MAX5987AETE+T

The MAX5986A–MAX5986C/MAX5987A provide a
complete power-supply solution as IEEE® 802.3afcompliant 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–
MAX5986C 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 323mA operating current limit.
The integrated step-down DC-DC converter uses a peak
current-mode control scheme and provides an easy-toimplement architecture with a fast transient response.
The step-down converter operates in a wide input voltage
range from 8.7V to 60V and supports up to 6.49W
of input power. The MAX5986A/MAX5986B/MAX5987A
operate at a fixed 215kHz switching frequency and
the MAX5986C operates at a fixed 430kHz switching
frequency. The DC-DC converter operates at a fixed
switching 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 performance and reliability.
The MAX5986A–MAX5986C/MAX5987A are available
in a 16-pin, 5mm x 5mm, TQFN power package and
operate over the -40°C to +85°C temperature range.