| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC-DC converter integrated on a smaller circuit area. SOLUTION: This converter operates on the principle of a charge pump, and comprises a first capacitor C1 alternately charged via four MOSFETs M1-M4 to the input voltage and then discharged in series with the input voltage via a second capacitor C2 connected to the output of the circuit. To set the starting current for charging the empty capacitors at that movement to a precisely defined small value, a switchable current mirror M3, M5 is used comprising one of the four MOSFETs (M3) and a further small MOSFET (M5) which is connected to a current source 4. A comparator 5 handles selection between the starting phase and the normal charge pump mode by comparing the output voltage Vout of the converter with a reference voltage Vref, charges the capacitors in an energy-saving way, and switches the current mirror via two small switches S2 and S3 connected to two of the four MOSFETs and the gates of two of the four MOSFETs.
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