max5940bevkit

19-3317; Rev 1; 1/05
MAX5940B Evaluation Kit
The MAX5940B evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board featuring
an Ethernet port, network powered device (PD) interface
controller circuit for -48V supply systems. The EV kit
uses the MAX5940B IEEE 802.3af-compliant network PD
interface controller in an 8-pin SO package. The
MAX5940B EV kit can also evaluate the MAX5940D
rated for an absolute maximum input voltage of 90V.
The MAX5940B features an internal isolation switch that
limits inrush current. The MAX5940B is used in powerover-LAN applications requiring DC power from an
Ethernet network port for PDs such as IP phones, wireless access nodes, and security cameras.
The MAX5940B EV kit receives power from an IEEE
802.3af-compliant power sourcing equipment (PSE).
See the MAX5922 and MAX5935* data sheets for PSE
controllers. The PSE provides the required -44V to -57V
DC power over an unshielded twisted-pair Ethernet network cable to the EV kit’s RJ-45 jack. The EV kit features
a 10/100BASE-TX Voice-over-IP (VoIP) magnetic module and two diode bridges for separating the DC power
provided by an endspan or midspan Ethernet system.
The EV kit demonstrates the full functionality of the
MAX5940B such as the PD detection signature, configurable PD classification signature, programmable
inrush current, and undervoltage lockout (UVLO). All of
these features are configurable on the EV kit and additional test points for voltage probing and interfacing
have been provided for the PD interface.
The MAX5940B EV kit also features a galvanically isolated
6W, 275kHz switching frequency flyback DC-DC converter, which uses the MAX5014 current-mode PWM
controller. The MAX5940B’s -48V output provides power
for the converter circuit. The DC-DC converter is configured for an output voltage of 4.25V and provides up to
1.4A at the output. High efficiency up to 82.2% is
achieved using a single transistor flyback DC-DC converter topology. The surface-mount transformer provides
1500V galvanic isolation for the output. UVLO, soft-start,
and thermal shutdown provide a robust 6W isolated
power supply.
Warning: The MAX5940B EV kit operates with high voltages. Dangerous voltages are present on this EV kit and
on equipment connected to it. Users who power up this
EV kit or power the sources connected to it must be careful to follow safety procedures appropriate to working with
high-voltage electrical equipment.
Under severe fault or failure conditions, this EV kit may
dissipate large amounts of power, which could result in
the mechanical ejection of a component or of component debris at high velocity. Operate this EV kit with
care to avoid possible personal injury.
Features
♦ IEEE 802.3af-Compliant PD Interface Circuit
♦ PD Detection and Configurable Classification
Signatures
♦ Programmable Inrush Current Limit
♦ Programmable UVLO
♦ Isolated 6W Flyback DC-DC Converter
♦ -36V to -60V Input Range
♦ Isolated 4.25V Output at 1.4A
♦ Evaluates Endspan and Midspan Ethernet
Systems
♦ Interface to an External DC-DC Converter
♦ Local Power Inputs (Wall Cube)
♦ Also Evaluates MAX5940D (IC Replacement
Required)
♦ Fully Assembled and Tested
Ordering Information
PART
TEMP RANGE
MAX5940BEVKIT
0°C to +70°C
IC-PACKAGE
8 SO
The EV kit can be reconfigured for interfacing to an
external DC-DC converter for an additional 7W of output power.
*Future product—Contact factory for availability.
________________________________________________________________ Maxim Integrated Products
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.
