PD64001 Datasheet, PDF (5/9 Pages) Microsemi Corporation – 1-Port PoE Manager

PD64001 1-port PoE Manager Datasheet
Preliminary
Detailed Application Description__
(See Figure 1)
The PD64001 performs a multitude of internal
operations and PoE functions, requiring a bare
minimum of external components.
The device is based on Atmel's ATtiny461 MCU.
Each PD64001 device handles one port. Figure 1
shows the device with its related components for a
1-port configuration.
Mode Configuration - set by the resistor divider
(R25/R26) tied in to the RMODE line. The values are
fixed for each mode of operation and described in
the "R Mode pin" section in this document.
Line Detection Circuitry – when performing a line
detection procedure, the PoE device utilizes certain
voltage levels over the output port. These levels are
produced by switched resistor dividers and sensed
by the PD64001 in order to confirm a valid PD
connection.
Current Loop Circuitry – the current is controlled by
Q3 MOSFET. The PD64001 supplies PWM signal
via pin#2 with a constant duty cycle (depending on
the R mode configuration). This PWM signal is
filtered and utilized as the current limit circuitry
voltage reference.
Sense Resistors – for each powered port, two
2-Ohm 2010 (1%) resistors connected in parallel
(1-Ohm equivalent) are used in series with the
output. In cases where the ambient temperature
drops below 70⁰C, or the product does not have to
meet 802.3at power, a single 1-Ohm 2010 (1%)
resistor is adequate.
Classification Circuitry – After a port is investigated,
the PD should be classified by a classification
current signature.
Two voltage levels are set over the port, derived
from a reference voltage filtered from PD64001
pin#4 (PWM signal) and sent to an operational
amplifier which controls Q3 MOSFET.
Output port - The load resistance of the PD attached
to the port is presented in parallel with R30.
The resulting voltage developed across both
resistances is monitored to establish the 802.3af/at
compatibility.
LED indication - The 1 port application may use the
PD64001 LED1 and LED2 pins for system status
indications as follows.
PD operating Status
IEEE802.3af – ON
IEEE802.3at – ON
IEEE802.3af - OVL/SC
IEEE802.3at - OVL/SC
Vmain out of range
LED1
ON
ON
Blink at 1Hz
Blink at 1Hz
Blink at 1Hz
LED2
OFF
ON
OFF
Blink at 1Hz
OFF
Copyright © 2008
Rev. 0.4 2008-05-08
Microsemi
Analog Mixed Signal Group
1 Hanagar st., P.O/ Box 7220 Hod Hasharon 45421, Israel Tel: [phone] Fax: [phone]
page 5