Linear Technology Corporation has introduced a new 3.5A, 65V input capability, synchronous step-down switching regulator. With its proprietary silent switcher architecture and spread-spectrum frequency modulation, the LT8641 can reduce EMI / EMC emissions by more than 25dB even at switching frequencies in excess of 2MHz, making it easy to pass automotive CISPR25 Class 5 peak and average limits .
Synchronous rectification provides up to 94% efficiency at a switching frequency of 2MHz. Its 3V to 65V input voltage range makes it ideal for single or dual battery automotive / transportation and industrial applications.
The LT8641's internal high-efficiency switch provides continuous output current up to 3.5A and a peak load of 5A, providing voltages as low as 0.81V. The device's burst mode operation keeps quiescent current below 2.5µA under no-load standby conditions, making it ideal for applications such as automotive "normally open" systems that require extended battery life. The unique design of the LT8641 maintains a minimum voltage drop of only 130mV at 1A under all conditions, which makes it excellent in scenarios such as cold turning of cars. In addition, the fast minimum on-time is only 35ns, enabling 2MHz constant frequency switching from 24V input to 3.3V output, enabling designers to optimize efficiency while avoiding critical noise-sensitive frequency bands.
The LT8641 utilizes internal top and bottom efficient power switches to integrate the necessary boost diodes, oscillators, control and logic circuits into a single chip. Low-ripple burst mode operation maintains high efficiency at low output currents while maintaining output ripple below 10mVP-P. Special design techniques and new high-speed processes achieve high efficiency over a wide input voltage range, and the LT8641's current-mode topology achieves fast transient response and excellent loop stability. Other features include internal compensation, power good flag, output soft start / tracking and thermal shutdown. The LT8641EUDC is available in a 3mm x 4mm QFN package.
