Maxim MAX5971B User manual
General Description
The MAX5971B evaluation kit (EV kit) is a fully assembled
and tested surface-mount PCB featuring an Ethernet
single-port power-sourcing equipment (PSE) circuit for
-54V supply rail systems. The IEEEM802.3af/at-compliant
MAX5971B PSE controller IC, in a 28-pin TQFN package,
features an internal n-channel power MOSFET forming
the main PSE circuit on the EV kit. The IC is used in
single-port power-over-Ethernet (PoE) applications.
The EV kit provides optical isolation for the IC’s I2C-
compatible 2-wire interface. The isolated interface can
connect to a PC’s USB port through an on-board
USB interface circuit. The EV kit can be reconfigured
for interfacing to a user’s stand-alone microcontroller
for isolated or nonisolated operation. In stand-alone
operation, the user must supply a separate +3.3V
power supply capable of supplying 35mA. The EV
kit requires a -32V to -60V power supply (-54V sup-
ply rail) capable of supplying 1A or more to the EV
kit for powering the powered device (PD) through the
10/100/1000BASE-TX Ethernet network port. The EV
kit demonstrates PD discovery, classification, current-
limit control, and other functions of an IEEE 802.3af/at-
compliant PSE.
The IC controls the -54V DC power to the Ethernet net-
work port by sensing current through the port and con-
trolling the IC’s internal power MOSFET. Current is fed
to a 1Gb x 1Gb MagJackMmodule Ethernet output port.
The EV kit demonstrates the full functionality of the IC,
such as configurable operational modes, port current
information through the I2C interface, high-power modes
(programmable up to 40W), PD detection (including
legacy PD detection), PD classification, overcurrent
protection, current foldback, undervoltage/overvoltage
protection, and AC-/DC-disconnect monitoring. All these
features are configurable on the EV kit, with additional
test points for voltage probing and current measure-
ments provided. The EV kit can also be configured for
midspan or end-point network operation. The EV kit soft-
ware is WindowsM2000, Windows XPM, and Windows
VistaMcompatible, providing a user-friendly interface
to demonstrate the IC features while providing access
to each register at the bit level. The program is menu
driven, offers a graphical user interface (GUI) with con-
trol buttons, and includes a macro engine for automated
evaluation and testing of the IC at the system level. The
program’s macro output files can be automatically saved.
Order the EV kit for a complete PC-based evaluation
of the IC. To evaluate the MAX5971A IC, order the
MAX5971A EV kit.
Features
S IEEE 802.3af/at-Compliant PSE Circuit
S Port Current Read-Out Through I2C Interface
S High-Power Class 5 Mode Configurable Up to 40W
S -32V to -60V Input Voltage Providing 1A
S Ethernet Network Ports
RJ45 10/100/1000BASE-TX Ethernet Network
Data Input Port
RJ45 10/100/1000BASE-TX Ethernet Network
PSE Output Port
S Demonstrates MAX5971B Internal Power Switch
and Current Sensing
S Demonstrates Standard and Legacy PD Detection
and Classification
S Configurable for Midspan or End-Point Mode
S Configurable AC/DC Load-Removal Detection and
Disconnect Monitoring
S Convenient Voltage and Current Test Points
S Demonstrates IC’s Output-Port LED Status
Indicators
S Optically Isolated I2C-Compatible 2-Wire PC
Interface
S Reconfigurable for Stand-Alone Operation or with
an External Microcontroller (Requires +3.3V, 35mA
Supply)
S Windows 2000-, Windows XP-, and Windows Vista
(32-Bit)-Compatible Software
S Proven PCB Layout
S Fully Assembled and Tested
MAX5971B Evaluation Kit
Evaluates: MAX5971B
_________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
19-5783; Rev 0; 3/11
Ordering Information appears at end of data sheet.
IEEE is a registered service mark of the Institute of Electrical
and Electronics Engineers, Inc.
MagJack is a registered trademark of Bel Fuse Inc.
Windows, Windows XP, and Windows Vista are registered
trademarks of Microsoft Corp.
