LT3685EMSE#PBF

The LT3685 is a monolithic step-down switching regulator with adjustable frequency (200kHz to 2.4MHz), accepting operating input voltages up to 38V and a maximum input voltage of 60V. An internal overvoltage protection circuit shuts down the power switch when VIN exceeds a typical value of 38V (36V minimum), allowing the device to safely withstand 60V transient voltages. Integrated on-chip are a high-efficiency 0.25Ω switch, a boost Schottky diode, and the necessary oscillator, control, and logic circuitry. A current mode topology is employed for fast transient response and excellent loop stability. The LT3685's high operating frequency allows the use of small, low-cost inductors and ceramic capacitors, minimizing total solution size while reducing output ripple. A low-current shutdown mode reduces input supply current to less than 1μA, while a resistor and capacitor on the RUN/SS pin provide a controlled output voltage ramp (soft-start). A power good flag signals when VOUT reaches 89% of the programmed output voltage. The LT3685 is available in a 10-pin MSOP package and a 3mm x 3mm DFN package, both with an exposed pad for reduced thermal resistance.

Applications

• Automotive battery regulation
• Set-top box
• Distributed power regulation
• Industrial power supply
• Wall transformer regulation

Key features

• Wide input range: 3.6V to 36V operating voltage
• Overvoltage lockout protection against transients up to 60V
• 2A maximum output current
• Adjustable switching frequency: 200kHz to 2.4MHz
• Low shutdown current: <1μA
• Integrated boost diode
• Synchronizable from 250kHz to 2MHz
• Power good flag
• Saturating switch design: 0.25Ω on-resistance
• 0.790V feedback reference voltage
• Output voltage: 0.79V to 20V
• Soft-start function
• Compact 10-pin thermally enhanced MSOP and (3mm x 3mm) DFN packages