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  • LM2734x and LM2734x-Q1 2-MHz, 1.5-A or 2-A, Wide Input Range, Step-Down, DC-DC Regulator With Frequency Synchronization

    • SNVS497F November   2008  – September 2016 LM27341 , LM27341-Q1 , LM27342 , LM27342-Q1

      PRODUCTION DATA.  

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  • LM2734x and LM2734x-Q1 2-MHz, 1.5-A or 2-A, Wide Input Range, Step-Down, DC-DC Regulator With Frequency Synchronization
  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
    6. 6.6 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 Boost Function
      2. 7.3.2 Low Input Voltage Considerations
      3. 7.3.3 High Output Voltage Considerations
      4. 7.3.4 Frequency Synchronization
      5. 7.3.5 Current Limit
      6. 7.3.6 Frequency Foldback
      7. 7.3.7 Output Overvoltage Protection
      8. 7.3.8 Undervoltage Lockout
      9. 7.3.9 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable Pin and Shutdown Mode
      2. 7.4.2 Soft-Start Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Inductor Selection
        1. 8.1.1.1 Inductor Calculation Example
      2. 8.1.2  Inductor Material Selection
      3. 8.1.3  Input Capacitor
      4. 8.1.4  Output Capacitor
      5. 8.1.5  Catch Diode
      6. 8.1.6  Boost Diode (Optional)
      7. 8.1.7  Boost Capacitor
      8. 8.1.8  Output Voltage
      9. 8.1.9  Feedforward Capacitor (Optional)
      10. 8.1.10 Calculating Efficiency and Junction Temperature
        1. 8.1.10.1 Schottky Diode Conduction Losses
        2. 8.1.10.2 Inductor Conduction Losses
        3. 8.1.10.3 MOSFET Conduction Losses
        4. 8.1.10.4 MOSFET Switching Losses
        5. 8.1.10.5 IC Quiescent Losses
        6. 8.1.10.6 MOSFET Driver Losses
        7. 8.1.10.7 Total Power Losses
        8. 8.1.10.8 Efficiency Calculation Example
        9. 8.1.10.9 Calculating Junction Temperature
          1. 8.1.10.9.1 Conduction
          2. 8.1.10.9.2 Convection
          3. 8.1.10.9.3 Method 1
          4. 8.1.10.9.4 Method 2
            1. 8.1.10.9.4.1 Method 2 Example
          5. 8.1.10.9.5 Method 3
            1. 8.1.10.9.5.1 Method 3 Example
    2. 8.2 Typical Applications
      1. 8.2.1 LM2734x Configuration From VIN = 7 V to 16 V, VOUT = 5 V For Full Load at 2 MHz
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 LM2734x Configuration From VIN = 7 V to 16 V, VOUT = 5 V For Full Load at 1 MHz
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
      3. 8.2.3 LM2734x Configuration From VIN = 5 V to 16 V, VOUT = 3.3 V For Full Load at 2 MHz
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
        3. 8.2.3.3 Application Curves
      4. 8.2.4 LM2734x Configuration From VIN = 5 V to 16 V, VOUT = 3.3 V For Full Load at 2 MHz With SYNC = GND
        1. 8.2.4.1 Design Requirements
        2. 8.2.4.2 Detailed Design Procedure
        3. 8.2.4.3 Application Curves
      5. 8.2.5 LM2734x Configuration From VIN = 5 V to 16 V, VOUT = 3.3 V For Full Load at 2 MHz With SYNC = 1 MHz
        1. 8.2.5.1 Design Requirements
        2. 8.2.5.2 Detailed Design Procedure
        3. 8.2.5.3 Application Curves
      6. 8.2.6 LM2734x Configuration From VIN = 3.3 V to 16 V, VOUT = 1.8 V For Full Load at 2 MHz With SYNC = 1 GND
        1. 8.2.6.1 Design Requirements
        2. 8.2.6.2 Detailed Design Procedure
        3. 8.2.6.3 Application Curves
      7. 8.2.7 LM2734x Configuration From VIN = 3.3 V to 16 V, VOUT = 1.8 V For Full Load at 2 MHz With SYNC = 1 MHz
        1. 8.2.7.1 Design Requirements
        2. 8.2.7.2 Detailed Design Procedure
        3. 8.2.7.3 Application Curves
      8. 8.2.8 LM2734x Configuration From VIN = 3.3 V to 9 V, VOUT = 1.2 V For Full Load at 2 MHz With SYNC = 2 MHz
        1. 8.2.8.1 Design Requirements
        2. 8.2.8.2 Detailed Design Procedure
        3. 8.2.8.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Compact Layout
      2. 10.1.2 Ground Plane and Shape Routing
      3. 10.1.3 FB Loop
      4. 10.1.4 PCB Summary
    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 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Community Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
  13. IMPORTANT NOTICE

