SNVS033D May   2004  – November 2015 LM2621

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 Recommended Operating Conditions
    3. 6.3 Thermal Information
    4. 6.4 Electrical Characteristics
    5. 6.5 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 Gated Oscillator Control Scheme
      2. 7.3.2 Low Voltage Start-Up
      3. 7.3.3 Output Voltage Ripple Frequency
      4. 7.3.4 Internal Current Limit and Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Step-Up DC-DC Converter Typical Application Using LM2621
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Setting the Output Voltage
          2. 8.2.1.2.2 Bootstrapping
          3. 8.2.1.2.3 Setting the Switching Frequency
          4. 8.2.1.2.4 Inductor Selection
          5. 8.2.1.2.5 Output Diode Selection
          6. 8.2.1.2.6 Input and Output Filter Capacitors Selection
        3. 8.2.1.3 Application Curves
      2. 8.2.2 5-V / 0.5-A Step-Up Regulator
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
      3. 8.2.3 2-mm Tall 5-V / 0.2-A Step-Up Regulator for Low Profile Applications
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
      4. 8.2.4 3.3-V / 0.5-A SEPIC Regulator
        1. 8.2.4.1 Design Requirements
        2. 8.2.4.2 Detailed Design Procedure
  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 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)(3)
MIN MAX UNIT
SW Pin Voltage –0.5 14.5 V
BOOT, VDD, EN and FB Pins –0.5 10 V
FREQ Pin 100 µA
Power Dissipation (TA=25°C) (2) 500 mW
TJmax(2) 150 °C
Lead Temp. (Soldering, 5 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) The maximum power dissipation must be derated at elevated temperatures and is dictated by Tjmax (maximum junction temperature), θJA (junction to ambient thermal resistance), and TA (ambient temperature). The maximum allowable power dissipation at any temperature is Pdmax = (Tjmax - TA)/ θJA or the number given in the Absolute Maximum Ratings, whichever is lower.
(3) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications.

6.2 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN NOM MAX UNIT
VDD 2.5 5 V
FB 0 VDD V
EN 0 VDD V
BOOT 0 10 V
Ambient Temperature, TA –40 85 °C

6.3 Thermal Information

THERMAL METRIC(1) LM2621 UNIT
DGK (VSSOP)
8 PINS
RθJA Junction-to-ambient thermal resistance (2) 160 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 52.7 °C/W
RθJB Junction-to-board thermal resistance 80.1 °C/W
ψJT Junction-to-top characterization parameter 5.5 °C/W
ψJB Junction-to-board characterization parameter 78.8 °C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance 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.

6.4 Electrical Characteristics

Unless otherwise specified: VDD= VOUT= 3.3 V, TJ = 25°C.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VIN_ST Minimum Start-Up Supply Voltage(1) ILOAD = 0 mA 1.1 V
ILOAD = 0 mA, –40°C to 85°C 1.2
VIN_OP Minimum Operating Supply Voltage (once started) ILOAD = 0 mA 0.65 V
VFB FB Pin Voltage 1.24 V
–40°C to 85°C 1.2028 1.2772
VOUT_MAX Maximum Output Voltage 14 V
VHYST Hysteresis Voltage(2) 30 mV
–40°C to 85°C 45
η Efficiency VIN = 3.6 V; VOUT = 5 V; ILOAD = 500 mA 87%
VIN = 2.5 V; VOUT = 3.3 V; ILOAD = 200 mA 87%
D Switch Duty Cycle 70%
−40°C to 85°C 60% 80%
IDD Operating Quiescent Current(3) FB Pin > 1.3 V; EN Pin at VDD 80 µA
FB Pin > 1.3 V; EN Pin at VDD, –40°C to 85°C 110
ISD Shutdown Quiescent Current(4) VDD, BOOT and SW Pins at 5.0 V; EN Pin < 200 mV 0.01 µA
VDD, BOOT and SW Pins at 5.0 V; EN Pin < 200 mV, –40°C to 85°C 2.5
ICL Switch Peak Current Limit 2.85 A
RDS_ON MOSFET Switch On Resistance 0.17 Ω
ENABLE SECTION
VEN_LO EN Pin Voltage Low(5) –40°C to 85°C 0.15VDD V
VEN_HI EN Pin Voltage High(5) –40°C to 85°C 0.7VDD V
(1) Output in regulation, VOUT = VOUT (NOMINAL) ± 5%
(2) This is the hysteresis value of the internal comparator used for the gated-oscillator control scheme.
(3) This is the current into the VDD pin.
(4) This is the total current into pins VDD, BOOT, SW and FREQ.
(5) When the EN pin is below VEN_LO, the regulator is shut down; when it is above VEN_HI, the regulator is operating.

6.5 Typical Characteristics

LM2621 10093401.png
VOUT = 5.0 V
Figure 1. Efficiency vs Load Current
LM2621 10093403.png Figure 3. VFB vs Temperature
LM2621 10093405.png Figure 5. ISD vs Temperature
LM2621 10093407.png
Figure 7. IOP vs VDD
LM2621 10093409.png Figure 9. Switching Frequency vs RFQ
LM2621 10093411.png Figure 11. Maximum Load Current vs Input Voltage
LM2621 10093402.png
VOUT = 3.3 V
Figure 2. Efficiency vs Load Current
LM2621 10093404.png Figure 4. IOP vs Temperature
LM2621 10093406.png Figure 6. ISD vs VDD
LM2621 10093408.png
VOUT = 3.3 V
Figure 8. VIN_ST vs Load Current
LM2621 10093410.png Figure 10. Peak Inductor Current vs Load Current