Product category: Analogue and Mixed Signal ICs
News Release from: National Semiconductor | Subject: LM2755, LM2757 and LM4510
Edited by the Electronicstalk Editorial Team on 08 October 2007
Power management products extend battery
life
National Semiconductor's new power management products extend battery life and enable next-generation visual effects in portable media devices.
National Semiconductor has added three power management products for driving light-emitting diodes (LEDs) and powering organic LED (OLED) displays to its PowerWiset product family The LM2755 LED driver, the LM2757 inductor-less switched capacitor boost regulator and the LM4510 high-voltage boost regulator are tiny system solutions that extend battery life and enable next-generation visual effects in portable media devices
This article was originally published on Electronicstalk on 5 Jan 2001 at 8.00am (UK)
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The LM2755 comes in a tiny, low-profile micro SMD package.
It enables multi-zone backlighting for three independent RGB (red-green-blue) or white indicator LEDs controlled by programmable pattern generators.
Programmability, exponential dimming steps and an I2C-compatible interface provides flexibility and customisation to fit multimedia functions such as gaming and mobile televisions.
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The LM2757, also in a micro SMD package, requires just four tiny ceramic capacitors for a total solution size of less than 12mm2.
With high output current and pin-selectable output voltages, the LM2757 delivers an inductor-less solution suitable for peripheral lighting features, such as keypad lighting.
The LM2757 can also be used to power USB On-The-Go (OTG) peripherals.
National's LM4510 is a synchronous high-voltage boost regulator that supports OLED displays which are much thinner and consume less energy than liquid crystal displays (LCDs).
The LM4510 features up to 85% efficiency for longer battery life and is offered in a small LLP package.
National's LM2755 charge-pump-based, constant-current LED driver independently drives three LEDs with a total output current up to 60mA.
The current waveform of each LED is a trapezoid whose parameters, including delay, rise time, fall time, high level and low level, can be programmed via an I2C-compatible interface.
The driver provides excellent efficiency without the use of an inductor by operating the charge pump in a gain of 3/2 or in Pass-Mode.
The proper gain from maintaining current regulation is selected based on LED forward voltage, so that efficiency is maximised over the input voltage range.
Offered in an 18-bump micro SMD package, the LM2755 achieves up to 90% efficiency, which prolongs battery life.
The LM2757 is a constant-frequency, pre-regulated, switched-capacitor boost regulator that operates at 1.25MHz to produce a low-noise output voltage.
Excellent efficiency is achieved without the use of an inductor by operating the charge pump in a gain of either 3/2 or 2 according to the input voltage and output voltage option selection.
The device can be configured to provide up to 100mA at 4.1V, 110mA at 4.5V or 180mA at 5V.
The LM2757 presents high impedance at the output voltage pin for applications that require the regulated output bus be driven by another supply while the LM2757 is shut down.
Offered in a 12-bump micro SMD package, the LM2757 achieves up to 90% efficiency, which prolongs battery life.
The LM4510 is a current-mode, step-up DC/DC convertor with a 1.2A internal NMOS switch designed to deliver up to 80mA at 18V from a Li-Ion battery.
The synchronous operation at heavy loads and nonsynchronous operation at light loads allow it to achieve up to 85% efficiency for longer battery life in power-constrained applications.
Moreover, the true shutdown isolation feature eliminates leakage current paths to ground in stand-by mode.
The device reduces the total solution size and cost through elimination of an external Schottky diode and from a 3.2V input, delivering a current range from 18 to 5V.
The system designer can optimise line and load transient responses using the external compensation network in a broad range of applications, such as USB power supply or OLED display bias.
Finally, the LM4510 offers a very robust solution due to the feedback fault and short-circuit protection feature on the output.
The LM4510 is available in a 10-pin thermally enhanced LLP package.
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