What this Boomer® stereo amp delivers on the board
The LM4866MTEX: The 20-PowerTSSOP (also called 20-HTSSOP) has a thermal pad underneath — that pad is the main heat path. A board layout that vias it to a ground plane keeps the junction temperature under control at full output into 3Ω. The supply range from 2V to 5.5V means it runs off a single Li-ion cell or a 5V USB rail.
Package rework and board-fit considerations
The exposed pad needs a solder stencil opening that covers 50-70% of the pad area; too much paste and the part floats, too little and the pad doesn't wet. RoHS non-compliant means the finish is tin-lead — it reflows at a lower temperature than lead-free SAC305, so if you're mixing this part on a lead-free board, set the reflow profile for the lead-free alloy and accept that the LM4866MTEX joints will be reflowed above their intended peak. The part itself is rated for the higher temp, but the solder joint reliability shifts.
Lifecycle and sourcing posture
Availability and current pricing confirmed against an RFQ — no stock-holding claim, quoted per BOM quantity.