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Low-Cost, Single-Channel CCFL Controller Reduces BOM Cost for LCD Backlighting
Single-Channel Controller for CCFL Backlighting Applications
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Note to Editor:
- The DS3991 is a low-cost CCFL controller for CCFLs that are used to backlight LCD panels.
- This device minimizes BOM cost for LCD backlighting.
- To reduce total solution cost and complexity, the DS3991 supports both push-pull and half-bridge drive schemes using a minimal number of external components.
- The DS3991 is ideal for backlighting LCD PC monitors and TVs.
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SUNNYVALE, CA—April 2, 2008—Maxim Integrated Products (Pink Sheets: MXIM) introduces the DS3991 low-cost, single-channel controller for CCFLs that are used to backlight liquid-crystal displays (LCDs). Supporting both push-pull and half-bridge drive schemes, this device converts a DC voltage (5V to 24V) to the high-voltage (300VRMS to 1400VRMS) AC waveform that is required to power CCFLs. These drive schemes use only a minimal number of external components, thus reducing component and assembly cost and making the design easy to implement. Additionally, the push-pull drive scheme provides an efficient DC-to-AC conversion and produces near-sinusoidal waveforms. Supporting both single- and multiple-lamp configurations, the DS3991 is ideal for backlighting LCD PC monitors and TVs.
The DS3991 drives two logic-level, n-channel MOSFETs that are tied between a step-up transformer and a ground. The transformer has a center tap on the primary side that is connected to the DC supply. The DS3991 alternately turns on the two MOSFETs to create the high-voltage AC waveform on the secondary side. By varying the duration of the MOSFET turn-on times, the controller is able to accurately control the amount of current flowing through the CCFL lamp.
The DS3991 operates from a single, 4.5V to 5.5V supply voltage and is available in a 16-pin SO package. Prices start at $0.45 (1000-up, FOB USA).
Maxim Integrated Products, a two billion dollar company, designs and manufactures ICs for analog and mixed-signal applications. The company has designed over 5400 products, more than any other analog semiconductor company, in the 25 years since its founding.
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