SNVSA37A October   2015  – May 2016 LM5175

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematic
  5. 5 Revision History
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Fixed Frequency Valley/Peak Current Mode Control with Slope Compensation
      2. 8.3.2  VCC Regulator and Optional BIAS Input
      3. 8.3.3  Enable/UVLO
      4. 8.3.4  Soft-Start
      5. 8.3.5  Overcurrent Protection
      6. 8.3.6  Average Input/Output Current Limiting
      7. 8.3.7  CCM/DCM Operation
      8. 8.3.8  Frequency and Synchronization (RT/SYNC)
      9. 8.3.9  Frequency Dithering
      10. 8.3.10 Output Overvoltage Protection (OVP)
      11. 8.3.11 Power Good (PGOOD)
      12. 8.3.12 Gm Error Amplifier
      13. 8.3.13 Integrated Gate Drivers
      14. 8.3.14 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown, Standby, and Operating Modes
      2. 8.4.2 MODE Pin Configuration
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1  Custom Design with WEBENCH Tools
        2. 9.2.2.2  Frequency
        3. 9.2.2.3  VOUT
        4. 9.2.2.4  Inductor Selection
        5. 9.2.2.5  Output Capacitor
        6. 9.2.2.6  Input Capacitor
        7. 9.2.2.7  Sense Resistor (RSENSE)
        8. 9.2.2.8  Slope Compensation
        9. 9.2.2.9  UVLO
        10. 9.2.2.10 Soft-Start Capacitor
        11. 9.2.2.11 Dither Capacitor
        12. 9.2.2.12 MOSFETs QH1 and QL1
        13. 9.2.2.13 MOSFETs QH2 and QL2
        14. 9.2.2.14 Frequency Compensation
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Custom Design with WEBENCH Tools
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Documentation Support
      1. 12.3.1 Related Documentation
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

7 Specifications

7.1 Absolute Maximum Ratings(1)

MIN MAX UNIT
VIN, EN/UVLO, VISNS, VOSNS, ISNS(+), ISNS(–) –0.3 60 V
BIAS –0.3 40
FB, SS, DITH, RT/SYNC, SLOPE, COMP –0.3 3.6
SW1, SW2 –1 60
SW1, SW2 (20 ns transient) –3.0 65
VCC, MODE, PGOOD –0.3 8.5
LDRV1, LDRV2 –0.3 8.5
BOOT1, HDRV1 with respect to SW1 –0.3 8.5
BOOT2, HDRV2 with respect to SW2 –0.3 8.5
BOOT1, BOOT2 –0.3 68
CS, CSG –0.3 0.3
Operating junction temperature –40 150 °C
Storage temperature, Tstg -65 150
(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.

7.2 ESD Ratings

VALUE UNIT
VESD(1) Human body model (HBM) ESD stress voltage(2) ±2000 V
Charged device model (CDM) ESD stress voltage(3) ±750
(1) Electrostatic discharge (ESD) to measure device sensitivity and immunity to damage caused by assembly line electrostatic discharges into the device.
(2) Level listed above is the passing level per ANSI/ESDA/JEDEC JS-001. JEDEC document JEP155 states that 500 V HBM allows safe manufacturing with a standard ESD control process.
(3) Level listed above is the passing level per EIA-JEDEC JESD22-C101. JEDEC document JEP157 states that 250 V CDM allows safe manufacturing with a standard ESD control process.

7.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)(1)
MIN NOM MAX UNIT
VIN Input voltage range 3.5 42 V
BIAS Bias supply voltage range 8 36
VOUT Output voltage range 0.8 55
EN/UVLO Enable voltage range 0 42
ISNS(+), ISNS(-) Average current sense common mode range 0 55
TJ Operating temperature range(2) –40 125 °C
Fsw Operating frequency range 100 600 kHz
(1) Recommended Operating Conditions are conditions under the device is intended to be functional. For specifications and test conditions, see Electrical Characteristics .
(2) High junction temperatures degrade operating lifetimes. Operating lifetime is de-rated for junction temperatures greater than 125°C.

