ADI LTC3446IDE#PBF

The LTC3446 combines a synchronous buck DC/DC converter with two very low dropout (VLDO) linear regulators to provide up to three stepped-down output voltages from a single input voltage. The input voltage range is ideally suited for Li-Ion battery-powered applications, as well as powering low voltage logic from 5V or 3.3V rails. The output voltage range extends down to 0.4V for the VLDO regulators and 0.8V for the buck. The 1A synchronous buck converter provides the main output with high efficiency, typically 85%. The two 300mA VLDO regulators can run off the main output to provide two additional lower voltage outputs. A built-in supply monitor provides a power good indication. The buck converter switches at 2.25MHz, allowing the use of small surface mount inductors and capacitors. Constant frequency current mode operation produces controlled output spectrum and fast transient response. A modeselect pin allows automatic Burst Mode operation to be enabled for higher efficiency at light load, or disabled for lower noise operation down to very light loads. The two VLDO regulators are stable with ceramic output capacitors as small as 1µF.

• High Efficiency Triple Step-Down Outputs from a Single Input Supply
• 1A Synchronous Buck Regulator Provides Main Step-Down Output and Powers Two 300mA VLDO Linear Regulators
• Output Voltages as Low as 400mV (VLDO Outputs)
• Power Good Output
• Input Voltage Range: 2.7V to 5.5V
• Independent Enable Pin for Each Supply
• Low (140µA Typ) No-Load Quiescent Current with All Outputs Enabled
• Constant Frequency Current Mode Operation
• 2.25MHz Switching Frequency Uses Small Inductors
• Defeatable Automatic Burst Mode Operation for High Efficiency at Light Loads
• ±1.5% Reference Accuracy
• Overtemperature Protection
• Thermally Enhanced 4mm × 3mm 14-Pin DFN Package

• Low Power Handheld Devices
• Low Voltage and Multivoltage Power for Digital Logic, I/O, FPGAs, CPLDs, ASICs and CPUs