SNVS029K March   2000  – February 2017 LM2678

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 - 3.3 V
    6. 6.6  Electrical Characteristics - 5 V
    7. 6.7  Electrical Characteristics - 12 V
    8. 6.8  Electrical Characteristics - Adjustable
    9. 6.9  Electrical Characteristics - All Output Voltage Versions
    10. 6.10 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 Switch Output
      2. 7.3.2 Input
      3. 7.3.3 C Boost
      4. 7.3.4 Ground
      5. 7.3.5 Feedback
      6. 7.3.6 ON/OFF
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Design Considerations
      2. 8.1.2 Inductor
      3. 8.1.3 Output Capacitor
      4. 8.1.4 Input Capacitor
      5. 8.1.5 Catch Diode
      6. 8.1.6 Boost Capacitor
      7. 8.1.7 Additional Application Information
    2. 8.2 Typical Application
      1. 8.2.1 All Output Voltage Versions
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 8.2.1.2.2 Capacitor Selection Guides
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Fixed Output Voltage Design Example
        1. 8.2.2.1 Detailed Design Procedure
          1. 8.2.2.1.1 Capacitor Selection
      3. 8.2.3 Adjustable Output Design Example
        1. 8.2.3.1 Detailed Design Procedure
          1. 8.2.3.1.1 Capacitor Selection
  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 Custom Design With WEBENCH® Tools
    2. 11.2 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 VSON Package Devices

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6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN MAX UNIT
Input supply voltage 45 V
Soft-start pin voltage –0.1 6 V
Switch voltage to ground(3) –1 VIN V
Boost pin voltage VSW + 8 V
Feedback pin voltage –0.3 14 V
Power dissipation Internally limited
Soldering temperature   Wave (4 s) 260 °C
Infrared (10 s) 240
Vapor phase (75 s) 219
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.
(3) The absolute maximum specification of the Switch Voltage to Ground applies to DC voltage. An extended negative voltage limit of –10 V applies to a pulse of up to 20 ns, –6 V of 60 ns and –3 V of up to 100 ns.

6.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)(2) ±2000 V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) ESD was applied using the human-body model, a 100-pF capacitor discharged through a 1.5-kΩ resistor into each pin.

6.3 Recommended Operating Conditions

MIN MAX UNIT
Supply voltage 8 40 V
Junction temperature, TJ –40 125 °C

6.4 Thermal Information

THERMAL METRIC(1) LM2678 UNIT
NDZ (TO-220) KTW (TO-263) NHM (VSON)
7 PINS 7 PINS 14 PINS
RθJA Junction-to-ambient thermal resistance See (2) 65 — — °C/W
See (3) 45 — —
See (4) — 56 —
See (5) — 35 —
See (6) — 26 —
See (7) — — 55
See (8) — — 29
RθJC(top) Junction-to-case (top) thermal resistance 2 2 — °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report.
(2) Junction to ambient thermal resistance (no external heat sink) for the 7-lead TO-220 package mounted vertically, with ½ inch leads in a socket, or on a PCB with minimum copper area.
(3) Junction to ambient thermal resistance (no external heat sink) for the 7-lead TO-220 package mounted vertically, with ½ inch leads soldered to a PCB containing approximately 4 square inches of (1 oz.) copper area surrounding the leads.
(4) Junction to ambient thermal resistance for the 7-lead DDPAK mounted horizontally against a PCB area of 0.136 square inches (the same size as the DDPAK package) of 1 oz. (0.0014 in. thick) copper.
(5) Junction to ambient thermal resistance for the 7-lead DDPAK mounted horizontally against a PCB area of 0.4896 square inches (3.6 times the area of the DDPAK package) of 1 oz. (0.0014 in. thick) copper.
(6) Junction to ambient thermal resistance for the 7-lead DDPAK mounted horizontally against a PCB copper area of 1.0064 square inches (7.4 times the area of the DDPAK 3 package) of 1 oz. (0.0014 in. thick) copper. Additional copper area reduces thermal resistance further.
(7) Junction to ambient thermal resistance for the 14-lead VSON mounted on a PCB copper area equal to the die attach paddle.
(8) Junction to ambient thermal resistance for the 14-lead VSON mounted on a PCB copper area using 12 vias to a second layer of copper equal to die attach paddle. Additional copper area will reduce thermal resistance further. For layout recommendations, see AN-1187 Leadless Leadfram Package (LLP).

6.5 Electrical Characteristics – 3.3 V

Specifications apply for TA = TJ = 25°C and RADJ = 5.6 kΩ (unless otherwise noted).
PARAMETER TEST CONDITIONS MIN(2) TYP(1) MAX(2) UNIT
VOUT Output voltage VIN = 8 V to 40 V,
100 mA ≤ IOUT ≤ 5 A 		TJ = 25°C 3.234 3.3 3.366 V
TJ = –40°C to 125°C 3.201 3.399
η Efficiency VIN = 12 V, ILOAD = 5 A 82%
(1) Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
(2) All room temperature limits are 100% tested during production with TA = TJ = 25°C. All limits at temperature extremes are specified through correlation using standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).

6.6 Electrical Characteristics – 5 V

Specifications apply for TA = TJ = 25°C and RADJ = 5.6 kΩ (unless otherwise noted).
PARAMETER TEST CONDITIONS MIN(2) TYP(1) MAX(2) UNIT
VOUT Output voltage VIN = 8 V to 40 V,
100 mA ≤ IOUT ≤ 5 A 		TJ = 25°C 4.9 5 5.1 V
TJ = –40°C to 125°C 4.85 5.15
η Efficiency VIN = 12 V, ILOAD = 5 A 84%
(1) Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
(2) All room temperature limits are 100% tested during production with TA = TJ = 25°C. All limits at temperature extremes are specified through correlation using standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).

