SNVS359E May   2005  – December 2014 LM5021

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 Operation Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Performance Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 PWM Comparator and Slope Compensation
      2. 7.3.2 Current Limit and Current Sense
      3. 7.3.3 Oscillator, Shutdown and Sync Capability
      4. 7.3.4 Gate Driver and Max Duty Cycle Limit
      5. 7.3.5 Soft-Start
      6. 7.3.6 Hiccup Mode Overload Current Limiting
      7. 7.3.7 Skip Cycle Operation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With VIN Below 20 V
      2. 7.4.2 Operation in Soft Start
      3. 7.4.3 Operation Under Normal Conditions
      4. 7.4.4 Operation in Skip Cycle
      5. 7.4.5 Operation at Overload
      6. 7.4.6 Operation in Hiccup Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Startup Circuit
      2. 8.1.2 Relationship Between Input Capacitor CIN and VCC Capacitor CVCC
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Primary Bulk Capacitance
        2. 8.2.2.2 Transformer
        3. 8.2.2.3 Main Switch FET and Output Rectifier
        4. 8.2.2.4 Timing Resistor
        5. 8.2.2.5 Soft-Start Time
        6. 8.2.2.6 Current Sensing Network
          1. 8.2.2.6.1 Gate Drive Resistor
          2. 8.2.2.6.2 VCC Capacitor
          3. 8.2.2.6.3 Startup Circuit
      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)(1)

MIN MAX UNIT
VIN to GND –0.3 30 V
VIN Clamp Continuous Current 5 mA
CS to GND –0.3 1.25 V
RT to GND –0.3 5.5 V
All other pins to GND –0.3 7.0 V
Operating Junction Temperature 150
Storage temperature range, Tstg –65 150 °C
(1) 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 Operation Conditions

over operating free-air temperature range (unless otherwise noted)
MIN MAX UNIT
VIN Voltage (4) 8 30 V
Junction Temperature –40 125 °C

6.4 Thermal Information

THERMAL METRIC(1) LM5021 UNIT
DGK P
8 PINS
RθJA Junction-to-ambient thermal resistance 163.3 53.5 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 56.7 42.9
RθJB Junction-to-board thermal resistance 83.2 30.6
ψJT Junction-to-top characterization parameter 5.9 20.1
ψJB Junction-to-board characterization parameter 81.9 30.5
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

6.5 Electrical Characteristics

MIN and MAX limits apply –40°C ≤ TJ ≤ 125°C. Unless otherwise specified: TJ= +25°C, VIN = 15 V, RT = 44.2 kΩ.(2)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
STARTUP CIRCUIT
IST Start up current Before VCC Enable 18 25 µA
VVIN_EN VCC Regulator enable threshold 17 20 23 V
VVIN_DIS VCC Regulator disable threshold 7.25 V
VVIN_CMP VIN ESD clamp voltage I = 5 mA 30 36 40 V
IVIN Operating supply current COMP = 0 VDC 2.5 3.75 mA
VCC SUPPLY
VVCC_EN Controller enable threshold 6.5 7 7.5 V
VVCC_DIS Controller disable threshold 5.3 5.8 6.3 V
VVCC VCC regulated output No External Load 8 8.5 9 V
VVCC_DO VCC dropout voltage (VIN - VCC) I = 5 mA 1.7 V
IVCC_LIM VCC regulator current limit VCC = 7.5 V (3) 15 22 mA
SKIP CYCLE MODE COMPARATOR
VSKP Skip cycle mode enable threshold ⅓ [COMP - 1.25 V] 75 125 175 mV
VSKP_HYS Skip cycle mode hysteresis 5 mV
CURRENT LIMIT
tCS_DLY CS limit to OUT delay CS stepped from 0 to 0.6 V, time to OUT transition low,
Cload = 0		 35 ns
VCS_MAX CS limit threshold 0.45 0.5 0.55 V
tLEB Leading edge blanking time 90 ns
RCS_BNK CS blanking sinking impedance 35 55 Ω
SOFT-START
VSS_OCV SS pin open-circuit voltage 4.3 5.2 6.1 V
ISS Soft-start current source 15 22 30 µA
VSS_OFF Soft-start to COMP offset 0.35 0.55 0.75 V
RCOMP COMP sinking impedance During SS ramp 60 Ω
OSCILLATOR
FOSC Frequency1 (RT = 44.2K) 135 150 165 kHz
FOSC Frequency2 (RT = 13.3K) 440 500 560 kHz
VSYNC Sync threshold 2.4 3.2 3.8 V
PWM COMPARATOR
tPWM_DLY COMP to OUT delay COMP set to 2 V
CS stepped 0 to 0.4 V, time to OUT transition low,
Cload = 0		 20 ns
DMIN Min duty cycle COMP = 0 V 0%
DMAX Max duty cycle (-1 Device) 75% 80% 85%
DMAX Max duty cycle (-2 Device) 50%
KPWM COMP to PWM comparator gain 0.33
VCOMP_OC COMP open circuit voltage 4.2 5.1 6 V
VCOMP_MAXD COMP at max duty cycle 2.75 V
ICOMP COMP short circuit current COMP = 0 V 0.6 1.1 1.5 mA
SLOPE COMPENSATION
VSLP Slope comp amplitude
(LM5021-1 only)		 CS pin to PWM Comparator offset at maximum duty cycle 70 90 110 mV
OUTPUT SECTION
VOUTH OUT high saturation IOUT = 50 mA,
VCC - OUT		 0.6 1.1 V
VOUTL OUT low saturation IOUT = 100 mA 0.3 1 V
IO_SRC Peak source current OUT = VCC/2 0.3 A
IO_SNK Peak sink current OUT = VCC/2 0.7 A
tr Rise time Cload = 1nF 25 ns
tf Fall time Cload = 1nF 10 ns
HICCUP MODE
VOVLD Over load detection threshold COMP pin VSS-OCV – 0.8 VSS-OCV – 0.6 VSS-OCV– 0.4 V
VHIC Hiccup mode threshold SS pin VSS-OCV – 0.8 VSS-OCV – 0.6 VSS-OCV– 0.4 V
VRST Hiccup mode Restart threshold SS pin 0.1 0.3 0.5 V
IDTCS Dead-time current source 0.1 0.25 0.4 µA
IOVCS Overload detection timer current source 6 10 14 µA
(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Recommended Operation Conditions are conditions under which operation of the device is intended to be functional. For specifications and test conditions, see the Electrical Characteristics.
(2) Min and Max limits are 100% production tested at 25°C. Limits over the operating temperature range are specified through correlation using Statistical Quality Control (SQC) methods. Limits are used to calculate Average Outgoing Quality Level (AOQL).
(3) Device thermal limitations may limit usable range.
(4) After initial turn-on at VIN = 20 V.

6.6 Typical Performance Characteristics

Unless otherwise specified: TJ = 25°C.
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Figure 1. VIN Start-Up Current
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Figure 3. VIN Current vs OUT Load
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Figure 5. OUT Driver Current vs Temperature
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Figure 7. Output Switching Frequency vs RT
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Figure 2. VIN UVLO
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Figure 4. VIN Voltage Falling vs VCC Voltage
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Figure 6. Hiccup Mode Deadtime vs Softstart Capacitance