SNVSA43B August   2014  – September 2017 LM43600

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 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 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 Peak Current Mode Controlled Step-Down Regulator
      2. 8.3.2  Light Load Operation
      3. 8.3.3  Adjustable Output Voltage
      4. 8.3.4  Enable (ENABLE)
      5. 8.3.5  VCC, UVLO and BIAS
      6. 8.3.6  Soft Start and Voltage Tracking (SS/TRK)
      7. 8.3.7  Switching Frequency (RT) and Synchronization (SYNC)
      8. 8.3.8  Minimum ON-Time, Minimum OFF-Time and Frequency Foldback at Dropout Conditions
      9. 8.3.9  Internal Compensation and CFF
      10. 8.3.10 Bootstrap Voltage (BOOT)
      11. 8.3.11 Power Good (PGOOD)
      12. 8.3.12 Overcurrent and Short-Circuit Protection
      13. 8.3.13 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Stand-by Mode
      3. 8.4.3 Active Mode
      4. 8.4.4 CCM Mode
      5. 8.4.5 Light Load Operation
      6. 8.4.6 Self-Bias Mode
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      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  Output Voltage Setpoint
        3. 9.2.2.3  Switching Frequency
        4. 9.2.2.4  Input Capacitors
        5. 9.2.2.5  Inductor Selection
        6. 9.2.2.6  Output Capacitor Selection
        7. 9.2.2.7  Feedforward Capacitor
        8. 9.2.2.8  Bootstrap Capacitors
        9. 9.2.2.9  VCC Capacitor
        10. 9.2.2.10 BIAS Capacitors
        11. 9.2.2.11 Soft-Start Capacitors
        12. 9.2.2.12 Undervoltage Lockout Setpoint
        13. 9.2.2.13 PGOOD
      3. 9.2.3 Application Performance Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Compact Layout for EMI Reduction
      2. 11.1.2 Ground Plane and Thermal Considerations
      3. 11.1.3 Feedback Resistors
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Development Support
      1. 12.1.1 Custom Design With WEBENCH® Tools
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

7 Specifications

7.1 Absolute Maximum Ratings

Over operating free-air temperature range (unless otherwise noted)(1)
PARAMETER MIN MAX UNIT
Input voltages VIN to PGND –0.3 42 V
EN to PGND –0.3 VIN + 0.3
FB, RT, SS/TRK to AGND –0.3 3.6
PGOOD to AGND –0.3 15
SYNC to AGND –0.3 5.5
BIAS to AGND –0.3 30
AGND to PGND –0.3 0.3
Output voltages SW to PGND –0.3 VIN + 0.3 V
SW to PGND less than 10ns Transients –3.5 42
CBOOT to SW –0.3 5.5
VCC to AGND –0.3 3.6
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, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

7.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±500
(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.

7.3 Recommended Operating Conditions

Over operating free-air temperature range (unless otherwise noted)(1)
PARAMETER MIN MAX UNIT
Input voltages VIN to PGND 3.5 36 V
EN –0.3 VIN
FB –0.3 1.1
PGOOD –0.3 12
BIAS input not used –0.3 0.3
BIAS input used 3.3 VIN or 28(2)
AGND to PGND –0.1 0.1
Output Voltage VOUT 1 28 V
Output Current IOUT 0 0.5 A
Temperature Operating junction temperature range, TJ –40 125 °C
(1) Recommended Operating Ratings indicate conditions for which the device is intended to be functional, but do not ensure specific performance limits. For specified specifications, see Electrical Characteristics.
(2) Whichever is lower.

7.4 Thermal Information

THERMAL METRIC(1)(2) LM43600 UNIT
PWP (HTSSOP)
16 PINS
RθJA Junction-to-ambient thermal resistance 39.9(3) °C/W
RθJC(top) Junction-to-case (top) thermal resistance 26.9 °C/W
RθJB Junction-to-board thermal resistance 21.7 °C/W
ψJT Junction-to-top characterization parameter 0.8 °C/W
ψJB Junction-to-board characterization parameter 21.5 °C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance 2.3 °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report.
(2) The package thermal impedance is calculated in accordance with JESD 51-7 standard with a 4-layer board and 1 W power dissipation.
(3) RθJA is highly related to PCB layout and heat sinking. See Figure 107 for measured RθJA vs PCB area from a 2-layer board and a 4-layer board.

