2.1-channel applications using two devices

AN4569

20/29

DocID026803 Rev 1

3.1.7

EMI filter

Figure 18. Schematics for EMI filter section

The purpose of the EMI filter is to avoid radiated emission. It is composed of three

capacitors: two 10 nF capacitors must be connected to GND and one 1nF capacitor must be

connected parallel to the speaker. The values of this capacitor must be trimmed in the

application.

3.2

Software configuration

No SW modifications are needed for the device that works in stereo BTL mode.

For the device that works in mono BTL mode, change the register configuration 0x05

(configuration register F) from 0x5C (default) to 0x5F to set to a single channel

configuration.

To switch on the power bridge, set to one the bit D7 of register 0x05.

To adjust the volume using a mono BTL device, change the channel 3 volume register

(address 0x0A).