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Varistor Products

Revision: July 16, 2009

©2009 Littelfuse, Inc.

MHS Varistor Series

Surface Mount Multilayer Varistors (MLVs) > MHS Series

Specifications are subject to change without notice.

Please refer to www.littelfuse.com/series/MHS.html for current information.

Lead (Pb) Soldering Recommendations

The principal techniques used for the soldering of

and Wave soldering. Typical profiles are shown on the right.

The recommended solder for the MHS suppressor is

Wave soldering is the most strenuous of the processes.

To avoid the possibility of generating stresses due to

thermal shock, a preheat stage in the soldering process

is recommended, and the peak temperature of the solder

process should be rigidly controlled.

When using a reflow process, care should be taken to

ensure that the MHS chip is not subjected to a thermal

gradient steeper than 4 degrees per second; the ideal

gradient being 2 degrees per second. During the soldering

peak temperature is essential to minimize thermal shock.

still necessary to ensure that any further thermal shocks

printed circuit boards being removed from the solder

process and subjected to cleaning solvents at room

temperature. The boards must be allowed to cool gradually

230

Reflow Solder Profile

Wave Solder Profile

Device Characteristics

transient voltage suppressor approaches a linear (ohmic)

relationship and shows a temperature dependent effect.

At or below the maximum working voltage, the suppressor

maximum rated working voltage). Leakage currents at

maximum rated voltage are below 100

μ

μA;

for 0402 size below 20

μ

μA.

100%

1E-9

1E-8

SUPPRESSOR CURRENT (ADC)

10%

1E-7

1E-6

1E-5

1E-4

1E-3

1E-2

25

50

75

100

125oC

o

o

o

o

Typical Temperature Dependance of the Characteristic

Speed of Response

The Multilayer Suppressor is a leadless device. Its

response time is not limited by the parasitic lead

inductances found in other surface mount packages.

The response time of the Z

N

such as ESD. Additionally, in “real world” applications,

the associated circuit wiring is often the greatest

factor effecting speed of response. Therefore, transient

suppressor placement within a circuit can be considered

important in certain instances.

GRAINS

DEPLETION

FIRED CERAMIC

DIELECTRIC

REGION

METAL

ELECTRODES

DEPLETION

REGION

METAL END

TERMINATION

Multilayer Internal Construction

Figure 5

Figure 6

Figure 7

Figure 8