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DESIGNATION QTY DESCRIPTION
C1 1
47FF Q20%, 100V electrolytic
capacitor (12.5mm x 13.5mm)
Panasonic EEEFK2A470Q
C2 1
1FF Q10%, 100V X7R ceramic
capacitor (1210)
AVX 12101C105KAT9A
C3, C5, C7 3
0.1FF Q10%, 100V X7R ceramic
capacitors (0603)
Murata GRM188R72A104KA35B
C4 1
0.47FF Q10%, 100V X7R ceramic
capacitor (0805)
Murata GRM21BR72A474KA73B
C6, C9, C10 3
0.1FF Q10%, 16V X7R ceramic
capacitors (0603)
Murata GRM188R71C104K or
TDK C1608X7R1C104K
C8 1
10FF Q20%, 6.3V X5R ceramic
capacitor (0805)
Murata GRM21BR60J106M or
TDK C2012X5R0J106M
C11 1
1.0FF Q10%, 6.3V X5R ceramic
capacitor (0603)
AVX 06036D105KA or
Taiyo Yuden JMK107BJ105KA
C12 1
1000pF Q10%, 50V X7R ceramic
capacitor (0603)
Murata GRM188R71H102K
C201,
C203–C210,
C217, C221
11
0.1FF Q10%, 16V X7R ceramic
capacitors (0603)
Murata GRM188R71C104K or
TDK C1608X7R1C104K
C202, C213,
C215 3
10FF Q20%, 6.3V X5R ceramic
capacitors (0805)
Murata GRM21BR60J106M or
TDK C2012X5R0J106M
C211, C212 2
10pF Q5%, 50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H100J or
TDK C1608C0G1H100J
C214 1
1FF Q10%, 10V X5R ceramic
capacitor (0603)
Murata GRM188R61A105K or
TDK C1608X5R1A105K
DESIGNATION QTY DESCRIPTION
C216 1
2.2FF Q10%, 6.3V X5R ceramic
capacitor (0603)
Murata GRM188R60J225K or
TDK C1608X5R0J225K
C218, C219 2
22pF Q5%, 50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H220J or
TDK C1608C0G1H220J
C220 1
3300pF Q10%, 50V X7R ceramic
capacitor (0603)
Murata GRM188R71H332K or
TDK C1608X7R1H332K
D1, D3 2
150mA, 100V small-signal diodes
(SOD323)
Fairchild 1N4148WS
(Top Mark: S1)
D2 1
58V, 600W transient voltage
suppressor (SMB)
Vishay SMBJ58A
(Top Mark: NG—with a single
cathode band at one end; band
aligns with band on silkscreen)
D4 1
1A, 100V general-purpose
diode (SMA)
Diodes Inc. S1B
D5 1
6.2A, 60V transient voltage
suppressor diode (SMB)
Diodes Inc. SMBJ60A-13-F
D6 1
100mA, 30V Schottky diode
(SOD323)
Diodes Inc. CMDSH-3
(Top Mark: S1)
D201 1 Green LED (0603)
Panasonic LNJ314G8TRA
FB201 0 Not installed, ferrite-bead
inductor—short (PC trace) (0603)
GND (x2), RTN,
VEE 4 Uninsulated banana jacks
J1 1 RJ45 connector module jack
(8-8)
J2 1
RJ45 1x1Gb MagJack, 1000
Base-T, 1 x 1 port, voice-over-IP
magnetics (700mA DC)
Bel Fuse Inc. 0826-1X1T-GH-F
_________________________________________________________________ Maxim Integrated Products 2
MAX5971B Evaluation Kit
Evaluates: MAX5971B
Component List
Downloaded from Elcodis.com electronic components distributor
DESIGNATION QTY DESCRIPTION
JU1–JU6 6 2-pin headers
JU7 1 5-pin header
JU8 0 Not installed, 8-pin (2 x 4) header
JU9–JU12 0 Not installed, 2-pin headers—
short (PC trace)
L1 1 10mH, 17mA inductor
Coilcraft DS1608C-106
P201 1
-20V, -2.4A, p-channel MOSFET
(3 SuperSOT)
Fairchild FDN304P
(Top Mark: 304)
R1 1 9.09kIQ1% 1/2W resistor (2010)
Panasonic ERJ-12SF9091U
R2, R14, R18,
R19, R20, R22,
R23, R24, R26,
R28
10 3kIQ5% resistors (0603)
R3, R10–R13,
R15, R16 71kIQ5% resistors (0402)
R4 1 2.2MIQ5% resistor (0805)
R5, R6 0 Not installed, resistors (1206)
R7, R8 2 0IQ5% resistors (1206)
R9 0 Not installed, resistor (0402)
R17, R21, R25,
R27 4180IQ5% resistors (0603)
R29 1 5.1kIQ5% resistor (0603)
R30, R31, R32 0
Not installed, resistors (0805)
R30 is open; R31 and R32 are
short (PC trace)
R201 1 0IQ5% resistor (0603)
R202 1 220IQ5% resistor (0603)
R203 1 10kIQ5% resistor (0603)
R204 1 2.2kIQ5% resistor (0603)
R205 1 1.5kIQ5% resistor (0603)
R206, R207 2 27IQ5% resistors (0603)
R208 1 1kIQ5% resistor (0603)
SW1 1 Microminiature pushbutton switch
TP1, TP3–TP10,
TP12 10 Miniature PC test points, yellow
TP2 1 Miniature PC test point, red
TP11, TP13 2 Miniature PC test points, black
U1 1
Single-port PSE controller
(28 TQFN-EP)
Maxim MAX5971BETI+
DESIGNATION QTY DESCRIPTION
U2 1
High-voltage linear regulator
(6 TDFN-EP)
Maxim MAX6765TTSD2+T
U3, U4 2
High-speed, 15Mbps logic gate
optocouplers (8 SO)
CEL/NEC PS9821-2-A
U5 1
TinyLogicMUHS dual buffer with
Schmitt trigger inputs (6 SC70)
Fairchild NC7WZ17P6X
(Top Mark: Z17)
U6 1
TinyLogic UHS dual buffer with
open-drain outputs (6 SC70)
Fairchild NC7WZ07P6X
(Top Mark: Z07)
U201 1
32-bit microcontroller
(68 QFN-EP)
Maxim MAXQ2000-RAX+
U202 1
93C46-type 2-wire EEPROM
(8 SO)
Atmel AT93C46EN-SH-B
U203 1
UART-to-USB converter
(32 TQFP, 7mm x 7mm)
FTDI FT232BL
U204 1
3.3V, 300mA regulator (5 SOT23)
Maxim MAX8888EZK33+T
(Top Mark: ADQC)
U205 1
2.5V, 120mA regulator (5 SC70)
Maxim MAX8511EXK25+T
(Top Mark: ADV)
USB 1 USB type-B right-angle female
connector
Y201 1
16MHz crystal
Hong Kong X’tals
SSM1600000E18FAF
Y202 1
6MHz crystal
Hong Kong X’tals
SSL6000000E18FAF
— 4 Rubber bumpers
— 1 USB-A male to USB-B male
cable, 6ft
— 7 Shunts ( JU1–JU7)
— 1 PCB: MAX5971B EVALUATION
KIT
_________________________________________________________________ Maxim Integrated Products 3
MAX5971B Evaluation Kit
Evaluates: MAX5971B
Component List (continued)
TinyLogic is a registered trademark of Fairchild
Semiconductor.