1
Evaluates: MAX5940B/MAX5940D
General Description
MAX5940B Evaluation Kit
Evaluates: MAX5940B/MAX5940D
Component List
DESIGNATION
QTY
0.068µF ±10%, 100V X7R
ceramic capacitor (1210)
Murata GRM32NR72A683K
C17
1
10µF ±10%, 25V tantalum
capacitor (C)
Vishay 293D106X9025C2
1
6800pF ±10%, 100V X7R
ceramic capacitor (0805)
Murata GRM219R72A682K
C18
1
1000pF ±10%, 50V X7R ceramic
capacitor (0603)
Murata GRM188R71H102K
C3
1
47µF ±20%, 100V electrolytic
capacitor (12.5mm x 13.5mm)
Sanyo 100CV47FS
C19, C20
2
0.01µF ±10%, 100V X7R ceramic
capacitors (0805)
Murata GRM21BR72A103K
C4
1
1000pF ±10%, 250VAC X7R UL
ceramic capacitor (2010)
Murata GA352QR7GF102KW01L
C21
1
0.68µF ±20%, 100V X7R ceramic
capacitor (1210)
TDK C3225X7R2A684M
C5, C6
2
330µF ±10%, 10V tantalum
capacitors (X)
Kemet T494X337K010AS
D1
1
56.7V 600W zener overvoltage
transient suppressor (SMB)
Vishay SMBJ51A
C7, C15
2
1.0µF ±10%, 50V X7R ceramic
capacitors (1206)
TDK C3216X7R1H105K
D2
1
3A 40V Schottky diode (SMC)
Diodes Incorporated B340
0.1µF ±10%, 16V X7R ceramic
capacitors (0603)
Murata GRM188R71C104K
D3, D4
2
1A 200V super-fast rectifiers
(SMB)
Diodes Incorporated MURS120
D5
1
51V 5% 3W zener diode (SMB)
Vishay BZG05C51
D6
1
300mA 75V high-speed diode
(SOD-123)
Diodes Incorporated 1N4148W
D7, D8
2
1A 200V standard recovery
power rectifiers (DFS case)
Vishay DF02SA
D9
1
1A 100V standard recovery
power rectifier (SMA)
Diodes Incorporated S1B
D10
0
Not installed, 1A 100V standard
recovery power rectifier (SMA)
Diodes Incorporated, S1B
recommended
D11
1
30V 500mW zener diode
(SOD123)
Diodes Incorporated BZT52C30
DESIGNATION
QTY
C1
1
C2
C8, C16
C9
C10
C11
C12
C13
C14
2
2
1
1
1
DESCRIPTION
1µF ±10%, 10V X5R ceramic
capacitor (0603)
Murata 188R61A105K
0.033µF ±10%, 50V X7R ceramic
capacitor (0805)
Murata GRM219R71H333K
4700pF 250VAC X7R ceramic
capacitor (2220)
Murata GA355DR7GC472KY02
1
22µF ±20%, 35V tantalum
capacitor (D)
Kemet T494D226M035AS
1
0.1µF ±10%, 50V X7R ceramic
capacitor (0805)
Murata GRM21BR71H104K
1
0.22µF ±10%, 10V X7R ceramic
capacitor (0603)
Murata GRM188R71A224K
DESCRIPTION
_______________________________________________________________________________________
MAX5940B Evaluation Kit
DESIGNATION
QTY
DESCRIPTION
DESIGNATION
QTY
1
10Ω ±5% resistor (0805)
DESCRIPTION
1MΩ ±5% resistor (0805)
J1
1
RJ-45 black through-hole
connector, 8P-8C
R15
R16
1
JU1
1
3-pin header
R17
1
24.3kΩ ±1% resistor (0805)
R18, R19
2
75Ω ±5% resistors (0805)
JU2
1
5-pin header
1
Not installed, resistor (0805)
1
150V, 4.3A n-channel MOSFET
(D-PAK)
Fairchild FQD5N15TM
R20
N1
R21
1
2kΩ ±1% resistor (0805)
R22
1
100kΩ ±1% resistor (0805)
R23
1
0Ω ±5% resistor (0805)
R24
1
150Ω ±5% resistor (1210)
T1
1
10/100BASE-TX voice-over-IP
magnetic module
Pulse Engineering H2005A
T2
1
6W 200µH transformer
(12-pin Gull Wing)
Cooper-Coiltronics CTX03-16649
Q1, Q2
2
60V, 200mA NPN transistors
(SOT-23)
Central Semiconductor CMPT3904
R1
0
Not installed, resistor (1206)
R2
0
Not installed, resistor (0805)
R3
1
25.5kΩ ±1% resistor (1206)
R4
R5
R6
R7
1
1
1
1
10kΩ ±1% 100ppm thick-film
resistor (0805)
Panasonic ERJ6ENF1002V
TP1, TP2, TP3
3
PC test points, red
732Ω ±1% 100ppm thick-film
resistor (1206)
