80mW into 16Ω — the bench-fit question
The MAX4409ETP+ is a Class AB stereo headphone amplifier from Analog Devices' DirectDrive® series, delivering 80mW per channel into a 16Ω load — enough to drive most consumer and pro-audio headphones to comfortable listening levels without an external buffer.
20-TQFN footprint and thermal pad
Housed in a 20-WFQFN with exposed pad (supplier device package 20-TQFN, 4x4 mm), the part needs a thermal land on the PCB — the exposed paddle is the primary heat path, and leaving it floating means the die temperature climbs faster at the 80mW output ceiling.
Protection features and the repair-bench angle
On-chip short-circuit and thermal protection mean the amplifier shuts down before a headphone jack short or a stalled output stage burns the die — the scorch mark you'd otherwise find on the QFN is prevented by the protection loop. The shutdown pin lets a microcontroller or GPIO hold the amp in zero-current standby; a depop circuit suppresses the turn-on thump that otherwise sends a DC transient into the headphones.