Power Electronics

20V, 2.5A (IOUT) Synchronous Step-Down Regulator

The LTC3626 from Linear Technology is a high-efficiency, 3MHz synchronous buck regulator that offers both input and output current limiting and monitoring. It incorporates a unique constant frequency/controlled on-time, current-mode architecture that delivers up to 2.5A of continuous output current at output voltages as low as 0.6V from a 3mm x 4mm QFN package. Its current-mode operation offers excellent line and load transient response even with high step-down ratios. The LTC3626 operates from an input voltage range of 3.6V to 20V, making it suitable for a wide range of applications, including dual/multiple-cell Li-Ion battery stacks and 5V to 18V intermediate bus systems. Its average input current and output current limiting are pin-programmable, making it well suited for applications such as USB power. The LTC3626's switching frequency is user programmable and synchronizable from 500kHz to 3MHz, enabling the use of tiny, low cost capacitors and inductors.

The LTC3626 uses internal switches with RDS(ON) of only 115mΩ and 70mΩ to deliver efficiencies as high as 95%. Its unique control architecture enables it to achieve duty cycles as low as 5%, while maintaining switching frequencies up to 2.25MHz, making it ideal for high step-down ratio applications, such as 12VIN to 1.2VOUT conversions. Burst Mode® operation is used to maximize light load efficiency, requiring only 300µA (at no load), important for applications demanding maximum battery run time. For applications requiring the lowest possible noise, the LTC3626 can be configured to run in forced continuous mode, for minimum noise and potential RF interference. Furthermore, an internal die temperature monitor provides a voltage proportional to temperature which can be programmed to limit maximum die temperatures. Additional features include a power good voltage monitor, output voltage tracking capability and short circuit protection.

The LTC3626EUDC is available in a 3mm x 4mm QFN-20. Pricing starts at $3.45 each in 1,000-piece quantities. An industrial-grade version, the LTC3626IUDC offers guaranteed performance over the -40°C to 125°C operating junction temperature range, priced at $3.97 each in 1,000-piece quantities. Both versions are available from stock.

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