SI3000PPT-EVB Silicon Laboratories Inc, SI3000PPT-EVB Datasheet - Page 14

• Manufacturer Part Number: SI3000PPT-EVB
• Description: BOARD EVALUATION FOR SI3000
• Manufacturer: Silicon Laboratories Inc

Specifications of SI3000PPT-EVB

• Main Purpose: Audio, CODEC
• Utilized Ic / Part: SI3000
• Description/function: Audio CODECs
• Product: Audio Modules
• For Use With/related Products: Si3000
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Si3000
2. Functional Description
The Si3000 is a highly integrated voice bandwidth audio
codec which contains a single 16-bit A/D converter and
D/A converter. The analog input path contains a
microphone input with selectable gain, a line level input
with selectable gain, and a handset input. Each of the
inputs go through a mixer prior to A/D conversion. The
result of this A/D conversion is a 16-bit 2s complement
signed number. Following the A/D converter is a digital
programmable gain amplifier. The analog output path
contains a digital programmable gain amplifier feeding a
single 16-bit D/A converter. The DAC output is provided
to a line output, a headphone drive output, and a
handset output. Control for the various functions
available on the Si3000 as well as the audio data are
communicated to the device over a serial interface.
The Si3000 can be connected directly to the Si3035,
Si3034, Si3044, or Si3056 in modem applications
requiring a voice channel, or the device can be used as
a stand-alone codec in other voice band applications.
The Si3000 offers high integration, and it needs only a
few low-cost, discrete components as shown in
Figure 13.
2.1. Analog Inputs
The typical connection diagram (Figure 13) shows the
recommended external analog circuitry for the Si3000.
The device supports three mono analog inputs—line
level, microphone level, and a handset input. Each of
these inputs is provided to a mixer circuit prior to A/D
conversion. Each analog input may also be muted by
writing the appropriate bits in the control registers.
Unused analog inputs should be tied to GND through a
0.1 F capacitor. This prevents any DC current flow.
14
DSP
Figure 14. Si3000 with Silicon Labs DAA System Diagram
System-Side
Voice Codec
Device
Si3000
DAA
Si3034/35/44/56 Chipsets
Rev. 1.4
2.2. Pre-amp/Microphone Bias Circuit
An internal amplifier with a selectable gain of 0 dB,
10 dB, 20 dB, or 30 dB is provided for the MIC input and
an internal amplifier with a selectable gain of 0 dB,
10 dB, or 20 dB, is provided for the LINEI input. AC
coupling is required for both inputs because any DC
offset on the input will be amplified if gain is selected.
Gain settings for the LINEI and MIC inputs are achieved
by writing the RX Gain Control 1 register 5. When gain
is disabled, these inputs become line level inputs with a
full-scale input of 1 Vrms.
A microphone bias circuit is provided on-chip which
consists of a 2.5 V reference output capable of sourcing
up to 5 mA of current. This circuit can be used for active
microphones requiring a bias source.
2.3. Programmable Input Gain/Attenuation
The signals from the microphone, line, or handset inputs
are mixed and then routed to the A/D converter and a
digital programmable gain circuit which provides up to
12 dB of gain or –34.5 dB of attenuation in 1.5 dB steps.
Level changes only take effect on zero crossings to
minimize audible artifacts. The requested level change
is implemented if no zero crossing is found after 256
frames. Write the ADC Volume Control register 6 to set
digital input gain/attenuation.
2.4. Analog Outputs
The analog outputs of the D/A converter are routed to a
line level output (LINEO), a pair of speaker outputs
(SPKRL and SPKRR), and a handset. Each analog
output can be independently muted.
Line-Side
Device
SPKR
DAA
Line
Discretes
Mic
Handset
TIP
RING