SLVS220G July   1999  – August 2016 TL7700

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 Community Resource
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

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9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

The TL7700 supply-voltage supervisor allows for any voltage greater than 500mV to be monitored. This flexibility allows it to be used in many applications from FPGAs and Microcontrollers to Industrial supply monitoring.

9.2 Typical Application

Figure 21 shows an application where the TL7700 device is being used to sense the voltage supply for a microcontroller that is supplied with 5 V. If the sense voltage drops below 4.5 V, the RESET pin is pulled LOW, signaling the microcontroller to reset.

TL7700 TL7700-AppExample.gif Figure 21. 5-V Supply Voltage Supervision

9.2.1 Design Requirements

  • When the TL7700 is used for system power-on reset, the output pulse duration, tpo, must be set longer than the power rise time. The value of tpo is: tpo = Ct × 105 seconds
  • The RESET output is an open-collector output, so a pullup resistor is required.

9.2.2 Detailed Design Procedure

The SENSE terminal input voltage, Vs, of the TL7700 typically is 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. See Sense-Voltage Hysteresis Setting for detailed information on how to set the hysteresis.

Resistor R2 should then be selected based on the R1 value and the desired Vs' voltage. In Figure 18, the sensing voltage, Vs', is calculated as: Vs' = Vs × (R1 + R2)/R2

9.2.3 Application Curve

TL7700 g_vs_ta.gif
Figure 22. Sense Input Voltage vs Temperature