Diodes brushless DC full bridge motor drivers provide PWM or DC voltage speed control

     Diodes Corporation introduces the AM9468 and AM9469 brushless DC motor drivers with bridge-tied load (BTL) drive architectures to minimize audible switching noise and electromagnetic interference (EMI). Provides intelligently driven cooling fans in laptops and desktop computers, instrumentation and similar devices, and supports a wide range of other medium voltage, low power motor drive applications.

     The AM9468/AM9469 uses an external pulse-width modulated PWM signal or a DC DC voltage, or voltage from a thermistor network for flexible motor speed control to adjust the duty cycle of the full bridge output driver stage based on the input signal. At the same time, a separate frequency generator provides an output speed that allows the motor speed to be monitored externally. The BTL architecture amplifies the sinusoidal flux density signal used to drive the motor coil, avoiding large changes in current during commutation and helping to achieve low noise operation. The speed control PWM duty cycle is superimposed on the BTL drive signal.

     The AM9468/AM9469 features a built-in quick-start circuit and rotor lock detection to protect the motor coil from overheating or burning out, and also ensures an automatic restart when the lock is released. Other features include current-limiting circuits and Hall biased outputs, all of which help to significantly reduce the number of external components and PCB footprint of the solution, as well as reduce component and manufacturing costs.

     The AM9468 is supplied in a standard, power-capable TSOP-16 package, while the AM9469 is supplied in a better heat-dissipating bare thermal pad TSOP-16EP package, capable of delivering or absorbing up to 700mA of output current. The thermal shut-off circuit with the AM9468/AM9469 provides overheat protection, a special feature that protects closed-loop coils and cooling fan PCBS in consumer product applications where heat dissipation is critical. Both devices have an operating temperature range of -40°C to 105°C.