6.7 Electrical Characteristics – 12 V

Specifications apply for TA = TJ = 25°C and RADJ = 5.6 kΩ (unless otherwise noted).
PARAMETER TEST CONDITIONS MIN(2) TYP(1) MAX(2) UNIT
VOUT Output voltage VIN = 15 V to 40 V,
100 mA ≤ IOUT ≤ 5 A 		TJ = 25°C 11.76 12 12.24 V
TJ = –40°C to 125°C 11.64 12.36
η Efficiency VIN = 24 V, ILOAD = 5 A 92%
(1) Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
(2) All room temperature limits are 100% tested during production with TA = TJ = 25°C. All limits at temperature extremes are specified through correlation using standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).

6.8 Electrical Characteristics – Adjustable

Specifications apply for TA = TJ = 25°C and RADJ = 5.6 kΩ (unless otherwise noted).
PARAMETER TEST CONDITIONS MIN(2) TYP(1) MAX(2) UNIT
VFB Feedback voltage VIN = 8 V to 40 V,
100 mA ≤ IOUT ≤ 5 A
VOUT programmed for 5 V		 TJ = 25°C 1.186 1.21 1.234 V
TJ = –40°C to 125°C 1.174 1.246
η Efficiency VIN = 12 V, ILOAD = 5 A 84%
(1) Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
(2) All room temperature limits are 100% tested during production with TA = TJ = 25°C. All limits at temperature extremes are specified through correlation using standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).

6.9 Electrical Characteristics – All Output Voltage Versions

Specifications are for TA = TJ = 25°C, VIN = 12 V for the 3.3-V, 5-V, and adjustable versions, and VIN = 24 V for the 12-V version (unless otherwise noted).
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
IQ Quiescent current VFEEDBACK = 8 V for 3.3-V, 5-V, and adjustable versions,
VFEEDBACK = 15 V for 12-V version		 4.2 6 mA
ISTBY Standby quiescent current ON/OFF pin = 0 V TJ = 25°C 50 100 µA
TJ = –40°C to 125°C 150
ICL Current limit TJ = 25°C 6.1 7 8.3 A
TJ = –40°C to 125°C 5.75 8.75
IL Output leakage current VIN = 40 V, ON/OFF pin = 0 V VSWITCH = 0 V 200 µA
VSWITCH = –1 V 16 15 mA
RDS(ON) Switch ON-Resistance ISWITCH = 5 A TJ = 25°C 0.12 0.14 Ω
TJ = –40°C to 125°C 0.225
fO Oscillator frequency Measured at switch pin TJ = 25°C 260 kHz
TJ = –40°C to 125°C 225 280
D Duty cycle Maximum duty cycle 91%
Minimum duty cycle 0%
IBIAS Feedback bias
current		 VFEEDBACK = 1.3 V (adjustable version only) 85 nA
VON/OFF ON/OFF threshold voltage TJ = 25°C 1.4 V
TJ = –40°C to 125°C 0.8 2
ION/OFF ON/OFF input current ON/OFF input = 0 V TJ = 25°C 20 μA
TJ = –40°C to 125°C 45

6.10 Typical Characteristics

LM2678 10088609.png Figure 1. Normalized Output Voltage
LM2678 10088611.png Figure 3. Efficiency vs Input Voltage
LM2678 10088604.png Figure 5. Switch Current Limit
LM2678 10088640.png Figure 7. Standby Quiescent Current
LM2678 10088614.png Figure 9. ON/OFF Pin Current (Sourcing)
LM2678 10088616.png
Figure 11. Feedback Pin Bias Current
LM2678 10088618.png
Discontinuous Mode Switching Waveforms, VIN = 20 V,
VOUT = 5 V, ILOAD = 500 mA, L = 10 μH, COUT = 400 μF,
COUTESR = 13 mΩ
A. VSW pin voltage = 10 V/div
B. Inductor current = 1 A/div
C. Output ripple voltage = 20 mV/div AC-coupled
Figure 13. Horizontal Time Base: 1 μs/div
LM2678 10088620.png
Load Transient Response for Discontinuous Mode, VIN = 20 V, VOUT = 5 V, vs L = 10 μH, COUT = 400 μF, COUTESR = 13 mΩ
A. Output voltage = 100 mV/div, AC-coupled
B. Load current = 200-mA to 3-A load pulse
Figure 15. Horizontal Time Base: 200 μs/div
LM2678 10088610.png Figure 2. Line Regulation
LM2678 10088612.png Figure 4. Efficiency vs ILOAD
LM2678 10088605.png Figure 6. Operating Quiescent Current
LM2678 10088613.png Figure 8. ON/OFF Threshold Voltage
LM2678 10088615.png Figure 10. Switching Frequency
LM2678 10088617.png
Continuous Mode Switching Waveforms, VIN = 20 V, VOUT = 5 V, ILOAD = 5 A, L = 10 μH, COUT = 400 μF, COUTESR = 13 mΩ
A. VSW pin voltage = 10 V/div
B. Inductor current = 2 A/div
C. Output ripple voltage = 20 mV/div AC-coupled
Figure 12. Horizontal Time Base: 1 μs/div
LM2678 10088619.png
Load Transient Response for Continuous Mode, VIN = 20 V,
VOUT = 5 V, L = 10 μH, COUT = 400 μF,
COUTESR = 13 mΩ
A. Output voltage = 100 mV/div, AC-coupled
B. Load current = 500-mA to 5-A load pulse
Figure 14. Horizontal Time Base: 100 μs/div
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