1 Features
• Integrated synchronous rectifier FET and driver:
0.27mΩ
• Operates from 5V external bias supply
• Dead-time compensation (DTC) works with digital
power controllers:
– Automatic or manual dead-time adjustment of
gate turn-on edges
• Ideal diode mode (IDM) for autonomous turnon
edge optimization by sensing 3rd quadrant
conduction
• body-diode conduction sensing threshold: –250mV
• Detection times of body diode conduction: as low
as 4ns
• High frequency operation: up to 5MHz
• VCC undervoltage lockout (UVLO)
• 3.3V or 5V input logic levels, 3.3V output logic
level
• 5mm × 6mm QFN package
– Top-side exposed die for excellent thermal path
top side
– Large thermal pads for low thermal resistance
bottom side
– Large drain and source pads and corner
pins for improved board level reliability (BLR)
performance

2 Applications
• Server power: 6V PSU
• Server power: 6/5/4V brick applications
• Center-tapped LLC converters
• Digital power-control applications
• TV power supply

3 Description
The LMS1225 device is an industry-first 22.5V,
synchronous-rectification power stage with an
integrated gate driver and a MOSFET. The device
provides body-diode conduction sensing and reporting
and integrates a high performance driver that allows
any digital PWM controller to achieve advanced
synchronous-rectification (SR) control. The device
contains a high-speed gate driver, a body-diode
conduction-sensing circuit, an autonomous turn-on
and dead time reporting features. The device
is designed for high-efficiency center-tapped LLC
applications, where SR dead-time optimization is
desired.
The LMS1225 device offers efficient operation at
high frequencies up to 5MHz. The gate drive control
turns on through PWM signal in standard operation
or autonomously turns on in IDM operation. In IDM
operation an internal high-speed comparator with a
–250mV threshold detects the body-diode conduction
and autonomously switches on the MOSFET at the
turn-on edge if the PWM signal is already high. The
device is capable of sensing body-diode conduction
time as low as 4ns. In both operation modes, turn-off
control relies on PWM falling edge.
The LMS1225 internal high-speed comparator with a
–250mV threshold detects the body-diode conduction
and reports the information to the digital-power
controller through the DTC pin. The device senses
body-diode conduction time as low as 4ns. The
SR turn-on and turn-off edge is optimized by the
digital-power controller which analyzes the body-diode
conduction information reported by the LMS1225 DTC
pin.
The benefits of the chipset include maximizing system
efficiency by minimizing body-diode conduction time,
robust and fast bi-directional current sensing. The
integrated approach promotes high power density with
a layout which is optimized by as much as 30% in
comparison to discrete solutions.