Features

• Dual High Efficiency DC/DC Converters:
    Step-Up (V_OUT = 1.8V to 5.25V, I_SW = 600mA)
    Step-Down (V_OUT = 0.615V to 5.5V, I_OUT = 400mA)
• 1.8V to 5.5V Input Voltage Range
• Up to 94% Efficiency
• Pin Selectable Burst Mode® Operation
• 45μA Quiescent Current in Burst Mode Operation
• 1.2MHz (LTC3523) or 2.4MHz (LTC3523-2) Switching Frequency
• Independent Power Good Indicator Outputs
• Integrated Soft-Start
• Thermal and Overcurrent Protection
• < 2μA Quiescent Current in Shutdown
• Small 16-Lead 3mm x 3mm x 0.75mm QFN Package

Typical Application

Description

The LTC3523/LTC3523-2 combine a 600mA step-up DC/DC converter with a 400mA synchronous step-down DC/DC converter in a tiny 3mm x 3mm package. The 1.2MHz/2.4MHz switching frequencies minimize the solution footprint while maintaining high efficiency. Both converters feature soft-start and internal compensation, simplifying the design.

Both the step-up and step-down converters are current mode controlled and utilize an internal synchronous rectifier for high efficiency. The step-up supports 0% duty cycle operation and the step-down converter supports 100% duty cycle operation to extend battery run time. If the MODE pin is held high, both converters automatically transition between Burst Mode operation and PWM operation improving light load efficiency. Fixed, low noise 1.2MHz/2.4MHz PWM operation is selected when MODE is grounded.

The LTC3523/LTC3523-2 provide a sub-2μA shutdown mode, overtemperature shutdown and current limit protection on both converters. The LTC3523/LTC3523-2 are housed in a 16-lead 3mm x 3mm x 0.75mm QFN package.