SLVSF13A March   2019  – August 2021 TL7700-SEP

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Sense-Voltage Setting
      2. 8.3.2 Sense-Voltage Hysteresis Setting
      3. 8.3.3 Output Pulse-Duration Setting
    4. 8.4 Device Functional Modes
  9. 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 Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Support Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2 Detailed Design Procedure

The SENSE terminal input voltage, Vs, for TL7700-SEP is typically 500 mV. By using two external resistors, any sense voltage over 500 mV can be sensed.

Resistor R1 should be selected first to set the desired hysteresis. Section 8.3.2 provides detailed information on how to set the hysteresis. For this application, a 240-kΩ resistor is selected.

Equation 4. V h y s =   I s × R 1
Equation 5. V h y s =   2.5   µ A × 240   k Ω = 0.6   V

Resistor R2 should then be selected based on the R1 value and the desired sense voltage (Vs'). Section 8.3.1 describes how to set Vs' and provides and equation. In this example, Vs' is set to 4.5 V by using the value of R1 selected earlier and using a 30-kΩ resistor for R2.

Equation 6. V s ' =   V s × ( R 1 + R 2 ) R 2
Equation 7. V s ' =   0.5   V × ( 240   k Ω + 30   k Ω ) 30   k Ω = 4.5   V

Finally, the output pulse duration (tPO) is set using the equation found in Section 8.3.3.

Equation 8. t p o = C T   Δ V C T I C T
Equation 9. t p o = 510   p F   1.5   V 15   µ A =   51   µ s