System Modules

signal of the comparator (Comp Out) controls the power switch Q1 through the output buffer, which consists of transistors Q2, Q3, and Q4, resistors R10, R13, R34, R35, R36, and R37, and capacitor C7.

For discontinuous conduction mode the comparator output is disconnected from the Q4 transistor gate. The PWM1 pin is connected to the Q4 transistor gate.

Digital PFC is driven by the MCU. The MC68HC908LB8 peripherals used for PFC are listed below:

AD converter — channels ADC1 and ADC2

PWM0 for generating sine wave

comparator

IRQ pin for zero-crossing detection

The PFC control algorithm

converts the sensed output voltage to a digital value

provides software PI regulator for a voltage feedback loop

programs its PWM channel to create the pattern of the input current

synchronizes operation with the mains frequency using mains zero-crossing detection

The control algorithm is described in 5.2 Control Algorithm Description.

DC-BUS VOLTAGE OUTPUT AND SENSING

INPUT EMI FILTER AND BRIDGE RECTIFIER

 

 

1

1

4

 

 

 

C1

 

J1

 

 

10nF 275V X2

 

PM100-INP_CONN-6

2

2

3

I6

6

 

 

L6

5

 

 

CMFIL2

I5

 

 

4

 

 

 

NC

 

 

 

3

 

 

 

I3

 

 

 

2

 

 

 

I2

1

2

 

1

 

I1

 

 

 

 

 

 

 

 

C5

 

 

 

4n7 250/1000V Y2

 

 

 

 

GND

 

1

R11

3K0

2

R14 2K0

PFC Current Sense

C8 82pF

GND

 

 

 

 

 

 

2.7mH

 

BOOST CONVERTER

 

 

 

JP6

 

 

 

 

 

 

L1B

 

 

 

 

 

 

1

 

U1

 

 

C2

 

PFCIND3

 

 

 

 

 

 

2

 

DF1510S

 

150nF 275V X23

 

 

5

D1

 

 

 

 

 

4 AC2

DC+ 1

 

 

 

 

 

 

DCB

CONN/HDR/2X1

1

 

 

 

 

 

 

 

 

MURS160T3

 

 

 

 

 

RV1

 

 

 

 

 

 

 

 

 

 

 

1

 

 

 

 

1

 

 

 

D

 

C3

1

 

R1

 

275V

 

 

 

 

 

 

 

 

 

C4

 

 

 

 

 

 

 

 

 

 

 

10nF 630V TC356 +

560K

 

 

 

 

 

2

 

 

 

G

 

 

 

22uF 450V

GND

2

 

 

 

 

PFC Gate

Q1

 

2

 

2

 

 

 

 

 

 

 

 

 

 

1

 

3

 

 

2

 

1

 

2

S

 

 

 

 

AC1

DC-

 

 

IRF820A

 

 

 

R2

 

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R4

2R7

 

 

 

 

 

 

R3

 

 

 

 

 

 

 

 

GND

 

560K

 

 

 

 

 

 

 

 

 

 

 

 

 

 

220K

 

 

 

 

 

PFC Current Sense

 

 

 

2

 

 

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

 

 

 

R6

 

1

 

 

 

 

 

 

 

15V

 

 

 

 

 

R5

 

 

 

 

 

 

 

 

 

 

 

510K

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

220K

 

 

 

 

 

 

 

 

 

 

 

2

 

2

 

MAINS ZERO CROSSING SENSING

 

 

 

 

 

 

DCB Divider

 

 

 

 

 

 

 

 

1

 

15V/1

 

 

1

 

1

 

 

 

 

 

 

 

 

R35

 

C6

R8

 

 

 

 

 

 

Zero Detect

 

 

 

 

R7

 

 

 

 

 

0R

 

 

18K

 

 

 

 

1

 

 

 

 

 

 

100nF

 

220K

D15

 

 

 

 

 

R36 0R

R37 0R

 

 

 

 

R9

 

 

 

 

 

 

 

 

 

 

BAT48

C27

 

 

2

 

 

 

 

2

 

2

 

 

 

47K

1n5

 

 

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

R34

 

 

GND

GND

 

 

 

 

 

GND

GND

 

 

 

0R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

D2

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BZV55C5V6

 

 

 

C7

 

 

 

 

 

 

 

GND

 

 

1

 

 

100nF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R10

 

 

 

6K8

 

5V

 

GND

C

 

2

B

 

 

Q2

 

 

 

BC846B

 

C10

 

E

 

R13

PFC Gate

 

220nF

 

 

 

1

620R

E

 

 

B

Q3

GND

R12

 

BC856B

 

10K

 

C

 

D

 

 

 

 

2

 

 

 

G

BUFFER CIRCUIT

Comp -

Comp Out

Q4

 

 

 

 

SMMBF0201

COMPARATOR CIRCUIT

GND

GND

Figure 4-3. Dimmable Light Ballast — Input and PFC

Dimmable Light Ballast with Power Factor Correction, Rev. 1

Freescale Semiconductor

27

Page 27
Image 27
Freescale Semiconductor M68HC08 manual Dimmable Light Ballast Input and PFC

M68HC08 specifications

Freescale Semiconductor, known for its innovative solutions in the field of embedded systems, developed the M68HC08 microcontroller family, which includes the MC68HC908QT2. This 8-bit microcontroller is engineered to meet the demands of diverse applications, including automotive, industrial, and consumer electronics.

The MC68HC908QT2 is designed around Freescale’s M68HC08 core, which is renowned for its efficient and reliable performance. This microcontroller integrates a powerful instruction set, enabling developers to create high-performance applications with relatively low power consumption. The device operates at a clock frequency of up to 3 MHz, which is adequate for various control tasks.

One of the key features of the MC68HC908QT2 is its memory architecture. It includes a 2 KB Flash memory for program storage, representing a significant advantage for developers requiring non-volatile memory. Additionally, it encompasses 128 bytes of EEPROM memory, allowing for data retention even after power loss. The microcontroller also has 256 bytes of RAM for efficient data manipulation during operation.

In terms of input/output capabilities, the MC68HC908QT2 supports a variety of interfacing options. The microcontroller features up to 20 general-purpose I/O pins for flexibility in connecting with peripheral devices. Additionally, it provides multiple analog-to-digital converters (ADC) and timers that facilitate efficient analog signal processing and precise control through timing functions.

The architecture of the MC68HC908QT2 also incorporates sophisticated on-chip peripherals, enhancing its functionality. These peripherals include PWM (Pulse Width Modulation) outputs, which are essential for applications requiring motor control and other precise duty cycle processes. The integrated watchdog timer ensures reliable operation by resetting the system in the event of an application failure.

Moreover, the MC68HC908QT2 is equipped with an efficient power management system, enabling operation in a low-power mode, ideal for battery-powered applications. This microcontroller is packaged in a compact 28-pin dual in-line package (DIP), making it suitable for space-constrained designs.

In summary, the Freescale Semiconductor MC68HC908QT2 microcontroller is distinguished by its robust performance, extensive memory options, and versatile I/O capabilities. Its advanced features, including built-in timers, ADC, and a power management system, make it an exceptional choice for developers seeking to implement reliable and efficient embedded solutions. With its comprehensive architecture, the MC68HC908QT2 remains a popular choice in the landscape of 8-bit microcontrollers.