Voltage converter for converting an input voltage to an output voltage and driving circuit comprising a voltage converter
The invention regards an improved voltage converter with increased current capability. The voltage converter architecture may be configured by software. In the prior art programmable charge pumps have been configured in such a way, that the unused stages were simply short circuited by a decoding logic. According to the invention these stages are used to increase the current capability of the first pumping stage. In particular the result is an increase in current capability of a proposed charge pump device by 10% to 15% without the need of additional parts and within the same area.
1. A voltage converter for converting an input voltage to an output voltage comprising a plurality of cascaded voltage multipliers and control circuitry for controlling the plurality of voltage multipliers, wherein the control circuitry comprises a switching means for activating at least one first voltage multiplier selected from the plurality of voltage multipliers and for switching at least one further voltage multiplier located in the cascade before the first voltage multiplier in the same way as the first voltage multiplier.
2. A voltage converter according to claim 1 , wherein that switching comprises activating and/or disabling.
3. A voltage converter according to claim 1 , wherein the first voltage multiplier is one of a number of activated voltage multipliers also located in the cascade at a second or higher order stage located in a sequence of stages at the end of the cascade.
4. A voltage converter according to claim 1 , wherein the further voltage multiplier is one of a number of further voltage multipliers located at the first or higher order stages of the cascade located in a sequence of stages at the beginning of the cascade.
5. A voltage converter according to claim 1 , wherein at least one of the plurality of voltage multipliers is formed by a charge pump.
6. A voltage converter according to claim 1 , wherein the charge pump comprises a charge storage element, a switch and a driver.
7. A voltage converter according to claim 1 , wherein one or more of the voltage multipliers have at least one clock input.
8. A voltage converter as claimed in claim 7 , wherein the control circuitry is connected to the clock input for supplying a clock signal to the voltage multiplier for controlling the voltage multiplier.
9. A voltage converter according to claim 1 , wherein the switching means is a programmable logic device.
10. A voltage converter as claimed in claim 9 , further comprising a programming means for operating the switching means as a function of the output and/or the input voltage.
11. A voltage converter as claimed in claim 9 , wherein the programming means comprises a software code section capable of activating a number of one or more first voltage multipliers in case of insufficient input voltage.
12. A voltage converter as claimed in claim 9 , wherein the programming means comprises a software code section for disabling a number of voltage multipliers selected from the plurality of voltage multipliers in case of sufficient input voltage.
13. A voltage converter as claimed in claim 9 , wherein the programming means comprises a software code section capable of selecting a number of one or more further voltage multipliers from the disabled voltage multipliers for switching the further voltage multipliers in the same way as the activated first voltage multiplier.
14. A driving circuit, comprising a voltage converter as claimed in claim 1 .
15. A driving circuit as claimed in claim 14 , working under a current load of 0.1 mA to 10 mA.
16. A method of converting an input voltage to an output voltage by means of a voltage converter comprising a plurality of cascaded voltage multipliers, wherein at least one first voltage multiplier selected from the plurality of voltage multipliers is activated and at least one further voltage multiplier located in the cascade before the first voltage multiplier is switched in the same way as the first voltage.
17. A voltage converter for converting an input voltage to an output voltage, comprising:
a plurality of cascaded voltage multipliers and control circuitry adapted to control the plurality of voltage multipliers, the control circuitry further comprising:
a bottom plate driver adapted to activate at least one first voltage multiplier selected from the plurality of voltage multipliers and to switch at least one further voltage multiplier located in the cascade before the first voltage multiplier in the same way as the first voltage multiplier.
18. A voltage converter as claimed in claim 17 , wherein a logic device commands the bottom plate driver to switch the at least one further voltage multiplier.