Downloaded from Elcodis.com electronic components distributor
SUPPLIER PHONE WEBSITE
AVX Corporation 843-946-0238 www.avxcorp.com
Bel Fuse Inc. 201-432-0463 www.belfuse.com
CEL/NEC 408588-2247 www.cel.com
Coilcraft, Inc. 847-639-6400 www.coilcraft.com
Diodes Incorporated 805-446-4800 www.diodes.com
Fairchild Semiconductor 888-522-5372 www.fairchildsemi.com
Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com
Panasonic Corp. 800-344-2112 www.panasonic.com
Taiyo Yuden 800-348-2496 www.t-yuden.com
TDK Corp. 847-803-6100 www.component.tdk.com
Vishay 402-563-6866 www.vishay.com
FILE DESCRIPTION
INSTALL.EXE Installs the EV kit files on your computer
MAX5971B.EXE Application program
FTD2XX.INF USB device driver file
POWER_ON.SMB Bitmap macro routine
TEST#1_MANUAL_MODE.SMB Bitmap macro routine
TEST#2_AUTO_MODE_DC.SMB Bitmap macro routine
TEST#3_AUTO_MODE_AC.SMB Bitmap macro routine
TEST#4_SEMIAUTO_MODE.SMB Bitmap macro routine
UNINST.INI Uninstalls the EV kit software
USB_Driver_Help.PDF USB driver installation help file
_________________________________________________________________ Maxim Integrated Products 4
MAX5971B Evaluation Kit
Evaluates: MAX5971B
Component Suppliers
MAX5971B EV Kit Files
Note: Indicate that you are using the MAX5971B when contacting these component suppliers.
Quick Start
Required Equipment:
• MAX5971BEVkit(USBcableincluded)
• -32Vto-60V,1AcapableDCpowersupply
• User-supplied Windows 2000, Windows XP, or
Windows Vista PC with a spare USB port
• USB I/O extension cable, straight-through, male-to-
female cable
• Voltmeterforconfirmingoutputvoltage
Warning: The GND banana jack is more positive than the
VEE or RTN banana jack. Use an isolated oscilloscope
for probing with respect to VEE or RTN.
Note: In the following sections, software-related items are
identified by bolding. Text in bold refers to items directly
from the EV kit software. Text in bold and underlined
refers to items from the Windows operating system.
Hardware Connections
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation. Caution: Do not turn on
the power supply until all connections are completed.
1) Visit www.maxim-ic.com/evkitsoftware to down-
load the latest version of the EV kit software,
5971BRXX.ZIP. Save the EV kit software to a
temporary folder and uncompress the ZIP file.
2) Install the EV kit software on your computer by
running the INSTALL.EXE program inside the
temporary folder. The program files are copied and
icons are created in the Windows Start | Programs
menu.
3) Verify that a shunt is not installed on jumpers JU1
(ILIM1, Class 0–Class 4), JU2 (ILIM2, Class 0–Class
4), JU3 (PWM enabled), JU4 (midspan mode), and
JU6 (AC disconnect).
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_________________________________________________________________ Maxim Integrated Products 5
MAX5971B Evaluation Kit
Evaluates: MAX5971B
4) Verify that a shunt is installed on jumper JU5 (legacy
mode disabled) and on pins 1-5 of jumper JU7
(0x40 address).
5) Connect the -32V to -60V DC power supply to the
metal VEE banana jack and the supply ground to
the metal GND banana jack. Do not turn on the
power supply until all connections are completed.
6) Connect a PD to the Ethernet output port RJ45 con-
nector (J2) on the EV kit’s MagJack module. This
step is optional if network connectivity and/or a PD
is not required.
7) Connect the EV kit’s network data input port J1 LAN
to the corresponding data LAN connection. Note:
This step is optional if network connectivity is not
required.
8) Turn on the power supply and set it to -54V.
9) Connect the USB cable from the PC to the EV kit
board. A New Hardware Found window pops up
when installing the USB driver for the first time.
If a window is not seen that is similar to the one
described above after 30s, remove the USB cable
from the board and reconnect it. Administrator privi-
leges are required to install the USB device driver
on Windows.
10) Follow the directions of the Found New Hardware
window to install the USB device driver. Manually
specify the location of the device driver to be
C:\Program Files\MAX5971B (default installation
directory) using the Browse button. During device
driver installation, Windows may show a warning
message indicating that the device driver Maxim
uses does not contain a digital signature. This is
not an error condition and it is safe to proceed
with installation. Refer to the USB_Driver_Help.PDF
document included with the software for additional
information.
11) Start the EV kit software by opening its icon in the
Start | Programs menu.
