MAX5945 Datasheet, PDF (1/44 Pages) Maxim Integrated Products – Quad Network Power Controller for Power-Over-LAN

19-3428; Rev 1; 9/05
EVAALVUAAILTAIOBNLEKIT
Quad Network Power Controller
for Power-Over-LAN
General Description
The MAX5945 quad network power controller is designed
for use in IEEE 802.3af-compliant power-sourcing equip-
ment (PSE). The device provides power devices (PD) dis-
covery, classification, current-limit, and both DC and AC
load disconnect detections. The MAX5945 can be used
in either endpoint PSE (LAN switches/routers) or midspan
PSE (power injector) applications. The MAX5945 is pin
and function compatible with LTC4259A.
The MAX5945 can operate autonomously or be con-
trolled by software through an I²C*-compatible inter-
face. Separate input and output data lines (SDAIN and
SDAOUT) allow usage with optocouplers. The
MAX5945 is a slave device. Its four address inputs
allow 16 unique MAX5945 addresses. A separate INT
output and four independent shutdown inputs (SHD_)
allow fast response from a fault to port shutdown. A
RESET input allows hardware reset of the device. A
special watchdog feature allows the hardware to grace-
fully take over control if the software crashes. A
cadence timing feature allows the MAX5945 to be used
in midspan systems.
The MAX5945 is fully software configurable and program-
mable. A class-overcurrent detection function enables
system power management to detect if a PD draws more
current than the allowable amount for its class. Other fea-
tures are input under/overvoltage lockout, overtempera-
ture protection, output-voltage slew-rate limit during
startup, power-good, and fault status. The MAX5945’s
programmability includes gate-charging current, current-
limit threshold, startup timeout, overcurrent timeout,
autorestart duty cycle, PD disconnect AC detection
threshold, and PD disconnect detection timeout.
The MAX5945 is available in a 36-pin SSOP package
and is rated for both extended (-40°C to +85°C) and
commercial (0°C to +70°C) temperature ranges.
Applications
Power-Sourcing Equipment (PSE)
Power-Over-LAN/Power-Over-Ethernet
Switches/Routers
Midspan Power Injectors
*Purchase of I²C components from Maxim Integrated
Products, Inc. or one of its sublicensed Associated
Companies, conveys a license under the Philips I²C Patent
Rights to use these components in an I²C system, provided
that the system conforms to the I²C Standard Specification as
defined by Philips.
Typical Operating Circuits appear at end of data sheet.
Features
♦ IEEE 802.3af Compliant
♦ Pin and Function Compatible with LTC4259A
♦ Controls Four Independent, -48V-Powered
Ethernet Ports in Either Endpoint or Midspan PSE
Applications
♦ Wide Digital Power Input, V_DIG, Common-Mode
Range: V_EE to (AGND + 7.7V)
♦ PD Violation of Class Current Protection
♦ PD Detection and Classification
♦ Provides Both DC and AC Load Removal
Detections
♦ I²C-Compatible, 3-Wire Serial Interface
♦ Fully Programmable and Configurable Operation
Through I²C Interface
♦ Current Foldback and Duty-Cycle-
Controlled/Programmable Current Limit
♦ Short-Circuit Protection with Fast Gate Pulldown
♦ Direct Fast Shutdown Control Capability
♦ Programmable Direct Interrupt Output
♦ Watchdog Mode Enable Hardware Graceful
Takeover
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX5945CAX**
MAX5945EAX
0°C to +70°C
-40°C to +85°C
36 SSOP
36 SSOP
**Future product—contact factory for availability.
Pin Configuration
TOP VIEW
RESET 1
MIDSPAN 2
INT 3
SCL 4
SDAOUT 5
SDAIN 6
A3 7
A2 8
A1 9
A0 10
DET1 11
DET2 12
DET3 13
DET4 14
DGND 15
VDD 16
SHD1 17
SHD2 18
MAX5945
SSOP
36 OSC_IN
35 AUTO
34 OUT1
33 GATE1
32 SENSE1
31 OUT2
30 GATE2
29 SENSE2
28 VEE
27 OUT3
26 GATE3
25 SENSE3
24 OUT4
23 GATE4
22 SENSE4
21 AGND
20 SHD4
19 SHD3
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