| 摘要 |
PURPOSE:To supply sufficient at transient period of a speaker load and also to limit an output at a low impedance load by limiting an output voltage when an output current being a prescribed value or over flows. CONSTITUTION:When an output current is increased with a low load impedance and a voltage across a resistor 28 reaches nearly 0.6V or over, an output current detection transistor (TR) 19 is turned on, a time constant capacitor 31 is charged via a time constant resistor 29, and when the voltage across the capacitor 31 reaches nearly 0.6V, a TR20 is also turned on. Then TRs 21, 22 are also turned on respectively and the level of cathode of a diode 25 and the anode of a diode 26 reach respectively a voltage generated by output voltage limit reference voltage Zener diodes 23, 24. Thus, when the level of the collector of the voltage amplification TR21 is made fluctuated to a voltage over the voltage of the Zener diodes 23, 24, output voltage limit switching diodes 25, 26 are turned on so as to limit the amplitude. |
