SG2074-2

Design Challenges

Presently, the vast majority of SMPS are

implemented in an analog fashion. But

analog implementations have significant

disadvantages that can be rectified by

implementing the SMPS using modern

digital mechanisms. Until recently, this

has not been cost effective, due to

performance and cost of the processors

required to do the job. The 56F800 and

56F8300 hybrid controllers specified

here have the required performance,

peripherals, and price targets to enable

SMPS to make the conversion from

analog to digital implementations.

Freescale Semiconductor Solution

The digital 56800/E Switched-Mode

Power Supply minimizes the number of

system components, maximizes the

system reliability, and makes it possible

to easily add advanced functions without

increasing cost.

The performance, integrated peripherals,

and low cost of the 56F800 and 56F8300

controllers specified here make the

digital SMPS possible and practical.

The system in this example is a 100-

Watt SMPS controlled by a 56F801

device on the primary side and a

56F8323 on the secondary side.

Optional components could include user

interfaces, such as an LCD or LED

display.

During normal operation, an AC/DC

rectifier controlled by a 56F801 will

correct the input power factor while

simultaneously rectifying the AC input

voltage. The output of the AC/DC

rectifier is a DC voltage that will feed the

DC/DC converter, which is controlled by

a 56F8323 device. The DC/DC converter

has a full bridge topology, used to

convert the DC Bus voltage to a precise

and constant DC output voltage. For the

Power Factor Correction (PFC)

converter, the 56F801 samples the input

AC voltage, input AC current, and DC

output voltage. The output DC voltage is

regulated by the 56F801, while

maintaining the same phase for both the

AC input current and voltage. The PWM

module on the 56F801 produces the

PWM pulse for the PFC main power

component. The DC/DC converter

controlled by the 56F8323 is operating

on a phase-shifted soft-switching mode,

so that switching losses and noise can

be kept to a minimum.

Control functions implemented within the

primary hybrid controller are:

> Input power factor correction

> Automatic detection of input voltage

frequency

Control functions implemented within the

secondary hybrid controller are:

> Power on/off control

> DC Bus voltage regulation

> Output DC voltage regulation

> DC/DC full-bridge phase-shifted

control strategy

> Power system monitoring and

communication protocols (optional)

> Fault and mode management

Freescale Ordering Information

Part Number

Product Highlights

Additional Information

DSP56F801

80 MHz, 40 MIPS, SCI, SPI, ADC, PWM, Quad Timer and

> 8K Program Flash

> 1K Program RAM

>2K Data Flash

> 1K Data RAM

MCU-friendly instruction set, OnCE for debug,

on-chip relaxation oscillator, 2K BootFLASH and

up to 11 GPIO available in a 48-pin LQFP.

DSP56F802

80 MHz, 40 MIPS, SCI, SPI, ADC, PWM, Quad Timer and

> 8K Program Flash

> 1K Program RAM

>2K Data Flash

> 1K Data RAM

MCU-friendly instruction set, OnCE for debug,

on-chip relaxation oscillator, 2K BootFLASH and

up to 4 GPIO available in a 32-pin LQFP.

DSP56F803

80 MHz, 40 MIPS, CAN, SCI, SPI, ADC, PWMs, Quadrature Decoder,

Quad Timer and

> 31.5K Program Flash

> 512K Program RAM

>4K Data Flash

> 2K Data RAM

MCU-friendly instruction set, OnCE for debug,

on-chip relaxation oscillator,2K BootFLASH,

external memory expansion, and up to 16 GPIO

available in a 100-pin LQFP.

MC56F8322

60 MHz, 60 MIPS, 2 SPI, 2 SCI, 2 ADC, PWM, COP, PLL, Decoder, 2 Quad

Timers, FlexCAN, an MCU-friendly instruction set, Enhanced OnCE for debug,

on-chip relaxation oscillator, and temperature sensor with

> 48KB Flash

> 12KB RAM

125°C) Temperature Ranges with up to 21 GPIOs

in a 48-pin LQFP

MC56F8323

60 MHz, 60 MIPS, 2 SPI, 2 SCI, 2 ADC, PWM, COP, PLL, Decoder, 2 Quad

Timers, FlexCAN, an MCU-friendly instruction set, Enhanced OnCE for debug,

on-chip relaxation oscillator, and temperature sensor with

> 48KB Flash

> 12KB RAM

Industrial (-40°C to 105°C) and Extended (-40°C to

125°C) Temperature Ranges with up to 27 GPIOs

in a 64-pin LQFP