SNVS446D June   2006  – January 2016 LM1771

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 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Timing Opinion
      2. 7.3.2 Short-Circuit Protection
      3. 7.3.3 Precision Enable
      4. 7.3.4 Soft-Start
      5. 7.3.5 Jitter
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 LM1771 Typical Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Design Guide
            1. 8.2.1.2.1.1 Frequency Selection
            2. 8.2.1.2.1.2 Inductor Selection
            3. 8.2.1.2.1.3 Output Capacitor
            4. 8.2.1.2.1.4 Feedforward Capacitor
            5. 8.2.1.2.1.5 Input Capacitor
          2. 8.2.1.2.2 MOSFET Selection
            1. 8.2.1.2.2.1 VDS Voltage Rating
            2. 8.2.1.2.2.2 RDSON
            3. 8.2.1.2.2.3 Gate Drive
            4. 8.2.1.2.2.4 Gate Charge
            5. 8.2.1.2.2.5 Rise and Fall Times
            6. 8.2.1.2.2.6 Gate Charge Ratio
            7. 8.2.1.2.2.7 Feedback Resistors
          3. 8.2.1.2.3 Efficiency Calculations
            1. 8.2.1.2.3.1 Quiescent Current
            2. 8.2.1.2.3.2 Conduction Loss
            3. 8.2.1.2.3.3 Switching Loss
            4. 8.2.1.2.3.4 Transitional Loss
            5. 8.2.1.2.3.5 DCR Loss
            6. 8.2.1.2.3.6 Efficiency
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Example Application 5 VIN to 1.8 VOUT
      3. 8.2.3 Example Application 5 VIN to 3.3 VOUT
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

6 Specifications

6.1 Absolute Maximum Ratings

See (1) (2)
MIN MAX UNIT
VIN –0.3 6 V
EN, FB, HG, LG –0.3 VIN V
Junction temperature 150 °C
Lead temperature   Soldering, 10 sec 260 °C
Storage temperature, Tstg –65 150 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications.

6.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

MIN MAX UNIT
VIN to GND 2.8 5.5 V
Junction temperature, TJ −40 125 °C

6.4 Thermal Information

THERMAL METRIC(1) LM1771 UNIT
NGG (WSON) DGK (VSSOP)
6 PINS 8 PINS
RθJA Junction-to-ambient thermal resistance 52.8 169.2 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 51.4 59.7 °C/W
RθJB Junction-to-board thermal resistance 27.2 89.3 °C/W
ψJT Junction-to-top characterization parameter 0.7 7.0 °C/W
ψJB Junction-to-board characterization parameter 27.3 87.9 °C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance 7.4 N/A °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953.

6.5 Electrical Characteristics

Specifications are for TJ = 25°C. All maximum and minimum limits apply over the full junction temperature range (−40°C to +125°C), unless otherwise specified. Minimum and maximum limits are ensured through test, design or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C and are provided for reference purposes only. Unless otherwise specified, VIN = 3.3 V.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VFB Feedback pin voltage 0.782 0.8 0.818 V
IQ Quiescent current VFB = 0.9 V 400 700 µA
TON Switch ON-time LM1771S - (500 ns) 0.4 0.5 0.6 µs
LM1771T - (1000 ns) 0.8 1 1.2
LM1771U - (2000 ns) 1.6 2 2.4
TOFF_MIN Minimum OFF-time LM1771S - (500 ns) 150 250 ns
LM1771T - (1000 ns) 135 225
LM1771U - (2000 ns) 120 220
TD Gate drive dead-time 70 ns
VIH_EN EN pin rising threshold 1.15 1.2 1.25 V
VEN_HYS EN pin hysteresis 50 200 mV
IFB Feedback pin bias current VFB = 0.9 V 50 nA
VUVLO Undervoltage lockout VIN Rising Edge 2.65 2.8 V
VUVLO_HYS Undervoltage lockout hysteresis 50 mV
VSC_TH Feedback pin short circuit latch threshold 0.42 0.55 0.65 V
RDS(ON) 1 HG FET driver pullup ON-resistance IHG = 20 mA 4 Ω
RDS(ON) 2 HG FET driver pulldown ON-resistance IHG = 20 mA 6 Ω
RDS(ON) 3 LG FET driver pullup ON-resistance ILG = 20 mA 4 Ω
RDS(ON) 4 LG FET driver pulldown ON-resistance ILG = 20 mA 6 Ω

6.6 Typical Characteristics

All curves taken at VIN = 3.3 V with configuration in typical application circuit shown in Typical Applications. TJ = 25°C, unless otherwise specified.
LM1771 20189007.png Figure 1. TON vs VIN (LM1771S)
LM1771 20189011.png Figure 3. TON vs VIN (LM1771U)
LM1771 20189010.png Figure 5. TON vs Temperature (LM1771T)
LM1771 20189013.png Figure 7. TOFF vs Temperature (LM1771S)
LM1771 20189042.png Figure 9. TOFF vs Temperature (LM1771U)
LM1771 20189014.png Figure 11. VEN Threshold vs Temperature
LM1771 20189016.png Figure 13. Quiescent Current vs Temperature
LM1771 20189004.png
VIN = 5 V VOUT = 1.8 V FSW = 545 kHz
Figure 15. Efficiency vs IOUT (LM1771T)
LM1771 20189005.png
VIN = 5 V VOUT = 3.3 V FSW = 500 kHz
Figure 17. Efficiency vs IOUT (LM1771U)
LM1771 20189009.png Figure 2. TON vs VIN (LM1771T)
LM1771 20189008.png Figure 4. TON vs Temperature (LM1771S)
LM1771 20189012.png Figure 6. TON vs Temperature (LM1771U)
LM1771 20189041.png Figure 8. TOFF vs Temperature (LM1771T)
LM1771 20189017.png Figure 10. Feedback Voltage vs Temperature
LM1771 20189018.png Figure 12. Short-Circuit Threshold vs Temperature
LM1771 20189015.png Figure 14. Dead-Time vs Temperature
LM1771 20189003.png
VIN = 5 V VOUT = 2.5 V FSW = 379 kHz
Figure 16. Efficiency vs IOUT (LM1771U)
LM1771 20189006.png
VIN = 5 V VOUT = 1.2 V FSW = 727 kHz
Figure 18. Efficiency vs IOUT (LM1771S)