Very low voltage drop transistor

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SUMMARY

The discussion centers on constructing a fast-reacting current overload protection device using low voltage drop transistors, specifically focusing on FETs. Participants recommend using low on-resistance FETs for this application and suggest conducting parametric searches on distributor websites like analog.com and digikey.com. One contributor advises exploring ESD protection techniques in ICs, referencing a method involving a resistor across the gate and drain of an n-type MOSFET to manage current surges effectively. The conversation highlights the scarcity of individually-packaged MOSFETs, emphasizing the need for power devices in circuit protection.

PREREQUISITES
  • Understanding of FET (Field Effect Transistor) operation and characteristics
  • Knowledge of ESD (Electrostatic Discharge) protection methods in integrated circuits
  • Familiarity with parametric search techniques on electronic component distributor websites
  • Basic principles of circuit protection and overload management
NEXT STEPS
  • Research low on-resistance FETs suitable for overload protection applications
  • Explore ESD protection techniques in integrated circuits, focusing on MOSFET configurations
  • Learn about tying FETs in parallel to reduce channel resistance
  • Investigate power devices specifically designed for circuit protection
USEFUL FOR

Electrical engineers, circuit designers, and hobbyists interested in developing overload protection devices using low voltage drop transistors.

Cliff_J
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I'd like to construct a fast-reacting current overload protection device. And rather than use a FET as a short to blow a fuse I'd rather just use a semiconductor in series that I can open on overload. This is similar in operation to some "intelligent circuit breakers" based on a Intra Technologies' MOSFET switch.

Anyone know of any common (cheap) off-the-shelf FETs that with really low voltage drops? Thanks in advance.

Cliff
 
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I think you mean FETs with really low on resistance. You should be able to do parametric searches at both the manufacturers' websites and on distributor websites.

- Warren
 
...like analog.com and digikey.com
 
Cliff_J said:
I'd like to construct a fast-reacting current overload protection device. And rather than use a FET as a short to blow a fuse I'd rather just use a semiconductor in series that I can open on overload. This is similar in operation to some "intelligent circuit breakers" based on a Intra Technologies' MOSFET switch.

Anyone know of any common (cheap) off-the-shelf FETs that with really low voltage drops? Thanks in advance.

Cliff

I'm not sure that this is the right way to solve the problem. If I were you, I'd go to the library and get a book on ESD protection in ICs. As a matter of fact, when I worked as an IC design engineer, we had a circuit like this in our intellectual properties library. Essentially, there was a resistor across the gate and drain of an n-type MOSFET. When a sudden current surge rushed across this resistor, the channel activated... in other words the drain was shorted to the source and most of the current went straight to ground without damaging the circuit.

Individually-packaged, ordinary MOSFETs are almost impossible to come by... although I think you individually access the FETs of 500 series inverter. Most individually-packaged FETs are either power devices or RF devices. If you want circuit protection, then you're looking at power devices. If you want to reduce the channel (or source-to-drain) resistance, then I would just suggest tying several FETs in parallel.

QuantumCowboy
 

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