Quick-start DC-DC converter circuit and method
AssigneeAlcatel Canada Inc.
InventorsTom Currelly, Randy Law
Life of this patent
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Abstract
A quick-starting low-voltage DC power supply circuit has a switch mode DC to DC converter connected to a DC supply source. A low-dropout-regulator (LDO) connected in parallel with the switch-mode DC to DC converter, and a diode is connected in series with the output of the low-dropout-regulator connecting the output of the low-dropout-regulator to the output of the switch-mode DC to DC converter. The arrangement is such that the start-up output voltage of the circuit is the output voltage of the low-dropout-regulator and the long-term output voltage of the circuit is supplied by the switch-mode DC to DC converter output.
Claims5
A quick-starting low-voltage DC power supply circuit comprising in combination:
- a switch-mode DC to DC converter connected to a DC supply source,
- a low-dropout-regulator (LDO) connected in parallel with said switch-mode DC to DC converter, and
- a diode in series with the output of said low-dropout-regulator connecting said output of said low-dropout-regulator to the output of said switch-mode DC to DC converter,
- whereby the start-up output voltage of said circuit is the output voltage of said low-dropout-regulator and the long term output voltage of said circuit is supplied to said switch-mode DC to DC converter output.
A power supply for supplying a regulated output voltage comprising:
- a switch-mode direct current-to-direct current (DC to DC) converter having an output and adapted to be connected to a source of direct current DC power,
- a rectifying element having an anode and a cathode, said cathode being connected to the output of the switch-mode DC to DC converter;
- and
- a linear regulator having an output coupled to said anode of said rectifying element, a supply input for connecting to said DC power supply,
- said linear regulator having a turn-on speed which is greater than that of said switch-mode DC-DC converter and the output of the said linear regulator has a lower voltage than that of the switch-mode DC-DC converter, and said rectifying element blocking flow of any energy from said switch-mode DC-DC converter to said linear regulator.
A method of quickly supplying low-voltage power to a power rail comprising providing a first low-voltage source which is connected to said power rail for bringing up to near a desired voltage level with a fast startup converter circuit and constituting a less robust source,
- providing a switch-mode direct current-to-direct current DC converter having an output connected to said power rail, said switch-mode direct current-to-direct current converter having a startup time which is greater than the startup time of said first power supply and constituting a robust source,
- and blocking flow of energy from said robust source to said less robust source when said robust source is up to said desired voltage level.
Dependencies are inferred from the claim text.