Ground-fault detecting circuit for btl amplifier

Abstract

Abstract PURPOSE:To detect the ground-fault from the current difference between the voltage and earth supply lines for the BTL (Bridged Transformer Less) amplifier, by utilizing the fact that the voltage and earth supply lines have an equal current level as long as no ground-fault occurs. CONSTITUTION:The differential amplifying circuit forms buffer amplifier 2 which produces the signals with the phase same as or opposite to input signal VIN. The in-phase signal is supplied to the 1st amplifying output circuit 3, and the opposite- phase signal is supplied to the 2nd amplifying output circuit 4 each. Then these outputs VOUT1 and VOUT2 of the opposite phases to each other drive load RL. For detection of the ground-fault, resistances R1 and R2 are inserted in series to the power supply lines of power voltage VCC and earth potential OV each. Thus the supply current is inverted into the voltage signal. And the difference if occurring to the current is detected to cut off the output transistors of output circuits 3 and 4. In such way, the protection is secured to the ground-fault.

Inventors

• 👤 Kunio Seki

Bibliographic Details