12) Observe as the program automatically detects the
USB interface circuit, starts the main program, and
then detects the I2C-compatible address configured
for the IC.
13) Select the BitMap Controls tab at the top of the GUI
(Figure 3).
14) Load and run the Power_on.smb macro program
from the File | Open | Run Macro menu bar. The
script automatically runs after selecting Open.
15) The network output port’s yellow and green status
LEDs on J2 should be lit.
16) Four other example macros allow quick testing of
the manual mode, auto mode, semiauto mode,
and with DC and/or AC load-disconnect detection.
These macros are:
• TEST#1_MANUAL_MODE.SMB
• TEST#2_AUTO_MODE_DC.SMB
• TEST#3_AUTO_MODE_AC.SMB
(JU6 not installed)
• TEST#4_SEMIAUTO_MODE.SMB
Note: JU7 must be on pins 1-5 (0x40 address) for
these macros.
17) Test points TP11, TP13 (VEE), and TP2 (GND) are
provided on the PCB to observe the desired signals
with an oscilloscope or voltage meter. Use an
isolated oscilloscope for probing with respect to
VEE or RTN.
18) Pressing pushbutton switch SW1 shuts down the
PSE output DC power and resets U1. The software
must be relaunched after a pushbutton reset.
Note: The GND banana jack is more positive than the
VEE or RTN banana jacks. Use an isolated oscillo-
scope for probing with respect to VEE or RTN.
Note: An uninstall program is included with the software.
Click on the UNINSTALL icon to remove the EV kit soft-
ware from the hard drive.
Detailed Description of Software
A mouse or the keyboard’s Tab key is used to navigate
various items on the main window (Figure 1). The EV kit
software features three tabs: Configuration,Events and
Status, and BitMap Controls. Most of the main window’s
available functions and a few more can be evaluated
by using the pulldown menu. The left status bar at the
bottom of the main window provides the USB interface
circuit status. The center status bar provides the current
EV kit and macro engine status.
Software Startup
Upon starting the program, the EV kit software starts in
the Auto Read state. The software automatically detects
the Slave Address and begins reading the contents
of each register from the IC, updating each tab sheet.
The software starts up with the Events and Status tab
selected.
Events and Status Tab
The Events and Status tab sheet (Figure 1) provides
the EV kit’s system and port events/status information
obtained from the IC registers. The System Events and
Status group box provides system-level information on
the VEE power supply, present operating mode, and
address in hexadecimal and decimal formats. The Port
Events group box provides the PSE port event or change
status. The Port Status group box provides the PSE port
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_________________________________________________________________ Maxim Integrated Products 6
MAX5971B Evaluation Kit
Evaluates: MAX5971B
operating status during detection, classification, and cur-
rent usage by the connected PD.
Configuration Tab
The Configuration tab sheet (Figure 2) provides a high-
level method of configuring the EV kit as a single-port
PSE. System and port-level configurations can be made
on this tab. Also, the IC’s watchdog timer, IC, or the
port can be immediately reset using the Reset button.
All other configuration changes on this tab take place
after the Update MAX5971B button has been pressed.
To view a specific port event or status after updating,
select the Events and Status tab. The port’s operating
mode, disconnect mode, detection/classification, and
various power settings can be set independently. After
configuring the port or making system changes, press
the Update MAX5971B button to write these changes to
the IC, thus updating the EV kit’s PSE port. Certain con-
figurations may not be enabled, depending on the IC’s
current state or status.
Figure 1. MAX5971B EV Kit Software (Events and Status Tab)
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_________________________________________________________________ Maxim Integrated Products 7
MAX5971B Evaluation Kit
Evaluates: MAX5971B
Figure 2. MAX5971B EV Kit Software (Configuration Tab)
BitMap Controls Tab
The BitMap Controls tab (Figure 3) provides a bit-level
method of configuring the EV kit as a single-port PSE. The
IC’s register contents are placed on the appropriate line
of the Register Read tables in binary and hexadecimal
format. If data changes between the next register read,
the updated register hexadecimal data is displayed in
red and blinks four times. The blink rate can be changed
in the Commands | Red Hex Data Blink Rate menu bar.
The status bar at the bottom left of the main window indi-
cates the USB interface circuit status. The center status
bar indicates the current EV kit and macro engine status.
Autoread and Run-Macro State Controls
When the Auto Read checkbox is checked, the program
continuously updates the main window registers and is oper-
ating in the autoread state. In the autoread state, data can
be written to the IC by entering or selecting the desired data
in the Register Address and Hexadecimal Data or Binary
Data combo boxes. Pressing the Write Byte button writes the
combo box data to the IC. To perform an immediate register
read, enter or select the desired Register Address and press
the Read Byte button. Hexadecimal or binary data can be
entered into the Hexadecimal Data or Binary Data combo
boxes and then the alternate combo box displays the cor-
responding number in the respective number base.
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_________________________________________________________________ Maxim Integrated Products 8
MAX5971B Evaluation Kit
Evaluates: MAX5971B
If the Auto Read checkbox is unchecked, the program’s
main window displays register data from the last read.
To obtain current data, a Read Byte must be performed
after selecting the appropriate register address from the
Register Address combo box. Autoread state does not
read the clear-on-read (CoR) registers.
