Unitrode UC3872
The UC3872 is a resonant lamp ballast controller optimized for driving cold cathode fluorescent, neon, and other gas discharge lamps. The resonant power stage develops a sinusoidal lamp drive voltage, and minimizes switching loss and EMI generation. Suitable for automotive and battery powered applications, the UC3872 draws only 1µA when disabled.| Part No. | UC3872 |
|---|---|
| Datasheet | UC3872 Download |
| Manufacturer |  Unitrode |
| Description | Resonant Lamp Ballast Controller |
| Buy | Stock & Price |
FEATURES
● Controls Different Types of Lamps: Cold Cathode Fluorescent, Neon, and Gas Discharge● Zero Voltage Switching (ZVS) of Push-Pull Drivers
● Accurate Control of Lamp Current
● Variable Lamp Intensity Control
● 1µA Disable Current
● 4.5V to 24V Operation
● Open Lamp Detection Circuitry
DESCRIPTION
Lamp intensity adjustment is accomplished with a buck regulator, which is synchronized to the external power stage’s resonant frequency. Soft start and open lamp detect circuitry have been incorporated to minimize component stresses. Open lamp detection is enabled at the completion of a soft start cycle. The chip is optimized for smooth duty cycle control to 100%. Other features include a precision 1.2% reference, undervoltage lockout, and accurate minimum and maximum frequency control. BLOCK DIAGRAM VCC 10 UVLO 3.0V REF REF 9 ENBL 11 (HIGH=ENABLE) COMP 4 0.1V + – INV 6 SS 5 – 20µA EA + 1.5V 200µA OPEN LAMP DETECT –– PWM 1 + + CT 7 OSCILLATOR SENSE ZERO DETECT OUT ZD 8 – SYNC 0.5V + 0.2V 14 GND Note: Pin numbers shown are for DIP package.
