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my idea,
just like switch regulator, usually use it to change one dc level to other dc level(it can be +/-) usually double the vdd..
this is my idea, if it wrong please check me..
thanks
Charge pumps use switches to control the connection of voltages to capacitors and then they can get higher or lower voltage levels. For instance, to generate a higher voltage, the first stage involves the capacitor being connected across a voltage and charged up. In the second stage, the capacitor is disconnected from the original charging voltage and reconnected with its negative terminal to the original positive charging voltage. Because the capacitor retains the voltage across it (ignoring leakage effects) the positive terminal voltage is added to the original, effectively doubling the voltage. The pulsing nature of the higher voltage output is typically smoothed by the use of an output capacitor.
A common application for charge pump circuits is in RS-232 level shifters where they are used to derive positive and negative voltages (often +10 V and -10 V) from a single 5 V or 3 V power supply rail.
Charge pumps can also be used as LCD or white LED drivers, generating high bias voltages from a single low-voltage supply, such as a battery. THIS LAST APPLICATION IS ONE OF THE MOST USED RIGHT NOW WITHIN ALL WHITE LEDS IN LCD MONITORS AND TVS
The internal chip charge pumps are used to generate 5V/3V from 1.8V supply and give it to swithes (to increase the Vgs and reduce its on resistances). negative chrage pumps can also be used for design of rail to rail buffer using the nmos input pair. Hope this helps.
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