An output buffer switch-on control circuit and a discharge current circuit

摘要

An output buffer switch-on control circuit includes several transistors and a discharge current control circuit. A first transistor has a first terminal connected to an internal voltage line and is controlled by an output data source. A second transistor has a first terminal connected to the internal voltage line and is controlled by a second terminal of the first transistor. The second transistor also has a second terminal connected to a first terminal of an output capacitor. A third transistor is controlled by the output data source and has a first terminal connected to a common voltage. A fourth transistor is digitally controlled and has a first terminal connected to the second terminal of the second transistor. The fourth transistor also has a second terminal connected to the common voltage. The discharge current control circuit is preferably actively-controlled and is connected between a second terminal of the first transistor and a second terminal of the third transistor. The discharge current control circuit preferably includes a discharge resistor and a mirrored current transistor feedback controlled by an output capacitor.