DATASHEET SEARCH SITE | WWW.ALLDATASHEET.COM
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 10
Technical content
digital isolators can directly replace optocouplers while providing substantial gains in performance and reliability. Figure 1. Optocoupler Block Diagram through the input side LED causes the open-collector output to remain high. IF is below its minimum threshold level.
Figure 2. Si87xx Isolator Block Diagram
- Fabricated in Mainstream Low-Power CMOS
times lower, and its part-to-part matching is 14 times tighter than Gallium Arsenide-based (GaAs) optocouplers.
- Use of a High-Frequency Carrier instead of Light
immunity above 1000 A/m for error-free operation.
- Use of Proprietary Design Techniques to Suppress EMI
- Use of Fully-Differential Architecture
The Si87xx is offered in three different grades, allowing the user to optimize input forward current versus CMTI. minimum CMTI of 35 kV/µs(min), (50 kV/µs typical). rising to 6 mA and a high-going input current turn-off threshold of 2.0 mA falling to zero. Figure 3. Device Transfer Characteristics
operation by optimizing the value of R1 for best CMTI performance. Figure 7. Complementary Output Buffer Drive
Rev. 0.3 7 4. Layout Recommendations 4.1. Bypass Capacitors Output bypass capacitors consist of a parallel combination of a 0.1 μF high-frequency bypass and a 1 μF bulk capacitor connected between VDD and GND and placed as close as possible to the package. Ceramic capacitors should be used for VDD bypass because of their low impedance, high ripple current characteristics, small physical size, and cost effectiveness. 4.2. Layout Guidelines Ensure that no traces are routed through the creepage/cle arance areas of the isolator. It is recommended that the NC pin on the Si87xx input side be connected to the input side ground plane; this increases CMTI performance by reducing coupling to the input pins. Minimize the trace lengths between isolators and connecting circuitry. To enhance the robu stness of a design in excessively noisy systems, it is further recommende d that the user also include 100 resistors in series with the outputs. 5. Summary The Si87xx is the ideal solution for upgrading optoco uplers in existing and new designs. These isolators outperform their optoco upler-based counterparts and of fer significant gains in devi ce performance and reliability. Si87xx family members can directly replace any one of a number of optocouplers from various suppliers.
8 Rev. 0.3 DOCUMENT CHANGE LIST Revision 0.1 to Revision 0.2 Updated "2. Device Overview" on page 1. Updated Figure 1 on page 1. Updated Figure 2 on page 2. Updated "3.1. Si87xx Device Transfer Characteristics" on page 3. Updated Figure 3 on page 3. Updatd "3.2. Replacing Optocouplers with Si87xx" on page 4. Updated Figure 4 on page 4. Updated Section 3.3 title on page 5. Updated "5. Summary" on page 7. Revision 0.2 to Revision 0.3 Updated "1. Introduction" on page 1. Updated "2. Device Overview" on page 1. Updated "3. Device Application" on page 3.
Rev. 0.3 9 NOTES:
10 Rev. 0.3 CONTACT INFORMATION Silicon Laboratories Inc.
400 West Cesar Chavez
Austin, TX 78701 Tel: 1+(512) 416-8500 Fax: 1+(512) 416-9669 Toll Free: 1+(877) 444-3032 Please visit the Silicon Labs Technical Support web page: https://www.silabs.com/support/pages/contacttechnicalsupport.aspx and register to submit a technical support request. Silicon Laboratories and Silicon Labs are trademarks of Silicon Laboratories Inc. Other products or brandnames mentioned herein are trademarks or registered trademarks of their respective holders. The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice. Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features or parameters. Silicon Laboratories reserves the right to make changes without further notice. Silicon Laboratories makes no warranty, rep- resentation or guarantee regarding the suitability of its products for any particular purpose, nor does Silicon Laboratories assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation conse- quential or incidental damages. Silicon Laboratories products are not designed, intended, or authorized for use in applications intended to support or sustain life, or for any other application in which the failure of the Silicon Laboratories product could create a situation where per- sonal injury or death may occur. Should Buyer purchase or use Silicon Laboratories products for any such unintended or unauthorized ap- plication, Buyer shall indemnify and hold Silicon Laboratories harmless against all claims and damages.