This article introduces the main features of Si2704/05/06/07, functional block diagrams, typical application circuit diagrams and bill of materials, as well as various system configuration diagrams and main features of the Si270x-EVB Class D amplifier development kit.
Silabs' Si2704/05/06/07 is a EMI-reduced digital audio processing Class D amplifier that integrates power stage, PWM DAC and digital audio processing (DAP) to simplify the design of low cost, high efficiency systems. Si270x has digital inputs Delta-Sigma PWM, patent-pending EMI, AM-band noise-free notch filter capable of outputting 2x5W to 3 ohm BTL, 88% efficiency with PSRR greater than 50dB, and 95dB dynamic range when THD is better than 0.1% Mainly used in PMP/MP3 docking stations, handheld consumer electronics, active/wireless speakers, TV and monitors, and TV sound cards.
Si2704/05/06/07 Application:
PMP/MP3 docking staTIons
Portable consumer audio electronics
Table top and portable radios
AcTIve/wireless speakers
TVs and monitors
TV sound bars 
Figure 1. Functional block diagram of Si2704/05/06/07 
Figure 2. Si2704/05/06/07 Typical Application Circuit Diagram Typical Application Circuit Bill of Materials (BOM): 
Figure 3. Basic configuration of the Si270x PMP docking station system 
Figure 4. Si270x PMP docking station system configuration with radio and digital media control 
Figure 5. Si270x Stereo Bidirectional Speaker System Configuration Diagram 
Figure 6. Si270x TV sound card system configuration diagram
Si270x-EVB Class D Amplifier Development Kit
Si270x-EVB Class D Amplifier Development Kit 
Figure 7. Outline drawing of the Si270x-EVB Class D Amplifier Development Kit
The Si270x Class D amplifier EVB consists of a baseboard and a daughter card. The baseboard is common and shared among all the Si270x 5 W per channel Class D audio amplifier daughter cards. The Si270x-EVB kit addresses the enTIre Si270x family of Class D amplifier Products.
The daughter card is populated with the Si2707 Class D amplifier which provides the following:
EMI miTIgation
Volume and tone controls
EQ and Dynamic Range Compressor DSP functions
Tunable noise-free notch for AM radio coexistence
The Si270x Class D amplifier EVB is supported by a full function graphical user interface (GUI) that runs on a standard PC and is connected to the EVB via USB. The baseboard includes the Si4730 AM/FM tuner, a stereo analog input, as well The daughter card also includes the required output filtering network. Speakers with impedances of 4 Ω and larger may be directly driven from this board; a separate line level output is provided.
The Si270x-EVB Class D Amplifier development kit includes:
Si270x Evaluation Board
External power supply
AM/FM adapter card and antennas cable
Audio cable
Documentation and software CD
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