LM3880 Datasheet | National Semiconductor

Description The LM3880 Power Sequencer offers the easiest method to control power up and power down of multiple power supplies (switchers or linear regulators). By staggering the startup sequence, it is possible to avoid latch conditions or large in-rush currents that can affect the reliability of the system. Available in a SOT23-6 package, the Power Sequencer contains a precision enable pin and three open drain output flags. Upon enabling the LM3880 the three output flags will sequentially release, after individual time delays, permitting the connected power supplies to startup. The output flags will follow a reverse sequence during power down to avoid latch conditions. Standard timing option of 30ms is available. EPROM capability allows every delay and sequence to be fully adjustable. Contact National Semiconductor if a nonstandard configuration is required. Features n n n n n n n Easiest method to sequence rails Power up and power down control Input voltage range of 2.7V to 5.5V Small footprint SOT23-6 Low quiescent current of 20 µA Standard timing options available Customization of timing and sequence available through factory programmability Applications n Multiple supply sequencing n Microprocessor / Microcontroller sequencing n FPGA sequencing Typical Application Circuit © 2006 National Semiconductor Corporation DS201926 .national. .. Connection Diagram Top View SOT23- 6 Package Pin Descriptions Pin # 1 2 3 4 5 6 Name VCC GND EN FLAG3 FLAG2 FLAG1 Function Input supply Ground Precision enable pin Open drain output #3 Open drain output #2 Open drain output #1 Ordering Information Sequence Designator Table Flag Order Sequence Number 1 2 3 4 5 6 See timing diagrams for more information Power Up 1-2-3 1-2-3 1-2-3 1-2-3 1-2-3 1-2-3 Power Down 3-2-1 3-1-2 2-3-1 2-1-3 1-3-2 1-2-3 .national. .. Ordering Information Timing Designator AA AB AC AD (Continued) Timing Designator Table td1 10ms 30ms 60ms...