LM3880EVAL

User's Guide SNVA172A – November 2006 – Revised May 2013 AN-1491 LM3880 Power Sequencer Demo Board 1 Introduction The LM3880 evaluation board has been designed to permit the designer to connect it directly to the power supplies of an existing system to enable sequencing. Upon enabling the device the three open drain output flags will rise in sequential order, 1-2-3. Once the part is disabled, the shutdown sequence will occur in reverse order 3-2-1. Therefore the last power supply that started up, will be the first to shutdown. The evaluation board contains the LM3880MF-1-AB device which has been factory set, so that each time delay between flags will be 30ms. Several different timing options are available as standard off the shelf parts, but if a custom timing or shutdown sequence is needed please contact Texas Instruments. The LM3880 has an internal EPROM that can be factory programmed to allow almost any sequencing combination to occur. For programming possibilities, see LM3880/LM3880Q Power Sequencer (SNVS451). 2 Timing Sequence The LM3880 demo board timing sequence of the output flags is shown in Figure 1. EN FLAG1 FLAG2 FLAG3 tD1 tD2 (30 ms) (30 ms) tD4 tD5 (30 ms) (30 ms) tD3 (30 ms) EN FLAG1 FLAG2 FLAG3 tD6 (30 ms) Figure 1. Timing Sequence All trademarks are the property of their respective owners. SNVA172A – November 2006 – Revised May 2013 Submit Documentation Feedback AN-1491 LM3880 Power Sequencer Demo Board Copyright © 2006–2013, Texas Instruments Incorporated 1 Schematic 3 www.ti.com Schematic The LM3880 demo board has been designed with the pullup resistors on board to permit connection to an enable pin of a switcher. The demo board can accommodate an input voltage from +2.7V to +5.5V. Input Supply (2.7V - 5.5V) R1 R2 R3 LM3880 VCC Enable EN FLAG1 Flag 1 FLAG2 Flag 2 FLAG3 Flag 3 GND Figure 2. Schematic 4 2 Bill of Materials Designator Description Part # Quantity Manufacturer U1 LM3880, Sequence 1, 30ms timing LM3880 1 Texas Instruments R1 100K Resistor, 0603 CRCW0603100KFKEA 1 Vishay R2 100K Resistor, 0603 CRCW0603100KFKEA 1 Vishay R3 100K Resistor, 0603 CRCW0603100KFKEA 1 Vishay AN-1491 LM3880 Power Sequencer Demo Board SNVA172A – November 2006 – Revised May 2013 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated Pin-Out www.ti.com 5 Pin-Out The pin-out and pin description of the LM3880 is shown in Figure 3 and in Table 1. 1 2 3 VCC FLAG1 GND FLAG2 EN FLAG3 6 5 4 Figure 3. Pin-Out Table 1. Pin Descriptions Pin # Name Function 1 VCC Input supply 2 GND Ground 3 EN Precision enable pin 4 FLAG3 Open drain output #3 5 FLAG2 Open drain output #2 6 FLAG1 Open drain output #1 SNVA172A – November 2006 – Revised May 2013 Submit Documentation Feedback AN-1491 LM3880 Power Sequencer Demo Board Copyright © 2006–2013, Texas Instruments Incorporated 3 Layout 6 www.ti.com Layout The demo board layout is based on a small 0.8” × 1.0” FR4 demo board with 2 layers of copper. The actual layout can be seen below. When looking at the board, pin 1 on the LM3880 is the top left. Figure 4. LM3880 Top Layer Figure 5. LM3880 Bottom Layer 4 AN-1491 LM3880 Power Sequencer Demo Board SNVA172A – November 2006 – Revised May 2013 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms and conditions of sale of semiconductor products. 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