Rainbow Electronics MAX5945 - Manual (Page 12)

MAX5945
Detailed Description
The MAX5945 four-port network power controller con-
trols -32V to -60V negative supply rail systems. Use the
MAX5945, which is compliant with the IEEE 802.3af
standard for PSE in power-over-LAN applications. The
MAX5945 provides PD discovery, classification, current
limit, both DC and AC load disconnect detections, and
other necessary functions for an IEEE 802.3af-compli-
ant PSE. The MAX5945 can be used in either endpoint
PSE (LAN switch/router) or midspan PSE (power injec-
tor) applications.
The MAX5945 is fully software-configurable and pro-
grammable with more than 25 internal registers. The
device features an I
2 C-compatible, 3-wire serial inter-
face and a class-overcurrent detection. The class-over-
current detection function enables system power man-
Quad Network Power Controller
for Power-Over-LAN
12 ______________________________________________________________________________________
50 µA
90 µA 100mA
MAX FAST
DISCHARGE
CONTROL
212mV 182mV
13V CLAMP
CURRENT-LIMIT
DETECTOR
4mV
OVERCURRENT
(OVC)
OPEN CIRCUIT
(OC)
CURRENT
LIMIT (ILIM)
PWR_EN
10V
VOLTAGE
SENSING
FOLDBACK
CONTROL
9-BIT ADC
CONVERTER
VOLTAGE PROBING
AND
CURRENT-LIMIT
CONTROL
CURRENT SENSING
SENSE_
GATE_
OUT_
DET_
A = 3
AC
DETECTION
ACD_ENABLE
AC DISCONNECT
SIGNAL
(ACD)
ACD
REFERENCE
CURRENT
DETECTION/
CLASSIFICATION
SM
PORT
STATE
MACHINE
(SM)
REGISTER FILE
SERIAL
PORT
INTERFACE
(SPI)
AUTO
MIDSPAN
A0
A1
A2
A3
ANALOG
BIAS/
SUPPLY
MONITOR
AGND
V EE
+10V ANALOG
+5V DIG
VOLTAGE
REFERENCES
CURRENT
REFERENCES
CENTRAL LOGIC UNIT
(CLU)
DGND OSC_IN SCL SDAIN SDAOUT V DD
OSCILLATOR
MONITOR
SHD_
RESET
INT
MAX5945
Figure 1. MAX5945 Functional Diagram