CMOS Switched Capacitor Voltage Converters
The MAX1720 and NCP1729 require only two low cost capacitors for voltage inverter functions and two diodes and three capacitors for voltage doubling functions. The operating current consumption for the MAX1720 is only 67 micro amperes and 122 micro Amperes for the NCP1729. This low quiescent current coupled with the shutdown feature allow the devices to conserve battery power by further reducing the supply current to a mere 0.4 micro amperes.
Both charge pumps supply an output current in excess of 50 milli amperes, twice the output of comparable devices on the market. The MAX1720 and the NCP1729 contain a switching frequency of 12 kHz and 35 kHz, respectively, that drives four integrated resistance MOSFET switches.
The low quiescent current, made lower by the use of the shutdown pin, high efficiency, low-input voltage operation, high output current, and compact package make these devices ideal for battery powered systems such as LCD panels, cell phones, electronic games, camcorders and handheld instruments.