SLVSBV8E June   2013  – February 2020 LMZ31704

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Application
  4. 4 Revision History
  5. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Package Specifications
    5. 5.5 Thermal Information
    6. 5.6 Electrical Characteristics
  6. 6 Device Information
    1. 6.1 Functional Block Diagram
    2.     Pin Functions
  7. 7 Typical Characteristics (PVIN = VIN = 12 V)
  8. 8 Typical Characteristics (PVIN = VIN = 5 V)
  9. 9 Typical Characteristics (PVIN = 3.3 V, VIN = 5 V)
  10. 10Application Information
    1. 10.1  Adjusting the Output Voltage
    2. 10.2  Capacitor Recommendations for the LMZ31704 Power Supply
      1. 10.2.1 Capacitor Technologies
        1. 10.2.1.1 Electrolytic, Polymer-Electrolytic Capacitors
        2. 10.2.1.2 Ceramic Capacitors
        3. 10.2.1.3 Tantalum, Polymer-Tantalum Capacitors
      2. 10.2.2 Input Capacitor
      3. 10.2.3 Output Capacitor
    3. 10.3  Transient Response
    4. 10.4  Transient Waveforms
    5. 10.5  Application Schematics
    6. 10.6  Custom Design With WEBENCH® Tools
    7. 10.7  VIN and PVIN Input Voltage
    8. 10.8  3.3 V PVIN Operation
    9. 10.9  Power Good (PWRGD)
    10. 10.10 SYNC_OUT
    11. 10.11 Parallel Operation
    12. 10.12 Light Load Efficiency (LLE)
    13. 10.13 Power-Up Characteristics
    14. 10.14 Pre-Biased Start-up
    15. 10.15 Remote Sense
    16. 10.16 Thermal Shutdown
    17. 10.17 Output On/Off Inhibit (INH)
    18. 10.18 Slow Start (SS/TR)
    19. 10.19 Overcurrent Protection
    20. 10.20 Synchronization (CLK)
    21. 10.21 Sequencing (SS/TR)
    22. 10.22 Programmable Undervoltage Lockout (UVLO)
    23. 10.23 Layout Considerations
    24. 10.24 EMI
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

Package Options

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

10.22 Programmable Undervoltage Lockout (UVLO)

The LMZ31704 implements internal UVLO circuitry on the VIN pin. The device is disabled when the VIN pin voltage falls below the internal VIN UVLO threshold. The internal VIN UVLO rising threshold is 4.5 V (max) with a typical hysteresis of 150 mV.

If an application requires either a higher UVLO threshold on the VIN pin or a higher UVLO threshold for a combined VIN and PVIN, then the UVLO pin can be configured as shown in Figure 39 or Figure 40. Table 8 lists standard values for RUVLO1 and RUVLO2 to adjust the VIN UVLO voltage up.

LMZ31704 slvsAW7_VinUVLO.gifFigure 39. Adjustable VIN UVLO
LMZ31704 slvsAW7_VinPVinUVLO.gifFigure 40. Adjustable VIN and PVIN Undervoltage Lockout

Table 8. Standard Resistor values for Adjusting VIN UVLO

VIN UVLO (V) 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0
RUVLO1 (kΩ) 68.1 68.1 68.1 68.1 68.1 68.1 68.1 68.1 68.1 68.1 68.1
RUVLO2 (kΩ) 21.5 18.7 16.9 15.4 14.0 13.0 12.1 11.3 10.5 9.76 9.31
Hysteresis (mV) 400 415 430 450 465 480 500 515 530 550 565

For a split rail application, if a secondary UVLO on PVIN is required, VIN must be ≥ 4.5 V. Figure 41 shows the PVIN UVLO configuration. Use Table 9 to select RUVLO1 and RUVLO2 for PVIN. If PVIN UVLO is set for less than 3.5 V, a 5.1-V zener diode should be added to clamp the voltage on the UVLO pin below 6 V.

LMZ31704 slvsAW7_PVinUVLO.gifFigure 41. Adjustable PVIN Undervoltage Lockout, (VIN ≥ 4.5 V)

Table 9. Standard Resistor Values for Adjusting PVIN UVLO, (VIN ≥ 4.5 V)

PVIN UVLO (V) 2.9 3.0 3.5 4.0 4.5
RUVLO1 (kΩ) 68.1 68.1 68.1 68.1 68.1 For higher PVIN UVLO voltages, see Table 8 for resistor values
RUVLO2 (kΩ) 47.5 44.2 34.8 28.7 24.3
Hysteresis (mV) 330 335 350 365 385