SC1543

400mA/200mA Dual 3.3V Smart Power Switch PRELIMINARY - October 9, 2000 SC1543 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION The SC1543 provides a glitch free 3.3V output when one of two 3.3V input sources is present. It does not require external logic to sequence from one input source to the other. Whenever VIN1 exceeds a predetermined threshold value the internal MOSFET connects it’s source voltage to the output. If the input at VIN1 is below the threshold another internal MOSFET connects VIN2 to the output. If both inputs are at 3.3V then VIN1 will be connected to the output. The SC1543 is designed to provide 400mA from the main input (VIN1) and 200mA from the secondary input (VIN2). A very low quiescent current of 10µA in shutdown mode reduces power dissipation. The internal logic and control circuit detects the voltage levels of VIN1 and VIN2, and compares them to an input reference voltage of 2.9V. An internally controlled period of switch overlap ensures that the transition between supplies is as glitch-free as possible. The SC1543 is available in an MSOP-8 surface mount package. FEATURES = = = = = Glitch free transitions between inputs Internal logic selects appropriate input 400mA load current capability from main input Low power shutdown mode Industrial temperature range APPLICATIONS = Mini PCI cards = Peripheral cards = Instantly available personal computers (IAPCs) ORDERING INFORMATION Part Number (1) Package MSOP-8 SC1543I...