A unique Silent Switcher® architecture, combined with spread spectrum frequency modulation, reduces EMI/EMC emissions by more than 25 dB even with switching frequencies in excess of 2 MHz, enabling it to easily pass the automotive CISPR25 class 5 peak and average limits. Synchronous rectification delivers efficiency as high as 94 % with a switching frequency of 2 MHz. Its 3 V to 65 V input voltage range makes it ideal for single or dual cell automotive/transportation and industrial applications.
The LT8641's internal high efficiency switches deliver up to 3.5 A of continuous output current and peak loads of 5 A to voltages as low as 0.81 V. The device's Burst Mode® operation keeps quiescent current under 2.5 μA 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 LT8641's unique design maintains a minimum dropout voltage of only 130 mV at 1 A under all conditions, enabling it to excel in scenarios such as automotive cold crank.
Furthermore, a fast minimum on-time of only 35 ns enables 2 MHz constant frequency switching from a 24 V input to a 3.3 V output, equipping designers to optimize efficiency while avoiding critical noise sensitive frequency bands. The LT8641's 18-lead 3 mm x 4 mm QFN package and high switching frequency keep external inductors and capacitors small, providing a compact, thermally efficient footprint.
The LT8641 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 10 mVP-P. Special design techniques and a new high speed process enable high efficiency over a wide input voltage range, and the LT8641’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 shutdown.
Features
- Silent Switcher® Architecture
- Ultralow EMI/EMC Emissions
- Spread Spectrum Frequency Modulation
- High Efficiency at High Frequency
- Up to 95 % Efficiency at 1 MHz
- Up to 94 % Efficiency at 2 MHz
- Wide Input Voltage Range: 3 V to 65 V
- 3.5 A Maximum Continuous Output, 5 A Peak Transient Output
- Ultralow Quiescent Current Burst Mode® Operation
- 2.5 μA IQ Regulating 12 VIN to 3.3 VOUT
- Output Ripple < 10 mVP-P
- Fast Minimum Switch-On Time: 35 ns
- Low Dropout under All Conditions: 130 mV at 1 A
- Safely Tolerates Inductor Saturation in Overload
- Adjustable and Synchronizable: 200 kHz to 3 MHz
- Peak Current Mode Operation
- Output Soft-Start and Tracking
- Small 18-Lead 3 mm × 4 mm QFN
Applications
- Automotive and Industrial Supplies
- General Purpose Step-Down
- GSM Power Supplies