SI8421BB-C-IS Silicon Laboratories Inc, SI8421BB-C-IS Datasheet - Page 20

• Manufacturer Part Number: SI8421BB-C-IS
• Manufacturer: Silicon Laboratories Inc

Specifications of SI8421BB-C-IS

• Operating Supply Voltage (typ): 3.3/5V
• Lead Free Status / RoHS Status: Compliant

Si8410/20/21
3.3. Layout Recommendations
Dielectric isolation is a set of specifications produced by safety regulatory agencies from around the world, which
describes the physical construction of electrical equipment that derives power from high-voltage power systems,
such as 100–240 V
specifications places a very high voltage between the input power pins of a product and the user circuits and the
user-touchable surfaces of the product. For the IEC relating to products deriving their power from the 100–240 V
power grids, the minimum test voltage is 2500 V
There are two terms described in the safety specifications:


Figure 12 illustrates the accepted method of providing the proper creepage distance along the surface.For a
120 V
application, this distance is 6.4 mm, and a wide-body SOIC package must be used. There must be no copper
traces within this 3.2 or 6.4 mm exclusion area, and the surface should have a conformal coating, such as solder
resist. The digital isolator chip must straddle this exclusion area.
3.3.1. Supply Bypass
The Si841x and Si842x families require a 1 µF bypass capacitor between V
The capacitor should be placed as close as possible to the package. See "4. Errata and Design Migration
Guidelines (Revision C Only)" on page 22 for more details.
3.3.2. Output Pin Termination
The nominal output impedance of an isolator driver channel is approximately 85 , ±40%, which is a combination
of the value of the on-chip series termination resistor and channel resistance of the output driver FET. When driving
loads where transmission line effects will be a factor, output pins should be appropriately terminated with controlled
impedance PCB traces.
20
Creepage—the distance along the insulating surface an arc may travel.
Clearance—the shortest distance through air that an arc may travel.
AC
application, this distance is 3.2 mm, and the narrow-body SOIC package can be used. For a 220–240 V
AC
systems or industrial power. The dielectric test (or HIPOT test) given in the safety
Figure 12. Creepage Distance
AC
(or 3750 V
IEC Specified
Creepage
Distance
Rev. 1.2
DC
, the peak equivalent voltage).
DD1
and GND1 and V
DD2
and GND2.
AC
AC