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PROTECTION PRODUCTS

PROTECTION PRODUCTS

SL05 THRU SL24

SL Connection Options

Device Connection for Protection of One High-Speed

Data Line

The SL series devices are designed to protect high-

speed data lines. The SLxx utilizes a low capacitance

compensation diode in series with, but in opposite

polarity to a TVS diode in each line to achieve an

effective capacitance of less than 5pF per device.

During a transient event, the internal rectifier must be

forward biased (TVS is reversed biased). Therefore,

each device will only suppress transient events in one

polarity. To achieve protection in both positive and

negative polarity, a second device is connected in anti-

parallel to the first. On unidirectional lines, a fast

switching steering diode may be used as an alternative

to using two SL devices.

The options for connecting the devices are as follows:

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Low capacitance protection of one high-speed

line: Protection of one unidirectional or bidirec-

tional high-speed line is achieved by connecting two

devices in anti-parallel. Pin 1 of the first device is

connected to the line and pin 2 is connected to

ground (or to a second line for differential protec-

tion). Pin 2 of the second device is connected to

line 1 and pin 1 is connected to ground (or line 2)

as shown. Pin 3 is not connected. During positive

duration transients, the first device will conduct

from pin 1 to 2. The steering diode conducts in the

forward direction while the TVS will avalanche and

conduct in the reverse direction. During negative

transients, the second device will conduct in the

same manner. For optimum protection, the ground

connections should be made directly to the ground

plane for best results. The path length is kept as

short as possible to reduce the effects of parasitic

inductance in the board traces. The path length

between the TVS and the protected line should

also be minimized.

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Connection Option for Unidirectional Lines Only:

An optional method for protecting unidirectional

(normal signal polarities above ground) lines is to

add a fast switching steering diode in parallel to the

SL TVS. Input/outputs are connected to pin 1 of

the SL device and the cathode of the rectifier. The

anode of the diode and pin 2 of the SL TVS are

connected to ground.

Two Devices : Bidirectional or

Unidirectional Line

One Devices with Steering Diode :

Unidirectional Line Only

I/O Line Protection

Applications Information