7.4 Thermal Information

THERMAL METRIC(1) LM5175 UNIT
HTSSOP QFN
28 PINS 28 PINS
RθJA Junction-to-ambient thermal resistance 33.1 34.7 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 17.7 26.6
RθJB Junction-to-board thermal resistance 14.9 6.3
ψJT Junction-to-top characterization parameter 0.4 0.3
ψJB Junction-to-board characterization parameter 14.7 6.2
RθJC(bot) Junction-to-case (bottom) thermal resistance 1.1 2.0
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

7.5 Electrical Characteristics

Typical values correspond to TJ = 25°C. Minimum and maximum limits apply over the –40°C to 125°C junction temperature range unless otherwise stated. VIN = 24 V unless otherwise stated.(1)
PARAMETER TEST CONDITION MIN TYP MAX UNIT
SUPPLY VOLTAGE (VIN)
VIN Operating input voltage 3.5 42 V
IQ VIN shutdown current VEN/UVLO = 0 V 1.4 10 µA
VIN standby current VEN/UVLO = 1.1 V, non-switching 0.7 2
VIN operating current VEN/UVLO = 2 V, VFB = 0.9 V 1.65 4 mA
VCC
VVCC(VIN) Regulation voltage VBIAS = 0 V, VCC open 6.95 7.35 7.88 V
VUV(VCC) VCC Undervoltage lockout VCC increasing 3.11 3.27 3.43
Undervoltage hysteresis 160 mV
IVCC VCC current limit VVCC = 0 V 65 mA
ROUT(VCC) VCC regulator output impedance IVCC = 30 mA, VIN = 3.5 V 9.3 16 Ω
BIAS
VBIAS(SW) BIAS switchover voltage VIN = 24 V 7.25 8 8.75 V
EN/UVLO
VEN(STBY) Standby threshold EN/UVLO rising 0.55 0.79 0.97 V
IEN(STBY) Standby source current VEN/UVLO = 1.1 V 1 2 3 µA
VEN(OP) Operating threshold EN/UVLO rising 1.17 1.23 1.29 V
ΔIHYS(OP) Operating hysteresis current VEN/UVLO = 2.4 V 1.5 3.5 5.5 µA
SS
ISS Soft-start pull up current VSS = 0 V 4.30 5.65 7.25 µA
VSS(CL) SS clamp voltage SS open 1.27 V
VFB - VSS FB to SS offset VSS = 0 V -15 mV
EA (ERROR AMPLIFIER)
VREF Feedback reference voltage FB = COMP 0.788 0.800 0.812 V
gmEA Error amplifier gm 1.27 mS
ISINK/ISOURCE COMP sink/source current VFB=VREF ± 300 mV 280 µA
ROUT Amplifier output resistance 20 MΩ
BW Unity gain bandwidth 2 MHz
IBIAS(FB) Feedback pin input bias current FB in regulation 100 nA
FREQUENCY
fSW(1) Switching Frequency 1 RT = 133 kΩ 180 200 220 kHz
fSW(2) Switching Frequency 2 RT = 47 kΩ 430 500 565
DITHER
IDITHER Dither source/sink current 10.5 µA
VDITHER Dither high threshold 1.27 V
Dither low threshold 1.16
SYNC
VSYNC Sync input high threshold 2.1 V
Sync input low threshold 1.2
PWSYNC Sync input pulse width 75 500 ns
CURRENT LIMIT
VCS(BUCK) Buck current limit threshold (Valley) VIN = VVISNS = 24 V, VVOSNS = 12 V, VSLOPE = 0 V, TJ = 25°C 53.2 76 98 mV
VCS(BOOST) Boost current limit threshold (Peak) VIN = VVISNS = 12 V, VVOSNS = 18 V, VSLOPE = 0 V, TJ = 25°C 119 170 221
IBIAS(CS/CSG) CS/CSG pin bias current VCS = VCSG = 0 V -75 µA
IOFFSET(CS/CSG) CSG pin bias current VCS = VCSG = 0 V 14
CONSTANT CURRENT LOOP
VSNS Average current loop regulation target VISNS(-) = 24 V, sweep ISNS(+), VSS = 0.8 V 43 50 57 mV
ISNS ISNS(+)/ISNS(–) pin bias currents VISNS(+) = VISNS(–) = VIN = 24 V 7 µA
Gm gm of soft-start pull down amplifier VISNS(+)–VISNS(–) = 55 mV, VSS = 0.5 V 1 mS
SLOPE
ISLOPE Buck adaptive slope current VIN = VVINSNS = 24 V, VVOSNS = 12 V, VSLOPE = 0 V 24 30 35 µA
Boost adaptive slope current VIN = VVINSNS = 12 V, VVOSNS = 18 V, VSLOPE = 0 V 13 17 21
gmSLOPE Slope compensation amplifier gm 2 µS
MODE
IMODE Source current out of MODE pin 17 20 23 µA
VDCM_HIC DCM with hiccup threshold 0.60 0.7 0.76 V
VCCM_HIC CCM with hiccup threshold 1.18 1.28 1.38
VCCM CCM no hiccup threshold 2.22 2.4 2.6
PGOOD
VPGD PGOOD trip threshold for falling FB Measured with respect to VREF –9 %
PGOOD trip threshold for rising FB Measured with respect to VREF 10 %
Hysteresis 1.6 %
ILEAK(PGD) PGOOD leakage current 100 nA
ISINK(PGD) PGOOD sink current VPGOOD = 0.4 V 2 4.2 6.5 mA
OUTPUT OVP
VOVP Output overvoltage threshold At the FB pin 0.86 V
Hysteresis 21 mV
NMOS DRIVERS
IHDRV1,2 Driver peak source current VBOOT - VSW = 7 V 1.8 A
Driver peak sink current VBOOT - VSW = 7 V 2.2
ILDRV1,2 Driver peak source current 1.8
Driver peak sink current 2.2
RHDRV1,2 Driver pull up resistance VBOOT - VSW = 7 V 1.9 Ω
Driver pull down resistance VBOOT - VSW = 7 V 1.3
VUV(BOOT1,2) BOOT1,2 to SW1,2 UVLO threshold HDRV1,2 shut off 2.73 V
BOOT1,2 to SW1,2 UVLO hysteresis HDRV1,2 start switching 280 mV
BOOT1,2 to SW1,2 threshold for refresh pulse 4.45 V
RLDRV1,2 Driver pull up resistance IDRV1,2 = 0.1 A 2 Ω
Driver pull down resistance IDRV1,2 = 0.1 A 1.5
tDT1 Dead time HDRV1,2 off to LDRV1,2 on 55 ns
tDT2 Dead time LDRV1,2 off to HDRV1,2 on 55
THERMAL SHUTDOWN
TSD Thermal shutdown temperature 165 °C
TSD(HYS) Thermal shutdown hysteresis 15
(1) All minimum and maximum limits are specified by correlating the electrical characteristics to process and temperature variations and applying statistical process control.

