DC/DC converter

US6226194A · kind A · utility

Assignee

• TEXAS INSTRUMENTS DEUTSCHLAND GMBH · DE

Inventors

• Erich Bayer · Straubing, DE
• Hans Schmeller · Nieheim, DE

Key dates

• Filing date: Jun 15, 2000
• Grant date: May 1, 2001
• Expiry date: Jun 15, 2020

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02M1/36
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

The invention relates to a DC/DC converter operating on the principle of a charge pump and comprising a first capacitor C1 alternatingly 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 as yet empty capacitors 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 V.sub.out of the converter to a reference voltage V.sub.ref, it switching the current mirror and--via two small switches S2 and S3 connected to the gates of two of the four MOSFETs--also two of the four MOSFETs so that the capacitors may be charged in an energy-saving way. As compared to existing more complicated achievements this novel DC/DC converter is producable integrated on a smaller circuit area, it in addition to this taking into account the short-circuit case of the converter. In one special e…