Two new ultra-high precision resistors from Vishay Precision Group (VPG), Bulk Metal Z-Foil current sensing resistors, are designed to improve LED brightness and efficiency in portable battery-powered applications.
Screen brightness is a very important function in the LED-backlit LCD display of portable devices. It is controlled by an LED panel mounted on the back of the LCD, thereby increasing the input voltage connected to the panel. These devices require stable and accurate current resistors, which should have a low thermal EMF and a low absolute TCR to avoid flickering of brightness and control the stability of the LED output voltage.
LED1625 and LED221 provide low TCR, nominal values are 0.05 ppm / C (0C to + 60C) and 0.2 ppm / C ratings (–55C to + 125C, + 25C ref.), And load life stability is ± 0.005% , And has a strict tolerance to ± 0.01%. LED1625 also provides a rated power of 1W with a resistance range of 0.3ohm to 10ohm, while LED221 has a rated power of 8W and a resistance range of 0.5ohm to 500ohm. The company stated that any conceivable value (up to six digits) within the device's resistance range can be used without additional cost or delivery time impact.