A macro can be run after loading the file from the File |
Open Macro menu bar. The opened macro is displayed
in the upper half of the Macro edit field and has an smb
file extension. Pressing the Run button runs the macro to
completion, with the output displayed in the Macro Script
Output edit field. Each edit box can be sized relative to
the other half using the splitter bar above the Script
Output text. Pressing the Single Step button instead of
the Run button causes the macro to execute a single line
with each activation of the Single Step button. The Reset
button is used to reset the macro script engine and clear
the Macro Script Output edit field. A macro can be run
regardless of the Auto Read checkbox status. A macro
can also be run immediately after opening by using the
File | Open/Run Macro menu item, selecting the desired
macro to run, and pressing the Open button. Pressing
the Cancel button exits this feature.
Figure 3. MAX5971B EV Kit Software (BitMap Controls Tab)
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_________________________________________________________________ Maxim Integrated Products 9
MAX5971B Evaluation Kit
Evaluates: MAX5971B
The Locate Slave button is used to search for a device
located on the I2C serial interface whose address has
been changed while the software was running. The valid
IC slave addresses are configured by jumper JU7 to one
of four addresses: 0x40, 0x42, 0x44, or 0x46. The IC
does respond to global address 0x60, although the EV kit
hardware cannot be set to this specific address.
Record Macro State Controls
When the Record checkbox is checked, the program
automatically enters the record macro state and disables
certain buttons and menus. Selecting the Commands
| Clear Script Input menu item clears any script cur-
rently in the Macro script input edit field. Comment lines
in a macro script begin with a # / ; ' * character. A line
of script is entered by selecting the appropriate Slave
Address,Register Address, and entering the desired
Hexadecimal Data or Binary Data in the respective
combo box. Pressing the Write Byte or Read Byte but-
ton then enters the script into the Macro input edit field.
For time delays in a macro, select the desired delay
time from the combo box on the right side of the Delay
button and then press the Delay button. The macro must
be saved before exiting the record macro state using the
File | Save Macro menu item. The macro file must have
an smb file extension name.
To edit a previously saved macro, open the macro using
the File | Open Macro menu item and make the desired
edits. The modified file must be saved prior to exiting the
record macro state. Uncheck the Record checkbox to
exit the record macro state. Additionally, a macro can be
created or edited using a plan text editor in “text mode.”
The file must be saved with an smb extension.
General-Purpose Advanced
User Interface Utility
There are two methods for communicating with the
IC: through the main window display or through the
general-purpose Advanced User Interface utility using
the View | Interface menu item. The utility configures
the I2C interface parameters, such as start and stop
bits, acknowledgments, and clock timing. The 2-wire
interface tab (Figure 4) allows the user to send general-
purpose I2C commands using the SMBus-WriteByte/
ReadByte and WriteWord/ReadWord commands. For
more information on the differences between the I2C
interface and the SMBusKinterface, refer to Application
Note 476: Comparing the I2C Bus to SMBus, available
at www.maxim-ic.com. When using the Advanced
User Interface utility, the main window display no longer
keeps track of changes sent to hardware. The EV kit
can be reinitialized to the startup screen settings by first
closing the Advanced User Interface utility, resetting the
IC by pressing the reset pushbutton switch (SW1), and
relaunching the software.
The Hunt for active listeners button scans the entire
2-wire address space, reporting each address that
is acknowledged. The SMBusWriteByte transmits the
device address, command, and 1 byte of data. The
SMBusReadByte transmits the device address, com-
mand, and then retransmits the device address and
reads 1 byte of data. The SMBusWriteWord and
SMBusReadWord operate the same, except 2 bytes of
data are used.
General Troubleshooting
Problem: Software reports it cannot find the USB
interface circuit.
• IstheUSBcommunicationscableconnected?
• IstheUSBinterfacecircuitpowerLED(D201)lit?
• Has Windows plug-and-play detected the board?
Bring up Control Panel →System →Device Manager,
and look at what device nodes are indicated for the
USB. If there is an unknown device node attached to
the USB, delete it—this forces plug-and-play to try
again.
Problem: Software reports MAX5971B IC not found,
exiting program.
• AretheOPTO_SCLandOPTO_SDAsignalspulledup
toOPTO_VCC(3.3V)?
• If using jumper wires to connect, could the OPTO_
SCLandOPTO_SDAsignalsbeswapped?Couldthe
OPTO_GNDgroundreturnbemissing?
Detailed Description of Hardware
The MAX5971B EV kit features a 10/100/1000BASE-
TX Ethernet single-port PSE controller circuit for -54V
supply rail systems. The EV kit’s PSE circuit uses the
IEEE 802.3af/at-compliant MAX5971B PSE controller
featuring an integrated n-channel power MOSFET and an
on-board single 1Gb x 1Gb MagJack module (integrated
in J2) to form the basic portion of a PSE circuit. The EV
kit has been designed as an IEEE 802.3af/at-compliant
PSE and demonstrates all the required functions such
as PD discovery, classification, current-limit control of
a connected PD at the Ethernet output port, and AC-/
DC-disconnect detection. A PC can be used to commu-
nicate with the slave device over the I2C interface, opti-
cally coupled logic, and the 2-wire-to-USB-port interface
circuit.
The EV kit PSE circuit requires a -32V to -60V power
supply (-54V supply rail) capable of supplying 1A or
more to the EV kit’s GND and VEE metal banana jacks or
SMBus is a trademark of Intel Corp.
