1 Features
• Input operating voltage range: 30V to 90V
– 100V absolute maximum
• 4× integrated gate drive control
• 165μA gate pull-up strength
• 100mA gate pull-down strength
• Ultra-low quiescent current of 0.27μA during
detection and classification phase (VIN1-IN2 < 23V)
• Linear gate regulation control for supply ORing
applications
– VTG_REG = 11mV
• Enable pin for user controlled device on/off
function
• –40°C to 125°C operating junction temperature
range
• Small footprint: 3mm × 3mm WSON-12
– Meets IPC-9592 spacing rules

2 Applications
• PoE powered devices (48V)
• Video surveillance: IP cameras
• Polarity agnostic power inputs

3 Description
The LM74681 is a 100V ideal diode bridge controller
capable of driving a MOSFET bridge, enabling
efficient low-loss bridge rectifier solutions in Power
over Ethernet (PoE) applications. It allows a Power
over Ethernet, powered device (PD) to receive
power from RJ-45 data pairs, spare pairs, or any
combination of the two, regardless of voltage polarity.
The integrated charge pump allows use of N-channel
MOSFETs, which are smaller and more cost effective
than P-channel MOSFETs for the same power level.
The LM74681 along with N-channel MOSFET bridge
can replace the conventional diode bridge and can
be conveniently implemented in both 2-pair and 4-
pair PoE PD systems. In the event of a power
source failure or short circuit, a rapid turn-off feature
reduces reverse current spikes. The device also
features an ultra-low quiescent current of 0.27μA,
which ensures that there is no data corruption during
the PoE PD detection and classification phase. This
device is characterized for operation over a junction
temperature range of –40°C to +125°C.