Package Options

Mechanical Data (Package|Pins)
  • DGQ|10
    • MPDS043F
  • DSC|10
    • MPDS239E
Thermal pad, mechanical data (Package|Pins)
  • DGQ|10
    • PPTD275A
  • DSC|10
    • QFND489A
Orderable Information
  • snvs497f_oa
  • snvs497f_pm
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DATA SHEET

LM2734x and LM2734x-Q1 2-MHz, 1.5-A or 2-A, Wide Input Range, Step-Down, DC-DC Regulator With Frequency Synchronization

1 Features

  • Space-Saving, 3 mm × 3 mm 10-Pin WSON and MSOP-PowerPAD Packages
  • Wide Input Voltage Range: 3 V to 20 V
  • Wide Output Voltage Range: 1 V to 18 V
  • LM27341 Delivers 1.5-A Maximum Output Current
  • LM27342 Delivers 2-A Maximum Output Current
  • High Switching Frequency: 2 MHz
  • Frequency Synchronization:
    1 MHz < fSW < 2.35 MHz
  • 150-mΩ NMOS Switch With Internal Bootstrap Supply
  • 70-nA Shutdown Current
  • Internal Voltage Reference Accuracy of 1%
  • Peak Current-Mode, PWM Operation
  • Thermal Shutdown
  • LM27341-Q1 and LM27342-Q1 are AEC-Q100 Grade 1 Qualified and Manufactured on an Automotive Grade Flow

2 Applications

  • Local 12-V to Vcore Step-Down Converters
  • Radio Power Supply
  • Core Power in HDDs
  • Set-Top Boxes
  • Automotive
  • USB Powered Devices
  • DSL Modems

3 Description

The LM2734x and LM2734x-Q1 regulators are monolithic, high-frequency, PWM step-down DC-DC converters in 10-pin WSON and 10-pin MSOP-PowerPAD packages. They contain all the active functions to provide local DC-DC conversion with fast transient response and accurate regulation in the smallest possible PCB area.

With a minimum of external components, the LM2734x and LM2734x-Q1 are easy to use. The ability to drive 1.5-A or 2-A loads respectively, with an internal 150-mΩ NMOS switch results in the best power density available. The world-class control circuitry allows for on-times as low as 65 ns, thus supporting exceptionally high frequency conversion. Switching frequency is internally set to 2 MHz and synchronizable from 1 to 2.35 MHz, which allows the use of extremely small surface mount inductors and chip capacitors. Even though the operating frequency is very high, efficiencies up to 90% are easy to achieve. External shutdown is included, which features an ultra-low shutdown current of 70 nA. The LM2734x and LM2734x-Q1 use peak current-mode control and internal compensation to provide high-performance regulation over a wide range of operating conditions. Additional features include internal soft-start circuitry to reduce inrush current, pulse-by-pulse current limit, thermal shutdown, and output overvoltage protection.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM2734x
LM2734x-Q1		 MSOP-PowerPAD (10) 4.90 mm × 3.00 mm
WSON (10) 3.00 mm × 3.00 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Circuit

LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005674.gif

4 Revision History

Changes from E Revision (April 2013) to F Revision

  • Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information sectionGo
  • Changed values in the Thermal Information table to align with JEDEC standardsGo

