P-channel load switch for tight spaces
The Texas Instruments CSD22205L is a P-channel NexFET power MOSFET in a 4-PICOSTAR package — a 4-pin XFLGA land-grid array that sits nearly flush on the board.
9.9 mOhm Rds(on) — what it buys you
Maximum on-resistance is 9.9 mOhm at 4.5 V gate drive with 1 A drain current. That low Rds(on) keeps conduction losses under 100 mW at 3 A — critical in a package that can only shed 600 mW at ambient. The drive voltage window is 1.5 V minimum for the highest Rds(on) tier, 4.5 V for the lowest; a 3.3 V logic-level gate drive lands between those points, so expect slightly higher than the 9.9 mOhm floor if the gate driver rail is 3.3 V.
8.5 nC gate charge — switching speed matters
Total gate charge at 4.5 V is 8.5 nC, and input capacitance at 4 V drain-source is 1390 pF. A modest 1 A gate driver can turn this FET on in under 10 ns; the real switching loss is in the output capacitance discharge, not the gate drive. For a 500 kHz to 1 MHz switching regulator, the gate-drive power penalty is small — roughly 40 µW per MHz of switching frequency.
Thermal reality in a 4-PICOSTAR package
The 4-PICOSTAR land-grid array measures roughly 1 mm × 1 mm — no exposed pad, no thermal slug. Maximum power dissipation is 600 mW at 25°C ambient, derated above that. The 7.4 A current rating is achievable only with aggressive PCB copper spreading and low duty-cycle pulsed operation; at DC the thermal limit kicks in well below that figure. Junction temperature range is -55°C to 150°C, so the silicon itself can survive hot environments, but the package limits how much heat it can move.
Active, ROHS3, and what that means for BOM planning
Product status is Active with ROHS3 compliance. The NexFET series is an ongoing TI portfolio — second-source risk is low.