Panasonic ERJ8ENF7320V
TP0
1
PC test point, black
U1
1
MAX5940BESA (8-pin SO)
392Ω ±1% 100ppm thick-film
resistor (1206)
Panasonic ERJ8ENF3920V
U2
1
Current-mode PWM controller
(8-pin SO)
Maxim MAX5014CSA
U3
1
High-isolation voltage
photocoupler (SOP-4)
CEL/NEC PS2703-1
U4
1
1.24V precision shunt regulator
(SOT-23-5L)
Texas Instruments
TLV431AIDBVR
U5
1
High-isolation voltage
photocoupler (SOD-4)
CEL/NEC PS2701A-1
None
2
Shunts (JU1, JU2)
None
4
Rubber bumpers
None
1
MAX5940B PC board
255Ω ±1% 100ppm thick-film
resistor (1206)
Panasonic ERJ8ENF2550V
R8
1
178Ω ±1% 100ppm thick-film
resistor (1812)
Panasonic ERJ12NF1780U
R9
1
470Ω ±5% resistor (0805)
R10
1
10kΩ ±1% resistor (0805)
R11
1
2.1kΩ ±1% resistor (0805)
R12
1
221Ω ±1% resistor (0805)
R13
1
100Ω ±5% resistor (0805)
1
0.68Ω ±1% resistor (1206)
Panasonic ERJ8RQFR68V
R14
Quick Start
The MAX5940B EV kit is fully assembled and tested.
Follow these steps to verify board operation. Do not
turn on the power supply until all connections are
completed.
Required Equipment:
An IEEE 802.3af-compliant PSE and a Category 5 or 5e
Ethernet network cable or:
• One 48V, 1A-capable DC power supply
• MAX5940B EV kit
• One voltmeter
_______________________________________________________________________________________
3
Evaluates: MAX5940B/MAX5940D
Component List (continued)
Evaluates: MAX5940B/MAX5940D
MAX5940B Evaluation Kit
Component Suppliers
SUPPLIER
CEL/NEC; California Eastern Laboratories
PHONE
FAX
800-997-5227
408-588-2213
WEBSITE
www.cel.com
Cooper-Coiltronics
561-752-5000
561-742-1178
www.cooperet.com
Diodes Incorporated
805-446-4800
805-446-4850
www.diodes.com
Fairchild
888-522-5372
—
IRC
361-992-7900
361-992-3377
Kemet
864-963-6300
864-963-6322
www.kemet.com
Murata
770-436-1300
770-436-3030
www.murata.com
www.fairchildsemi.com
www.irctt.com
Panasonic
714-373-7366
714-737-7323
www.panasonic.com
Pulse Engineering
858-674-8100
858-674-8262
www.pulseeng.com
Sanyo Electronic Device
619-661-6835
619-661-1055
www.sanyodevices.com
TDK
847-803-6100
847-390-4405
www.component.tdk.com
—
—
Vishay
www.vishay.com
Note: Indicate that you are using the MAX5940B when contacting these component suppliers.
Hardware Connections
1) Verify that a shunt is installed on pins 1 and 2 of
jumpers JU1 (Class 1–4) and JU2 (Class 1).
2) Use one of the following methods to power the
MAX5940B EV kit:
If network connectivity is required: connect a
Category 5 Ethernet network cable from the
MAX5940B EV kit input port RJ-45 (J1) connector to
the corresponding PSE Ethernet LAN connection,
which provides power to the EV kit. Test points
TP4–TP9 provide the ethernet data signals.
If network connectivity is not required: connect a
48V DC power supply to the GND and -48V pads on
the MAX5940B EV kit.
3) Activate the PSE power supply or turn on the external DC power supply.
4) Using a voltmeter, verify that the EV kit provides
+4.25V across the VOUT and PGND pads. PGND is
galvanically isolated from the EV kit’s input GND
and output GND2 pads.
5) Observe desired signals with an oscilloscope or
voltage meter on test point TP1 (U1 PGOOD pin),
TP2 (U1 PGOOD), TP3 (U1 GATE), and TP0 (-48V)
pads provided on the PC board.
