AN1914 Freescale Semiconductor / Motorola, AN1914 Datasheet - Page 3

• Manufacturer Part Number: AN1914
• Description: 3-Phase BLDC Motor Control with Sensorless Back EMF Zero Crossing Detection Using DSP56F80x
• Manufacturer: Freescale Semiconductor / Motorola

The BLDC motor control greatly benefits from the flexible PWM module, fast ADC and Quadrature
Timer module. The PWM offers flexibility in its configuration, enabling efficient control of the BLDC
motor.
The PWM block has the following features:
The PWM module is capable of providing the six PWM signals with bipolar switching (the diagonal
power switches are driven by the same signal) and six-step BLDC commutation control where one
motor phase is left unpowered so the Back EMF can be detected. The PWM duty cycle can be set
asynchronously to the commutation of the motor phases using the channel swap feature.
The Quadrature Timer feature set is as follows:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Program Flash
Program RAM
Data Flash
Boot Flash
Data RAM
Software-programmable, Phase Lock Loop-based frequency synthesizer for the DSP core
clock
Three complementary PWM signal pairs, or six independent PWM signals
Features of complementary channel operation
Deadtime insertion
Separate top and bottom pulse width correction via current status inputs or software
Separate top and bottom polarity control
Edge-aligned or center-aligned PWM signals
15-bits of resolution
Half-cycle reload capability
Integral reload rates from one to 16
Individual software-controlled PWM output
Programmable fault protection
Polarity control
20-mA current sink capability on each PWM pin
Write-protectable registers
Four channels, independently programmable as input capture or output compare
Each channel has its own timebase source
Each of four channels can use any of four timer inputs
Rising edge, falling edge, or both edges input capture trigger
DSP56F80x MC PWM Module in Motor Control Applications
Freescale Semiconductor, Inc.
8188 x 16-bit
For More Information On This Product,
DSP56F801
2K x 16-bit
1K x 16-bit
1K x 16-bit
2K x 16-bit
Table 2-1. Memory Configuration
Go to: www.freescale.com
32252 x 16-bit
DSP56F803
512 x 16-bit
4K x 16-bit
2K x 16-bit
2K x 16-bit
Motorola DSP Advantages and Features
32252 x 16-bit
DSP56F805
512 x 16-bit
4K x 16-bit
2K x 16-bit
2K x 16-bit
61436 x 16-bit
DSP56F807
8K x 16-bit
2K x 16-bit
4K x 16-bit
2K x 16-bit
3