IRPLCFL3 International Rectifier, IRPLCFL3 Datasheet - Page 6

• Manufacturer Part Number: IRPLCFL3
• Description: KIT DESIGN CFL TRIAC DIMMING
• Manufacturer: International Rectifier

Specifications of IRPLCFL3

• Main Purpose: Lighting, Ballast Control
• Utilized Ic / Part: IR2156
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Other names: *IRPLCFL3

Dimming Characteristic
DESIGN CONSIDERATIONS
Protection Circuits
The SD pin of the IR2156 is used as lamp removal protection. If there is no lamp
present the voltage at SD pin will be pulled above the 5.1V threshold via R22 and R21
charging C19. When a lamp is in circuit the voltage at the junction of R21 and R22 will
be held low via D11 and R14.
The current sense resistor R20 has been selected so that if the lamp fails to strike as
the frequency approaches resonance in ignition mode, IC2 will shut down thus
protecting the Q1 and Q2. The VDC pin of IC2 is not used and needs to be tied to VCC
via R15. In order for the system to operate the frequency of the ballast is controlled
entirely through the closed loop system.
Layout Issues
Care should be taken when laying out this circuit as with any closed loop control
system. There should be a star point for all of the 0V returns, particularly IC1 pin 4, IC2
pin 8, R20, C12, R14, D12, C9, C10, C11 and C14, which is then returned to the
negative side of C4 via a single track which is as short as possible. This point should as
close to IC2 COM pin 8 as possible and C21 should be located as close to IC2 as
possible with short tracks. This will avoid potential ground loop problems.
D1 to D4, C3 and C4 should all be close together with connecting tracks as short as
possible. The connecting track from C5 and C6 to the MOSFET half-bridge should also
be kept short and as far away from the error amplifier as possible. C14 should be close
to IC1 and IC2 with short tracks to the positive supply pins to provide maximum
decoupling. All tracks carrying HF currents in the output section should be kept away
from IC1 and IC2 and associated components.
IRPLCFL3
OUTPUT
LIGHT
100%
MINIMUM
50%
10%
0
Dimmer Position
MAXIMUM
6