# LT1395运放的输入电压范围

1. LT1395运放的共模输入电压范围是多少？输入共模电压和电源电压之间的关系是怎样的。数据手册只给出了5V和±5V条件下的输入共模电压范围。假如采用Vs=+7V单端供电，输入共模电压范围是多少？
2. 同样运放输出电压和电源电压的关系呢？
3. 想用这款芯片做电压跟随，有没有推荐的资料呢？谢谢！
Parents
• Hi Feng Xuejian 476:   The common mode input range and output swing are really relative to the supplies.

1.  On a single 5V supply, the input CM range is specified as from 1.0V to 4.0V.  Maximum guarantees over temperature (on +/-5V) extend an extra 0.5V of headroom, or 1.5V from each rail.  This should extend to a single 7V supply as from 1.5V min to 5.5V upper limit.

2.  The output headroom is quite constant, relative to the supply voltages, although with a heavy load (see the 150 Ohm case) it does need more headroom.  With a light load, the output can swing up to 0.8V from the top (1.3V worst case), and down to 0.8V above the bottom (again 1.3V worst case).  So on a single 7V supply, worst case output swing would be 1.3V to 5.7V.

3.  Do you mean G=1 voltage follower?  Yes, it can do that within the limits above.

还想问一下:

1. LT1395电流反馈运算放大器做电压跟随器的时候，整个电压跟随器的输入阻抗是多大呢？

2.我用LT1395搭了一个电压跟随器，反馈电阻用的是360Ω。输入信号由函数发生器提供，幅值1.6-4.4V，频率5MHz的矩形波。但是，经示波器另一通道观察，实际施加到跟随器输入端的电压却是1.6-4.18V，而跟随器输出电压为560mv-2.68V，和输入信号大小也不一致。在供电电压从6V-12V上述现象均存在。是不是反馈电阻的大小选择有问题？还是跟随器输入阻抗不够？就上述现象希望您帮我分析分析。

谢谢！