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________________________________________________________________ Maxim Integrated Products 10
MAX5971B Evaluation Kit
Evaluates: MAX5971B
PCB pads. A separate +3.3V power supply capable
of
supplying 35mA is also required for the IC’s optically iso-
lated I2C-compatible 2-wire interface when the optically
isolated USB interface circuit is not used. A MAX6765
linear regulator (U2) provides the required +3.3V for the
optical isolation at the PSE side.
The IC controls the -54V DC power to the output port by
regulating the port’s current. The current is fed to the
J2 Ethernet output port’s RJ45 output module. An IEEE
802.3af/at-compliant PD connects to the Ethernet out-
put port (J2) on the EV kit. The PD can be located up
to 350ft from the EV kit when connected with a twisted
4-pair Ethernet cable. The 10/100/1000BASE-TX mag-
netic module (J2) is decoupled to the EV kit’s chassis
ground internally. The EV kit’s isolated chassis ground
(Chassis_GND) PCB pad connects to the network system
ground. Note that the 10/100/1000BASE-TX magnetic
output module RJ45 jack (J2) is rated for up to 700mA of
current. See the 35W or More Power Operation Without an
Ethernet Connection section for operation at or above 35W.
The EV kit features configurable operational modes,
PD detection (including legacy PD detection), PD
classification, overcurrent protection, current foldback,
undervoltage/overvoltage protection (+28.5V, +62.5V
(typ) (GND - VEE)), respectively), AC-/DC-disconnect
monitoring, high-power Class 5 mode operation, and
port current information through the I2C interface. The
Class 5 overcurrent and current-limit protection can be
reconfigured through jumpers or can be programmed
through the software.
The IC starts up in automatic operation mode and
pushbutton switch SW1 can be used to reset the IC or
enter shutdown mode. Semiautomatic and manual modes
can only be accessed through their respective register
using the software’s high-level Configuration window.
Figure 4. Advanced User Interface Window (2-Wire Interface Tab)
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________________________________________________________________ Maxim Integrated Products 11
MAX5971B Evaluation Kit
Evaluates: MAX5971B
PD-blocking diode D4 can be bypassed to reduce
power dissipation when AC-disconnect monitoring is
not required. The IC features an internal triangular-
wave oscillator for AC-disconnect detection and can be
bypassed to operate in DC-disconnect detection mode.
The internal oscillator must be shut down using jumper
JU6 if AC-disconnect detection is not required.
The output port also features a 600W overvoltage tran-
sient suppressor diode (D2) and decoupling capacitor
(C5) for transient protection at the output port. The EV
kit’s input port power rails (GND and VEE) are protected
by reverse-protection diode D5.
Test points and jumpers have been provided for voltage
probing and current measurements of the power circuit.
Additionally, since the GND is more positive than VEE
or RTN, use an isolated oscilloscope when probing
signals with respect to VEE or RTN. Yellow and green
LEDs on output module J2 indicate when the port’s
power is turned on and the PoE status, respectively.
The EV kit can also be reconfigured for interfacing with-
out connecting to an Ethernet system. Banana jacks
are included for the PSE GND and RTN output power
sources for this method of evaluation. Since the GND
is more positive than VEE or RTN, use an isolated
oscilloscope when probing signals with respect to
VEE or RTN.
The EV kit provides optical isolation for the I2C-compatible
2-wire interface, required by the IC operating as a slave
device, by optical couplers U3 and U4. The optically
isolated interface connects to a computer’s USB port
through the USB interface circuit. The EV kit’s I2C-
compatible 2-wire interface can be reconfigured for
interfacing to a stand-alone microcontroller for isolated
(2-wire) or nonisolated (2-wire) serial operation. A sepa-
rate +3.3V power supply capable of supplying 35mA is
required for the IC’s nonisolated I2C-compatible 2-wire
interface.
The optical isolation consists of optocoupler U3, which
provides galvanic isolation for the serial-interface clock
line (SCL) and serial-interface input data line (SDA) sig-
nals. Optocoupler U4 provides galvanic isolation for the
serial output and data line (SDA) and INT signals. The
SCL and SDA signals’ 2-wire serial interface are com-
bined on the isolated 2-wire side prior to feeding logic
buffers U5 and U6. The respective two-hole PCB pads
(OPTO_SCL, OPTO_SDA, OPTO_INT, OPTO_GND, and
OPTO_VCC) are used for 2-wire isolated stand-alone
operation. For nonisolated stand-alone 2-wire operation,
jumper JU8 shorting traces must be cut open and then
the SCL, SDA, INT, and 3_3V PCB jumper holes must be
connected to the microcontroller circuit. Note: The EV
kit’s provided 3_3V is at +3.3V. The OPTO_GND, GND,
and VEE planes are isolated by the optical couplers.
Since the GND is more positive than VEE or RTN, use
an isolated oscilloscope when probing signals with
respect to VEE or RTN.
The device slave address is configured by jumper JU7
and can be configured to one of four addresses: 0x40,
0x42, 0x44, or 0x46. Global address 0x60 is accepted
by the IC regardless of the jumper settings. See Table 9
for more information on setting the device slave address.
Jumper Selection
The EV kit features several jumpers to reconfigure the kit
for various PSE configurations, operating modes, and PD
requirements. Additionally, PCB pads and jumpers are
provided for connecting an external microcontroller and
setting the I2C slave address, respectively.
