LM2781 Datasheet | National Semiconductor

Description The LM2781 is a charge pump that inverts an input voltage in the range of 1.8V to 5.5V to the corresponding output voltage of -1.8V to -5.5V. With use of three or four low-cost external ceramic capacitors, the LM2781 can provide up to 50m A of output current. The LM2781 operates at a 210k Hz typical switching frequency to minimize supply current (0.7m A typ.). Two charge pumps operate 180˚ out of phase to significantly reduce the output voltage ripple pared to that of traditional singlephase charge pump circuits. If larger output ripple can be tolerated, optional capacitor C2 may be omitted to reduce the cost and size of the solution. The LM2781 is available in an 8-pin Micro SMD chip-scale package. See also: LM2780, a slow clock (12k Hz typ) version of this topology with extremely low supply current. Features n Inverts Input Voltage n Ultra-Low Voltage Ripple and 8Ω Typical Output Resistance with Two Flying Capacitors n Output Resistance of 18Ω Using One Flying Capacitor n 210k Hz (typ.) Switching Frequency n 8-pin micro SMD Package (1.4mm x 1.4mm x 0.5mm) Applications n n n n n n Cellular Phones Pagers PDAs Op-Amp Power Supplies Interface Power Supplies Handheld Instruments Typical Application Circuit © 2003 National Semiconductor Corporation DS200447 .national. Connection Diagram 8-Bump Thin Micro SMD Package NS Package Number TPA08 .. Pin Description Pin A1 B1 C1 A2 C2 A3 B3 C3 Name C2+ VIN C1+ SD GND C2VOUT C1Description Secondary flying-capacitor connection Input voltage. Input range: 1.8V to 5.5V Primary flying-capacitor connection Shutdown pin logic input. Low = on, High = shutdown Ground Secondary flying-capacitor connection Output voltage. VOUT = -VIN Primary flying capacitor connection Ordering Information Order Number LM2781TP LM2781TPX Package Description TPA08: Thin Micro SMD TPA08: Thin Micro SMD Package Marking 12 12 Supplied as Tape and reel, 250 pcs. Tape and reel, 3000 pcs. .national. Absol...