POE-VOICE-RD Silicon Laboratories Inc, POE-VOICE-RD Datasheet - Page 2

• Manufacturer Part Number: POE-VOICE-RD
• Description: KIT REF DESIGN PWR OVER ETHERNET
• Manufacturer: Silicon Laboratories Inc

Specifications of POE-VOICE-RD

• Main Purpose: Reference Design, Power Over Ethernet , Voice Transmission
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: C8051F340, CP2201, Si3400
• Primary Attributes: Embedded Ethernet, Power over Ethernet, 8 kHz Voice Sampling System
• Secondary Attributes: Graphical User Interface
• Processor To Be Evaluated: C8051F340
• Interface Type: Ethernet
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant
• Other names: 336-1326

PoE-VOICE-RD
2.1. Power Section
The PoE-VoIP-EB Reference Design Board contains a Power Over Ethernet circuit based on the Si3400. In addition
to performing all the functions required by the IEEE 802.3af specification, the Si3400 contains a switching regulator
capable of regulating many voltages including 5 or 3.3 V. Since the Si3400 output will be passed through an LDO
(used for the auxiliary 9 V supply), a 5 V output was chosen.
For this application the Si3400 is configured to put out approximately 5.2 V and diodes D1 and D2 are connected to
"diode OR" the 9 V adapter power. A linear post regulator is used to produce the 3.3 V output. While the Si3400 can
be configured to supply about 10 W of output power, the output from the linear regulator is limited to about 500 mA
average for thermal reasons.
See
2.2. MCU, Ethernet Controller, and Microphone Section
The MCU and Ethernet controller section of the board contain a C8051F340 MCU and a CP2201 Ethernet
Controller. The MCU is pre-programmed with the reference design software and the CP2201 is pre-programmed
with several web pages that are accessible from a web browser. The on-chip ADC is shared between the embedded
temperature and light sensors and the microphone. When the light and temperature sensors are being sampled, the
ADC sampling rate is 300 Hz. When the microphone is being sampled, the ADC is oversampled at 32 kHz for a
resulting output word rate of 8 kHz.
The microphone section of the PoE-VoIP-EB Reference Design Board contains an electret condenser microphone
with a dual-stage amplifier circuit. The amplifier gain has been tuned to provide optimal reception at distances of 1 to
3 meters. As the person speaking moves further away, a digital gain of up to 4x is applied to the sound stream. The
digital gain is automatically applied and the automatic gain control state is displayed on the red LED (D4). The red
LED is shown at the bottom of Figure 1 and the various automatic gain control states are listed in Table 1.
2
www.silabs.com/PoE
Not Connected
Silence Detected
Normal Speech
2x Sensitivity Boost
4x Sensitivity Boost
State
for more information about the Si3400.
Table 1. Automatic Gain Control States
and the microphone is not currently
the light and temperature sensors.
The PC application is not running
being sampled. ADC is sampling
Digital gain is turned off.
Digital gain is turned off.
Digital gain is set to 2.
Digital gain is set to 4.
Description
Rev. 0.2
(15 times per second)
(4 times per second)
(once per second)
Blinking Very Fast
Blinking Slow
Blinking Fast
Red LED
Solid Off
Solid On