SLVSEQ3A September   2018  – December 2018 TVS1801

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Voltage Clamp Response to 8/20 µs Surge Event
      2.      Functional Block Diagram
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
    1.     Pin Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings - JEDEC
    3. 7.3 ESD Ratings - IEC
    4. 7.4 Recommended Operating Conditions
    5. 7.5 Thermal Information
    6. 7.6 Electrical Characteristics
    7. 7.7 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
      1. 8.4.1 Protection Specifications
      2. 8.4.2 Reliability Testing
      3. 8.4.3 Zero Derating
      4. 8.4.4 Bidirectional Operation
      5. 8.4.5 Transient Performance
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Detailed Design Procedure

If the TVS1801 is in place to protect the device, the voltage will rise to the breakdown of the diode at 24.4 V during a surge event. The TVS1801 will then turn on to shunt the surge current to ground. With the low dynamic resistance of the TVS1801, even large amounts of surge current will have minimal impact on the clamping voltage. The dynamic resistance of the TVS1801 is around 50 mΩ, which means a 25-A surge current will cause a voltage raise of 25 A × 50 mΩ = 1.25 V. Because the device turns on at 24.4 V, this means the module input will be exposed to a maximum of 24.4 V + 1.25 V = 26.9 V during surge pulses, close to the LM2734 absolute maximum. Because this is a transient pulse, this will likely be safe for the system.

In addition, the TVS1801 provides protection against reverse voltage application that could accidentally be caused by shorts between pins. If –12 V is applied to the VBUS pin, the LM2734 will not be harmed because the series diode will prevent the voltage from being applied to the input, and the TVS1801 will not shunt current because the reverse working voltage is –18 V. If the TVS1800 or a unidirectional device is used in this case, a –12-V short would cause the device to shunt current until it fails.

Finally, the small size of the device also improves fault protection by lowering the effect of fault current coupling onto neighboring traces. The small form factor of the TVS1801 allows the device to be placed extremely close to the input connector, which lowers the length of the path fault current going through the system compared to larger protection solutions.