MC68HC908MR8CFA Freescale Semiconductor, MC68HC908MR8CFA Datasheet - Page 154

• Manufacturer Part Number: MC68HC908MR8CFA
• Description: IC MCU 8K FLASH 8MHZ PWM 32-LQFP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908MR8CFA

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: SCI
• Peripherals: LVD, POR, PWM
• Number Of I /o: 16
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 7x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

Pulse-Width Modulator for Motor Control
9.6.2 Dead-Time Insertion
Technical Data
154
NOTE:
As shown in
be used to drive top-side/bottom-side transistors.
When controlling DC-to-AC inverters such as this, the top and bottom
PWMs in one pair should never be active at the same time.
In
currents would flow through the two transistors as they discharge the
bus capacitor. The IGBTs could be weakened or destroyed.
Simply forcing the two PWMs to be inversions of each other is not always
sufficient. Since a time delay is associated with turning off the transistors
in the motor drive, there must be a “dead-time” between the deactivation
of one PWM and the activation of the other.
A dead-time can be specified in the dead-time write-once register. This
8-bit value specifies the number of CPU clock cycles to use for the
dead-time. The dead-time is not affected by changes in the PWM period
caused by the prescaler.
Dead-time insertion is achieved by feeding the top PWM outputs of the
PWM generator into dead-time generators, as shown in
When output control is enabled, the odd OUT bits, rather than the
PWM generator outputs, are fed into the dead-time generators. See
9.6.4 Output Port Control
Pulse-Width Modulator for Motor Control (PWMMC)
Figure
9-12, if PWM1 and PWM2 were on at the same time, large
Figure
9-12, in complementary mode, each PWM pair can
Register.
MC68HC908MR8 — Rev 4.1
Freescale Semiconductor
Figure
9-13.