1SMB11CAT3G Просмотр технического описания (PDF) - Unspecified

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1SMB11CAT3G

TVS Diodes Surface Mount > 600W > 1SMB10CAT3G Series

Unspecified 

TVS Diodes

Surface Mount > 600W > 1SMB10CAT3G Series

Application Notes

Response Time

In most applications, the transient suppressor device is

placed in parallel with the equipment or component to be

protected. In this situation, there is a time delay associated

with the capacitance of the device and an overshoot

condition associated with the inductance of the device and

the inductance of the connection method. The capacitive

effect is of minor importance in the parallel protection

scheme because it only produces a time delay in the

transition from the operating voltage to the clamp voltage

as shown in Figure 5.

The inductive effects in the device are due to actual turn-on

time (time required for the device to go from zero current

to full current) and lead inductance. This inductive effect

produces an overshoot in the voltage across the

equipment or component being protected as shown in

Figure 6. Minimizing this overshoot is very important in the

application, since the main purpose for adding a transient

suppressor is to clamp voltage spikes. The SMB series

have a very good response time, typically < 1 ns and

negligible inductance. However, external inductive effects

could produce unacceptable overshoot. Proper circuit

layout minimum lead lengths and placing the suppressor

device as close as possible to the equipment or

components to be protected will minimize this overshoot.

Some input impedance represented by Zin is essential

to prevent overstress of the protection device. This

impedance should be as high as possible, without

restricting the circuit operation.

Duty Cycle Derating

The data of Figure 1 applies for non-repetitive conditions

and at a lead temperature of 25ºC. If the duty cycle

increases, the peak power must be reduced as indicated

by the curves of Figure 7. Average power must be derated

as the lead or ambient temperature rises above 25ºC. The

average power derating curve normally given on data

sheets may be normalized and used for this purpose.

At first glance the derating curves of Figure 7 appear to be

in error as the 10 ms pulse has a higher derating factor

than the 10 s pulse. However, when the derating factor for

a given pulse of Figure 7 is multiplied by the peak power

value of Figure 1 for the same pulse, the results follow the

expected trend.

Figure 5.

Figure 6.

Figure 7. Typical Derating Factor for Duty Cycle

© 2017 Littelfuse, Inc.

Specifications are subject to change without notice.

Revised: 11/17/17

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