7.5 Electrical Characteristics

Limits apply over the recommended operating junction temperature (TJ) range of –40°C to 125°C, unless otherwise stated. Minimum and Maximum limits are specified through test, design or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated, the following conditions apply: VIN = 12 V, VOUT = 3.3 V, FS = 500 kHz.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
SUPPLY VOLTAGE (VIN PINS)
VIN-MIN-ST Minimum input voltage for start-up 3.8 V
ISHDN Shutdown quiescent current VEN = 0 V 1.1 3.1 µA
IQ-NONSW Operating quiescent current (non-switching) from VIN VEN = 3.3 V
VFB = 1.5 V
VBIAS = 3.4 V external		 6 11 µA
IBIAS-NONSW Operating quiescent current (non-switching) from external VBIAS VEN = 3.3 V
VFB = 1.5 V
VBIAS = 3.4 V external		 85 140 µA
IQ-SW Operating quiescent current (switching) VEN = 3.3 V
IOUT = 0 A
RT = open
VBIAS = VOUT = 3.3 V
RFBT = 1 Meg		 33 µA
ENABLE (EN PIN)
VEN-VCC-H Voltage level to enable the internal LDO output VCC VENABLE high level 1.2 V
VEN-VCC-L Voltage level to disable the internal LDO output VCC VENABLE low level 0.4 V
VEN-VOUT-H Precision enable level for switching and regulator output: VOUT VENABLE high level 2 2.1 2.42 V
VEN-VOUT-HYS Hysteresis voltage between VOUT precision enable and disable thresholds VENABLE hysteresis –305 mV
ILKG-EN Enable input leakage current VEN = 3.3 V 0.8 1.75 µA
INTERNAL LDO (VCC PIN AND BIAS PIN)
VCC Internal LDO output voltage VCC VIN ≥ 3.8 V 3.3 V
VCC-UVLO Undervoltage lockout (UVLO) thresholds for VCC VCC rising threshold 3.14 V
Hysteresis voltage between rising and falling thresholds –567 mV
VBIAS-ON Internal LDO input change over threshold to BIAS VBIAS rising threshold 2.96 3.2 V
Hysteresis voltage between rising and falling thresholds –74 mV
VOLTAGE REFERENCE (FB PIN)
VFB Feedback voltage TJ = 25°C 1.009 1.016 1.023 V
TJ = –40°C to 85°C 0.999 1.016 1.031
TJ = –40°C to 125°C 0.999 1.016 1.039
ILKG-FB Input leakage current at FB pin FB = 1.011 V 0.2 65 nA
THERMAL SHUTDOWN
TSD (1) Thermal shutdown Shutdown threshold 160 °C
Recovery threshold 150 °C
CURRENT LIMIT AND HICCUP
IHS-LIMIT Peak inductor current limit 1.04 1.33 1.56 A
ILS-LIMIT Inductor current valley limit 0.46 0.60 0.75 A
SOFT START (SS/TRK PIN)
ISSC Soft-start charge current 1.17 2.2 2.85 µA
RSSD Soft-start discharge resistance UVLO, TSD, OCP, or EN = 0 V 16 kΩ
POWER GOOD (PGOOD PIN)
VPGOOD-HIGH Power-good flag overvoltage tripping threshold % of FB voltage 110% 113%
VPGOOD-LOW Power-good flag undervoltage tripping threshold % of FB voltage 83% 90%
VPGOOD-HYS Power-good flag recovery hysteresis % of FB voltage 6%
RPGOOD PGOOD pin pulldown resistance when power bad VEN = 3.3 V 40 125 Ω
VEN = 0 V 60 150
MOSFETS (2)
RDS-ON-HS High-side MOSFET ON-resistance IOUT = 0.5 A
VBIAS = VOUT = 3.3 V		 419 mΩ
RDS-ON-LS Low-side MOSFET ON-resistance IOUT = 0.5 A
VBIAS = VOUT = 3.3 V		 231 mΩ
(1) Specified by design.
(2) Measured at package pins.

7.6 Timing Requirements

MIN NOM MAX UNIT
CURRENT LIMIT AND HICCUP
NOC Hiccup wait cycles when LS current limit tripped 32 Cycles
TOC Hiccup retry delay time 5.5 ms
SOFT START (SS/TRK PIN)
TSS Internal soft-start time when SS pin open circuit 3.86 ms
POWER GOOD (PGOOD PIN)
TPGOOD-RISE Power-good flag rising transition deglitch delay 220 µs
TPGOOD-FALL Power-good flag falling transition deglitch delay 220 µs

7.7 Switching Characteristics

Over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
SW (SW PIN)
tON-MIN(1) Minimum high side MOSFET ON time 125 165 ns
tOFF-MIN(1) Minimum high side MOSFET OFF time 200 250 ns
OSCILLATOR (SW PINS AND SYNC PIN)
FOSC-DEFAULT Oscillator default frequency RT pin open circuit 445 500 570 kHz
FADJ Minimum adjustable frequency With 1% resistors at RT pin 200 kHz
Maximum adjustable frequency 2200 kHz
Frequency adjust accuracy 10%
VSYNC-HIGH Sync clock high level threshold 2 V
VSYNC-LOW Sync clock low level threshold 0.4 V
DSYNC-MAX Sync clock maximum duty cycle 90%
DSYNC-MIN Sync clock minimum duty cycle 10%
TSYNC-MIN Minimum sync clock ON-time and OFF-time 80 ns
(1) Specified by design.

