Texas Instruments Corporation

Rakesh Raja

Sudhir Nagaraj

Sooping Saw

Michael Edwin Butenhoff

Anuj Jain

Nicholas James Oborny

Paul Vulpoiu

Wen Pin Lin

Abidur Rahman

David H Elwart, Ii

Ryan Paul Kehr

Gowtham Vemulapalli

Ishtiaque Amin

Matthew Hein

Kuang Yu Chiang

A method for electrically producing a stalled state in a stepper motor having a first coil and a second coil is provided. The method includes driving a first sinusoidal current through the first coil, and driving a second sinusoidal current through the second coil, wherein the first and second sinusoidal currents are in phase.

Stepper motor

A method for synchronous serial communication includes encoding, by a master device, a header field to be initially transmitted in a frame with a header identification code and a slave count value that defines a number of slave devices communicatively coupled to the master device. A plurality of address fields to be transmitted in the frame are also encoded by the master device. Each of the address fields corresponding to a different one the slave devices. A first of the address fields to be transmitted in the frame corresponds to a last of the slave devices to receive the header field, and a last of the address fields to be transmitted in the frame corresponds to a first of the slave devices to receive the header field. The frame is transmitted to the slave devices by the master device.

Multi-slave serial communication

Enhanced motor power control circuitry is presented herein. In one implementation, a circuit includes power transistor elements in a half-bridge arrangement configured to selectively switch current for a phase of a motor according to control signals applied to corresponding gate terminals. The circuit also includes control circuitry configured to produce the control signals to achieve target states among the power transistor elements. The control signals have ramp rates determined based at least on polarities of the current through the power transistor elements during inactive states.

Electric motor power control circuitry

In one embodiment, a method includes detecting, by a stall detection sensor in a driver coupled to a stepper motor, a first set of time-off periods in a rising commutation phase of motor current during current regulation. The stall detection sensor further detects a second set of time-off periods in a falling commutation phase of motor current during current regulation. Next, the stall detection sensor compares the first set of time-off periods with the second set of time-off periods and determines whether the stepper motor is stalled based on the comparison of the first set of time-off periods with the second set of time-off periods.

Stall detection in stepper motors using differential back-EMF between rising and falling commutation phase of motor current

An analog signal-to-pulse width modulation (PWM) converter includes a ramp generator generating a ramp signal and a comparator circuit comparing the ramp signal to a first voltage, a second voltage, and to an analog input signal. A duty cycle calculation circuit generates a first control signal to the ramp generator to generate the ramp signal. Based on signals from the comparator circuit, the duty cycle calculation circuit calculates the ratio of the time it takes for the ramp signal to exceed the analog input signal from when the ramp signal exceeds the first voltage to the time it takes for the ramp signal to exceed the second voltage from when the ramp signal exceeds the first voltage. A PWM signal generator generates a PWM output signal based on the ratio calculated by the duty cycle calculation circuit.

Pulse width modulation technique with time-ratio duty cycle computation

A transistor, e.g., field effect transistor FET, ringing adjustment circuit and method comprising the measuring of a voltage from a transistor (e.g., a node of a FET) during the transistor turning on and turning off, determining the voltage oscillation in the measured voltage by performing a derivative function on the measured voltage and detecting a switch in a voltage change rate from positive to negative or negative to positive, and comparing the voltage change rate after the detected switch to adjust drive current applied to the transistor to optimize efficiency while minimizing voltage oscillation and ringing.

Transistor ringing adjustment circuit and method

An electronic circuit includes a first switch driver, a second switch driver, and a switch node coupled to the first and second switch drivers, and configured to couple to a motor. The electronic circuit also includes slew rate measurement circuitry coupled to the switch node and configured to measure a slew rate of switching operations at the switch node. The electronic circuit also includes a controller coupled to the first switch driver, to the second switch driver, and to the slew rate measurement circuitry, and configured to compare a measured slew rate provided by the slew rate measurement circuitry with a target slew rate, and to selectively adjust control signals to at least one of the first and second switch drivers based on a comparison result. The first and second switch drivers are configured to drive switches to power the motor based on the control signals.

Motor drive switch control with adaptive slew rate monitoring

An analog signal-to-pulse width modulation (PWM) converter includes a ramp generator generating a ramp signal and a comparator circuit comparing the ramp signal to a first voltage, a second voltage, and an analog input signal. A duty cycle calculation circuit generates a first control signal to the ramp generator to generate the ramp signal. Based on signals from the comparator circuit, the duty cycle calculation circuit calculates the ratio of the time it takes for the ramp signal to exceed the analog input signal from when the ramp signal exceeds the first voltage to the time it takes for the ramp signal to exceed the second voltage from when the ramp signal exceeds the first voltage. A PWM signal generator generates a PWM output signal based on the ratio calculated by the duty cycle calculation circuit.

A system comprises a buffer circuit coupled to a comparator, and an adaptive threshold control circuit coupled to a timer and comparator. Buffer circuit receives a first voltage across a control terminal and a first current terminal of a transistor and a second voltage across a second current terminal and the first current terminal of the transistor. Comparator compares first voltage to a first threshold, generating a first trigger signal when it crosses first threshold, and compares second voltage to a second threshold, generating a second trigger signal when it crosses second threshold. Timer determines length of time between trigger signals. Adaptive threshold control circuit generates a first control signal for first trigger signal, and a second control signal for second trigger signal, and provides a control signal to comparator indicative of whether length of time is greater than or less than user-programmed value, causing comparator to adjust first threshold.

Adaptive threshold control system for detecting and adjusting the duration of regions of operation during transistor turn on and turn off

In a described example an apparatus includes: an FET driver circuit configured to supply current to a coil in a stepper motor, the FET driver circuit configured to regulate the current to the coil using a fixed delta current; a current chopper pulse width modulated circuit coupled to the FET driver circuit configured to supply pulses corresponding to a step control signal and a direction control signal; a back electromotive force (BEMF) monitor coupled to the current chopper circuit configured to measure an off time pulse and to output a BEMF monitor signal; and a controller coupled to the current chopper pulse width modulated circuit to supply the step and direction control signals and coupled to receive the BEMF monitor signal.

Methods and apparatus for robust and efficient stepper motor BEMF measurement

A system and method for a decay lock loop for time varying current regulation in electric motors determines if a predetermined electrical current regulation level for an electric motor has been obtained within a tuning control time window. A coarse control loop increases or decreases a fast current decay, in response to a determination that the predetermined electrical current regulation level has not been obtained within the tuning control time window, until the predetermined electrical current regulation level falls within the tuning control time window. A fine control loop increments or decrements an amount of fast current decay during a total decay time, in response to a determination that the predetermined electrical current regulation level has been obtained within the tuning control time window, until a predetermined timing of the predetermined electrical current regulation level has been obtained.

Decay lock loop for time varying current regulation in electric motors

Conventional circuits often have undesirable characteristics to due 'hot spots' or use a large amount of area. Here, however, a charging circuit is provides that uses an improved driver. Namely, an amplifier within a current sensor is used to control the rate that a switch can charge an external capacitor. This is accomplished through the adjustment of the gain of the amplifier during a charging mode.

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Allen, TX, United States of America

Rakesh Raja