High-Power Class 5 and ILIM1/ILIM2 Selection
The EV kit features two jumpers to configure the IC’s
PSE PD classification mode, Class 0–Class 4 mode, or
high-power Class 5 mode. Jumper JU1 sets the IC’s
ILIM1 configuration and JU2 sets the ILIM2 configuration.
Table 1 lists the jumper options for the modes used to
detect a valid PD connected to the PSE Ethernet output
port. Refer to the MAX5971B IC data sheet for more infor-
mation on all classification modes available.
LED Driver PWM Enable and Port PoE Status
The EV kit features a 2-pin jumper (JU3) to enable or dis-
able the IC’s internal PWM driver for the LED pin. The IC’s
LED pin also serves as a port-status indicator using the
LED driver. The RJ45 connector (J2), providing data and
power at the output port, features 2 LEDs—a yellow LED
indicating that the EV kit is powered by -54V and a green
PSE port-status LED. Table 2 lists the LED driver jumper
options and Table 3 provides the port status. Refer to
the MAX5971B IC data sheet for more information on the
multifunction LED features.
Midspan/End-Point PoE Selection and Configuration
The EV kit features a 2-pin jumper (JU4) to set the IC for
midspan or end-point operation. The PSE circuit must
also be reconfigured for operating in midspan or end-
point configuration.
Table 4 lists the jumper options and Table 5 lists the
PSE circuit resistor changes for the two configurations
of operation. In Table 5, installed resistors are 0I, 1206
surface-mount components. Refer to the MAX5971B IC
data sheet for more information on the configurations.
Legacy High-Capacitance-Detection Operation
The EV kit features a 2-pin jumper (JU5) to set the IC’s ini-
tial startup legacy operational mode. In legacy mode, PD
signature capacitances up to 47FF (typ) are accepted.
Table 6 lists the jumper options. Refer to the MAX5971B
IC data sheet for more information.
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SHUNT POSITION LEGACY PIN LEGACY MODE
Not installed Internally pulled high Enabled, detect high capacitance
Installed* Connected to VEE through resistor R15 Disabled
SHUNT POSITION OSC PIN RESISTOR DISCONNECT-DETECTION MODE
R3 R9
Installed Connected to VEE Not installed Installed DC-disconnect detection
Not installed* Connected to VEE
through capacitor C6 Installed Not installed AC-disconnect detection, uses IC’s
internal oscillator
IC CLASSIFICATION ILIM1 PIN (JU1) ILIM2 PIN (JU2) OVERCURRENT
THRESHOLD (mA) CURRENT LIMIT (mA)
Class 0–Class 4* Not installed Not installed Class 5 disabled Class 5 disabled
Class 5 Installed Not installed 748 850
Class 5 Not installed Installed 792 900
Class 5 Installed Installed 836 950
SHUNT
POSITION PWMEN PIN LED PWM
OPERATION
Not installed* Internally pulled high Enabled
Installed Connected to VEE
through resistor R12 Shutdown
GREEN LED J2 PORT STATUS
Off Not powered or disconnected
On Powered, valid PD
Blinking 2 flashes Overcurrent fault during power-on
Blinking 5 flashes Detected invalid low-/high-discovery
signature resistance
SHUNT POSITION MIDSPAN PIN PSE CONFIGURATION
Not installed* Internally pulled high Midspan
Installed Connected to VEE through resistor R13 End point
CONFIGURATION RESISTOR
R5 R6 R7 R8
Midspan* Not installed Not installed Installed Installed
End point Installed Installed Not installed Not installed
________________________________________________________________ Maxim Integrated Products 12
MAX5971B Evaluation Kit
Evaluates: MAX5971B
Table 6. Legacy Modes (JU5)
Table 7. OSC and AC-/DC-Disconnect-Detection Functions (JU6)
Table 5. PSE Circuit Changes for Midspan/End-Point Configuration
Table 1. ILIM1/ILIM2 Functions (JU1, JU2)
Table 2. PWMEN Functions (JU3) Table 3. Green LED Status (J2)
*Default position. Refer to the MAX5971B IC data sheet for more information on Class 0–Class 4 overcurrent and current-limit
information.
*Default position.
Table 4. Midspan Functions (JU4)
*Default position.
*Default position.
*Default position.
*Default position.
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________________________________________________________________ Maxim Integrated Products 13
MAX5971B Evaluation Kit
Evaluates: MAX5971B
AC-Disconnect Monitoring Oscillator and
AC-/DC-Disconnect Operation
The EV kit features a 2-pin jumper (JU6) to disable the
IC’s internal triangular-wave oscillator at the OSC pin.
The oscillator is used for AC-disconnect monitoring of
the PD and is disabled for DC-disconnect operation.
For AC-disconnect operation, the internal oscillator is
used along with RCD components R3, C4 and D3, and
blocking-diode D4. Perform a power-on or reset the IC
using switch SW1 to effect the changes.
For DC-disconnect operation, shut down the internal
oscillator by installing a shunt on jumper JU6. Then
remove resistor R3 and install a 0I0402 surface-mount
resistor on the R9 pads to bypass blocking-diode D4.
Diode D3 remains installed. Refer to the AC Disconnect
Monitoring and DC Disconnect Monitoring sections in
the MAX5971B IC data sheet for additional information.
Table 7 lists the jumper options for the oscillator and AC/
DC configurations. Refer to the MAX5971B IC data sheet
for more information.
