National Semiconductor Announces Addition of Three New Power | Regulator Management Products to the PowerWise Series of Energy-Efficient Chips, LM2755 LED Driver, LM2757 Inductor Switched Capacitor Boost Regulator, and LM4510 High Voltage Boost regulator. These three compact new products can drive LEDs and organic light-emitting diode (OLED) displays, making them ideal for portable multimedia devices. In addition to extending the battery life of the system, they also support a new generation of visual effects.
The LM2755 driver chip is available in a small, slim micro SMD package that provides multi-band backlighting for three independent red, green and blue LEDs or white indicator LEDs controlled by a programmable pattern generator. The chip is not only programmable, but also has multi-level light and dark control and an I2C compatible interface, so it can flexibly meet customers' needs for various multimedia functions, such as games and mobile TV.
The LM2757 is also available in a micro SMD package that requires only four small ceramic capacitors, so the overall solution does not exceed 12 square millimeters. The chip can output very high current and can select the output voltage through the pin, which can be used to illuminate peripheral devices without an inductor, such as backlighting the keypad. The LM2757 chip also provides regulated power to USB On-The-Go peripherals.
National's LM4510 is a synchronous high-voltage boost regulator that supports OLED displays, which are thinner and consume less power than liquid crystal displays. The chip's small LLP package delivers up to 85% efficiency and extends battery life.
National Semiconductor LM2755LED Driver Specifications
National's LM2755 chip is a charge pump that provides a constant current LED driver that can drive three LEDs with a total output current of up to 60mA. The current waveform of each LED is trapezoidal, and all parameters including delay, rise time, high and low level can be set through the I2C compatible interface. The LM2755 driver can operate with a 3/2-gain gain pump or with a “pass-mode†operation, eliminating the need for inductors for maximum efficiency. The proper gain to keep the current stable can be set based on the forward voltage of the LED to ensure maximum energy efficiency over the specified input voltage range. The LM2755 is available in an 18-bump micro SMD package with up to 90% energy efficiency for extended battery life.
National Semiconductor LM2757 Boost Regulator Specifications
National's LM2757 chip is a constant frequency preset switched capacitor boost regulator operating at up to 1.25MHz, but with very low output voltage noise. This regulator eliminates the need for an inductor and determines the gain factor (3/2x or 2x) based on the selected input and output voltages, then operates with a charge pump for energy efficiency optimization.
In addition, the different configurations of this chip can provide different drive currents, such as output voltage of 4.1V, drive current up to 100mA; output voltage of 4.5V, drive current up to 110mA; output voltage of 5V, drive current It is up to 180mA. The output voltage pin of the LM2757 has a very high impedance. After the chip is turned off, another power supply can supply power to the regulated output bus. The LM2757 is available in a 12-bump micro SMD package with up to 90% energy efficiency, helping to extend battery life.
National Semiconductor LM4510 Organic Light Emitting Diode (OLED) Display Power Specifications
National's LM4510 is a current mode step-up DC/DC converter with a 1.2A NMOS switch. The NMOS switch allows a lithium battery to output 80mA of drive current at 18V. The chip can be operated in different modes. For example, when the load is high, the chip can adopt the synchronous operation mode; if the load is low, the asynchronous operation mode can be used instead. Because of this flexibility, the energy efficiency is as high as 85. % can further extend battery life.
In addition, the chip uses a true shutdown isolation design to avoid current leakage through the ground in standby mode. The chip helps reduce system size and system cost by eliminating the need for an external Schottky diode. In addition, the chip can increase the input voltage of 3.2V to 18V to 5V, and then output a stable current. System designers can use external compensation networks to dramatically improve transient response of lines and loads, especially for USB power supplies or OLED display bias circuits. Finally, it is worth mentioning that the LM4510 chip provides a feedback fault and short circuit protection for the output, so it is a very reliable solution.
The LM4510 is available in a thermally enhanced 10-pin LLP package.
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