SBVS082K June   2007  – June 2024 TPS74901

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics: IOUT = 50mA
    7. 5.7 Typical Characteristics: IOUT = 1 A
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagrams
    3. 6.3 Feature Description
      1. 6.3.1 Enable and Shutdown
      2. 6.3.2 Power-Good
      3. 6.3.3 Internal Current Limit
      4. 6.3.4 Thermal Protection
    4. 6.4 Device Functional Modes
      1. 6.4.1 Normal Operation
      2. 6.4.2 Dropout Operation
      3. 6.4.3 Disabled
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Input, Output, and BIAS Capacitor Requirements
      2. 7.1.2 Transient Response
      3. 7.1.3 Dropout Voltage
      4. 7.1.4 Output Noise
      5. 7.1.5 Programmable Soft-Start
      6. 7.1.6 Sequencing Requirements
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 Power Dissipation
        2. 7.4.1.2 Thermal Considerations
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Device Nomenclature
      2. 8.1.2 Development Support
        1. 8.1.2.1 Evaluation Modules
        2. 8.1.2.2 Spice Models
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.1 Enable and Shutdown

The enable (EN) pin is active high and is compatible with standard digital-signaling levels. VEN below 0.4V turns the regulator off and VEN above 1.1V turns the regulator on. Unlike many regulators, the enable circuitry has hysteresis and deglitching for use with relatively slowly ramping analog signals. This configuration allows the TPS74901 to be enabled by connecting the output of another supply to the EN pin. The enable circuitry typically has 50mV of hysteresis and a deglitch circuit to help avoid ON-OFF cycling because of small glitches in the VEN signal.

The enable threshold is typically 0.8V and varies with temperature and process variations. Temperature variation is approximately –1mV/°C; process variation accounts for most of the rest of the variation to the 0.4V and 1.1V limits. If precise turn-on timing is required, a fast rise-time signal must be used to enable the TPS74901.

If not used, EN can be connected to either IN or BIAS. If EN is connected to IN, then connect EN as close as possible to the largest capacitance on the input to prevent voltage droops on that line from triggering the enable circuit.

The TPS749 has an internal active pulldown circuit that connects the output to GND through an 833Ω resistor when the device is disabled. This resistor discharges the output with a time constant of:

τ  =  833   ×   R L 833 +   R L  ×  C O U T