

OUT-

RC network

TS2007FC Datenblatt(PDF) 28 Page - STMicroelectronics