Features

• Wide Input Voltage Range: 3.6V to 25V
• 2.2A Maximum Output Current
• Adjustable Switching Frequency: 300kHz to 2.8MHz
• Low Shutdown Current: IQ < 1µA
• Integrated Boost Diode
• Power Good Flag
• Saturating Switch Design: 0.18Ω On-Resistance
• 1.265V Feedback Reference Voltage
• Output Voltage: 1.265V to 20V
• Soft-Start Capability
• Small 10-Pin Thermally Enhanced (3mm x 3mm) DFN Package

Typical Application

Description

The LT1938 is an adjustable frequency (300kHz to 2.8MHz) monolithic buck switching regulator that accepts input voltages up to 25V. A high efficiency 0.18Ω switch is included on the die along with a boost Schottky diode and the necessary oscillator, control and logic circuitry. Current mode topology is used for fast transient response and good loop stability. The LT1938's high operating fre- quency allows the use of small, low cost inductors and ceramic capacitors resulting in low output ripple while keeping total solution size to a minimum. The 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 ag signals when VOUT reaches 90% of the programmed output voltage. The LT1938 is available in a 3mm x 3mm DFN package with Exposed Pad for low thermal resistance.