Rainbow-electronics MAX5945 Uživatelský manuál

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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
AGNDV
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.
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Shrnutí obsahu

Strany 1 - Quad Network Power Controller

General DescriptionThe MAX5945 quad network power controller is designedfor use in IEEE 802.3af-compliant power-sourcing equip-ment (PSE). The device

Strany 2

MAX5945Quad Network Power Controllerfor Power-Over-LAN10 ______________________________________________________________________________________DETECTI

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MAX5945Quad Network Power Controllerfor Power-Over-LAN______________________________________________________________________________________ 11PIN NAM

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MAX5945Detailed DescriptionThe MAX5945 four-port network power controller con-trols -32V to -60V negative supply rail systems. Use theMAX5945, which i

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agement where it detects a PD that draws more currentthan the allowable amount for its class. The MAX5945’sextensive programmability enhances system f

Strany 6

MAX5945Setting R19h[PWR_ON_] (Table 21) high immediatelyterminates detection/classification routines and turns onpower to the port(s).R14h[DET_EN_, CL

Strany 7

Table 2 shows the IEEE 802.3af requirement for a PSEclassifying a PD at the power interface (PI).Powered StateWhen the part enters PWR MODE, the tSTAR

Strany 8

MAX5945Overcurrent ProtectionA sense resistor (RS), connected between SENSE_ andVEE, monitors the load current. Under all circum-stances, the voltage

Strany 9

MOSFET Gate DriverConnect the gate of the external n-channel MOSFET toGATE_. An internal 50µA current source pulls GATE_ to(VEE+ 10V) to turn on the M

Strany 10

MAX5945The MAX5945 also features three other undervoltageand overvoltage interrupts: VEEundervoltage interrupt(VEEUV), VDDundervoltage interrupt (VDDU

Strany 11

Start and Stop ConditionsBoth SCL and SDA remain high when the interface isnot busy. A master signals the beginning of a transmis-sion with a START (S

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MAX5945Quad Network Power Controllerfor Power-Over-LAN2 _______________________________________________________________________________________ABSOLUT

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MAX5945Bit TransferEach clock pulse transfers one data bit (Figure 8). Thedata on SDA must remain stable while SCL is high.AcknowledgeThe acknowledge

Strany 14

Message Format for Writing the MAX5945A write to the MAX5945 comprises of the MAX5945’sslave address transmission with the R/W bit set to 0, fol-lowed

Strany 15

MAX5945Message Format for ReadingThe MAX5945 reads using the MAX5945’s internallystored command byte as an address pointer, the sameway the stored com

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MAX5945Quad Network Power Controllerfor Power-Over-LAN______________________________________________________________________________________ 23ADDRESS

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MAX5945Quad Network Power Controllerfor Power-Over-LAN24 ______________________________________________________________________________________ADDRESS

Strany 18

If the port remains in current limit or the PGOOD condi-tion is not met at the end of the startup period, the portshuts down and the corresponding STR

Strany 19

MAX5945function. OSC_FAIL generates an interrupt only if atleast one of the ACD_EN (R13h[7:4]) bits is set high.A thermal-shutdown circuit monitors th

Strany 20

Software resets of ports (RESET_P_ bit, Table 22) donot affect the mode register.Setting DCD_EN_ to 1 enables the DC load disconnectdetection feature

Strany 21

MAX5945In MANUAL mode, R14h works like a pushbutton. Setthe bits high to begin the corresponding routine. The bitclears after the routine finishes.Whe

Strany 22

ther extend the programming range of these timers andalso increase the programming resolution.When the MAX5945 shuts down a port due to anextended ove

Strany 23

MAX5945Quad Network Power Controllerfor Power-Over-LAN_______________________________________________________________________________________ 3ELECTRI

Strany 24

MAX5945when the port is already powered and during shut-down. PWR_OFF_ is ignored when the port is alreadyoff and during shutdown. After execution, th

Strany 25

Writing a 1 to CLR_INT (Table 22) clears all the eventregisters and the corresponding interrupt bits in registerR00h. Writing a 1 to RESET_P_ turns of

Strany 26

MAX5945the bits in register R12h to 00. A high in HWMODE_switches the port into auto mode by setting the bits inregister R12h to 11. If WD_INT_EN is s

Strany 27

Use TF_PR[3:0] to set the nominal value for tDISCaccording to the following formula:tDISCnominal = 238ms + 16ms x Nwhere N is the decimal value of the

Strany 28

MAX5945Use the program registers (Table 29) to set the nominalvalue for tFAULTand tSTARTfor all ports according tothe following formula:tFAULTnominal

Strany 29

MAX5945Quad Network Power Controllerfor Power-Over-LAN______________________________________________________________________________________ 35Table 3

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MAX5945Quad Network Power Controllerfor Power-Over-LAN36 ______________________________________________________________________________________Table 3

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MAX5945Quad Network Power Controllerfor Power-Over-LAN______________________________________________________________________________________ 37Figure

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MAX5945Quad Network Power Controllerfor Power-Over-LAN38 ______________________________________________________________________________________Figure

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MAX5945Quad Network Power Controllerfor Power-Over-LAN______________________________________________________________________________________ 39Figure

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MAX5945Quad Network Power Controllerfor Power-Over-LAN4 _______________________________________________________________________________________ELECTRI

Strany 35

MAX5945Quad Network Power Controllerfor Power-Over-LAN40 ______________________________________________________________________________________Figure

Strany 36

MAX5945Quad Network Power Controllerfor Power-Over-LAN______________________________________________________________________________________ 41DESIGNA

Strany 37

MAX5945Quad Network Power Controllerfor Power-Over-LAN42 ______________________________________________________________________________________MAX5945

Strany 38

MAX5945Quad Network Power Controllerfor Power-Over-LAN______________________________________________________________________________________ 43MAX5945

Strany 39

MAX5945Quad Network Power Controllerfor Power-Over-LANMaxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodi

Strany 40

MAX5945Quad Network Power Controllerfor Power-Over-LAN_______________________________________________________________________________________ 5ELECTRI

Strany 41

MAX5945Quad Network Power Controllerfor Power-Over-LAN6 _______________________________________________________________________________________Note 2:

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MAX5945Quad Network Power Controllerfor Power-Over-LAN_______________________________________________________________________________________ 7DIGITAL

Strany 43

MAX5945Quad Network Power Controllerfor Power-Over-LAN8 _______________________________________________________________________________________OVERCUR

Strany 44

MAX5945Quad Network Power Controllerfor Power-Over-LAN_______________________________________________________________________________________ 9OVERCUR

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