Transient Voltage Suppression Devices

Application information

Data lines protection

• Surgector
• Metal oxide varistor
• Avalanche diode

Telecommunications primary circuits

• Sugector
• Metal oxide varistor
• Gas tube

Telecommunications secondary circuits

• Surgector
• Avalanche diode

AC power lines

• Metal oxide varistor

DC power & automotive applications

• Surgector
• Metal oxide varistor
• Avalanche diode

With-in circuit applications

• surgector
• Metal oxide varistor
• Avalanche diode

Comparision of Surge Suppression devices

(uS = microsecond)
(markings: + means positive feature, - means negative feature, * means other information)

Surgector

+ Ideal for datacom and telecom
+ Leakage: < 50 nA
+ Shunt capacitance: < 50 pF
+ Subnanosecond response
+ Lifetime infinite @200 Amps, 8x20 uS pulse shape
+ Failure mode: short circuit
- Cannot be used with DC circuits with current more than holding current
- Low surge current capability 200 Amps @ 8x20 uS
- Limited AC line protection
* High-input impedance until breakdown (low leakage)
* Repeatable breakdown/threshold voltage
* High-surge current-handling capability
* Withstand and respond to rapidly recurring surges
* Fast recovery to high impedance (turn-off)
* Dual polarity protection
* No degration of essential characteristics with use

Metal-oxide varistor (MOV)

+ Ideal for AC power line; suitable for low-voltage logic
+ Subnanosecond response
+ Up to 70 000 Amps surge
+ Lifetime @ 100 Amps, 8x20 uS pulse shape: 1000 surges
+ Failure mode: short circuit
- Shunt capacitance >500 pF
- Leakage approxinately 10 microamps
- Clamp voltage goes up with current
* Wide voltage range
* Wide energy range
* Excellent clamp ratio
* Fast response time
* Low standby
* Power
* No follow-on current
* UL recognized

Avalanche diode

+ Ideal for low-voltage logic protection
+ Subnanosecond response
+ Lifetime @ 50 Amps, 8x20 uS pulse shape: infinite
+ Shunt capacitance: 50 pF
+ Failure mode: short circuit
- Low surge capability: 50 Amps @ 8x20 uS pulse shape
- Leakage approximately 10 microamps

Gas tube

+ Wide use in telecom for primary protection
+ High surge capability: > 20 000 Amps
+ Leakage: picoamps
+ Shunt capacitance: < 1 pF
+ Lifetime @ 500 Amps, 8x20 uS pulse width: 200 surges
- Response time: < 5 microseconds
- Failure mode: open circuit
- Follow-on current because of "crowbar"

Sources

GE/RCA Transient Voltage Suppressors, GE/RCA/Intersil Semicondoctors