4
Detailed Description of
Hardware
The MAX5940B EV kit features an Ethernet-port network
PD interface controller circuit for -48V supply rail
systems. The MAX5940B IEEE 802.3af-compliant network PD interface controller in an 8-pin SO package.
The MAX5940B has an internal isolation switch that also
limits inrush current from the PSE. The MAX5940B is
used in power-over-LAN applications for powering PDs
from an unshielded twisted-pair (UTP) Ethernet
Category 5 or 5e network cable and PSE port using
endspan or midspan Ethernet systems.
The MAX5940B EV kit receives power (12.95W, max)
from an IEEE 802.3af-compliant PSE and a UTP cable
connected to the EV kit’s RJ-45 connector J1. It uses a
10/100BASE-TX VoIP magnetic module (T1) and two
diode-bridge power rectifiers (D7, D8) to separate the
-48V DC power sent by the PSE. The MAX5940B EV kit
can accept power from an endspan or midspan PSE network configuration. Diode D8 provides the midspan
power and diode D7 provides the endspan power. Test
points TP4–TP9 pick off the Ethernet data signals from
the IP magnetic module T1. Magnetic module T1 is a
dual module; however, only a single module is required.
_______________________________________________________________________________________
MAX5940B Evaluation Kit
Test points TP0 (-48V), TP1 (PGOOD), TP2 (PGOOD),
and TP3 (GATE) provide for voltage probing and/or
interfacing with an external DC-DC converter.
The MAX5940B EV kit’s galvanically isolated, 6W flyback
DC-DC converter uses a MAX5014 current-mode PWM
controller. The MAX5940B’s VOUT and GND2 pins (-32V
to -60V DC) provide power for the DC-DC converter
input circuit. The flyback DC-DC converter is configured
for an output voltage of +4.25V and provides up to 1.4A
at the output while achieving up to 82.2% efficiency.
Minimal component count is obtained by using a singletransistor (N1) flyback DC-DC converter topology. The
surface-mount transformer T2 provides 1500V galvanic
isolation for the output. Current-sense resistor R14 limits
the peak current through transistor N1 and primary of
transformer T2 to 1.5A. Isolated feedback voltage is
achieved by using optical coupler U3 and shunt regulator U4. Voltage feedback resistors R10 and R17 set the
output voltage. Diodes D4 and D5 limit the voltage at the
primary windings of T2 during switching. Resistor R15
and capacitor C18 form a snubber network that suppresses transient overvoltage ringing at diode D2
caused by transformer T2 leakage inductance and the
junction capacitance of diode D2.
Soft-start capacitor C14 enables the voltage at VOUT to
ramp up in a controlled manner without any voltage
overshoot. Internal UVLO and thermal shutdown within
the MAX5014 provide for a robust 6W isolated powersupply design. The MAX5014 PWM controller operates
at 275kHz and the duty cycle is limited to 85% maximum. Refer to the MAX5014 data sheet for more information on this controller.
The EV kit can easily be reconfigured to interface with
an external DC-DC converter for an additional 7W of
output power using the provided -48VOUT and GND2
PC board pads and test points TP0, TP1, and TP2.
Additionally, the EV kit can also be reconfigured for
stand-alone operation with an external DC-DC converter
rated for up to 12.95W.
The MAX5940B EV kit also provides a circuit for powering
the EV kit from a wall adapter or “local input” DC power
source. Apply the local DC power source (36V to 44V) to
the local input power (+) and local input power (-) PC
board pads. Once the local input voltage is above 36V,
optical coupler U4 turns off the MAX5940B internal
MOSFET by pulling the GATE voltage low. Transistor Q1
turns off transistor Q3, which enables the DC-DC converter to run. Diode D3 prevents the PSE supply from
back-driving the local power source. See the Local Input
Power Source section for more information on using a
wall adapter or “local input” DC power source.
Caution: The -48VOUT is not isolated from the power
coming from the RJ-45 jack J1.
Jumper Selection
The MAX5940B EV kit features several jumpers to
reconfigure the EV kit’s PD classification and external
DC-DC converter operation.
