Patent ID: 7705572
Filing Date: 2010-04-27
Classification: H02P

Abstract:
1. A power supply device, comprising: a filter, for receiving a pulse width modulation signal and accordingly outputting a first direct-current voltage; and voltage driving unit, coupled to the filter, the voltage driving unit comprising: a voltage-regulation feedback unit, for receiving the first direct-current voltage and accordingly outputting a second direct-current voltage; and current amplification component, coupled to the voltage-regulation feedback unit for receiving an operational voltage and the second direct-current voltage, performing a current amplification operation on the second direct-current voltage, and accordingly outputting a driving voltage, wherein the driving voltage is fed back to the voltage-regulation feedback unit; wherein the voltage-regulation feedback unit regulates the driving voltage fed back to the voltage-regulation feedback unit according to the first direct-current voltage; and wherein the current amplification component is a first pnp-type bipolar junction transistor and the power supply device further comprises a protection device coupled to the current amplification component, the protection device comprises a resistance component and a second pnp-type bipolar junction transistor, the resistance component is coupled between the operational voltage and an emitter of the first pnp-type bipolar junction transistor, the second pnp-type bipolar junction transistor has an emitter coupled to the operational voltage, a base coupled to the emitter of the first pnp-type bipolar junction transistor, and a collector coupled to a base of the first pnp-type bipolar junction transistor, and a collector of the first pnp-type bipolar junction transistor outputs the driving voltage; wherein when a large current flows into the resistance component via the current amplification component, the second pnp-type bipolar junction transistor enters a saturation region to turn on for the first pnp-type bipolar junction transistor entering a cut-off region to turn off.