MC56F8257MLH Freescale Semiconductor, MC56F8257MLH Datasheet - Page 262

• Manufacturer Part Number: MC56F8257MLH
• Description: DSC 64K FLASH 60MHZ 64-LQFP
• Manufacturer: Freescale Semiconductor
• Series: 56F8xxxr

Specifications of MC56F8257MLH

• Core Processor: 56800E
• Core Size: 16-Bit
• Speed: 60MHz
• Connectivity: CAN, I²C, LIN, SCI, SPI
• Peripherals: LVD, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Ram Size: 4K x 16
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 16x12b, D/A 1x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 64-LQFP
• Product: DSCs
• Processor Series: 56800E
• Core: 56800E
• Device Million Instructions Per Second: 60 MIPs
• Maximum Clock Frequency: 60 MHz
• Number Of Programmable I/os: 54
• Data Ram Size: 8 KB
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 12 bit, 8 Channel
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

Functional Description
the different phases occur at nearly the same time. This can be troublesome from a noise
standpoint, especially if ADC readings of the inverter must be scheduled near those
times. Phase shifting the PWM signals can open up timing windows between the
switching edges to allow a signal to be sampled by the ADC. However, phase shifting
does NOT affect the duty cycle so average load voltage is not affected.
An additional benefit of phase shifted PWMs appears in
Bridge circuit is driven by 4 PWM signals to control the voltage waveform on the
primary of a transformer. Both left and right side PWMs are configured to always
generate a square wave with 50% duty cycle. This works out nicely for the H-Bridge
since no narrow pulse widths are generated reducing the high frequency switching
requirements of the transistors. Notice that the square wave on the right side of the H-
Bridge is phase shifted compared to the left side of the H-Bridge. As a result, the
transformer primary sees the bottom waveform across its terminals. The RMS value of
this waveform is directly controlled by the amount of phase shift of the square waves.
Regardless of the phase shift, no DC component appears in the load voltage as long as the
duty cycle of each square wave remains at 50% making this technique ideally suited for
transformer loads. As a result, this topology is frequently used in industrial welders to
adjust the amount of energy delivered to the weld arc.
262
. VAL1 ($0100)
VAL5
VAL3
VAL0 ($0000)
VAL4
VAL2
INIT ($FF00)
PWMA
PWMB
Figure 7-210. Phase Shifted Outputs Example
MC56F825x/4x Reference Manual, Rev. 2, 10/2010
Preliminary
Figure
7-211. In this case, an H-
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