National Semiconductor creates analog-intensive solutions that differentiate customers’ products by providing greater energy efficiency, precision, portability, better audio and sharper images in electronic systems. Analog technologies, also known as linear technologies, are the essential link between the digital world of ones and zeroes and the real world of light, sound, temperature, speed, and pressure. National’s technologies address issues facing system designers in markets such as mobile handsets, communications and industrial applications.
National’s analog portfolio features leading-edge operational amplifiers, interface technologies, data converters, and power management solutions. These devices provide solutions for high-efficiency lighting, precision data acquisition, high-speed serial communication and power conversion. As a recognized world leader in power management, National continues to pioneer new energy-efficient devices, sub-systems and architectures for next-generation system designs.
Linear regulators are Step-Down regulators only. There are 2 types of regulators, Shunt and series-pass regulators.
For IC linear voltage regulators, the regulator type determines the configuration of the pass device as well as the dropout voltage. Standard voltage regulators use an NPN Darlington configuration and have a dropout voltage between 1.5V and 2.2 V. Low dropout (LDO) regulators differ from standard regulators in that the pass device consists of a single PNP transistor.
Linear regulators provide significant advantages over switching regulators in simplicity, cost, and output noise. The only difference between a 'normal' linear regulator and a LDO one is that, the LDO type can have a lower constant voltage-drop across the series-pass element.
The LM117 series of adjustable 3-terminal positive voltage regulators is capable of supplying in excess of 1.5A over a 1.2V to 37V output range. They are exceptionally easy to use and require only two external resistors to set the output voltage. Further, both line and load regulation are better than standard fixed regulators. Also, the LM117 is packaged in standard transistor packages which are easily mounted and handled.
In addition to higher performance than fixed regulators, the LM117 series offers full overload protection available only in IC's. Included on the chip are current limit, thermal overload protection and safe area protection. All overload protection circuitry remains fully functional even if the adjustment terminal is disconnected.
The LM317AEMP/NOPB is 4 pin SOT-223 that has a Guaranteed 1% output voltage tolerance, max. 0.01%/V line regulation, max. 0.3% load regulation and 1.5A output current. It is has a adjustable output down to 1.2V with a 80 dB ripple rejection.