Rainbow Electronics MAX5945 - Manual

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 I
2 C*-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
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
♦ I 2 C-Compatible, 3-Wire Serial Interface
♦ Fully Programmable and Configurable Operation
Through I 2 C 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
MAX5945
Quad Network Power Controller
for Power-Over-LAN
________________________________________________________________ Maxim Integrated Products 1
36
35
34
33
32
31
30
29
28
27
26
25
24
23
1
2
3
4
5
6
7
8
9
10
11
12
13
14
OSC_IN
AUTO
OUT1
GATE1
SENSE1
OUT2
GATE4
GATE2
SENSE2
V EE
OUT3
GATE3
SENSE3
OUT4
DET4
DET3
DET2
DET1
A0
A1
A2
A3
SDAIN
SDAOUT
SCL
MIDSPAN
SSOP
TOP VIEW
MAX5945
22
21
20
19
15
16
17
18
SENSE4
AGND V DD
DGND
RESET
INT
SHD1
SHD2 SHD3
SHD4
Pin Configuration
19-3428; Rev 1; 9/05
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX5945CAX** 0°C to +70°C 36 SSOP
MAX5945EAX -40°C to +85°C 36 SSOP
*Purchase of I 2 C components from Maxim Integrated
Products, Inc. or one of its sublicensed Associated
Companies, conveys a license under the Philips I
2 C Patent
Rights to use these components in an I 2 C system, provided
that the system conforms to the I 2 C Standard Specification as
defined by Philips.
**Future product—contact factory for availability.
Typical Operating Circuits appear at end of data sheet.