LM65645 datasheet(12/66 Pages) TI2

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7 Detailed Description

7.1 Overview

The LM656x5 is a family of high-efficiency, high-power density, ultra-low EMI buck converters. These converters

operate over a wide input voltage range of 3V to 65V (70V <100ms) with pin selectable fixed output voltages of

3.3V, 5V, or as in adjustable output configuration.

The current-mode control architecture, with 30ns typical minimum on-time, allows high conversion ratios at high

frequencies, fast transient response, and excellent load and line regulation. If the minimum on-time or minimum

off-time does not support the desired conversion ratio, the switching frequency is automatically reduced. This

feature allows regulation to be maintained during load dump events and cold cranking situations.

This device is designed to minimize end-product cost and size while operating in high-performance industrial

environments. The LM656x5 can be set to operate at fixed 400kHz, fixed 2.2MHz, or in adjustable mode from

300kHz to 2.2MHz by using the RT pin. An integrated compensation network combined with an accurate current

limit scheme minimizes bill of material cost and component count.

The LM656x5 has been designed for low EMI. The device includes the following:

• Mode pin-configurable ±5% or ±10% dual random spread spectrum (DRSS) frequency hopping

• Symmetrical pin out minimizing parasitic package inductance

• Operation over a frequency range above and below AM radio band

• Pin-configurable for AUTO or FPWM mode along with external clock synchronization capabilities

These features can eliminate shielding and other expensive EMI mitigation measures.

To use the device in reliability-conscious environments, the LM656x5 has a package with enlarged corner

terminals for improved board level reliability and wettable flanks, allowing optical inspection.

LM65625, LM65635, LM65645

SNVSCH3 – JUNE 2025

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LM65645 Datasheet(PDF) 12 Page - Texas Instruments