The operating frequency of the system is determined by the inductance of

the primary and the bulk capacitor across the primary at resonance.

Fres = Resonance Frequency

Determine the ballast capacitor value using the equation below.

Vsec = Transformer secondary voltage

Vrun = Lamp running voltage

Ilamp = Lamp current

Fres = Resonance frequency

Cballast = Ballast capacitor

The capacitor voltage is 90 degrees out of phase with the lamp running

voltage.

From this equation, determine the value of the ballast capacitor.

1. Supply high voltage.

2. Operation frequency range from 40 to 80kHz.

3. Deliver output power from 2.5 to 14 watts.

4. Slim or low profile type easily built into your design.

5. Available in through-hole and SMT recess or gull wing type.

6. Operate in Royer and direct IC drive.

7. 1500 volt primary to secondary isolation.

8. Ferrite core material.

9. Designed for floating and non-floating applications.

10. Transformer secondary is machine wound on sections to increase

leakage inductance and reduce voltage gradient between layers.

Layout and Circuit Considerations

• The high voltage traces must be separated from low voltage traces.

• The ballast capacitor must be placed closer to the transformer secondary

pin.

• Avoid long wire connections from the transformer to the lamp. Stray

capacitance between wire and ground will reduce efficiency.

• Incorporate open lamp and overload protection in the circuit design. Open

lamp will cause full voltage in the transformer output and will burn the

transformer. Most of the CCFL IC has protection built in the circuit for

open and overload condition.

Bulk

i

s

C

L

F

×

×

=

Pr

Re

2

1

π

)

(

2

sec

2

V

V

F

I

C

run

res

lamp

ballast

−

×

×

=

π

Schematic Relation to Part Number

Schematic A

Schematic B

Schematic C

Schematic D

Schematic E

CTX110652-R

CTX110655-R

CTX210403-R

CTX110603-R

CTX110600-R

CTX410805-R

CTX210652-R

CTX110657-R

CTX210407-R

CTX110605-R

CTX210600-R

CTX410807-R

CTX110659-R

CTX210409-R

CTX110607-R

CTX410809-R

CTX210655-R

CTX210411-R

CTX110609-R

CTX210657-R

CTX310403-R

CTX110611-R

CTX210659-R

CTX310405-R

CTX210603-R

CTX310407-R

CTX210605-R

CTX310409-R

CTX210607-R

CTX310411-R

CTX210609-R

CTX210611-R