7.6 Typical Characteristics

At TA = 25°C, unless otherwise stated.
LM5175 D009_SNVA37.gif
VOUT=12 V Fsw=300 kHz L1=4.7 μH
IOUT=3 A
Figure 1. Efficiency vs VIN
LM5175 D004_snva37.gif
Figure 3. Oscillator Frequency
LM5175 D006_snva37.gif
Figure 5. IIN Standby
LM5175 D010_SNVA37.gif
Figure 7. IIN Shutdown vs VIN
LM5175 D012_SNVA37.gif
Figure 9. Buck Current Limit vs Temperature
LM5175 D014_SNVA37.gif
Figure 11. VREF vs Temperature
LM5175 fccm_boost.gif
VOUT=12 V VIN=6 V
Figure 13. Forced CCM Operation (Boost)
LM5175 loadtr24vin_2a_4a.gif
VIN=24 V VOUT=12 V Load 2A to 4A
Figure 15. Load Step (Buck)
LM5175 loadtr12vin_2a_4a.gif
VIN=12 V VOUT=12 V Load 2A to 4A
Figure 17. Load Step (Buck-Boost)
LM5175 hiccup_mode.gif
VIN=24 V VOUT=12 V Hiccup Enabled
Figure 19. Hiccup Mode Current Limit
LM5175 D008_SNVA37.gif
VOUT =12 V Fsw=300 kHz L1=4.7 μH
Figure 2. Efficiency vs Load
LM5175 D002_SNVSA37.gif
Figure 4. VCC vs VIN
LM5175 D007_snva37.gif
Figure 6. IIN Operating vs VIN
LM5175 D013_SNVA37.gif
Figure 8. ENABLE/UVLO Rising Threshold vs Temperature
LM5175 D011_SNVA37.gif
Figure 10. Boost Current Limit vs Temperature
LM5175 fccm_buck.gif
VOUT=12 V VIN=24 V
Figure 12. Forced CCM Operation (Buck)
LM5175 fccm_buckboost.gif
VOUT=12 V VIN=12 V
Figure 14. Forced CCM Operation (Buck-Boost)
LM5175 loadtr6vin_2a_4a.gif
VIN=6 V VOUT=12 V Load 2A to 4A
Figure 16. Load Step (Boost)
LM5175 linetr8v_24v_1a.gif
VIN=8 V to 24 V VOUT=12 V IOUT=1A
Figure 18. Line Transient