150V Low IQ Inverting Synchronous Switching Regulator Controller

Linear Technology Korea (CEO Hong Sa-kwak) announced the release of a high-voltage inverting switching regulator controller (product name: LTC3896) that drives all N-channel synchronous MOSFET power stages.

Most low-power or mid-range inverting DC/DC converters use coupled inductors or transformers. However, the LTC3896 uses only a single inductor and converts a positive input voltage of 4V to (150V – |VOUT–|) into a negative output voltage regulated to the range of –60V to –0.8V at an output current of up to 15 amperes. With very high efficiency of up to 96%, it is ideal for transportation, industrial, telecommunications, and power distribution applications.

The LT3896 includes a true ground-referenced control pin, eliminating the need for separate level-shift components for the interface. This component consumes only 40µA during output voltage regulation in standby mode, making it ideal for always-on systems. The LTC3896's powerful 1Ω N-channel MOSFET gate driver can be controlled from 5V to 10V, and logic or standard-level MOSFETs can be used to maximize efficiency.


To prevent high on-chip power consumption in high input voltage applications, the LTC3896 includes an NDRV pin. This pin drives the gate of an optional external N-channel MOSFET operating as a low dropout linear regulator to supply IC power. The EXTVCC pin receives power from the output voltage or another bias source to reduce power consumption and improve efficiency.

The LTC3896 operates at an adjustable fixed frequency in the range of 50 kHz to 900 kHz and can be synchronized with an external clock from 75 kHz to 850 kHz. Users can select forced continuous operation, pulse-skipping, or low-ripple Burst Mode® operation under light loads. 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 DCR (drop across the output inductor) or using an selectable sense resistor for maximum efficiency. The current foldback function limits MOSFET heat dissipation under overload conditions. Additional features include adjustable burst clamp and current limiting, a power good output signal, an integrated bootstrap diode, and adjustable soft start.

The LTC3896 is available in a TSSOP-38 thermally enhanced package with several pins removed to ensure high-voltage clearance. Two operating temperature ratings are available: extended and industrial versions ranging from –40°C to 125°C, and a high-temperature automotive version ranging from –40°C to 150°C. It is offered at $4.70 per unit in 1,000-unit quantities.