Figure 1 shows the integrated operational amplifier output over-current protection circuit, for some reason (such as output short circuit, etc.) to an integrated amplifier and output overcurrent protection circuit Serve constant current source, the integrated operational amplifier from being lost due to Mountain overcurrent damage.
In the figure, according to the integrated FET 3DJ7 output op amp, and using approximate constant current source connection. When the circuit is working properly, the field effect transistor presents a low impedance, does not influence the circuit's output voltage range. When the output short circuit, the FET presents high impedance of the circuit output current has been limited.
The role of diode D1, in the energy output negative voltage, and together constitute the current source FET. D2 and D1 are the same, the output is in the circuit voltage, and together constitute the current source FET.
FET drain-source saturation current should be whichever IDSS integrated operational amplifier output current is slightly larger than the tube, since most integrated operational amplifier output current is no more than ± 10mA, so I can use as 3DJ6H, 3DJ7G other tube. Idss not get too big or too small, too large if Idss, weakening Idss protection is too small, in the larger integrated operational amplifier output current, the current source impedance increases, limiting the scope of the circuit's output amplitude.
Modest when the circuit output, the load is light, can be a resistance of about 500Ω resistor to replace the FET can also be also achieved the desired results.