LM5145 datasheet(18/73 Pages) TI2

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7 Detailed Description

7.1 Overview

The LM25137 is a dual-channel, switching DC/DC controller that features all of the functions necessary to

implement a high-efficiency synchronous buck regulator. The device is offered from a controller family with three

options for functional safety applications: Capable, SIL 2, or SIL 3, with the latter two options designated by an

"F" suffix in the part number.

Operating over a wide input voltage range from 4V to 42V, the LM25137 is configured to provide a fixed 3.3V, 5V

or 12V output, or an adjustable output between 0.8V and 36V. This easy-to-use controller integrates high-side

and low-side MOSFET gate drivers, each capable of sourcing 2A and sinking 3A peak current. Adaptive dead-

time control is designed to minimize body diode conduction during switching transitions.

Peak current-mode control using a shunt resistor or inductor DCR current sensing provides inherent line feed

forward, cycle-by-cycle peak current limiting, and easy loop compensation. Current-mode control also supports

a wide duty cycle range for high input voltage and low-dropout applications as well as when a high voltage

conversion ratio (for example, 10-to-1) is required. The oscillator frequency is user-programmable between

100kHz to 2.2MHz, and the frequency can be synchronized as high as 2.5MHz by applying an external clock to

PFM/SYNC. A user-selectable PFM mode feature enables discontinuous conduction mode (DCM) operation to

further improve efficiency and reduce power dissipation during light-load conditions.

The LM25137 incorporates features to simplify the compliance with automotive EMI requirements (CISPR 25).

An optional spread spectrum frequency modulation (DRSS) technique reduces the peak EMI signature, while the

adaptive gate drivers minimize high-frequency emissions. Finally, 180° out-of-phase interleaved operation of the

two controller channels reduces input filtering and capacitor requirements.

The LM25137 is provided in a 36-pin VQFN package with a wettable flank pinout and an exposed pad to aid in

thermal dissipation.

LM25137

SNVSCU4 – OCTOBER 2025

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LM5145 Datasheet(PDF) 18 Page - Texas Instruments