What this part is and where it fits
The LTC4414EMS8#PBF is a PowerPath source selector switch controller from Analog Devices. It does not contain internal power switches — instead, it drives an external P-channel MOSFET to OR two input power sources (2:1 ratio) and deliver the higher-voltage source to the output. This architecture lets the designer scale the current rating by choosing the external FET, making it suitable for high-current switch applications beyond what an integrated load switch could handle. The 3 V to 36 V supply range covers common battery stacks and industrial rails. The 33 µA quiescent current keeps the standby drain low in battery-backup scenarios. The -40°C to 85°C temperature grade suits industrial control cabinets, automotive cabin environments, and outdoor telecom enclosures. For full under-hood automotive (-40°C to 125°C), the LTC4414IMS8#PBF variant is the extended-temperature option.
External MOSFET — the key design decision
Because the LTC4414EMS8#PBF has no internal switches, the BOM must include a P-channel MOSFET. The controller's gate drive is sized for standard and logic-level FETs. The external FET selection determines the maximum load current, RDS(on) losses, and thermal budget — the controller itself only dissipates the 33 µA supply current plus gate drive losses. This is a different procurement profile than an integrated load switch: the buyer sources the FET separately, and the total BOM cost depends on the FET chosen.
Timing and sequencing
The 600 µs turn-on delay prevents false triggering during input power glitches. The 20 µs turn-off delay ensures the output holds up during brief source interruptions. For designs sequencing multiple rails, these delays matter — the output capacitor must sustain the load through the 20 µs window if both inputs drop.
Package and footprint
The 8-MSOP package (3.00 mm width) is a compact surface-mount footprint. The supplier device package is 8-MSOP; the alternate package/case listing includes 8-MSOP as a cross-compatible option.