Power supply apparatus capable of supplying a stable converted voltage
AssigneeRohm Co., Ltd.
InventorsIsao Yamamoto, Yoichi Tamegai
Life of this patent
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Abstract
A power supply apparatus switchably operates an LDO regulator and a DC/DC converter connected in parallel so as to control a battery voltage Vbat from a power supply at a constant output voltage VO. A detected voltage Vs at a shared output terminal shared by the LDO regulator and the DC/DC converter is input to a feedback input terminal and fed back to the LDO regulator and the DC/DC converter. In order to suppress an undershoot occurring when switching from the LDO regulator to the DC/DC converter, a timing signal generating unit supplies a capability switching timing signal to a pre-drive circuit and switches the control capability of the DC/DC converter from a low capability mode at startup to a high capability mode.
Claims13
A power supply apparatus comprising:
- a series regulator that converts a power supply voltage into a first voltage to output the first voltage to a common output terminal;
- a switching regulator that converts the power supply voltage into a second voltage to output the converted voltage to the common output terminal;
- a common feedback unit that feeds a detected voltage at the common output terminal back to said series regulator and said switching regulator;
- a control terminal that inputs a switching control signal;
- a switching control unit that switchably puts said series regulator and said switching regulator into operation in response to the switching control signal;
- and
- a capability switching unit that controls the capability of said switching regulator to be lowered than normal in the beginning of its operation caused by said switching unit.
A power supply control method comprising:
- receiving, from a control terminal, a switching control signal which designates switching from a series regulator that converts a power supply voltage into a first voltage to output the first voltage to a common output terminal, to a switching regulator that converts the power supply voltage into a second voltage to output the second voltage to the common output terminal;
- turning said switching regulator on with a capability lower than normal when the switching control signal is received;
- turning said series regulator off when a predetermined period of time elapses since the generation of the switching control signal;
- and
- switching said switching regulator from a low capability to a normal capability when a predetermined period of time elapses since the turning said series regulator off.
Dependencies are inferred from the claim text.