SLVSBM9E October   2013  – September 2018 LMZ31520

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Efficiency
  3. 3 Description
    1.     Simplified Application
  4. 4 Specifications
    1. 4.1 Absolute Maximum Ratings
    2. 4.2 Recommended Operating Conditions
    3. 4.3 Thermal Information
    4. 4.4 Package Specifications
    5. 4.5 Electrical Characteristics
  5. 5 Device Information
    1.     Pin Functions
    2. 5.1 Functional Block Diagram
  6. 6 Typical Characteristics (PVIN = VIN = 12 V)
  7. 7 Typical Characteristics (PVIN = VIN = 5 V)
  8. 8 Application Information
    1. 8.1  Adjusting the Output Voltage
    2. 8.2  Frequency Select
    3. 8.3  Capacitor Recommendations for the LMZ31520 Power Supply
      1. 8.3.1 Capacitor Technologies
        1. 8.3.1.1 Electrolytic, Polymer-Electrolytic Capacitors
        2. 8.3.1.2 Ceramic Capacitors
        3. 8.3.1.3 Tantalum, Polymer-Tantalum Capacitors
        4. 8.3.1.4 Input Capacitor
        5. 8.3.1.5 Output Capacitor
    4. 8.4  Transient Response
    5. 8.5  Application Curves Device configured for FCCM mode of operation, (pin 3 connected to pin 19).
    6. 8.6  Application Schematics
    7. 8.7  Custom Design With WEBENCH® Tools
    8. 8.8  VIN and PVIN Input Voltage
    9. 8.9  3.3 V PVIN Operation
    10. 8.10 Power Good (PWRGD)
    11. 8.11 Slow Start (SS_SEL)
    12. 8.12 Auto-Skip Eco-mode / Forced Continuous Conduction Mode
    13. 8.13 Power-Up Characteristics
    14. 8.14 Pre-Biased Start-Up
    15. 8.15 Remote Sense
    16. 8.16 Output On/Off Inhibit (INH)
    17. 8.17 Overcurrent Protection
    18. 8.18 Current Limit (ILIM) Adjust
    19. 8.19 Thermal Shutdown
    20. 8.20 Layout Considerations
    21. 8.21 EMI
  9. 9 Revision History
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
        1. 10.1.1.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Community Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  11. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Tape and Reel Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RLG|72
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1 Adjusting the Output Voltage

The VADJ control sets the output voltage of the LMZ31520. The output voltage adjustment range is from 0.6V to 3.6V. The adjustment method requires the addition of RSET, which sets the output voltage, and the connection of SENSE+ to VOUT. The RSET resistor must be connected directly between the VADJ (pin 13) and AGND (pin 9). The SENSE+ pin (pin 14) must be connected to VOUT either at the load for improved regulation or at VOUT of the device.

The LMZ31520 relies on a precision trimmed 0.6 V reference for the feedback voltage regulation and operates by regulating the valley of the voltage ripple appearing at the VADJ pin. The voltage ripple is a function of the input voltage and the output voltage, therefore the RSET resistor will change based on the input voltage. Table 1 gives the calculated external RSET resistor for a number of common bus voltages for PVIN of 12 V, 5 V, and 3.3 V. The recommended switching frequency is 500 kHz which can be configured by leaving the FREQ_SEL pin open. To adjust the frequency, see Table 2.

Table 1. RSET Resistor Values

RSET (Ω) RSET (Ω)
VOUT (V) PVIN = 12 V PVIN = 5 V PVIN = 3.3 V VOUT (V) PVIN = 12 V PVIN = 5 V PVIN = 3.3 V
0.60 open open open 2.15 566 563 560
0.65 18787 18681 18588 2.20 548 545 542
0.70 9024 8993 8966 2.25 532 528 525
0.75 5939 5923 5908 2.30 516 513 510
0.80 4427 4416 4406 2.35 502 498 495
0.85 3529 3521 3513 2.40 488 484 481
0.90 2934 2927 2921 2.45 475 471 468
0.95 2511 2505 2500 2.50 462 459 456
1.00 2195 2190 2185 2.55 451 447 444
1.05 1950 1945 1941 2.60 439 436 433
1.10 1754 1749 1745 2.65 429 425 422
1.15 1594 1589 1586 2.70 419 415 412
1.20 1460 1456 1453 2.75 409 405 402
1.25 1348 1344 1341 2.80 400 396 393
1.30 1251 1248 1244 2.85 391 387 384
1.35 1168 1164 1161 2.90 382 379 375
1.40 1095 1091 1088 2.95 374 370 367
1.45 1031 1027 1024 3.00 367 363 359
1.50 973 970 968 3.05 359 355 352
1.55 922 919 916 3.10 352 348 345
1.60 876 873 870 3.15 345 341 338
1.65 834 831 828 3.20 339 335 331
1.70 797 793 790 3.25 332 328 325
1.75 762 759 756 3.30 326 322 318
1.80 730 727 724 3.35 320 316 312
1.85 701 698 695 3.40 315 310 307
1.90 674 671 668 3.45 309 305 301
1.95 650 646 643 3.50 304 300 296
2.00 626 623 620 3.55 299 294 291
2.05 605 602 599 3.60 294 289 286
2.10 585 581 578