SC1545

500mA SmartLDO With Power Up Signal Sequencing PRELIMINARY - January 17, 2000 TM SC1545 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION The SC1545 was designed for instantly available motherboard applications. As part of the Semtech family of SmartLDO’s it provides additional control functions not available in a standard LDO. The device provides the capability to control three separate supplies. There is an on-board 500mA, 2.5V LDO with current limit protection, and drive pins for an N-channel MOSFET and a P-channel MOSFET. Internal logic circuitry ensures that the system starts up in a controlled manner, and that the correct outputs are enabled during specific sequences of BF_CUT and SLP. The LDO draws its power from the 5V standby supply, and the N-channel MOSFET drive is derived from the 12V supply. The SC1545 is available in the surface mount SO-8 package. FEATURES 500mA LDO with Over Current Protection (OCP) ±2.5% LDO regulation over line, load and temperature Power sequencing for three supplies APPLICATIONS Instantly available motherboards Embedded systems Desktop computers ORDERING INFORMATION Part Number SC1545CS (1) Package SO-8 Note: (1) Add suffix ‘TR’ for tape and reel packaging. TYPICAL APPLICATION CIRCUIT 2.5V IN Q1 2.5V OUT Si4410 C1 2 x 100uF C2 100uF 3.3V IN Q2 3.3V OUT IRLMS6802 C3 2 x 100uF C4 100uF U1 1 2.5V OUT 2 3 4 C5 10uF VO GND PDR NDR SC1545 5VSTBY 12VIN BF_CUT SLP 8 7 6 5 C6 1uF C7 0.1uF 5V STANDBY 1...