General 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 10mA of output current. The regulated output for the LM2687 is adjustable between −1.5V and −5.2V. The LM2687 operates at 100 kHz (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 comes in a small 8-pin MSOP package.
●Features
●■ Inverts and regulates the input supply voltage
●■ Small MSOP-8 package
●■ 91% typical charge pump power efficiency at 10mA
●■ Low output ripple (1mV typical)
●■ Shutdown lowers Quiescent current to 0.05 µA (typical)
●Applications
●■ Wireless Communication Systems
●■ Cellular Phone Power Amplifier Biasing
●■ Interface Power Supplies
●■ Handheld Instrumentation
●■ Laptop Computers and PDA’s
