zeptobars: 假冒的发烧运放OPA627(AD744？) 更新
本帖最后由 卡西利亚斯 于 2014-5-3 12:08 编辑原文:Fake audiophile opamps: OPA627 (AD744?!)
作者:zeptobars（俄毛）
Walking around ebay I noticed insanely cheap OPA627's. It's rather old, popular and high-quality opamps, often used in audiophile gear. Manufacturer (Texas Instruments / Burr Brown) sells them 16-80$ each (depending on package & options) while on ebay it's cost was 2.7$, shipping included.
我逛易趣的时候，注意到OPA627非常便宜，这是一种很老很Pop很HQ的运放，通常用于发烧设备，TI/BB原厂每片出厂价根据包装和类型不同在16-80刀之间，但易趣上只卖2刀7还包邮！！！
Obviously, something fishy was going on. I ordered one, and for comparison - older one in metal can package, apparently desoldered from some equipment. Let's see if there is any difference.
显然，这很可疑。我买了一片，用来和金封拆机货做比较。下面让我们看看不同的地方。
http://image15-c.poco.cn/mypoco/myphoto/20140503/12/17470468720140503121102095.jpg
Plastic one was dissolved in acid, metal can was easily cut:
塑封的得拿酸融掉，金封的很容易就剪开了
http://image15-c.poco.cn/mypoco/myphoto/20140503/12/17470468720140503121058089.jpg
Comparison
对比
Genuine TI/BB OPA627 chip first. We can see here at least 4 laser-trimmed resistors - now we see why it could cost that much. Laser trimmed resistors are needed here due to unavoidable manufacturing variation - parts inside opamps needs to be balanced perfectly.
首先是正野TI/BB OPA627 ， 我们能看到至少有4个激光蚀刻的电阻，现在我们知道为什么它那么贵了。激光蚀刻电阻能将因为工艺而不一致的运放内部调正到完美的平衡。
http://image15-c.poco.cn/mypoco/myphoto/20140503/12/17470468720140503121107043.jpg
“Chinese" 2.7$ chip. There is only 1 laser trimmed resistor, but we also notice markings AD (Analog Devices?) and B744. Is it really AD744? If we check datasheet на AD744 - we'll see that metal photo perfectly matches one in the datasheet .
中国产 2刀7的芯片， 只有一只激光蚀刻的电阻， 我注意到上面有 AD和B744的标记，它真的是AD744吗。 我检查了AD744的规格书，我们发现这副图惊人的和规格书里的相似。
http://image15-c.poco.cn/mypoco/myphoto/20140503/12/17470468720140503121054027.jpg
What happened here?
花生了什么树？
Some manufacturer in China put an effort to find cheaper substitute for OPA627 - it appeared to be AD744. AD744 has similar speed (500ns to 0.01%), similar type (*FET), supports external offset compensation. AD744 also support external frequency compensation (for high-speed high-gain applications) but there was no corresponding pin on the OPA627 - so this feature is unused.
有些中国的厂家努力挖掘更便宜的OPA627替代品，显然就是AD744. AD744有很相似的速度（500ns to 0.01%) , 相似的类型（*FET），支持外接失调补偿。AD744还为高速高增益应用提供支持外部频率补偿，但OPA627没有相应的脚位，所以这个特性没有使用。
On the other hand AD744 has higher noise (3x) and higher offset voltage (0.5mV vs 0.1mV).
另一方面，AD744的噪音更高（3倍于OPA627）和更高的失调电压（0.5mv, OPA627是0.1mv)
So they bought AD744 in the form of dies or wafers, packaged them and marked as OPA627. It does not seems they earned alot of money here - it's more of an economic sabotage. Good thing that they did not used something like LM358 - in that case it would have been much easier to notice the difference without looking inside...
所以，他们买了AD744的晶圆或者裸片，包装后印上OPA627。我不在乎他们赚了多少钱，但这是更多对打乱了市场，好在他们没有用类似LM358的东西，那会让人在没看过内部的情况下，也很容易注意到不同。
Be careful when choosing suppliers - otherwise your design might get "cost-optimized" for you :-)
选购时候要当心，否则你的设计会被你自己 “成本优化” 。
PS1： 汕头佬买晶圆自己封会哭死的，俄毛脑筋不行啊，他们直接买片子打磨刻字不就好了。
PS2：有人认为俄毛的金封不是OPA627，下面贴个“真*OPA627” 裸片图。
补充内容 (2020-9-25 16:11):
最下面这个BB 627字样的图才是真货，其他都是假的。 谢谢分享，貌似图片显示还是不给力呀。。。 分析的透彻 可惜看不到图 图片挂了一半啊楼主 感谢分享，因此测量50k电阻的方法还是适用的 图片呢 高清的大图是25M，还是；老毛子的网站。。。。。 看不见图啊！猫很凶悍的样子。 那个神级的说量1,5脚电阻倒像是对的! :o 本帖最后由 卡西利亚斯 于 2014-5-11 18:06 编辑
本帖最后由 卡西利亚斯 于 2014-5-3 12:08 编辑
原文:Fake audiophile opamps: OPA627 (AD744?!)
