LM2687 Datasheet | National Semiconductor

Description The LM2687 CMOS Negative Regulated Switched Capacitor Voltage Inverter delivers a very low noise adjustable output for an input voltage in the range of +2.7V to +5.5V. Four low cost capacitors are used in this circuit to provide up to 10m A of output current. The regulated output for the LM2687 is adjustable between - 1.5V and - 5.2V. The LM2687 operates at 100 k Hz (typical) switching frequency to reduce output resistance and voltage ripple. With an operating current of only 500 µA (charge pump power efficiency greater than 90% with most loads) and 0.05 µA typical shutdown current, the LM2687 provides ideal performance for cellular phone power amplifier bias and other low current, low noise negative voltage needs. The device es in a small 8-pin MSOP package. Features n n n n n Inverts and regulates the input supply voltage Small MSOP-8 package 91% typical charge pump power efficiency at 10m A Low output ripple (1m V typical) Shutdown lowers Quiescent current to 0.05 µA (typical) Applications n n n n n Wireless munication Systems Cellular Phone Power Amplifier Biasing Interface Power Supplies Handheld Instrumentation Laptop puters and PDA’s Typical Application Circuit DS101180-1 Connection Diagram 8-Pin MSOP DS101180-2 © 1999 National Semiconductor Corporation DS101180 .national. Ordering Information Device Order Number LM2687MM LM2687MMX Package Number MUA08A MUA08A Package Marking- S12A S12A Supplies As Tape and Reel (1000 units/reel) Tape and Reel (3500 units/reel) Note: - The small physical size of the MSOP-8 package does not allow for the full part number marking. Devices will be marked with the designation shown in the column Package Marking. Pin Description Pin No. 1 2 3 4 5 6 7 8 Name Cap+ GND Cap- SD VNEG VFB VOUT VIN Positive terminal for C1. Ground. Negative terminal for C1. Active low, logic-level shutdown input. Negative unregulated output voltage. Feedback input. Connect VFB to an external resistor divider between VOUT and a positive...