MAX5986A_13 Datasheet, PDF (1/24 Pages) Maxim Integrated Products – IEEE 802.3af-Compliant, High-Efficiency, Class 1/Class 2, PDs with Integrated DC-DC Converter

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
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.
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.
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.
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.
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.
Applications
S IEEE 802.3af Compliant
S PoE Class 1/Class 2 Classification
S Simplified Wall Adapter Interface
S Intelligent MPS
S Sleep and Ultra-Low-Power Mode (MAX5986A/
MAX5986B)
S Efficient, Integrated DC-DC Converter (with
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
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
(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.
WiMAX is a registered certification mark and registered service
mark of WiMAX Forum.
IEEE 802.3af-Powered Devices
IP Phones
Wireless Access Nodes
Ordering Information appears at end of data sheet.
IP Security Cameras
WiMAX^® Base Stations
For related parts and recommended products to use with this part,
refer to www.maximintegrated.com/MAX5986A/MAX5987A.related.
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