Changes from D Revision (April 2013) to E Revision

  • Changed layout of National Semiconductor Data Sheet to TI formatGo

5 Pin Configuration and Functions

DSC Package
10-Pin WSON
Top View
DGQ Package
10-Pin MSOP-PowerPAD
Top View

Pin Functions

PIN TYPE(1) DESCRIPTION
NO. NAME
1, 2 SW O Output switch. Connects to the inductor, catch diode, and bootstrap capacitor.
3 BOOST I Boost voltage that drives the internal NMOS control switch. A bootstrap capacitor is connected between the BOOST and SW pins.
4 EN I Enable control input. Logic high enables operation. Do not allow this pin to float or be greater than VIN + 0.3 V.
5 SYNC I Frequency synchronization input. Drive this pin with an external clock or pulse train. Ground it to use the internal clock.
6 FB I Feedback pin. Connect FB to the external resistor divider to set output voltage.
7 GND G Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible to this pin for accurate regulation.
8 AVIN I Supply voltage for the control circuitry.
9, 10 PVIN I Supply voltage for output power stage. Connect a bypass capacitor to this pin.
DAP DAP G Signal or power ground and thermal connection. Tie this directly to GND (pin 7).
See Application Information regarding optimum thermal layout.
(1) G = Ground, I = Input, O = Output

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN MAX UNIT
AVIN, PVIN –0.5 24 V
SW voltage –0.5 24 V
Boost voltage –0.5 28 V
Boost to SW voltage –0.5 6 V
FB voltage –0.5 3 V
SYNC voltage –0.5 6 V
EN voltage –0.5 VIN + 0.3 V
Soldering, infrared reflow (5 s) 260 °C
Junction temperature, TJ 150 °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) 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)(2) ±2000 V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) Human body model, 1.5 kΩ in series with 100 pF.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)(1)
MIN MAX UNIT
AVIN, PVIN 3 20 V
SW voltage –0.5 20 V
Boost voltage –0.5 24 V
Boost to SW voltage 3 5.5 V
Junction temperature –40 125 °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 Ratings is not implied. The recommended Operating Ratings indicate conditions at which the device is functional and should not be operated beyond such conditions.

6.4 Thermal Information

THERMAL METRIC(1) LM2734x, LM2734x-Q1 UNIT
DSC (WSON) DGQ (MSOP-PowerPAD)
10 PINS 10 PINS
RθJA Junction-to-ambient thermal resistance(2) 47.6 49.5 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 36.5 53.6 °C/W
RθJB Junction-to-board thermal resistance 22.5 33.7 °C/W
ψJT Junction-to-top characterization parameter 0.4 3.9 °C/W
ψJB Junction-to-board characterization parameter 22.7 33.4 °C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance 4.7 3.5 °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report.
(2) Thermal shutdown will occur if the junction temperature exceeds 165°C. The maximum power dissipation is a function of TJ(MAX), RθJA and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) – TA)/ RθJA. All numbers apply for packages soldered directly onto a 3" × 3" PCB with 2 oz. copper on 4 layers in still air.

6.5 Electrical Characteristics

TJ = 25°C, VIN = 12 V, and VBOOST – VSW = 4.3 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
SYSTEM PARAMETERS
VFB Feedback voltage TJ = 0°C to 85°C 0.99 1 1.01 V
TJ = –40°C to 125°C 0.984 1 1.014
ΔVFB/ΔVIN Feedback voltage line regulation VIN = 3 V to 20 V 0.003% V
IFB Feedback input bias current TJ = 25°C 20 nA
TJ = –40°C to 125°C 100
OVP Overvoltage protection VFB at which PWM halts 1.13 V
UVLO Undervoltage lockout VIN rising until VSW is switching TJ = 25°C 2.75 V
TJ = –40°C to 125°C 2.6 2.9
Undervoltage hysteresis VIN falling from UVLO TJ = 25°C 0.47
TJ = –40°C to 125°C 0.3 0.6
SS Soft-start time 0.5 1 1.5 ms
IQ Quiescent current IQ = IQ_AVIN + IQ_PVIN VFB = 1.1 (not switching) 2.4 mA
VEN = 0 V (shutdown) 70 nA
IBOOST Boost pin current fSW= 2 MHz TJ = 25°C 8.2 mA
TJ = –40°C to 125°C 10
fSW= 1 MHz 4.4 6
OSCILLATOR
fSW Switching frequency SYNC = GND TJ = 25°C 2 MHz
TJ = –40°C to 125°C 1.75 2.3
VFB_FOLD FB pin voltage SYNC input is overridden 0.53 V
fFOLD_MIN Frequency foldback minimum VFB = 0 V 220 250 kHz
LOGIC INPUTS (EN, SYNC)
fSYNC SYNC frequency range 1 2.35 MHz
VIL EN, SYNC logic low threshold Logic falling edge 0.4 V
VIH EN, SYNC logic high threshold Logic rising edge 1.8
tSYNC_HIGH SYNC, time required above VIH to ensure a logical high 100 ns
tSYNC_LOW SYNC, time required below VIL to ensure a logical low 100 ns
ISYNC SYNC pin current VSYNC < 5 V 20 nA
IEN Enable pin current VEN = 3 V 6 15 µA
VIN = VEN = 20 V 50 100
INTERNAL MOSFET
RDS(ON) Switch ON-resistance TJ = 25°C 150 mΩ
TJ = –40°C to 125°C 320
ICL Switch current limit TJ = –40°C to 125°C LM27342 2.5 4 A
LM27341 2 3.7
DMAX Maximum duty cycle SYNC = GND TJ = 25°C 93%
TJ = –40°C to 125°C 85%
tMIN Minimum ON-time 65 ns
ISW Switch leakage current 40 nA
BOOST LDO
VLDO Boost LDO output voltage 3.9 V
THERMAL
TSHDN Thermal shutdown temperature Junction temperature rising 165 °C
Thermal shutdown hysteresis Junction temperature falling 15

