Microchip Technology Inc.

Microchip Technologies, Inc.

Ward Brown

Howard Hendricks

Randy L Yach

Keith Edwin Curtis

Stephen Bowling

Sean Steedman

Hartono DArmawaskita

Roshan Samuel

John Charais

Huamin Zhou

Clark Rogers

Brant Ivey

Cristian Nicolae Groza

Mudit Gupta

Zacharias Martin Smit

Steve Kennelly

Janmichael Aberouette

Chintan Desai

Dave Suda

Razvan Dochia

An operational amplifier with totem pole connected output transistors having inputs coupled to multiplexers for selectable coupling of signals and voltage levels thereto. The high and low output transistors may be forced hard on or hard off in addition to normal coupling of signals thereto. The operation of the output transistors may be dynamically changed to pass only positive going signals, negative going signals, placed in a tristate high impedance state, hard connected to a supply voltage and/or hard connected to supply common return. A core independent peripheral (CIP) may also be coupled to the operational amplifier for dynamically changing the multiplexer inputs in real time, as can external control signals to a control circuit coupled to the multiplexers.

Operational amplifier with controllable output modes

Low cost linear Hall Effect sensors are used for determining motor shaft positions and generating voltages proportional to the motor shaft positions. The voltages from the linear Hall Effect sensors are compared to a triangle waveform and PWM signals are generated therefrom. A constant current source and constant current sink are used in the triangle waveform generator. The voltages from the linear Hall Effect sensors are adjusted to change the PWM duty cycles used to startup and vary the speed of the motor. Comparators compare the voltages from the Hall Effect sensors and product the PWM signals having duty cycles proportional to the voltage drive requirements of the motor.

Linear hall effect sensors for multi-phase permanent magnet motors with PWM drive

A universal asynchronous receiver/transmitter (UART) interface is disclosed. The UART interface may include a configurable asynchronous receiver and transmitter unit; and a configurable state machine, wherein the state machine allows configuration of the receiver and transmitter unit to support various baud rates and provide for start bit and stop bit configuration, wherein the state machine is further configurable to automatically support a plurality of communication protocols.

UART with automated protocols

BLDC adaptive zero crossing detection compares BEMF voltages from a floating phase of a BLDC motor to a reference voltage, measures a rising time interval during a rising BEMF period when the BEMF voltages are greater than the reference voltage, and a falling time interval during a falling BEMF period when the BEMF voltages are less than the reference voltage. The reference voltage is adjusted so that the rising and falling time intervals are substantially the same, thereby causing the drive voltage to be in phase with the motor self-generated voltage, thus ensuring maximum efficiency of the BLDC motor.

BLDC adaptive zero crossing detection

A pulse width modulated (PWM) trapezoidal commutation drive to a brushless direct current (BLDC) motor is sine modified so that the applied drive voltage substantially matches the induced voltage generated in the BLDC motor. The values of the cosine of the angles between &#x2212;30 degrees and +30 degrees are used to modify the duty cycle of the PWM drive signal dependent upon the rotor angular positions determined from the times between the zero crossing BEMF voltages measured at the unconnected motor terminals.

Sine modified trapezoidal drive for brushless DC motors

A constant current output sink or source eliminates a current limiting series resistor for a light emitting diode (LED) and maintains a constant light intensity from the LED for all operating and manufacturing variables of a digital device since the current through the LED is maintained at a constant value. The constant current output sink or source may be programmable for selection of a constant current value from a plurality of constant current values available.

Constant current output sink or source

An enhanced complementary waveform generator (ECWG) generates two complementary pulse width modulation (PWM) outputs determined by rising and falling event sources. In a simple configuration of the ECWG, the rising and falling event sources are the same signal which is a PWM signal having the desired period and duty cycle. The ECWG converts this single PWM input into dual complementary PWM outputs. The frequency and duty cycle of the dual PWM outputs substantially match those of the single input PWM signal. Blanking and deadband times may be introduced between the dual complementary PWM outputs, and the dual complementary PWM outputs may also be phase delayed.

Enhanced complementary waveform generator

Drive voltages to a sensorless brushless DC motor are regulated by varying the width of a single drive pulse (PWM pulse) centered in each of the commutation periods. Switching losses are thereby cut to an absolute minimum because there are only two transitions (on and off) in each drive commutation period. Back EMF zero-cross detectors determine the electrical timing relationships during each electrical cycle. Since the PWM drive pulses are always centered in each of the commutation periods, there will always be back EMF available for measurement of 'zero-crossings.' A digital device controls power switching transistors to produce one single PWM pulse during each of the commutation periods.

Synchronized minimum frequency pulse width modulation drive for sensorless brushless direct current motor

Slow speed operation of a brushless DC (BLDC) motor is enhanced by gating off some of the PWM pulses in each commutation period. By doing so, longer PWM pulse widths may be used at PWM signal frequencies that are inaudible while still allowing desired slow speed operation of the BLDC motor. Centering the non-gated PWM pulses in each commutation period where peak back EMF occurs, further reduces losses and improves delivery of maximum torque from the BLDC motor.

Slow speed operation of brushless direct current motors by gating pulse width modulation drive

Zero-crossing detection accuracy is enhanced in a sensorless brushless direct current (BLDC) motor by increasing the PWM drive frequency in anticipation of a zero-crossing event in any one or more commutation periods. Once a zero-crossing event is detected, the PWM frequency can go back to a lower normal operating frequency. Switching losses of the power drive transistors are thereby minimized while maintaining accurate zero-crossing detection for stable operation of the BLDC motor.

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Chandler, AZ, United States of America

Ward Brown