Single-channel low-side switch with integrated protection
The BTS3207NHUMA1 is a single-output, low-side N-channel power switch from Infineon's HITFET® family, delivering up to 640 mA continuous output with a maximum Rds(on) of 500 mOhm. The non-inverting On/Off interface directly accepts logic-level control signals without a separate Vcc supply rail — the gate drive is self-biased from the load voltage.
Rds(on) at junction temperature and fault protection
The 500 mOhm Rds(on) is specified as a maximum at 25°C junction — at 150°C the on-resistance roughly doubles to about 1 Ohm, raising conduction loss by the same factor. For a 640 mA load the I²R loss at hot junction is about 0.4 W, which the SOT-223 package can dissipate with adequate board copper, but the thermal impedance of the PG-SOT223-4 footprint should be checked against the ambient temperature and the load duty cycle. This protection set is sized for resistive, capacitive, and moderate inductive loads; for highly inductive loads the over-voltage clamp absorbs the flyback energy.