This document introduces a 2MHz dual buck regulator that can deliver 3.3V and 1.8V from a 16V input without interfering with the AM radio band
The document describes the LT3640, a dual-channel constant frequency current mode monolithic buck switching regulator. It is designed to operate at 2MHz to avoid interference with AM radio bands while delivering 3.3V and 1.8V outputs from high input voltages typical in automotive (up to 36V) and industrial systems.
The device features a fast minimum on-time of approximately 6ns, enabling it to maintain high efficiency at high step-down ratios where traditional converters fail. It includes two channels: a non-synchronous high-voltage buck converter for inputs up to 35V and a synchronous low-voltage buck converter that can cascade from the first channel or operate independently.
| Operating Frequency | 2MHz |
|---|---|
| Minimum On-Time | about 6ns |
| High Voltage Input Range | 4V to 35V |
| Output Voltage Range | 0.6V minimum |
It operates outside the AM radio band to avoid interference issues associated with switching frequencies falling within that tuned frequency range.
The device monitors catch diode current and ensures cycle-by-cycle current limit to provide protection against a shorted output.
Yes, while it can be cascaded from the 3.3V channel, the low voltage channel can also operate from a separate supply source.