What the TC670ECHTR actually does
The Microchip TC670ECHTR is a dedicated fan failure detector — it monitors a fan's tachometer output and pulls its open-drain alarm pin low when the fan stalls or slows below a programmed threshold. The internal temperature sensor lets it track its own ambient, but the primary job is fan supervision, not general-purpose temperature logging.
Housed in a 6-pin SOT-23 package (SOT-23-6, supplier device package SOT-23-6), the TC670ECHTR occupies minimal board area — about 3×3 mm footprint. The open-drain output means the alarm pin needs a pull-up resistor to the logic supply; the pin itself sinks current when active.