6.6 Typical Characteristics

TA = 25°C, VIN = 12 V, and VBOOST – VSW = 4.3 V (unless otherwise noted)
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005676.png
VOUT = 5 V fSW = 2 MHz
Figure 1. Efficiency vs Load Current
See Figure 34
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005680.png
VOUT = 3.3 V fSW = 2 MHz
Figure 3. Efficiency vs Load Current
See Figure 40
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005684.png
VOUT = 1.8 V fSW = 2 MHz
Figure 5. Efficiency vs Load Current
See Figure 49
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056109.png
VIN = 10 V to 15 V VOUT = 3.3 V No CFF
Figure 7. Line Transient
See Figure 43
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056110.png Figure 9. Short Circuit
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005653.png Figure 11. Soft Start With EN Tied to VIN
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056112.png
VIN = 12 V L = 2.2 µH Iout =1 A
VOUT = 5 V COUT = 44 µF
Figure 13. Bode Plot
See Figure 34
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056114.png
VIN = 5 V L = 1.0 µH Iout =1 A
VOUT = 1.8 V COUT = 44 µF
Figure 15. Bode Plot
See Figure 49
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005655.png Figure 17. Sync Functionality
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005628.png
VSYNC = GND fSW = 2 MHz
Figure 19. Oscillator Frequency vs Temperature
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005630.png Figure 21. VFB vs Temperature
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005632.png
VIN = 12 V
Figure 23. Current Limit vs Temperature
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005634.png
IQ = IAVIN + IPVIN
Figure 25. IQ (Shutdown) vs Temperature
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056100.png
VOUT = 5 V IOUT = 100 mA – 2 A at Slewrate = 2 A / µs
Figure 2. Load Transient
See Figure 34
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056102.png
VOUT = 3.3 V IOUT = 100 mA – 2 A at Slewrate = 2 A / µs
Figure 4. Load Transient
See Figure 40
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056105.png
VOUT = 1.8 V IOUT = 100 mA – 2 A at Slewrate = 2 A / µs
Figure 6. Load Transient
See Figure 49
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056108.png
VIN = 10 V to 15 V VOUT = 3.3 V
Figure 8. Line Transient
See Figure 40
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056111.png Figure 10. Short-Circuit Release
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005654.png Figure 12. Soft Start With EN Tied to VIN
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056113.png
VIN = 12 V L = 1.5 µH Iout =1 A
VOUT = 3.3 V COUT = 44 µF
Figure 14. Bode Plot
See Figure 40
LM27341 LM27342 LM27341-Q1 LM27342-Q1 300056115.png
VIN = 5 V L = 0.56 µH Iout =1 A
VOUT = 1.2 V COUT = 68 µF
Figure 16. Bode Plot
See Figure 55
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005656.png Figure 18. Loss of Synchronization
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005629.png
Figure 20. Oscillator Frequency vs VFB
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005631.png Figure 22. VFB vs VIN
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005633.png
Figure 24. RDSON vs Temperature
LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005635.png
Figure 26. IEN vs VEN

 
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