作者:zeptobars（俄毛）
Walking around ebay I noticed insanely cheap OPA627's. It's rather old, popular and high-quality opamps, often used in audiophile gear. Manufacturer (Texas Instruments / Burr Brown) sells them 16-80$ each (depending on package & options) while on ebay it's cost was 2.7$, shipping included.
我逛易趣的时候，注意到OPA627非常便宜，这是一种很老很Pop很HQ的运放，通常用于发烧设备，TI/BB原厂每片出厂价根据包装和类型不同在16-80刀之间，但易趣上只卖2刀7还包邮！！！
Obviously, something fishy was going on. I ordered one, and for comparison - older one in metal can package, apparently desoldered from some equipment. Let's see if there is any difference.
显然，这很可疑。我买了一片，用来和金封拆机货做比较。下面让我们看看不同的地方。
http://i1364.photobucket.com/albums/r733/90998/aa1_zps4eca3694.jpg
Plastic one was dissolved in acid, metal can was easily cut:
塑封的得拿酸融掉，金封的很容易就剪开了
http://i1364.photobucket.com/albums/r733/90998/a2_zps3a553546.jpg
Comparison
对比
Genuine TI/BB OPA627 chip first. We can see here at least 4 laser-trimmed resistors - now we see why it could cost that much. Laser trimmed resistors are needed here due to unavoidable manufacturing variation - parts inside opamps needs to be balanced perfectly.
首先是正野TI/BB OPA627 ， 我们能看到至少有4个激光蚀刻的电阻，现在我们知道为什么它那么贵了。激光蚀刻电阻能将因为工艺而不一致的运放内部调正到完美的平衡。
http://i1364.photobucket.com/albums/r733/90998/a3_zpsc5224c31.jpg
“Chinese" 2.7$ chip. There is only 1 laser trimmed resistor, but we also notice markings AD (Analog Devices?) and B744. Is it really AD744? If we check datasheet на AD744 - we'll see that metal photo perfectly matches one in the datasheet .
中国产 2刀7的芯片， 只有一只激光蚀刻的电阻， 我注意到上面有 AD和B744的标记，它真的是AD744吗。 我检查了AD744的规格书，我们发现这副图惊人的和规格书里的相似。
http://i1364.photobucket.com/albums/r733/90998/a4_zps229b9b3b.jpg
What happened here?
花生了什么树？
Some manufacturer in China put an effort to find cheaper substitute for OPA627 - it appeared to be AD744. AD744 has similar speed (500ns to 0.01%), similar type (*FET), supports external offset compensation. AD744 also support external frequency compensation (for high-speed high-gain applications) but there was no corresponding pin on the OPA627 - so this feature is unused.
有些中国的厂家努力挖掘更便宜的OPA627替代品，显然就是AD744. AD744有很相似的速度（500ns to 0.01%) , 相似的类型（*FET），支持外接失调补偿。AD744还为高速高增益应用提供支持外部频率补偿，但OPA627没有相应的脚位，所以这个特性没有使用。
On the other hand AD744 has higher noise (3x) and higher offset voltage (0.5mV vs 0.1mV).
另一方面，AD744的噪音更高（3倍于OPA627）和更高的失调电压（0.5mv, OPA627是0.1mv)
So they bought AD744 in the form of dies or wafers, packaged them and marked as OPA627. It does not seems they earned alot of money here - it's more of an economic sabotage. Good thing that they did not used something like LM358 - in that case it would have been much easier to notice the difference without looking inside...
所以，他们买了AD744的晶圆或者裸片，包装后印上OPA627。我不在乎他们赚了多少钱，但这是更多对打乱了市场，好在他们没有用类似LM358的东西，那会让人在没看过内部的情况下，也很容易注意到不同。
Be careful when choosing suppliers - otherwise your design might get "cost-optimized" for you :-)
选购时候要当心，否则你的设计会被你自己 “成本优化” 。
PS1： 汕头佬买晶圆自己封会哭死的，俄毛脑筋不行啊，他们直接买片子打磨刻字不就好了。
PS2：有人认为俄毛的金封不是OPA627，下面贴个“真*OPA627” 裸片图。 这就是烧咯 楼主揭了JS的底细:P 一种方法是测电流 一种方法是测15 17 57 脚之前的阻值 还有一种方法是 放大160倍 看芯片 主楼强悍，挖到内部晶片了，让JS无处躲藏。
这么说我们用的都是AD744？ 不过十元不到的价格也没什么遗憾了，声音还不错。 价格还是能体现出内在品质的 哪个是激光刻的电阻？ 好帖,真长知识了 真伪难辨呀
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