LM293输出不是高低电平

首先先确定输入是否都在共模电压范围之内，不同的两输入，输出情况在datasheet中都有给出，

1. When both IN- and IN+ are both within the common-mode range:
(a) If IN- is higher than IN+ and the offset voltage, the output is low and the output transistor is sinking  current
(b) If IN- is lower than IN+ and the offset voltage, the output is high impedance and the output transistor is not conducting

2. When IN- is higher than common-mode and IN+ is within common-mode, the output is low and the output transistor is sinking current

3. When IN+ is higher than common-mode and IN- is within common-mode, the output is high impedance and  the output transistor is not conducting

 
4. When IN- and IN+ are both higher than common-mode, the output is low and the output transistor is sinking current。

感谢你的回答，LM293的共模电压问题我也看过，应该不是这个问题。现在是+输入端小于﹣输入端，比如，+输入端电压4.13V，﹣输入端电压4.35V，结果输出端电压时3.05V（工作电压时8.5V）这个电压会随＋端输入电压增大而增大，减小而减小，而不是那种脉冲般的跳变。这才是我纠结的地方。另外，两个输出端，一个驱动三极管，一个驱动门电路。

LM293是OC输出，输出端有没有加上拉电阻？我怀疑您的输出端没有上拉，我用TINA仿真了一下，没问题。