PD Classification Signature Selection
The MAX5940B EV kit has two jumpers that set the
desired PD classification signature to a PSE connected
to the EV kit’s input port J1 connector. The 3-pin jumper
JU1 and 5-pin jumper JU2 configure the classification
signature. Table 1 lists the jumper options.
Table 1. PD Classification Signature
Selection
CLASS
Class 0
Class 1
Class 2
Class 3
Class 4
JU1 SHUNT
2–3
1, 2
1, 2
1, 2
1, 2
JU2 SHUNT
Don’t care
1, 2
1, 3
1, 4
1, 5
_______________________________________________________________________________________
5
Evaluates: MAX5940B/MAX5940D
The EV kit demonstrates the full functionality of the
MAX5940B such as PD detection signature, configurable PD classification signature, programmable inrush
current, and programmable UVLO. Resistor R3 sets the
PD detection signature. A smaller value resistor should
be used to compensate for diode bridges with higher
resistance. Resistors R4–R8 determine the PD classification signature and appropriately configured jumpers
JU1 and JU2. A single resistor is required to determine
the classification. Gate capacitor C2 sets the inrush current. To utilize the UVLO feature of the MAX5940B, PC
board pads are provided to install resistors R1 and R2.
Resistors R1 and R2 set the UVLO threshold voltage
and also determine the PD detection signature. For
reconfiguring the EV kit for UVLO operation, see the
UVLO Configuration section. Also, for proper operation,
set the UVLO voltage to a minimum of 12V.
Evaluates: MAX5940B/MAX5940D
MAX5940B Evaluation Kit
External DC-DC Converter or Stand-Alone Operation
The MAX5940B EV kit features PC board pads and test
points to interface directly with an external DC-DC converter. The GND2 and -48VOUT PC board pads provide
power to the external -48V DC-DC converter. TP1
(PGOOD) and TP2 (PGOOD) provide interfacing with the
external converter. TP0 is an additional -48V test point
connection. Gate capacitor C2 must be replaced and
depends on the total input capacitance of both DC-DC
converters (EV kit and external).
For stand-alone operation without the EV kit’s 6W flyback
DC-DC converter, remove several components. Short the
PC board pads across capacitor C14 to disable the EV
kit’s on-board 6W flyback DC-DC converter. Also remove
bulk capacitor C3. Additionally, replace gate capacitor
C2, which depends upon the external DC-DC converter
input capacitance. See the Gate Capacitor Selection
section for selecting capacitor C2. The maximum power
available at the GND2 and -48VOUT pads depends on
the classification settings of jumpers JU1 and JU2. To
reconfigure the MAX5940B EV kit for either method of
operation, see Table 2.
Local Input Power Source
Opticoupler U5; transistors Q1 and Q2; and resistors
R21, R22, and R23 along with diodes D9, D11, and the
PC board pads for diode D10 enable the MAX5940B EV
kit to be configured for various configurations using a
local input power source with the PSE source. Use the
Local Input Power (+) and Local Input Power (-) PC board
pads to connect the local input power supply. The local
input power-supply operating voltage range must be
within 36V to 44V for the EV kit. This voltage range can be
changed with proper selection of diode D11 and resistor
R21.
When the local input power source is above 36V, it will
always take precedence over the PSE source. In this
case, U5 turns off the MAX5940B internal MOSFET by
pulling the GATE voltage low and the local power is
supplied directly to the GND2 and -48VOUT pads.
Once taking over, the local power source pollutes the
discovery and classification signatures of the
MAX5940B EV kit and prevents the PSE from powering
up the EV kit until the local power has dropped to 0V.
If the local input power source is below 32V and if the
PSE power comes up first, the PSE will provide power
through the MAX5940B IC VOUT pin. Diode D9 will prevent the PSE from back-driving the local input power
source when it is below 32V.
As an option when configuring the MAX5940B EV kit for
a local input power source, cut open the PC board
trace, shorting the diode D10 PC board pads, and
install the recommended diode. D10 prevents the local
input power source from polluting the discovery and
classification signatures of the MAX5940B EV kit. In this
configuration, the PSE power source can continuously
detect the EV kit and provide power right away after the
local power source voltage has dropped below 32V.
