Patent ID: 6330463
Filing Date: 2001-12-11
Classification: H02J

Abstract:
Voltage supply apparatus, in particular for a radio telephone, in a motor vehicle having:a main voltage source which is connected to one input of a voltage matching circuit which derives at least one supply voltage from the voltage present at its input,an auxiliary voltage source which can be connected via a controllable switch to the voltage matching circuit,a voltage monitoring circuit to which a voltage signal corresponding to the voltage of the main voltage source is supplied and which supplies a switch control signal in order to connect the auxiliary voltage source to the voltage matching circuit in an emergency in the event of failure of the main voltage source,wherein the voltage matching circuit comprises a first voltage converter which outputs a first supply voltage at its output, and a second voltage converter which supplies a second supply voltage which is less than the first supply voltage,wherein the first voltage converter has a filter circuit and a voltage-raising circuit, andwherein the voltage-raising circuit has a control input which is connected to the output of the first voltage converter, in order to keep the supply voltage at a stabilized value independently of the voltage which is present at the input.