_________________________________________________________________ Maxim Integrated Products 3
MAX5986A Evaluation Kit
Evaluates: MAX5986A
Quick Start
Required Equipment
• MAX5986A EV kit
• An IEEE 802.3af/at-compliant PSE and a Category
5e Ethernet network cable
• -48V, 1A capable DC power supply
• Voltmeter
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) Use one of the following methods to power the EV kit:
a. If network connectivity is required: Connect a
Category 5e Ethernet network cable from the EV
kit input port RJ45 connector to the correspond-
ing PSE Ethernet LAN connection that provides
power to the EV kit.
b. If network connectivity is not required: Connect
a -48V DC power supply between the V- and V+
PCB pads on the EV kit. Connect the power-
supply positive terminal to the V+ PCB pad and
the negative terminal to the V- PCB pad.
2) Activate the PSE power supply or turn on the external
DC power supply.
3) Using a voltmeter, verify that the EV kit provides +5V
across the OUT and VSS PCB pads.
Detailed Description of Hardware
The MAX5986A EV kit features an Ethernet port and net-
work PD interface controller circuit for -57V supply rail
systems. The EV kit contains a MAX5986A IEEE 802.3af/
at-compliant network PD interface controller in a 16-pin
TQFN-EP package. The IC is used in PoL applications
for powering PDs from an unshielded twisted-pair (UTP)
Ethernet Category 5e network cable and PSE port using
endspan or midspan Ethernet systems.
The EV kit receives power from an IEEE 802.3af/at-
compliant PSE and a UTP cable connected to the EV
kit’s RJ45 magnetic jack. The EV kit uses a 1 x 1 gigabit
RJ45 magnetic jack and two active full-wave bridge
power rectifiers to separate the -57V DC power sent by
the PSE. The EV kit can accept power from an endspan
or midspan PSE network configuration.
The EV kit can also accept power from a wall adapter
power source. When a wall adapter power source is
detected between the WAD_IN and WAD_GND PCB
pads, the IC’s internal isolation switch disconnects VCC
from VDD, which allows the wall adapter to supply power
to the EV kit.
The EV kit demonstrates the full functionality of the IC
such as PD detection signature, PD classification signa-
ture, inrush current control, and UVLO. Resistor R5 sets
the PD detection and classification signatures. The EV kit
is set to a Class 1 PD by resistor R5.
The EV kit’s integrated DC-DC step-down converter is
configured for a nonisolated output voltage of +5V and
provides up to 768mA at the output while achieving up
to 86.68% and 90.22% efficiencies at +36V and +12V
input, respectively. The integrated step-down converter
operates at a fixed 275kHz switching frequency.
Wall Adapter Power Source
(WAD_IN, WAD_GND)
The EV kit can also accept power from a wall adapter
power source. Use the WAD_IN (0V) and WAD_GND
(-10V to -57V) PCB pads to connect the wall adapter
power source. The wall adapter power source operating-
voltage range must be within +10V to +57V for the EV kit.
When the wall adapter power source is above +10V it
always takes precedence over the PSE source. Once the
wall adapter power source is detected, the IC’s internal
isolation switch disconnects VCC from VDD. The wall
adapter power is supplied to VCC (through diode D2)
and VSS. Once it takes over, the classification process
is disabled.
When the wall adapter power source is below +8.5V, the
PSE provides power through the IC’s VSS. Diode D2 pre-
vents the PSE from back-driving the wall adapter power
source when it is below +8.5V.
Undervoltage Lockout (UVLO)
The EV kit operates up to a -57V supply with a turn-on
UVLO threshold (VON) at -37.6V and a turn-off UVLO
threshold (VOFF) at -30.0V. When the input voltage is
above VON, the EV kit is enabled. When the input voltage
goes below VOFF, the EV kit is disabled.