SNOSB22C October   2008  – October 2014 LM5574-Q1

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 Handling 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 Shutdown And Standby
      2. 7.3.2 Current Limit
      3. 7.3.3 Soft-Start
      4. 7.3.4 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 High Voltage Start-Up Regulator
      2. 7.4.2 Oscillator and Sync Capability
      3. 7.4.3 Error Amplifier and PWM Comparator
      4. 7.4.4 Ramp Generator
      5. 7.4.5 Maximum Duty Cycle and Input Drop-Out Voltage
      6. 7.4.6 Boost Pin
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Bias Power Dissipation Reduction
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  External Components
        2. 8.2.2.2  R3 (RT)
        3. 8.2.2.3  L1
        4. 8.2.2.4  C3 (CRAMP)
        5. 8.2.2.5  C9
        6. 8.2.2.6  D1
        7. 8.2.2.7  C1
        8. 8.2.2.8  C8
        9. 8.2.2.9  C7
        10. 8.2.2.10 C4
        11. 8.2.2.11 R5, R6
        12. 8.2.2.12 R1, R2, C2
        13. 8.2.2.13 R4, C5, C6
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Trademarks
    2. 11.2 Electrostatic Discharge Caution
    3. 11.3 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(1)(2)

MIN MAX UNIT
VIN to GND 76 V
BST to GND 90 V
PRE to GND 76 V
SW to GND (Steady State) –1.5 V
BST to VCC 76 V
SD, VCC to GND 14 V
BST to SW 14 V
OUT to GND Limited to VIN
SYNC, SS, FB, RAMP to GND 7 V

6.2 Handling Ratings

MIN MAX UNIT
Tstg Storage temperature range –65 150 °C
V(ESD) Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins(1) 2 kV
(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 6 75 V
Operation Junction Temperature –40 150 °C

6.4 Thermal Information

THERMAL METRIC(1) LM5574-Q1 UNIT
PW
16 PINS
RθJA Junction-to-ambient thermal resistance 90 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 30
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

6.5 Electrical Characteristics

VIN = 48V, RT = 32.4kΩ, typical values correspond to TJ = 25°C. Minimum and maximum limits apply over -40°C to 125°C junction temperature range unless otherwise stated.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
STARTUP REGULATOR
VCCReg VCC Regulator Output 6.85 7.15 7.5 V
VCC LDO Mode turn-off 9 V
VCC Current Limit VCC = 0 V 25 mA
VCC SUPPLY
VCC UVLO Threshold (VCC increasing) 5.01 5.35 5.69 V
VCC Undervoltage Hysteresis 0.35 V
Bias Current (Iin) FB = 1.3 V 3.7 4.5 mA
Shutdown Current (Iin) SD = 0 V 57 85 µA
SHUTDOWN THRESHOLDS
Shutdown Threshold (SD Increasing) 0.43 0.7 0.9 V
Shutdown Hysteresis 0.1 V
Standby Threshold (Standby Increasing) 1.15 1.225 1.3 V
Standby Hysteresis 0.1 V
SD Pull-up Current Source 5 µA
SWITCH CHARACTERISTICS
Buck Switch Rds(on) 750 1650 mΩ
BOOST UVLO 4 V
BOOST UVLO Hysteresis 0.56 V
Pre-charge Switch Rds(on) 70 Ω
Pre-charge Switch on-time 250 ns
CURRENT LIMIT
Cycle by Cycle Current Limit RAMP = 0 V 0.58 0.7 0.9 A
Cycle by Cycle Current Limit Delay RAMP = 2.5 V 75 ns
SOFT-START
SS Current Source 7 10 14 µA
OSCILLATOR
Frequency1 180 200 220 kHz
Frequency2 RT = 11kΩ 425 485 545 kHz
SYNC Source Impedance 11 kΩ
SYNC Sink Impedance 110 Ω
SYNC Threshold (falling) 1.3 V
SYNC Frequency RT = 11kΩ 550 kHz
SYNC Pulse Width Minimum 15 ns
RAMP GENERATOR
Ramp Current 1 VIN = 60 V, VOUT=10 V 467 550 633 µA
Ramp Current 2 VIN = 10 V, VOUT=10 V 36 50 64 µA
PWM COMPARATOR
Forced Off-time 390 500 590 ns
Min On-time 80 ns
COMP to PWM Comparator Offset 0.7 V
ERROR AMPLIFIER
Feedback Voltage Vfb = COMP 1.205 1.225 1.245 V
FB Bias Current 17 nA
DC Gain 70 dB
COMP Sink / Source Current 3 mA
Unity Gain Bandwidth 3 MHz
DIODE SENSE RESISTANCE
DSENSE 250 mΩ
THERMAL SHUTDOWN
Tsd Thermal Shutdown Threshold 180 °C
Thermal Shutdown Hysteresis 25 °C
(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Recommended Operating Conditions are conditions under which operation of the device is intended to be functional. For ensured specifications and test conditions, see the Electrical Characteristics.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications.

6.6 Typical Characteristics

30070720.gif
Figure 1. Oscillator Frequency vs RT
30070747.png
Figure 3. Soft Start Current vs Temperature
30070724.gif
Figure 5. VCC vs VIN
RL = 7kΩ
30070726.gif
Figure 7. Demoboard Efficiency vs IOUT and VIN
30070746.png
Figure 2. Oscillator Frequency vs Temperature
FOSC = 200 kHz
30070723.gif
Figure 4. VCC vs ICC
VIN = 12 V
30070725.gif
Figure 6. Error Amplifier Gain And Phase
AVCL = 101