Specifications

PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Book 23
Band-In-Use (BIU) and Packet Detect (PKD) LED
Connections
The PL Smart Transceiver supplies two output signals, PKD and BIU, that are intended to drive low-current light-
emitting diodes (LEDs). Both signals are active-high and must be connected to separate LEDs, with series current-
limiting resistors added between the LEDs and ground. The PKD and BIU pins are rated to source up to 12mA.
A Band-In-Use detector, as defined under CENELEC EN 50065-1, must be active whenever a signal that exceeds
86dBμV
RMS
anywhere in the frequency range 131.5kHz to 133.5kHz is present for at least 4ms. The Band-In-Use
detector is defined by CENELEC EN 50065-1 as part of the CENELEC access protocol. The Smart Transceiver
incorporates the CENELEC access protocol, and the PL Smart Transceiver can be programmed to enable or disable its
operation (See the CENELEC Access Protocol section in Chapter 8). When the PL Smart Transceiver is programmed to
enable the CENELEC access protocol the state of the Band-in-Use signal regulates the flow of packet transmissions in
accordance with CENECLEC-defined conditions. When the CENELEC access protocol is disabled, an active BIU signal
has no affect on PL Smart Transceiver transmissions
The Band-In-Use function is defined for use in the CENELEC C-band and is not required for A-band operation. When
the PL Smart Transceiver is programmed with proper A-band transceiver parameters, as described in Chapter 8, an
active BIU signal does not prevent the PL Smart Transceiver from transmitting.
The PKD signal is active whenever a LonTalk packet addressed to any device is being received by the PL Smart
Transceiver. The receive sensitivity of the transceiver is considerably greater than that of the BIU indicator. The PKD
signal will go active when the PL Smart Transceiver receives packets whose signal level is as small as 36dBμV
RMS
.
Thus it is not uncommon for the PKD indicator to signal that a packet is present without the BIU indicator turning on;
this occurs in cases where the signal strength of a received packet is less than the BIU threshold.
ESD protection diodes should be connected to the BIU and PKD lines in applications where BIU and PKD drive LEDs
that could be subject to ESD exceeding 2kV. Refer to the Design for Electrostatic Discharge Compliance section of
Chapter 6 for recommendations regarding ESD protection.
TXON Output Signal
TXON is a buffered version of the internal signal used to control the transceiver’s transmit amplifier. The TXON output
pin is active high while the PL Smart Transceiver is transmitting packets. This pin is rated to source up to 12mA. TXON
can be used to drive a low-current LED to indicate transmit activity. A series current-limiting resistor is required
between the LED and ground. ESD protection diodes should be connected to this pin in applications where the TXON
signal line could be subjected to ESD exceeding 2kV.