Reset/Shutdown and Automatic Modes
The EV kit features switch SW1 to reset the IC or set
the IC’s initial startup operational mode to auto mode.
Semiautomatic and manual modes can only be accessed
through their respective register using software. Refer
to the MAX5971B IC data sheet for more information.
Table 8 lists the switch options.
I2C-Compatible 2-Wire Slave address Selection
The EV kit features a 2-pin jumper (JU7) to set the slave
address to one of four addresses: 0x40, 0x42, 0x44, or
0x46 of the slave address on the I2C-compatible 2-wire
interface. Global address 0x60 is accepted by the IC
regardless of the jumper settings. The EV kit’s software
automatically sets the LSB for the proper read/write
command. Table 9 lists the jumper addressing options.
Stand-Alone Microcontroller Interface
(Isolated/Nonisolated)
The EV kit features PCB pads and a jumper to interface
directly with a microcontroller. The 8-pin (2 x 4) jumper
(JU8) has shorting connections on the bottom layer
that must be cut open to disable the optical coupler
interface for nonisolated evaluation. The jumper shorting
connections must be in place for evaluating an isolated
stand-alone microcontroller interface. Table 10 lists the
selectable jumper options.
35W or More Power Operation Without
an Ethernet Connection
The 10/100/1000BASE-TX magnetic output module RJ45
jack (J2) is rated for up to 700mA of current and cannot
be used for PSE operation at greater than 35W power.
The EV kit features PCB pads and banana jacks to
interface directly with the EV kit’s output port power when
operating at 35W or more. Use the GND and RTN PCB
pads or jacks to access the output port’s power without
an Ethernet connection.
External +3.3V Operation
The EV kit’s on-board +3.3V linear regulator circuit
can be reconfigured to operate the EV kit circuit with
an externally supplied +3.3V DC source. The EV kit’s
on-board linear regulator (U2) must be disabled and
several components reconfigured to operate the EV kit
with an externally supplied +3.3V source as follows:
• CutopentheshortingtracesonresistorsR31andR32
pads.
• Connect the external +3.3V ground terminal to the
VEE PCB pad or VEE test point (TP13 or TP11).
• Connecttheexternalsupplypositivetothe3_3Vtest
point (TP12).
The externally supplied +3.3V DC source must be able to
supply 50mA of current or more.
IC Pins’ Signal Measurements
The EV kit features test points to facilitate voltage
measuring at the ports’ respective LED, ILIM1, ILIM2,
PWMEN, MIDSPAN, LEGACY, and EN pin signals of the
IC. For the VEE connection, test points TP11 and TP13
can be used.
The output port current can be measured by replacing
any output port single resistor (R5 or R6) when operating
in midspan, or when operating in end point (R7 or R8).
Replace the respective resistor with a 1IQ1% 1206
surface-mount resistor.
J2 Port LED Status +3.3V Operation
The EV kit’s J2 port green LED status indicator is
configured to operate from the -54V supply. Alternatively,
the green LED status indicator can be reconfigured to
operate off the on-board +3.3V linear regulator circuit. To
evaluate this mode of operation, two components on the
EV kit must be reconfigured as follows:
• RemoveresistorR29.
• Installa200I0805 surface-mount resistor at R30.
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SWITCH POSITION EN PIN EV Kit OPERATION MODE
Not pressed Internally pulled high Automatic
Pressed Connected to VEE through resistor R16 Reset or shutdown
SHUNT POSITION
(AD0 BIT) AD0 PIN SLAVE ADDRESS READ/WRITE
1-5* Connected to VEE 0x40 Read
0x41 Write
1-3 Connected to 3_3V 0x42 Read
0x43 Write
1-2 Connected to SCL 0x44 Read
0x45 Write
1-4 Connected to SDA 0x46 Read
0x47 Write
JU8 PIN NUMBER
SHORT POSITION ISOLATION MODE EV KIT PCB PAD TO MICROCONTROLLER CONNECTION
1-2
(Shorted)* Isolated OPTO_VCC PCB pad connects to the microcontroller +3.3V power supply.
3-4
(Shorted)* Isolated OPTO_SCL PCB pad connects to the microcontroller serial-clock line.
5-6
(Shorted)* Isolated OPTO_SDA PCB pad connects to the microcontroller SDA data line.
7-8
(Shorted)* Isolated OPTO_INT PCB pad connects to the microcontroller interrupt pin.
— Isolated OPTO_GND PCB pad connects to the microcontroller power-supply ground.
1-2
(Cut open)** Nonisolated JU8-2: 3_3V pin receives power from the microcontroller supply.
3-4
(Cut open) Nonisolated JU8-4: SCL pin connects to the microcontroller serial-clock line.
5-6
(Cut open) Nonisolated JU8-6: SDA pin connects to the microcontroller SDA data line.
7-8
(Cut open) Nonisolated JU8-8: INT pin connects to the microcontroller interrupt pin.
** Nonisolated TP11 or TP13: VEE connects to the microcontroller power-supply ground.
________________________________________________________________ Maxim Integrated Products 14
MAX5971B Evaluation Kit
Evaluates: MAX5971B
Table 8. EN Operational Modes (SW1)
Table 9. AD0 Slave Address Selection (JU7)
Table 10. Jumper JU8 and Microcontroller PCB Pads Function
*Default position.
*Default set by PCB trace.
**See the External +3.3V Operation section for configuring the EV kit in nonisolated mode.
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