LTC4417 Datasheet

• Selects Highest Priority Supply from Three Inputs
• Blocks Reverse and Cross Conduction Currents
• Wide Operating Voltage Range: 2.5V to 36V
• –42V Protection Against Reverse Battery Connection
• Fast Switchover Minimizes Output Voltage Droop
• Low 28μA Operating Current
• <1μA Current Draw from Supplies Less than V_OUT
• 1.5% Input Overvoltage/Undervoltage Protection
• Adjustable Overvoltage/Undervoltage Hysteresis
• P-Channel MOSFET Gate Protection Clamp
• Cascadable for Additional Input Supplies
• 24-Lead Narrow SSOP and 4mm × 4mm QFN Packages

• Industrial Handheld Instruments
• High Availability Systems
• Battery Backup Systems
• Servers and Computer Peripherals

The LTC4417 connects one of three valid power supplies to a common output based on priority. Priority is defined by pin assignment, with V1 assigned the highest priority and V3 the lowest priority. A power supply is defined as valid when its voltage has been within its overvoltage (OV) and undervoltage (UV) window continuously for at least 256ms. If the highest priority valid input falls out of the OV/UV window, the channel is immediately disconnected and the next highest priority valid input is connected to the common output. Two or more LTC4417s can be cascaded to provide switchover between more than three inputs.

The LTC4417 incorporates fast non-overlap switching circuitry to prevent both reverse and cross conduction while minimizing output droop. The gate driver includes a 6V clamp to protect external MOSFETs. A controlled output ramp feature minimizes start-up inrush current. Open drain VALID outputs indicate the input supplies have been within their OV/UV window for 256ms.