150V Synchronous Step-Down DC/DC Controller Released

Linear Technology Korea (CEO Hong Sa-kwak) announced the release of a high-voltage non-isolated synchronous step-down switching regulator controller (product name: LTC3895) using an external N-channel MOSFET.

The input voltage range of 4V to 140V (150V abs max) is designed to operate with high input voltage sources or inputs with high voltage surge conditions, eliminating the need for external surge protection devices. The LTC3895 ensures continuous operation with a maximum duty cycle of 100% while the input voltage dips down to 4V, making it suitable for transportation, industrial control, robotics, and datacom applications.

The output voltage can be set from 0.8V to 60V at an output current of up to 20 amperes with a high efficiency of 96%. This product consumes only 40µA in standby mode when output voltage is regulated, making it ideal for always-on systems. The internal charge pump circuit enables 100% duty cycle operation during dropout, a useful feature when operating from a discharged battery.

The LTC3895's powerful 1Ω N-channel MOSFET gate driver can be adjusted between 5V and 10V, and logic-level or standard MOSFETs can be used to maximize efficiency. To reduce high on-chip power consumption in high input voltage applications, the LTC3895 drives the gate by selecting an external N-channel MOSFET that operates as a low-dropout linear regulator capable of supplying IC power. The EXTVCC pin can be powered from the output of a switching regulator or another possible source, reducing power consumption and improving efficiency.

The LTC3895 operates at a selected fixed frequency between 50 kHz and 900 kHz and can be synchronized with an external clock between 75 kHz and 850 kHz. Users can select forced continuous operation, pulse-skipping, or low-ripple Burst Mode® operation under light load conditions.

This product's current-mode architecture provides easy loop compensation, fast transient response, and excellent line regulation. Current sensing is achieved by measuring the voltage drop across the output inductor (DCR) for maximum efficiency or by using an optional sense resistor. A minimum on-time of 80ns enables a high step-down ratio at high switching frequencies. The current foldback function limits MOSFET heat dissipation under overload conditions. Additional features include fixed 5V or 3.3V output options, an integrated bootstrap diode, a power-good output signal, adjustable input overvoltage lockout, and a soft-start function.

The LTC3895 is supplied in a package with improved thermal performance compared to the TSSOP-38, featuring multiple pins removed for high-voltage applications. It is available in two operating temperature ratings: an industrial version with a rating of -40 to 125°C and a high-temperature automotive version with a rating of -40 to 150°C. It is priced at $4.70 per unit in 1,000-unit quantities.