标准TTL电路电源电压范围:5V+/-(0.25-0.5V)输入电平U IH=2V,U IL=0.8V输出电平U OH=2.7V,U OL=0.4V输入电流I IH=40uA,I IL=1600uA输出电流I OH=0.4mA,I OL=16mA
+5V，(偏差:正,负0.25V)
－3～5V
