1 Features
• Versatile synchronous buck DC/DC controller
– 4V to 42V wide input voltage range
– Fixed 3.3V, 5V or adjustable output voltage
from 0.8V to 36V
– –40°C to 150°C junction temperature range
– Integrated high-current MOSFET gate drivers
with 1.65A source and 2.4A sink capability
– Lossless inductor DCR or shunt current sensing
– 25ns tON(min) for high VIN to VOUT conversion
– 80ns tOFF(min) for high duty-cycle applications
– 10μA no-load sleep quiescent current
– 2.3μA shutdown quiescent current
• Optimized for CISPR 25 Class 5 EMI requirements
– Dual Random Spread Spectrum (DRSS) with
5% or 10% frequency modulation
– 100kHz to 3.2MHz switching frequency
– Optional synchronization to an external clock
– Selectable PFM or FPWM operation
• Inherent protection features for robust design
– Hiccup-mode overcurrent protection
– Precision enable input and open-drain PGOOD
indicator for sequencing and control
– VCC and gate-drive UVLO protection
– Fixed 3ms output voltage soft start
– Thermal shutdown protection with hysteresis
• 16-pin, 3mm × 3mm package with wettable flanks
• Create a custom design using the LM25139 device
with the WEBENCH® Power Designer

2 Applications
• Personal electronics: computer peripherals
• Industrial: 24V bus systems, power delivery
• Enterprise systems: high-performance computing

3 Description
The LM25139 is a 42V, synchronous, buck DC/DC
controller with ultra-low IQ for single-output, highcurrent
regulator circuits. Deriving from a family
of wide-VIN range controllers, the device uses
a peak current-mode control architecture for fast
transient response, convenient loop compensation,
and excellent load and line regulation performance.
A high-side switch minimum on time of 25ns provides
large step-down ratios, enabling the direct conversion
from 12V and 24V inputs to low-voltage rails for
reduced system design cost and complexity. The
LM25139 continues to operate during input voltage
dips as low as 4V, at nearly 100% duty cycle if
needed, making the device an excellent choice for
high-performance applications.
The LM25139 comes in a thermally enhanced, 16-
pin VQFN package with wettable flank pins and an
exposed pad to aid in thermal dissipation.