MAX5945EVKIT Maxim Integrated, MAX5945EVKIT Datasheet - Page 6

• Manufacturer Part Number: MAX5945EVKIT
• Description: Power Management IC Development Tools Evaluation Kit/Evaluation System for the MAX5945
• Manufacturer: Maxim Integrated
• Series: MAX5945r

MOSFET and sensing current through the respective
port’s current-sense resistor. The current is fed to a
10/100 base-TX VoIP magnetic module connected to
the respective Ethernet network output port’s RJ-45
jack. An IEEE 802.3af-compliant PD connects to the
respective Ethernet network output port on the EV kit.
The PD can be located up to 350ft from the EV kit when
connected with Category 5 Ethernet cable. The
MAX5945 EV kit provides separate and independent
power control for each of the four Ethernet network out-
put ports. The 10/100 base-TX VoIP magnetic module
is decoupled to the EV kit’s chassis ground by system
chassis capacitors C19–C22, C24, and C25. The EV
kit’s isolated chassis ground (Chassis_GND) PC board
pad connects to the network system ground.
The MAX5945 EV kit features configurable operational
modes, PD detection, PD classification, overcurrent
protection, current foldback, under/overvoltage protec-
tion, DC and AC disconnect monitoring. The overcur-
rent protection can be programmed through software
and/or changing current-sense resistors R1–R4 for the
desired output port. Each of the four modes of opera-
tion (auto, semi, manual, shutdown) can be evaluated
after configuring jumper JU6 and configuring the
appropriate MAX5945 register (see Table 3). PD detec-
tion diodes D1–D4 can be bypassed to reduce power
dissipation when AC disconnect monitoring is not
required, using jumpers JU15–JU18. Each port’s AC
detection circuit resistor-capacitor diode (RCD) net-
work can be reconfigured with a jumper also. See
Tables 4, 8, and 9 for various AC detection-disconnect
and oscillator configurations. Each port features a
600W bidirectional overvoltage transient suppressor
diode (D9–D12) and decoupling capacitor (C26–C29)
for transient protection at the port.
Test points and jumpers have been provided for volt-
age probing and current measurements of each chan-
nel’s power circuit. Additionally, a 6-pin 0.100in center
header is also provided for monitoring the SHDN1,
SHDN2, SHDN3, SHDN4, and RESET signals routed to
the MAX5945 pins from the respective switch (S1–S5).
When using the header signals, caution should be
exercised since the DGND and GND are shorted by
resistor R72’s PC board shorting trace. Green LEDs
near each port’s RJ-45 output jack indicate when the
respective port power is turned on.
A 100Hz oscillator circuit that meets the IEEE 802.3af
PSE power interface (PI) parameters for AC disconnect
detection is provided by the MAX5945 EV kit. Five ICs
make up the 100Hz oscillator circuit, which consists of
U5, a programmable Dallas Semiconductor 40MHz
EconOscillator/divider squarewave oscillator and a
MAX7491 dual universal switched-capacitor filter, U4.
MAX5945 Evaluation Kit/Evaluation System
6
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Voltage reference source U6 (MAX6106) provides
2.048V for the circuit and level shifts the sine wave’s
output. The MAX4599, an SPDT analog switch, and U3,
an LMX358 dual-output op amp, provides support func-
tions for the oscillator circuit. An external sine-wave
oscillator meeting the IEEE 802.3af PSE PI parameters
can be connected to the EV kit’s BNC connector
(OSC_INPUT) after reconfiguring jumper JU7. The EV
kit’s 100Hz oscillator circuit can be shut down using
jumper JU8 if an external oscillator is used or AC dis-
connect detection is not required.
The EV kit provides the required optical isolation for the
I
operate as a slave device. The optically isolated inter-
face connects to a PC parallel port through a
MAXSMBus interface board. The MAXSMBus interface
board requires a dedicated 9V power supply capable
of supplying 250mA. The EV kit’s I
or 3-wire interface can be reconfigured for interfacing
to a stand-alone microcontroller for isolated (2-wire) or
nonisolated (3-wire) serial operation. Additionally, for
stand-alone microcontroller operation, the MAXSMBus
interface board and 9V power supply are not required.
The optical isolation consists of optocoupler U7, which
provides galvanic isolation for the serial interface clock
line (SCL) and serial interface input data line signals.
Optocoupler U8 provides galvanic isolation for the seri-
al output and data line (SDAOUT) and INT signals. The
SCL and SDAOUT signals’ 3-wire serial interface are
combined on the isolated 2-wire side prior to feeding
logic buffer U9. The SCL_IN, SDA, INT_OUT,
OPTO_GND and VCC PC board pads are used for a 2-
wire isolated stand-alone operation. For nonisolated
stand-alone 3-wire operation, jumper JU9 must be
reconfigured and then the SCL, SDAIN, SDAOUT, INT,
DGND, and VDIG PC board pads must be connected
to the microcontroller circuit. Note that VDIG is at
+3.3V, which is required by the EV kit. The OPTO_GND
and GND, DGND planes are isolated by the optical
couplers. However, when using the EV kit in a non-
isolated configuration, caution should be exercised
since DGND and GND are shorted by resistor R72’s
PC board shorting trace.
The MAX5945 slave address is configured by four
jumpers (JU1–JU4) and can be configured from 0x40
through 0x5F hexadecimal serial address. Global
address 0x60 is accepted by the MAX5945 regardless
of the jumper settings. Refer to Table 1 and the
Address Inputs section in the MAX5945 data sheet for
more information on setting the MAX5945 slave
address.
2
C-compliant 3-wire interface so the MAX5945 can
2
C-compliant 2-wire