UVLO Configuration, Gate Capacitor
Selection, and Ethernet Data-Signal
Interfacing
Programmable UVLO Configuration
The MAX5940B EV kit features a UVLO circuit that prevents operation below the programmed input-supply
start voltage. Resistors R1 and R2 set the input voltage
Table 2. External Converter or Stand-Alone Operation
EV KIT
OPERATION
On-Board and
External DC-DC
Converters
Stand-Alone
6
REMOVE
None
EV KIT MODIFICATIONS
• Calculate new C2 value, using C3 and external DC-DC converter total input capacitance.
• Use TP0, TP1, TP2 to interface with an external DC-DC converter.
• Use GND2 and -48VOUT pads to power an external converter.
• Calculate new C2 value, using an external DC-DC converter total input capacitance.
Resistor R20 • Short capacitor C14 PC board pads.
Capacitor C3 • Use TP0, TP1, TP2 to interface with an external DC-DC converter.
• Use GND2 and -48VOUT pads to power an external converter.
_______________________________________________________________________________________
MAX5940B Evaluation Kit


VREF
R2 = 
 × 25.5kΩ
VIN

STARTUP 
R1 = 25.5kΩ − R2
where VIN STARTUP is the desired startup voltage
(≥+12V) at which the EV kit starts and VREF is typically
2.47V. Additionally, the total series resistance of R1 and
R2 must equate to 25.5kΩ. Resistors R1 and R2 provide
the PD detection signature’s resistive component when
using the UVLO feature. For proper operation, the R1/R2
divider voltage of the UVLO pin of the MAX5940B must
not exceed 7.5V at the maximum input voltage.
Gate Capacitor Selection
The MAX5940B gate capacitor value depends upon the
total capacitance connected to the MAX5940B IC
-48VOUT and GND2 pins. Typically, this is the sum of
any DC-DC converter input capacitance (including C3
and C21, if used) and any connected bulk capacitance.
Gate capacitor C2 is a 0805 surface-mount PC board
footprint and is chosen using the following equation:
Where I INRUSH is the desired inrush current (set to
100mA for this EV kit) and CIN is the total input capacitance connected to the MAX5940B -48VOUT and GND2
pins (only C3 as configured). When reconfiguring the EV
kit for powering an external DC-DC converter, see the
External DC-DC Converter or Stand-Alone Operation
section for removing certain components.
Ethernet Data Signal Interfacing
The EV kit features several test points to interface with
the Ethernet data signals. Test points TP4, TP5, and
TP8 provide for interfacing with the Ethernet data
receive signals. Test points TP6, TP7, and TP9 provide
interfacing with the Ethernet data transmit signals. All
trace lengths to/from module T1 have been matched to
within 3mils in length. The data sheet for module T1, a
10/100BASE-TX VoIP magnetic module, should be consulted prior to interfacing with the EV kit’s test point
Ethernet data signals. The 10/100BASE-TX VoIP magnetic module (T1) can be replaced with a module rated
for 1000BASE-TX for evaluation on Ethernet systems
operating at 1000Mbps. The MAX5940B EV kit has not
been verified under actual network operating conditions.
A dual magnetic module is used for T1; however, only a
single module is required.
 C × 10µA 
C2 =  IN

 IINRUSH 
_______________________________________________________________________________________
7
Evaluates: MAX5940B/MAX5940D
turn-on and UVLO of the MAX5940B. To evaluate the
programmable UVLO feature, remove resistor R3 and
then install surface-mount resistors R1 (1206 case) and
R2 (0805 case). Using the desired startup voltage, calculate resistors R1 and R2 using the following equations:
8
3
4
Figure 1. MAX5940B EV Kit Schematic (PD Main Circuit)
_______________________________________________________________________________________
1
3
2
JU1
2
1
JU2
2
1
R6
392Ω
1%
CLASS2
5
3
R21
2.0kΩ
1%
1
4
Q1
GATE
R8
178Ω
1%
CLASS4
2
3
GND2
R22
100kΩ
R7
255Ω
1%
R1
OPEN
R2
SHORT
(PC TRACE)
CLASS3
R3*
25.5kΩ
1%
*A SMALLER VALUE RESISTOR SHOULD BE USED TO COMPENSATE
FOR DIODE BRIDGES WITH HIGHER RESISTANCE.
