Electronics News
Archive : 7 February 2008 год
AnalogicTech has introduced the AAT1239-1, a constant current boost converter capable of driving up to10 white LEDs (WLEDs) connected in series. Designed for backlight applications in PNDs, eDictionaries, electronic photo frames and cellular handsets, the new driver IC uses AnalogicTech’s proprietary Simple Serial Control (S2CWire) single-wire interface to reduce the display flicker that occurs with commonly-used low frequency PWM control schemes. By driving up to 10 WLEDs in a serial string, the AAT1239-1 simplifies the use of larger LCD panels in a wide array of battery-powered portable devices. Operating off a 2.7V to 5.5V input range, the AAT1239-1 delivers a maximum continuous output of 40V at 30mA and delivers a constant LED current for up to 10 WLEDs in series.
An integrated soft start function eliminates output voltage overshoot across the full input voltage range. The single-wire S2CWire interface controls WLEDs across 26 discrete current steps. It requires no additional circuitry. The AAT1239-1 also features a true load disconnect function that isolates the load from the power source while in the OFF or disabled state. By guaranteeing <1.0 microamps shutdown current, this feature extends battery life by eliminating leakage current in power-limited portable applications. The WLED driver IC offers efficiency levels up to 82%. A 2MHz switching frequency provides fast response. The AAT1239-1 also offers short-circuit, overvoltage and over-temperature protection. Qualified across the -40 C to +85 C temperature range, the AAT1239-1 is available in a Pb-free, 12-pin TSOPJW package.
Source: www.channel-e.biz
Linear Technology introduces the LTC4311 Rise Time Accelerator for heavily loaded I2C/SMBus systems operating at bus speeds of up to 400kHz. Systems where multiple devices are connected to the same bus can exhibit high bus capacitance well beyond the 400pF I2C specification. The capacitive loading causes slow rise times that can affect data reliability and dictate the maximum practical speed of the bus. The LTC4311 alleviates these issues by using a boosted pull-up current during the rising bus transitions, while disabling the current sources during falling transitions and during logic lows and logic highs for improved low state noise margins. The LTC4311 is ideal for portable applications, including cameras, notebook computers and full-featured cell phones.
The LTC4311 is capable of operating from supply voltages as low as 1.6V and as high as 5.5V. It provides an ENABLE pin for a low current shutdown of less than 5uA, with no bus loading during shutdown or when powered down. The LTC4311 auto-detects the bus idle state and reduces supply current to only 26uA in standby mode. For additional reliability, the LTC4311 survives ±8kV Human Body Model ESD on its pins. Specified over the commercial and industrial temperature ranges, the LTC4311 is offered in tiny 2mm x 2mm 6-pin DFN and SC70 packages. Pricing begins at $1.55 in 1,000 piece quantities.