Figure 4 shows the I/O-transfer characteristic of the circuit with the values in Figure 3, where D1A and D1B are 6.8V 1N4099 zener diodes and D2A and D2B are 3V 1N5225 zener diodes.

• 图4显示了电路用图3值的I/O转换特性，而D1A和D1B为6.；8V 1N4099齐纳二极管和D2A和D2B为3V 1N5225齐纳二极管。