LM5145 datasheet(18/69 Pages) TI

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9 Detailed Description

9.1 Overview

The LM25143 is a dual-phase or dual-channel switching controller that features all of the functions necessary

to implement a high-efficiency synchronous buck power supply operating over a wide input voltage range from

3.5 V to 42 V. The LM25143 is configured to provide a fixed 3.3-V or 5-V output, or an adjustable output

between 0.6 V to 36 V. This easy-to-use controller integrates high-side and low-side MOSFET drivers capable of

sourcing 3.25-A and sinking 4.25-A peak current. Adaptive dead-time control is designed to minimize body diode

conduction during switching transitions.

Current-mode control using a shunt resistor or inductor DCR current sensing provides inherent line feedforward,

cycle-by-cycle peak current limiting, and easy loop compensation. It 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 100 kHz to 2.2 MHz, and the

frequency can be synchronized as high as 2.5 MHz by applying an external clock to DEMB.

An external bias supply can be connected to VCCX to maximize efficiency in high input voltage applications.

A user-selectable diode emulation feature enables discontinuous conduction mode (DCM) operation to further

improve efficiency and reduce power dissipation during light-load conditions. Fault protection features include

the following:

• Current limiting

• Thermal shutdown

• UVLO

• Remote shutdown capability

The LM25143 incorporates features to simplify the compliance with CISPR 11 and CISPR 32 EMI requirements.

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

the adaptive gate drivers with slew rate control minimize high-frequency emissions. Finally, 180° out-of-phase

interleaved operation of the two controller channels reduces input filtering and capacitor requirements.

The LM25143 is provided in a 40-pin VQFN package with an exposed pad to aid in thermal dissipation.

LM25143

SNVSC10 – MARCH 2022

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