POE-VOICE-RD Silicon Laboratories Inc, POE-VOICE-RD Datasheet - Page 7

• 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
6.2. Detecting PoE power vs. Auxiliary power
The Si3400 provides a signal named “PLOSS” which indicates the presence of PoE power. This signal is level-
shifted and routed from the Si3400 into a digital input on the MCU.
The PLOSS Indicator, shown in Figure 8, will be cleared to “0” if PoE power is available. The indicator is set to “1”
if PoE power is lost and the embedded system is running from the auxiliary power supply.
Click the Exit button once you have finished listening to sound from the embedded system.
Figure 8. Listening to sound from the Embedded System
Usage Note 1: If running on PoE power, plugging in the 9 V AC adapter will override the PoE power. Once the
power injector detects that the PoE load current has dropped, it will stop supplying power and the PLOSS will
change to “1” to indicate a PoE power failure. Operation will not be interrupted.
Usage Note 2: If the 9 V auxiliary power adapter is removed while the system is running, PoE power will not
resume instantaneously. Rather, the Si3400 must perform “Detection, Classification, and Power Sequencing” in
order to receive power from the IEEE802.3af Power Source. While this procedure typically lasts less than 100 ms,
it will cause a supply voltage dip large enough to trigger the built-in V
Monitors on both the 8051F340 and
DD
CP2201. To provide seamless switching between power sources, a large valued capacitor may be used to keep the
supply voltage constant during the switchover.
Rev. 0.2
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