Fairchild Enhancements Eradicate CMOS SCRLatch-Up in 74HC Logic Data Manual
Summary
This detailed application note provides essential technical guidance on mitigating and eliminating Silicon Controlled Rectifier (SCR) latch-up in high-speed CMOS logic circuits. It explains the fundamental mechanism of this parasitic failure—a common cause of system malfunction and potential damage to integrated circuits. The manual covers triggering methods, analysis techniques, and incorporates proprietary layout enhancements and protective circuit designs for robust performance. This resource is essential reading for electrical engineers and digital designers committed to achieving maximum reliability and ensuring long-term stability in advanced CMOS systems.
Manual Details
| Brand | Fairchild |
|---|---|
| Pages | 10 |
| File Size | 144.29 KB |
| Published | June 06, 2026 |
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Frequently Asked Questions
What is SCR latch-up in CMOS circuits?
It is a parasitic phenomenon that forms a thyristor structure (P-N-P-N) capable of shorting Vcc to ground.
What external conditions can trigger this latch-up?
Triggering sources include extraneous noise, system transients, or applying an excessively large voltage across the device.
Under what condition does regenerative current multiplication occur?
Runaway occurs when the product of the two transistors’ Beta values, B(NPN)xB(PNP), is greater than one.
How can system reliability against latch-up be improved?
It requires proper design techniques, specialized layout modifications, or adding external protection circuits.