NOTE: RESISTOR R4–R8 TCR IS 100ppm.
RCLASS
R5
732Ω
1%
R4
10kΩ
1%
D11
CLASS1
-48V
-48VOUT
U5
D9
GND2
TP0
C1
0.068µF
100V
CLASS0
LOCAL INPUT POWER (-)
-48V
GATE
D1
-48V
LOCAL INPUT POWER (+)
-48V
GND
1
2
3
TP3
RCLASS
GATE
TP9
TP8
TP7
TP6
TP5
TP4
Q2
6
4
3
1
11
8
5
2
9
7
12
10
RCLASS
VEE
U1
GND
5
D10
TX1+
RX1-
21
22
24
-48VOUT
PGOOD
SS_SHDN
PGOOD
GND2
1
+
D7
J1-8
J1-7
J1-5
J1-4
4 AC
3 AC
J1-2
J1-1
J1-6
J1-3
2
-
-48V
J1
RJ-45 8-PIN CONNECTOR
R20
OPEN
C2
6800pF
100V
RX1+
GND2
SHORT
(PC TRACE)
19
T1 TX1H2005A
23
RXCT1
RD2+
20
TXCT1
RD215
RX2+
TD2+
13
RX2TD218
TX2+
RCT1
16
TX2TCT1
14
RXCT2
TCT2
17
TXCT2
RCT2
TD1-
TD1+
RD1-
RD1+
TP2
TP1
-48VOUT
6
7
8
SS_SHDN
PGOOD
OUT
PGOOD
PGOOD
MAX5940B
UVLO
R23
0Ω
3
4
2
1
GND
GND
R19
75Ω
R18
75Ω
C19
0.01µF
1
+
D8
2
-
-48V
C20
0.01µF
4 AC
3 AC
CHASSIS_GND
C4
1000pF
250VAC
Evaluates: MAX5940B/MAX5940D
MAX5940B Evaluation Kit
_______________________________________________________________________________________
C15
1.0µF
C17
-48VOUT 10µF
25V
C16
0.1µF
R12
221Ω
1%
SS_SHDN
R11
2.1kΩ
1%
C14
0.22µF
3
4
-48VOUT
3
8
4
6
OPTO
VCC
U2
U3
2
1
2
U4
R9
470Ω
VDD
CS
5
7
GND2
MAX5014 NDRV
SS_SHDN
GND
1
V+
-48VOUT
5
3
4
C10
0.033µF
C13
0.1µF
R13
100Ω
1
3
R14
0.68Ω
1%
R17
24.3kΩ
1%
C12
22µF
35V
N1
4
D4
D5
6
5
1
D6
10
7
11
8
12
9
C11
4700pF
250VAC
-48VOUT
VOUT
R10
10kΩ
1%
C9
1µF
R16
1MΩ
D3
-48VOUT
GND2
C21
0.68µF
100V
T2
3
-48VOUT
D2
C18
1000pF
C7
1.0µF
R15
10Ω
C5
330µF
10V
C8
0.1µF
VOUT
C6
330µF
10V
R24
150Ω PGND
VOUT
Evaluates: MAX5940B/MAX5940D
C3
47µF
100V
MAX5940B Evaluation Kit
Figure 2. MAX5940B EV Kit Schematic (6W 4.25V Isolated Power-Supply Circuit)
9
Evaluates: MAX5940B/MAX5940D
MAX5940B Evaluation Kit
Figure 3. MAX5940B EV Kit Component Placement Guide—
Component Side
Figure 4. MAX5940B EV Kit PC Board Layout—Component
Side
Figure 5. MAX5940B EV Kit PC Board Layout—VCC Layer 2
Figure 6. MAX5940B EV Kit PC Board Layout—GND Layer 3
Figure 7. MAX5940B EV Kit PC Board Layout—Solder Side
Figure 8. MAX5940B EV Kit Component Placement Guide—
Solder Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.