Electronic Design

Step-Down 2.4-MHz Regulator Holds Down Quiescent Current

With very low quiescent current and high input transient protection, the LT3480 2-A, 38-V step-down switching regulator from Linear Technology Corp. is well-suited for automotive or telecom applications, which require always-on operation and maximum battery life. The device’s Burst Mode operation keeps quiescent current below 70 µA in no-load standby conditions. The 3.6-V to 36-V input voltage range and 60-V transient protection make it ideal for load-dump and cold-crank conditions found in automotive applications. A 3-A internal switch can deliver up to 2 A of continuous output current to voltages as low as 0.79 V. Users can program the switching frequency from 200 kHz to 2.4 MHz, allowing them to optimize efficiency while avoiding critical noise-sensitive frequencies. The high switching frequency, combined with a 3- by 3-mm DFN-10 or thermally enhanced MSOP-10E package, keep the external capacitors and inductors small and allow a compact, thermally efficient footprint.

The LT3480 uses a high-efficiency 3-A, 0.25-Ω switch, with the boost diode, oscillator, and control and logic circuitry integrated on-chip. Besides the low quiescent current, the Burst Mode maintains high efficiency at low output currents while keeping output ripple below 15 mV pk-pk. Special design techniques and a new high-voltage process enable fast transient response and excellent loop stability. Other features include external synchronization (from 250 kHz to 2 MHz), a power-good flag, and soft-start capability.


All versions of the LT3480 are available from stock.


The LT3480EDD (DFN) and LT3480EMSE (MSOP) start at $3.45 and $3.55 each, respectively, for 100-piece quantities. The LT3480IDD and LT3480IMSE, which are tested and guaranteed to operate at junction temperatures from −40°C to 125°C, cost $4.14 and $4.26 each in similar quantities.


Visit www.linear.com.

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