Figure 4. LT8640 Typical Automotive Schematic for a 5V Output
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Figure 5. LT8640 Efficiency Graph of Figure 4 Circuit at 1MHz, 2MHz & 3MHz
The LT8640’s 3.4V to 42V input voltage range makes it ideal for automotive and industrial applications. The internal high efficiency switches deliver up to 5A of continuous output current and peak loads of 7A to voltages as low as 0.97V. Its Burst Mode® operation offers only 2.5µA of quiescent current, making it well suited for applications such as automotive always-on systems, which need to extend operating battery life.
The LT8640’s unique design maintains a minimum dropout voltage of only 100mV (@1A) under all conditions, enabling it to excel in scenarios such as automotive cold-crank. Furthermore, a fast minimum on time of only 40ns enables 2MHz constant frequency switching from a 16V input to a 1.5V output, enabling designers to optimize efficiency while avoiding critical noise-sensitive frequency bands. The LT8640’s 20-lead 3mm x 4mm QFN package and high switching frequency keeps external inductors and capacitors small, providing a compact, thermally efficient footprint.
The rapid growth of extremely complex electronic systems in automobiles has created even higher demands on power management ICs. In the past, high load currents, fast switching frequencies and high efficiency designs collectively created big EMI challenges. However, the LT8640’s unique design offers