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3

IRPLDIM2U

FUNCTIONAL DESCRIPTION

The IRPLDIM2U Demo Board consists of an EMI filter, an active power factor correction front end, a ballast

control section, a digital control section and a resonant lamp output stage. A block diagram of the design is shown

in Figure 3.

The EMI filter blocks ballast generated noise. The power factor correction is used for sinusoidal input current and

a regulated DC bus. The ballast control section provides frequency modulation control of a traditional RLC lamp

resonant output circuit for preheating, igniting and ballasting the lamp. It is easily adaptable to a wide variety of

lamp types. The digital control section provides the Digitally Addressable Lighting Interface (DALI) and the neces-

sary circuitry and software to perform closed-loop dimming, lamp fault detection, shutdown and auto-restart.

You can connect the board directly to the DALI input (2 connections) or you can use the RS232/DALI converter

board (for demo purposes with the IRPLDIM2U board) to connect it to the PC.

The ballast control circuit uses the IR21592 Dimming Ballast Control IC programmed by the PIC16F628

microcontroller. The IR21592 controls the ballast according to the signals received from the microcontroller. The

microcontroller is connected to the ballast and the IC to receive diagnostic signals.

The communication between the ballast and the external world is done with two signals: TX (digital serial signal

transmitted from the network to the microcontroller) and RX (digital serial signal from the microcontroller to the

network). This system allows the ballast to communicate bi-directionally with the network (a PC or generally a

DALI system). A digital interface assures high voltage isolation between DALI inputs and the resonant lamp output

stage. The microcontroller manages the communication between interface and ballast IC.

The complete circuit is shown in Appendix A. In the circuit thick races represent high frequency and high current

paths. Lead lengths should be minimized to avoid high-frequency noise problems. Appendix B shows the Bill of

Materials.

Fig. 3 IRPLDIM2 Block diagram

IRPLDIM2 Reference Design

OPTO

Interface

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

VDC

VCO

CPH

DIM

MAX

MIN

FMI

N

IPH

LO

CO

M

VCC

VB

VS

HO

SD

CS

1

2

3

4

5

6

7

8

18

17

16

15

14

13

12

11

RA2

RA3

RA4

RA5

VSS

RB0

RB1

RB2

RB7

VDD

RA6

RA7

RA0

RA1

RB5

RB6

9

10

RB3

RB4

EMI Filter

L

Rectifier

PFC

Output Stage

Lamp

PC

Interface

Micro

IR-IC

Half Bridge

Driver

Dimming Feedback

Preheat Feedback

Lamp Fault

light level

Fade time

Fade rate

On/Off

Fault condition

actual level

light status

ballast

DALI

input

RS232/

DALI

converter

N

E

NOTE: Ballast can also be

connected directly to a DALI

compliant system..

PC and RS232/DALI converter

are used for demo purposes.