SNVS405G December   2005  – April 2015 LM3674

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  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 Dissipation Ratings
    6. 6.6 Electrical Characteristics
    7. 6.7 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Circuit Operation
      2. 7.3.2 PWM Operation
        1. 7.3.2.1 Internal Synchronous Rectification
        2. 7.3.2.2 Current Limiting
    4. 7.4 Device Functional Modes
  8. Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Soft-Start
      2. 8.1.2 Low-Dropout (LDO) Operation
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Application for Fixed Voltage Configuration
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Inductor Selection
          2. 8.2.1.2.2 Input Capacitor Selection
          3. 8.2.1.2.3 Output Capacitor Selection
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Typical Application Circuit for Adjustable Voltage Option
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Output Voltage Selection for Adjustable (LM3674-ADJ)
        3. 8.2.2.3 Application Curves
  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 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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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
VIN pin: voltage to GND −0.2 6 V
EN, FB, and SW pins GND − 0.2 VIN + 0.2 V
Continuous power dissipation(3) Internally Limited
Junction temperature (TJ-MAX) 125 °C
Maximum lead temperature (soldering, 10 seconds) 260 °C
Storage temperature, Tstg –65 °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- or Aerospace-specified devices are required, please contact the TI Sales Office/Distributors for availability and specifications.
(3) In applications where high power dissipation and/or poor package resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX), the maximum power dissipation of the device in the application (PD-MAX) and the junction-to-ambient thermal resistance of the package (RθJA) in the application, as given by the following equation: TA-MAX = TJ-MAX – (RθJA × PD-MAX). See Dissipation Ratings for PD-MAX values at different ambient temperatures.

6.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins(1) ±2000 V
Charged device model (CDM), per JEDEC specification JESD22-C101, all pins(2) ±200 V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)(1)
MIN MAX UNIT
Input voltage(2) 2.7 5.5 V
Recommended load current 0 600 mA
Junction temperature, TJ –30 125 °C
Ambient temperature,TA –30 85 °C
(1) All voltages are with respect to the potential at the GND pin.
(2) Input voltage range recommended for ideal applications performance for the specified output voltages are given below:
VIN = 2.7 V to 5.5 V for 1 V ≤ VOUT < 1.8 V
VIN = (VOUT + VDROP OUT) to 5.5 V for 1.8 ≤ VOUT ≤ 3.3 V, where VDROP OUT = ILOAD × (RDSON (P) + RINDUCTOR)

6.4 Thermal Information

THERMAL METRIC(1) LM3674 UNIT
DBV (SOT-23)
5 PINS
RθJA Junction-to-ambient thermal resistance 4-layer board 130 °C/W
2-layer board 250
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

6.5 Dissipation Ratings

over operating free-air temperature range (unless otherwise noted)
RθJA TA ≤ 25°C (POWER RATING) TA = 60°C (POWER RATING) TA = 85°C (POWER RATING)
250°C/W (2-layer board) 400 mW 260 mW 160 mW
130°C/W (4-layer board) 770 mW 500 mW 310 mW

6.6 Electrical Characteristics

Typical limits are TA = 25°C; unless otherwise noted, specifications apply to the LM3674 with VIN = EN = 3.6 V(1)(2)(3)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VFB Feedback voltage(4)(5) IO = 10 mA, −30°C ≤ TJ ≤ 125°C –4% 4%
Line regulation 2.7 V ≤ VIN ≤ 5.5 V, IO = 100 mA 0.083 %/V
Load regulation 100 mA ≤ IO ≤ 600 mA, VIN = 3.6 V 0.0010 %/mA
VREF Internal reference voltage See(6) 0.5 V
ISHDN Shutdown supply current EN = 0 V 0.01 µA
EN = 0 V, –30°C ≤ TJ ≤ 125°C 1
IQ DC bias current into VIN No load, device is not switching (FB = 0 V) 300 µA
No load, device is not switching (FB = 0 V)
–30°C ≤ TJ ≤ 125°C
600
RDSON (P) Pin-to-pin resistance for PFET ISW = 200 mA 380 500
RDSON (N) Pin-to-pin resistance for NFET ISW = 200 mA 250 400
ILIM Switch peak current limit Open loop(7) 1020 mA
Open loop(7), –30°C ≤ TJ ≤ 125°C 830 1200
VIH Logic high input –30°C ≤ TJ ≤ 125°C 1 V
VIL Logic low input –30°C ≤ TJ ≤ 125°C 0.4 V
IEN Enable (EN) input current 0.01 µA
–30°C ≤ TJ ≤ 125°C 1
FOSC Internal oscillator frequency PWM mode 2 MHz
PWM mode, −30°C ≤ TJ ≤ 125°C 1.6 2.6
(1) All voltages are with respect to the potential at the GND pin.
(2) Minimum and maximum limits are specified by design, test, or statistical analysis. Typical numbers represent the most likely values.
(3) The parameters in the Electrical Characteristics are tested at VIN = 3.6 V unless otherwise specified. For performance curves over the input voltage range, see Typical Characteristics.
(4) ADJ configured to 1.5-V output.
(5) For VOUT < 2.5 V, VIN = 3.6 V; for VOUT ≥ 2.5 V, VIN = VOUT + 1.
(6) For the ADJ version the resistor dividers should be selected such that at the desired output voltage, the voltage at the FB pin is 0.5 V.
(7) See Typical Characteristics for closed loop data and its variation with regards to supply voltage and temperature. Electrical Characteristics reflect open loop data (FB = 0 V and current drawn from the SW pin ramped up until cycle-by-cycle current limit is activated). Closed-loop current limit is the peak inductor current measured in the application circuit by increasing output current until output voltage drops by 10%.

6.7 Typical Characteristics

(unless otherwise stated: VIN = 3.6 V, VOUT = 1.5 V, TA = 25°C)
LM3674 20167244.png
FB = 0 V, No Switching
Figure 1. Quiescent Current vs Supply Voltage
LM3674 20167206.pngFigure 3. Feedback Bias Current vs Temperature
LM3674 20167298.pngFigure 5. Output Voltage vs Temperature
LM3674 20167210.gifFigure 7. RDSON vs Temperature
LM3674 20167267.png
VOUT = 1.2 V, L = 2.2 µH, DCR = 200 mΩ
Figure 9. Efficiency vs Output Current
LM3674 20167269.png
VOUT = 1.8 V, L = 2.2 µH, DCR = 200 mΩ
Figure 11. Efficiency vs Output Current
LM3674 20167297.png
Figure 13. Open or Closed Loop Current Limit vs Temperature
LM3674 20167247.pngFigure 15. Load Transient
LM3674 20167224.png
Output Current = 10 mA
Figure 17. Start-Up
LM3674 20167205.gifFigure 2. IQ Shutdown vs Temperature
LM3674 20167265.pngFigure 4. Output Voltage vs Supply Voltage
LM3674 20167266.pngFigure 6. Output Voltage vs Output Current
LM3674 20167216.gifFigure 8. Switching Frequency vs Temperature
LM3674 20167268.png
VOUT = 1.5 V, L = 2.2 µH, DCR = 200 mΩ
Figure 10. Efficiency vs Output Current
LM3674 20167299.png
VOUT = 3.3 V, L = 2.2 µH, DCR = 200 mΩ
Figure 12. Efficiency vs Output Current
LM3674 20167218.png
Figure 14. Line Transient Response
LM3674 20167223.png
Output Current = 300 mA
Figure 16. Start-Up