National Semiconductor today added three new power management products for driving light-emitting diodes (LEDs) and powering organic LED (OLED) displays to its PowerWise energy-efficient product family. 

National’s new products, 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.

The LM2755, in a tiny, low-profile micro SMD package, 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 provide flexibility and customisation to fit various multimedia functions such as gaming and mobile television.
 
The LM2757, also in a micro SMD package, requires just four tiny ceramic capacitors for a total solution size of less than 12 mm squared.  With high output current and pin-selectable output voltages, the LM2757 delivers a compelling inductor-less solution well-suited 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 percent efficiency for longer battery
life and is offered in a small LLP package.
 
Features

Technical features of National’s LM2755 LED driver National’s LM2755 charge-pump-based, constant-current LED driver independently drives three LEDs with a total output current up to 60 mA.  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 maximized over the input voltage range. Offered in an 18-bump micro SMD package, the LM2755 achieves up to 90
percent efficiency, which prolongs battery life.

Technical features of National’s LM2757 boost regulator National’s LM2757 is a constant-frequency, pre-regulated, switched-capacitor boost regulator that operates at 1.25 MHz 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 100 mA at 4.1V, 110 mA at 4.5V or 180 mA 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 percent efficiency, which prolongs battery life.

Technical features of National’s LM4510 OLED display power supply National’s LM4510 is a current-mode, step-up DC-DC converter with a 1.2A internal NMOS switch designed to deliver up to 80 mA at 18V from a Li-Ion battery.  The synchronous operation at heavy loads and non-synchronous operation at light loads allow it to achieve up to 85 per cent 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 18V to 5V.  The system designer can optimize 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.
 
About National’s power management products National solves power management design problems in space and energy constrained applications from feature-rich handheld devices through large line-powered systems. From the novice power designer to the power expert, National’s products, people and design tools enable customers to design green-powered systems with complex power supplies in the shortest amount of time.

High-performance products include switching regulators such as National’s flagship SIMPLE SWITCHER family, and application-specific products including white-LED drivers and Power-over-Ethernet controllers.

Availability and pricing

Available now, the LM2755 and LM2757 are priced at $1.50 each, and the LM4510 is $1.80 in 1,000-unit quantities.

Contact information

For product information, contact the National Semiconductor European Customer Support Centre on +44 (0) 870 240 2171.