SNVS595L September   2008  – November 2014 LM22680 , LM22680-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: LM22680
    3. 6.3 Handling Ratings: LM22680-Q1
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Electrical Characteristics
    7. 6.7 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 Precision Enable and UVLO
      2. 7.3.2 Soft-Start
      3. 7.3.3 Switching Frequency Adjustment and Synchronization
      4. 7.3.4 Self Synchronization
      5. 7.3.5 Boot-Strap Supply
      6. 7.3.6 Internal Loop Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Current Limit
      2. 7.4.2 Thermal Protection
      3. 7.4.3 Duty-Cycle Limits
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Output Voltage Divider Selection
      2. 8.1.2 Power Diode
    2. 8.2 Typical Application
      1. 8.2.1 Typical Buck Regulator Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 External Components
          2. 8.2.1.2.2 Inductor
          3. 8.2.1.2.3 Input Capacitor
          4. 8.2.1.2.4 Output Capacitor
          5. 8.2.1.2.5 Boot-Strap Capacitor
        3. 8.2.1.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 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 43 V
EN Pin Voltage –0.5 6
SS, RT/SYNC Pin Voltage –0.5 7
SW to GND(3) –5 VIN
BOOT Pin Voltage VSW + 7
FB Pin Voltage –0.5 7
Power Dissipation Internally Limited
Junction Temperature(4) 150 °C
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. Functional operation of the device and/or non-degradation at the absolute-maximum-ratings or other conditions beyond those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating Conditions indicate conditions at which the device is functional and should not be operated beyond such conditions.
(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 ‘SW to GND’ applies to dc voltage. An extended negative voltage limit of –10 V applies to a pulse of up to 50 ns.
(4) For soldering specifications, refer to Application Report Absolute Maximum Ratings for Soldering (SNOA549).

6.2 Handling Ratings: LM22680

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 2 kV
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

6.3 Handling Ratings: LM22680-Q1

MIN MAX UNIT
Tstg Storage temperature range –65 150 °C
V(ESD) Electrostatic discharge Human body model (HBM), per AEC Q100-002(1) –2 2 kV
(1) AEC Q100-002 indicates HBM stressing is done in accordance with the ANSI/ESDA/JEDEC JS-001 specification.

6.4 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN MAX UNIT
VIN Supply Voltage 4.5 42 V
Junction Temperature Range –40 125 °C

6.5 Thermal Information

THERMAL METRIC(1) LM22680,
LM22680-Q1		 UNIT
DDA
8 PINS
RθJA Junction-to-ambient thermal resistance(2) 60 °C/W
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report (SPRA953).
(2) The value of RθJA for the SO PowerPAD exposed pad (MR) package of 60°C/W is valid if package is mounted to 1 square inch of copper. The RθJA value can range from 42 to 115°C/W depending on the amount of PCB copper dedicated to heat transfer.

6.6 Electrical Characteristics

Typical values represent the most likely parametric norm at TA = TJ = 25°C, and are provided for reference purposes only. Unless otherwise specified: VIN = 12 V.
PARAMETER CONDITIONS MIN(2) TYP(1) MAX(2) UNIT
VFB Feedback Voltage VIN = 4.7 V to 42 V 1.266 1.285 1.304 V
VIN = 4.7 V to 42 V, –40°C ≤ TJ ≤ 125°C 1.259 1.311
IQ Quiescent Current VFB = 5 V 3.4 mA
VFB = 5 V, –40°C ≤ TJ ≤ 125°C 6
ISTDBY Standby Quiescent Current EN Pin = 0 V 25 40 µA
ICL Current Limit 2.8 A
–40°C ≤ TJ ≤ 125°C 2.32 3.4
IL Output Leakage Current VIN = 42 V, EN Pin = 0 V, VSW = 0 V 0.2 2 µA
VSW = –1 V 0.1 3 µA
RDS(ON) Switch On-Resistance 0.2 0.24 Ω
–40°C ≤ TJ ≤ 125°C 0.32
fO Oscillator Frequency 500 kHz
–40°C ≤ TJ ≤ 125°C 400 600
TOFFMIN Minimum Off-time 200 ns
–40°C ≤ TJ ≤ 125°C 100 300
TONMIN Minimum On-time 100 ns
IBIAS Feedback Bias Current VFB = 1.3 V 230 nA
VEN Enable Threshold Voltage Falling 1.6 V
Falling, –40°C ≤ TJ ≤ 125°C 1.3 1.9
VENHYST Enable Voltage Hysteresis 0.6 V
IEN Enable Input Current EN Input = 0 V 6 µA
FSYNC Maximum Synchronization Frequency VSYNC = 3.5 V, 50% duty-cycle 1 MHz
VSYNC Synchronization Threshold Voltage 1.75 V
ISS Soft-Start Current 50 µA
–40°C ≤ TJ ≤ 125°C 30 70
TSD Thermal Shutdown Threshold 150 °C
(1) Typical values represent most likely parametric norms at the conditions specified and are not ensured.
(2) MIN and MAX limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlation using Statistical Quality Control (SQC) methods. Limits are used to calculate TI's Average Outgoing Quality Level (AOQL).

6.7 Typical Characteristics

Vin = 12 V, TJ = 25°C (unless otherwise specified)
LM22680 LM22680-Q1 30080727.png
VOUT = 3.3 V fO= 500 kHz
Figure 1. Efficiency vs IOUT and VIN
LM22680 LM22680-Q1 30080703.png Figure 3. Current Limit vs Temperature
LM22680 LM22680-Q1 30080705.png Figure 5. Feedback Bias Current vs Temperature
LM22680 LM22680-Q1 30080706.png Figure 7. Standby Quiescent Current vs Input Voltage
LM22680 LM22680-Q1 30080709.png Figure 9. Normalized Feedback Voltage vs Input Voltage
LM22680 LM22680-Q1 30080742.png Figure 11. Soft-Start Current vs Temperature
LM22680 LM22680-Q1 30080704.png
Figure 2. Normalized Switching Frequency vs Temperature
LM22680 LM22680-Q1 30080708.png Figure 4. Normalized RDS(ON) vs Temperature
LM22680 LM22680-Q1 30080710.png Figure 6. Normalized Enable Threshold Voltage vs Temperature
LM22680 LM22680-Q1 30080707.png Figure 8. Normalized Feedback Voltage vs Temperature
LM22680 LM22680-Q1 30080713.png Figure 10. Switching Frequency vs RT/SYNC Resistor