请教一个关于OP AMP的基本问题。内附图 - 未名空间MITBBS历史存档

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请教一个关于OP AMP的基本问题。内附图

请教一个关于OP AMP的基本问题。内附图# EE - 电子工程

g*g2006-12-18 08:12

1 楼

attached is the circuit in the P14 of the datasheet from LM5025, national
semi.
you can find it at www.national.com LM5025 datasheet.
my stupid questions are:
1. what is function for U3A, R31, R32,C31? just for adding an extra pole at
2*Pi*R31*C32? or other functions else?
2. why + of U3A need to be connected to reference 1.2V? can I put it to
second GND?
3.why the output of U3A is positive??
thanks for your help

l*g2006-12-18 08:12

2 楼

eeee.. what is the reference for the output?

at

【在 g*****g 的大作中提到】

: attached is the circuit in the P14 of the datasheet from LM5025, national
: semi.
: you can find it at www.national.com LM5025 datasheet.
: my stupid questions are:
: 1. what is function for U3A, R31, R32,C31? just for adding an extra pole at
: 2*Pi*R31*C32? or other functions else?
: 2. why + of U3A need to be connected to reference 1.2V? can I put it to
: second GND?
: 3.why the output of U3A is positive??
: thanks for your help

c*l2006-12-18 08:12

3 楼

我大概猜，U3A只是个反相功能。就是说用U3B做error amp，驱动opto coupler是不行的
需要反相一下才能驱动。
1.2 V可能是otp的静态工作电压。需要维持这个电压，opto才能上下rail距离相等
不然，会在一个方向上达到rail，就不能regulate了

at

【在 g*****g 的大作中提到】