NS portable LED/OLED display driver LM2755/57/4510

NS announced the PowerWise series high efficiency chip products added three new power management products, which are LM2755 light emitting diode driver, LM2757 inductance switched capacitor boost regulator and LM4510 high voltage boost regulator. These three compact new products can drive light-emitting diodes and organic light-emitting diode (OLED) display, the most suitable for portable multimedia devices. In addition to effectively extend the battery life of the system, they can also support a new generation of visual effects.

LM2755 driver chip micro SMD package can be compact and slim, 3 separate red green and blue light emitting diodes, or controlled by the white index of programmable graphics generator provides light emitting diode with backlight. This chip is not only programmable, but also has multi-level light and dark control and a I2C compatible interface, so flexible to meet customer demand for a variety of multimedia features, such as games, mobile TV, etc..

LM2757 chip is also used in micro SMD package, only 4 small ceramic capacitors, so the overall size of the program does not exceed 12 mm2 (sq.mm). The chip can output extremely high current, and can choose the output voltage through the pin, without the inductor can provide lighting for the peripheral devices, such as a small keyboard backlight. LM2757 chip can also provide a regulated power supply for USB On-The-Go peripherals.

LM4510 chip NS is a synchronous high voltage boost regulator, can support organic light emitting diode (OLED) display, the display and liquid crystal display more slim, and less power consumption. The chip uses a small LLP package, energy efficiency up to 85%, can effectively extend battery life.

NS LM2755 chip is a charge pump, which can provide a constant current LED driver, can drive 3 LEDs, the total output current up to 60mA. The current waveform of each light emitting diode is trapezoidal, and all parameters including time delay, rise time and high and low level can be set by the I2C compatible interface. LM2755 drivers can use 3/2 times the gain of the charge pump operation or use "through mode" (Pass-Mode) operation, so without the use of inductors can play a very high efficiency. The appropriate gain to maintain current stability can be set according to the forward voltage of the LED, thereby ensuring maximum energy efficiency in the specified input voltage range. LM2755 chip using 18 ball micro SMD package, up to 90% energy efficiency can greatly extend the battery life.

NS's LM2757 chip is a constant frequency preset switching capacitor boost regulator, operating at frequencies up to 1.25MHz, but the output voltage is extremely low noise. The regulator does not need to use inductors, according to the selected input and output voltage to determine the gain factor (3/2 times or 2 times), and then use the charge pump operation, so as to achieve energy efficiency optimization. In addition, this chip can provide different configurations of different driving current, for example if the output voltage is 4.1V, the drive current is up to 100mA; if the output voltage is 4.5V, the drive current is up to 110mA; if the output voltage is 5V, the drive current is up to 180mA. The output voltage pin of the LM2757 chip has a high impedance, and the other power supply can provide power supply for the voltage output bus after the chip is turned off. LM2757 chip using 12 ball micro SMD package, energy efficiency of up to 90%, thus helping to extend battery life.

NS LM4510 chip is a current mode boost DC / DC converter with built-in 1.2A NMOS switch. NMOS switch can make a lithium battery output current of 80mA at 18V. This chip can use different modes of operation, such as load is high, the chip can use synchronous operation mode; if the load is low, you can use the non synchronous mode of operation because of this flexibility, so the energy efficiency as high as 85%, can further extend battery life. In addition, this chip uses a real stop isolation design, can avoid the current leakage through the standby mode when the ground wire. Since it is not necessary to add an external Schottky diode, the chip is helpful to reduce the system volume and reduce the system cost. In addition, this chip can increase the input voltage 3.2V to 18V to 5V, and then output a stable current. System design engineers can use the external compensation network, a substantial improvement in the line and load transient response, especially suitable for USB power supply or organic light-emitting diode display bias circuit and other different applications. Finally, it is worth mentioning that, LM4510 chip in particular for the output feedback fault and short-circuit protection, so it is a very reliable solution.

LM4510 chip uses a 10 pin LLP package with stronger heat dissipation.

Prices and availability

LM2755 and LM2757 two chips with a single price of $1.50, while the LM4510 chip is a single price of $1.80, the three models are based on the purchase of units for the 1000, and has a bulk supply.

For details, please visit: www.national.com/CHS.

Source: China Power Grid