SUNNYVALE, CA -Maxim Integrated Products (NASDAQ: MXIM)
introduces the MAX8729, a fully integrated controller optimized to drive multiple cold-cathode fluorescent lamps
(CCFL) used in LCD monitor and TV applications. The MAX8729 drives multiple lamps by using a half-bridge inverter
consisting of two external n-channel power MOSFETs. Its half-bridge topology minimizes the component count, while
providing near sinusoidal drive waveforms over the entire input range. The MAX8729 operates in resonant mode during
striking, and switches over to fixed-frequency operation after the lamps are lit. This unique feature ensures
reliable striking under all conditions and reduces transformer stress.
The MAX8729 achieves a 10:1 dimming range by turning the CCFL on and off using a digitally adjusted PWM (DPWM)
method. CCFL brightness can be set with an analog voltage on the CNTL pin. Synchronization and phase-shift features
for both the switching and DPWM frequencies permit daisy-chaining multiple MAX8729s. The switching and DPWM
frequencies can be easily adjusted with external resistors. Phase-shift select pins, PS1 and PS2, can be used to
program up to four different phase shifts, allowing up to six MAX8759s to be used together.
drivers of the MAX8729 drive large power MOSFETs typically used in applications where one transformer powers four
CCFLs in parallel. An internal 5.3V linear regulator powers the MOSFET drivers and most of the internal
The MAX8729 is available in a low-cost, 24-pin QSOP, and operates over -40 degrees Celsius to
+85 degrees Celsius temperature range. Prices start at $4.53 (1000-up, FOB USA). A preassembled MAX8729 evaluation
kit with recommended external components is available to reduce design time.