ML4425

`Stand-alone operation
`Motor starts and stops with power to IC
`On-board start sequence: Align ® Ramp ® Set Speed
`Patented Back-EMF commutation technique provides jitterless torque for minimum "spin-up" time
`Onboard speed control loop
`PLL used for commutation provides noise immunity from PWM spikes, compared to noise sensitive zero crossing technique
`PWM control for maximum efficiency
`Direct FET drive for 12V motors; drives high voltage motors with IC buffers from IR, IXYS, Harris, Power Integrations, Siliconix, etc.

Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied.

VDD .......................................................................... 14V
Logic Inputs (, SPEED FB, BRAKE) .......... GND - 0.3 to 7V
All Other Inputs and Outputs .. GND -0.3V to VDD + 0.3V
Output Current (LA, LB, LC, HA, HB, HC) ............ ±50mA
Junction Temperature .............................................. 150ºC
Storage Temperature Range ...................... 65ºC to 150ºC
Lead Temperature (Soldering 10 sec.) ..................... 260ºC
Thermal Resistance (qJA)
28-Pin Narrow PDIP ......................................... 48ºC/W
28-Pin SOIC ..................................................... 75ºC/W
32-Pin TQFP ..................................................... 80ºC/W

The ML4425 PWM motor controller provides all of the
functions necessary for starting and controlling the speed of delta or wye wound Brushless DC (BLDC) motors without Hall Effect sensors. Back EMF voltage is sensed from the motor windings to determine the proper commutation phase sequence using a PLL. This patented sensing technique will commutate a wide range of 3- Phase BLDC motors and is insensitive to PWM noise and motor snubbing circuitry.

The ML4425 limits the motor current using a constant offtime PWM control loop. The velocity loop is controlled with an onboard amplifier. The ML4425 has circuitry to ensure that there is no shoot-through in directly driven external power MOSFETs.

The timing of the start-up sequence of ML4425 is determined by the selection of three timing capacitors. This allows optimization for a wide range of motors and loads.