Silicon Laboratories SiM3U1xx Manual do Utilizador descarregar pdf (Página 20)

AN726

20 Rev. 0.1

6.3. Revision 1.0 High Power Configuration

Instead of directly driving the speaker, the high-drive I/O can interface with external MOSFETs as shown in

Figure 22, enabling higher-power applications. The board includes footprints for these external MOSFETs to

enable development with this configuration. The pull-up and pull-down resistors (~100 k) ensure that the tristate

reset state of the high drive I/O does not cause the FETs to accidentally conduct current. When using these

external MOSFETs, uninstall the R32, R35, R38, and R41 0  resistors.

Figure 23 illustrates an alternate full-bridge high-power output network. The diode and RC circuits on the MOSFET

gates ensure that the two devices will not both be conducting simultaneously.

Figure 22. Half-Bridge Class-D Output Network–External MOSFETs

The Revision 1.0 hardware provides footprints to a 9 V dc adapter connector and high power LDO. These

components can be populated to provide a higher current source to the external MOSFET transistors and VIOHD.

Alternatively, an external supply can connect to the transistors alone by removing the R48 0  resistor and placing

the positive terminal on the P_PWR test point.

VIOHD

PB4.0 (R+)

PB4.1 (R-)

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