Some questions about CMOS Opamps

[qiushidaren]

Hi all, I am studying the CMOS opamp now, but I am just a novice in this field so I want to ask you gurus some questions about it, your suggestions and comments will be highly appreciated!
Here are my questions:
What is SCR?
What is junction temperature rise and drift?
What does maxim storage temperature range mean for CMOS opamp?

 

[vicky]

HI DEAR,

Silicon-controlled rectifier
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SCR schematic symbolA silicon-controlled rectifier (or semiconductor-controlled rectifier) is a 4-layer solid state device that controls current flow. The name "silicon controlled rectifier" is a trade name for the type of thyristor commercialized at General Electric in 1957.

Contents [hide]
1 Theory of operation
2 Modes of operation
3 Applications
4 References
5 See also



[edit] Theory of operation
An SCR can be seen as a conventional rectifier controlled by a gate signal. It is a 4-layered 3-terminal device. A p-type layer acts as anode and an n-type layer as a cathode; the p-type layer closer to the n-type(cathode) acts as a gate. k': k; "k


An SCR (left) can be thought of as two BJT transistors working together (right).
[edit] Modes of operation
In the normal 'off' state the device restricts current flow to the leakage current. When the gate to cathode voltage exceeds a certain threshold, the device turns 'on' and conducts current. The device will remain in the 'on' state even after gate current is removed so long as current through the device remains above the holding current. Once current falls below the holding current for an appropriate period of time, the device will switch off.

If the applied voltage increases rapidly enough, capacitive coupling may induce enough charge into the gate to trigger the device into the 'on' state; this is referred to as dv/dt triggering. This is usually prevented by limiting the rate of voltage rise across the device, perhaps by using a snubber. dv/dt triggering may not switch the SCR into full conduction rapidly and the partially-triggered SCR may dissipate more power than is usual, possibly harming the device.

SCRs can also be triggered by increasing the forward voltage beyond their rated breakdown voltage, but again, this does not rapidly switch the entire device into conduction and so may be harmful so this mode of operation is also usually avoided. Also, the actual breakdown voltage may be substantially higher than the rated breakdown voltage, so the exact trigger point will vary from device to device





a drift is a comparatively long-term change in an attribute or value of a system or equipment operational parameter.

The drift should be characterized, such as "diurnal frequency drift" and "output level drift."

Drift is usually undesirable and unidirectional, but may be bidirectional, cyclic, or of such long-term duration and low excursion rate as to be negligible.

 

[jamesqjf]

Good material, thanks

 

[Jevil]

Thank you,these questiongs I also want to know.

 

[wszywps]

very nice

 

[layes2]

-40---125

 

[Jim cage]

Depending on the application the temperature can be from -45 to 85 or from -10 to 70 (military application usually require higher temperature since we send our soldiers to russia and afganistan with the same equipment...)

for home/indoor enviroment the temperature is much lower.