Cherry Semiconductor Corp. (East Greenwich, RI) announced the new CS5231 linear regulator, which is claimed to ensure trouble-free transition between two power inputs. It was also created to simplify design for network interface cards (NICs) modem cards and other PCI bus interface cards, in compliance with Intel's Instantly Available PC (IAPC) standard. The CS5231 integrates a 3.3V, 500mA linear regulator with auxiliary control circuitry that supplies consistent, uninterrupted 3.3V output during normal operation or when the system enters a power-down deep sleep mode. The CS5231 monitors its 5V input voltage, which is disabled when it enters the deep sleep state. When the +5V input goes below 4.4V (nominal), the CS5231 switches to an external PFET which provides power from a 3.3V auxiliary input. The 3.3V output features a +/-2 percent accuracy over the full temperature range. The CS5231 features thermal shutdown (180 degrees C typical) and current limiting (850mA, typical) to protect against system faults. The CS5231 contains an internal NPN-PNP pass transistor for its linear regulator, so the PFET and two filter capacitors are the only external components required. The CS5231 is supplied in a 5-lead plastic surface-mountable D2PAK rated for a temperature range of 0 to 70 degrees C. In quantities of 10,000 pieces, the CS5231 is priced at $1.63 each.