The TC670 is an integrated fan speed sensor that predicts and/or detects fan failure, preventing thermal damage to systems with cooling fans. When the fan speed falls below a user-specified level, the TC670 asserts an ALERT signal. With this design, a critical minimum fan speed is determined by the user. The fan alert level is then set with a resistor divider on the THRESHOLD pin (Pin 1) of the TC670. When the minimum fan speed is reached, the ALERT pin (Pin 5) changes from a digital high to low. This failure detection works with all linear-controlled 2-wire fans. The TC670 eliminates the need for 3-wire fan solutions.