The LT8640’s internal high efficiency switches deliver up to 5A of continuous output current and peak loads of 7A to voltages as low as 0.97V. The devices’s Burst Mode® operation keeps quiescent current under 2.5µA in no-load standby conditions, 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 at 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, equipping 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 keep external inductors and capacitors small, providing a compact, thermally efficient footprint.

The LT8640 utilizes internal top and bottom high efficiency power switches with the necessary boost diode, oscillator, control and logic circuitry integrated into a single die. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 10mVPK-PK.

Special design techniques and a new high speed process enable high efficiency over a wide input voltage range, and the LT8640’s current-mode topology enables fast transient response and excellent loop stability. Other features include internal compensation, a power good flag, output soft-start/tracking and thermal protection.

The LT8640EUDC is packaged in a 3mm x 4mm QFN package and is priced at $4.35 each. An industrial temperature version, the LT8640IUDC, is tested and guaranteed to operate from a –40°C to 125°C operating junction temperature and is priced at $4.79 each. An automotive temperature version, the LT8640HUDC, is tested and guaranteed to operate from a

–40°C to 150°C operating junction temperature and is priced at $5.04 each. All pricing is for 1,000-piece quantities and all versions are available from stock.

Features:

－ Ultralow EMI/EMC Emissions

－ Spread Spectrum Frequency Modulation

－ High Efficiency at High Frequency

－ Wide Input Voltage Range: 3.4V to 42V

－ Ultralow Quiescent Current Burst Mode Operation:

－ 2.5μA IQ Regulating 12VIN to 3.3VOUT, Output Ripple < 10mVP-P

－ Fast Minimum Switch-On Time: 40ns

－ Low Dropout Under All Conditions: 100mV at 1A

－ Safely Tolerates Inductor Saturation in Overload

－ Adjustable & Synchronizable: 200kHz to 3MHz

－ Peak Current Mode Operation

－ Accurate 1V Enable Pin Threshold

－ Internal Compensation

－ Output Soft-Start & Tracking

－ Small 18-Lead 3mm × 4mm QFN