ADM8828

a FEATURES Inverts Input Supply Voltage 99% Voltage Conversion Efficiency 25 mA Output Current Shutdown Function Requires Only Two Capacitors 1 ␮F Capacitors 18 ⍀ Output Resistance +1.5 V to +5.5 V Input Range 600 ␮A Quiescent Current 20 nA Shutdown Current (ADM8828) APPLICATIONS Handheld Instruments LCD Panels Cellular Phones PDAs Remote Data Acquisition Op Amp Power Supplies Switched-Capacitor Voltage Inverter with Shutdown ADM8828/ADM8829 FUNCTIONAL BLOCK DIAGRAMS OUT 1 6 CAP+ ADM8828 IN 2 TOP VIEW 5 SHDN CAP– 3 (Not to Scale) 4 GND OUT 1 6 CAP+ ADM8829 IN 2 TOP VIEW 5 NC CAP– 3 (Not to Scale) 4 GND NC = NO CONNECT GENERAL DESCRIPTION The ADM8828/ADM8829 is a charge-pump voltage inverter which may be used to generate a negative supply from a positive input. Input voltages ranging from +1.5 V to +5.5 V can be inverted into a negative –1.5 V to –5.5 V output supply. This inverting scheme is ideal for generating a negative rail in single power-supply systems. Only two small external capacitors are needed for the charge pump. Output currents up to 25 mA with greater than 99% efficiency are achievable. The ADM8828 also features a low power shutdown (SHDN) pin. This can be used to disable the device and reduce the quiescent current to 20 nA. The ADM8828/ADM8829 is available in a 6-lead SOT-23 package. +1.5V TO +5.5V INPUT C1 + 1␮F CAP+ IN ADM8828/ ADM8829 CAP– SHDN GND OUT SHUTDOWN CONTROL C2 + 1␮F INVERTED NEGATIVE OUTPUT Figure 1. Typical Circuit Confi...