EVALUATION KIT AVAILABLE
MAX5986A/MAX5986B/MAX5987A
IEEE 802.3af-Compliant, High-Efficiency, Class 1/
Class 2, PDs with Integrated DC-DC Converter
General Description
Benefits and Features
The MAX5986A/MAX5986B/MAX5987A provide a com-
plete power-supply solution as IEEE 802.3af-compliant
S IEEE 802.3af Compliant
®
S PoE Class 1/Class 2 Classification
S Simplified Wall Adapter Interface
S Intelligent MPS
Class 1/Class 2 Powered Devices (PDs) in a Power-over-
Ethernet (PoE) system. The devices integrate the PD
interface with an efficient DC-DC converter, offering a low
external part count PD solution. The MAX5987A includes
a low-dropout regulator and the MAX5986A/MAX5986B
include sleep and ultra-low power modes.
S Sleep and Ultra-Low-Power Mode (MAX5986A/
MAX5986B)
S Efficient, Integrated DC-DC Converter (with
The PD interface provides a detection signature and
a Class 1/Class 2 classification signature with a single
external resistor. The PD interface also provides an
isolation power MOSFET, a 60mA (max) inrush current
limit, and a 201mA (MAX5986A) or 323mA (MAX5986B/
MAX5987A) operating current limit.
Integrated Switches)
S 8.7V to 60V Wide Input Voltage Range
S 3.0V to 14V Programmable Output Voltage Range
S Internal Compensation
S Fixed 214kHz/275kHz Switching Frequency
The integrated step-down DC-DC converter uses a peak
current-mode control scheme and provides an easy-to-
implement architecture with a fast transient response.
The step-down converter operates in a wide input volt-
age range from 8.7V to 60V and supports up to 3.84W
(MAX5986A) or 6.49W (MAX5986B/MAX5987A) of input
power. The MAX5986A operates at a fixed 275kHz
switching frequency, while the MAX5986B/MAX5987A
operate at a fixed 215kHz switching frequency. The
DC-DC converter operates at a fixed 275kHz switch-
ing frequency, with an efficiency-boosting frequency
foldback that reduces the switching frequency by half at
light loads.
S Frequency Foldback for High-Efficiency Light-
Load Operation
S Built-In Output-Voltage Monitoring
S Open-Drain RESET Output (MAX5987A)
S Protects Against Overload, Output Short Circuit,
Output Overvoltage, and Overtemperature
S Hiccup-Mode Runaway Current Limit
S Back-Bias Capability to Optimize the Efficiency
S Integrated TVS Diode Withstands Cable Discharge
Event (CDE)
S Internal LDO Regulator with Up to 100mA Load
The devices feature an input undervoltage-lockout
(UVLO) with wide hysteresis and long deglitch time
to compensate for twisted-pair cable resistive drop
and to assure glitch-free transition during power-on/-off
conditions. The devices also feature overtemperature
shutdown, short-circuit protection, output overvoltage
protection, and hiccup current limit for enhanced perfor-
mance and reliability.
(MAX5987A)
S Fixed 3.3V or Adjustable Output Voltage Through
an External Resistive Divider
S 49mA (typ) Inrush Current Limit
S Pass 2kV, 200m CAT-6 Cable Discharge Event
IEEE is a registered service mark of the Institute of Electrical
and Electronics Engineers, Inc.
The MAX5986A/MAX5986B/MAX5987A are available in a
16-pin, 5mm x 5mm, TQFN power package and operate
over the -40°C to +85°C temperature range.
WiMAX is a registered certification mark and registered service
mark of WiMAX Forum.
Applications
IEEE 802.3af-Powered Devices
IP Phones
Ordering Information appears at end of data sheet.
Wireless Access Nodes
IP Security Cameras
For related parts and recommended products to use with this part,
refer to www.maximintegrated.com/MAX5986A/MAX5987A.related.
®
WiMAX Base Stations
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-6261; Rev 1; 12/12