MAX5971B Datasheet, PDF (1/46 Pages) Maxim Integrated Products – Single-Port, 40W, IEEE 802.3af/at, PSE Controller with I2C

19-5336; Rev 0; 6/10
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Single-Port, 40W, IEEE 802.3af/at,
PSE Controller with I²C
General Description
The MAX5971B is a single-port power controller designed
for use in IEEE^M 802.3af/at-compliant power-sourcing
equipment (PSE). This device provides powered device
(PD) discovery, classification, current limit, and DC and
AC load-disconnect detections. The MAX5971B sup-
ports both fully automatic operation and software pro-
grammability, and features an integrated power MOSFET
and sense resistor. The device supports detection and
classification operation from a single 54V supply. In
addition, it supports 2-event classification and new Class
5 classification of high-power PDs. The MAX5971B pro-
vides up to 40W to a single port (Class 5 enabled) and
still provides high-capacitance detection for legacy PDs.
The device provides four operating modes to suit differ-
ent system requirements. By default, auto mode allows
the device to operate automatically at its default settings
without any software. Semiautomatic mode automatically
detects and classifies a device connected to the port
after initial software activation, but does not power the
port until instructed to by software. Manual mode allows
total software control of the device and is useful for
system diagnostics. Shutdown mode terminates all port
activities and securely turns off power to the port.
The IC features an I²C-compatible, 2-wire serial inter-
face, and is fully software-configurable and program-
mable. The device provides instantaneous readout of
port current through the I²C interface. The device’s
extensive programmability enhances system flexibility,
enables field diagnosis and allows for uses in other, non
standard applications.
The device provides input undervoltage lockout (UVLO),
input undervoltage detection, input overvoltage lockout,
overtemperature protection, output voltage slew-rate limit
during startup, and LED status indication. The MAX5971B
programmability includes startup timeout, overcurrent
timeout, and load-disconnect detection timeout.
The device is available in a space-saving, 28-pin TQFN
(5mm x 5mm) power package and is rated for the
extended (-40NC to +85NC) temperature range.
Applications
Single-Port PSE End-Point Applications
Single-Port PSE Power Injectors (Midspan Applications)
Switches/Routers
Features
S IEEE 802.3af/at Compliant
S Up to 40W for Single-Port PSE Applications
S Integrated Power MOSFET and Sense Resistor
S Supports 54V Single-Supply Operation
S PD Detection and Classification
S I²C-Compatible, 2-Wire Serial Interface
S Instantaneous Readout of Port Current Through
I²C Interface
S Programmable Current Limit for Class 5 PDs
S High-Capacitance Detection for Legacy Devices
S Supports Both DC and AC Load Removal
Detections
S Current Foldback and Duty-Cycle-Controlled
Current Limit
S LED Indicator for Port Status
S Direct Fast-Shutdown Control Capability
S Space-Saving, 28-Pin TQFN (5mm x 5mm) Power
Package
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX5971BETI+
-40NC to +85NC
28 TQFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Typical Operating Circuit
-54V
VEE
AGND
OUT
VEE_DIG
OUTP
LED
PWMEN MAX5971B
LEGACY
DET
MIDSPAN
ILIM1
OSC
ILIM2
EN
SDA SCL AD0 INT
PSE OUTPUT
SERIAL INTERFACE
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