Semiconductor supplier Maxim Integrated Products News - Alert has readied a new six-string white light-emitting diode WLED driver that provides a complete backlighting solution for large notebook and netbook displays.
In fact, the MAX17127 is a WLED driver for liquid-crystal displays LCDs under 21 inches. It is a high-efficiency step-up controller that integrates a 48 volt metal-oxide semiconductor field-effect transistor MOSFET capable of driving up to six strings in parallel and 13 LEDs per string. By eliminating an external power MOSFET, this integration reduces bill of material BOM cost and saves printed circuit board space. The complete backlighting solution occupies an area of 16 mm square.
The step-up controller frequency can be programmed from 250kHz to 1MHz, allowing flexibility in selecting external components. It features a wide input-voltage range of 5 V to 26 V, making it well suited for both netbooks that use a 2- to 3-cell Li+ battery and notebooks that use a larger battery.
The current in each string can be programmed from 10 mA to 30 mA using an external resistor, which helps in setting the appropriate brightness level. According to the maker, better than 2 percent accurate current matching between strings ensures even LED brightness. The MAX17127 operates in a direct-dimming mode with a dimming frequency ranging from 100 Hz to 25 kHz. The LED current is directly controlled by the external dimming signal's frequency and duty cycle. The wide dimming range eliminates the audible noise issues usually encountered in white LED drivers. Plus, a low feedback voltage at each LED string helps reduce power loss and improve efficiency.
The MAX17127 offers multiple features to protect the controller from faults, including overcurrent, overtemperature, and open-/short-string conditions. Additionally, the step-up controller has cycle-by-cycle current limiting and soft-start capability to control inrush current.
The MAX17127 comes in a thermally enhanced, lead-free 4 mm x 4 mm, 20-pin thin quad flatpack, no lead TQFN package. And operates over the -40 C to +85 C extended temperature range. Prices start at $0.73 in quantities of 1000 and higher, as per the supplier's release.
To date, Maxim has developed over 6300 products serving the industrial, communications, consumer, and computing markets. And reported revenue in excess of $1.6 billion for fiscal 2009.