7.8 Typical Characteristics

Unless otherwise specified, VIN = 12 V, VOUT = 3.3 V, FS = 500 kHz, L = 22 µH, COUT = 100 µF, CFF = 33 pF. See Application Performance Curves for bill of materials (BOM) for other VOUT and FSW combinations.
LM43600 C002_Eff_43600_3p3V500k.png
VOUT = 3.3 V FSW = 500 kHz
Figure 1. Efficiency
LM43600 C003_Eff_43600_5V500k.png
VOUT = 5 V FSW = 500 kHz
Figure 3. Efficiency
LM43600 C007_Eff_43600_12V500k.png
VOUT = 12 V FSW = 500 kHz
Figure 5. Efficiency
LM43600 C012_Reg_43600_3p3V500k.png
VOUT = 3.3 V FSW = 500 kHz
Figure 7. VOUT Regulation
LM43600 C013_Reg_43600_5V500k.png
VOUT = 5 V FSW = 500 kHz
Figure 9. VOUT Regulation
LM43600 C017_Reg_43600_12V500k.png
VOUT = 12 V FSW = 500 kHz
Figure 11. VOUT Regulation
LM43600 C022_DO_43600_3p3V500k.png
VOUT = 3.3 V FSW = 500 kHz
Figure 13. Dropout Curve
LM43600 C023_DO_43600_5V500k.png
VOUT = 5 V FSW = 500 kHz
Figure 15. Dropout Curve
LM43600 C027_DO_43600_12V500k.png
VOUT = 12 V FSW = 500 kHz
Figure 17. Dropout Curve
LM43600 43600_3V3_500kHz_Freq_Drop.png
VOUT = 3.3 V FSW = 500 kHz
Figure 19. Switching Frequency vs VIN in Dropout Operation
LM43600 lm43600-3p3-500k_radiated.gif
VOUT = 3.3 V FSW = 500 kHz IOUT = 0.5 A
Measured on the LM43600PWPEVM with default BOM. No input filter used.
Figure 21. Radiated EMI Curve
LM43600 lm43600_3p3_500k_Conducted.gif
VOUT = 3.3 V FSW = 500 kHz IOUT = 0.5 A
Measured on the LM43600PWPEVM with default BOM. Input filter: Lin = 1 µH Cd = 47 µF CIN4 = 68 µF
Figure 23. Conducted EMI Curve
LM43600 Gen_Curve_On_Resistance.png
Figure 25. High-Side and Low-side On Resistance vs Junction Temperature
LM43600 Gen_Curve_EN_Threshold.png
Figure 27. Enable Threshold vs Junction Temperature
LM43600 Gen_Curve_PG_Threshold.png
Figure 29. PGOOD Threshold vs Junction Temperature
LM43600 Gen_Curve_46000Curr_Lim.png
VIN = 12 V VOUT = 3.3 V FS = 500 kHz
Figure 31. Peak and Valley Current Limits vs Temperature
LM43600 C004_Eff_43600_5V200k.png
VOUT = 5 V FSW = 200 kHz
Figure 2. Efficiency
LM43600 C005_Eff_43600_5V1M.png
VOUT = 5 V FSW = 1 MHz
Figure 4. Efficiency
LM43600 C008_Eff_43600_24V500k.png
VOUT = 24 V FSW = 500 kHz
Figure 6. Efficiency
LM43600 C014_Reg_43600_5V200k.png
VOUT = 5 V FSW = 200 kHz
Figure 8. VOUT Regulation
LM43600 C015_Reg_43600_5V1M.png
VOUT = 5 V FSW = 1 MHz
Figure 10. VOUT Regulation
LM43600 C018_Reg_43600_24V500k.png
VOUT = 24 V FSW = 500 kHz
Figure 12. VOUT Regulation
LM43600 C024_DO_43600_5V200k.png
VOUT = 5 V FSW = 200 kHz
Figure 14. Dropout Curve
LM43600 C025_DO_43600_5V1M.png
VOUT = 5 V FSW = 1 MHz
Figure 16. Dropout Curve
LM43600 C028_DO_43600_24V500k.png
VOUT = 24 V FSW = 500 kHz
Figure 18. Dropout Curve
LM43600 43600_5V_1MHz_Freq_Drop.png
VOUT = 5 V FSW = 1 MHz
Figure 20. Switching Frequency vs VIN in Dropout Operation
LM43600 lm43600_5_500k_radiated.gif
VOUT = 5 V FSW = 500 kHz IOUT = 0.5 A
Measured on the LM43600PWPEVM with L = 44 µH, COUT = 66 µF, CFF = 33 pF. No input filter used.
Figure 22. Radiated EMI Curve
LM43600 lm43600_5_500k_Conducted.gif
VOUT = 5 V FSW = 500 kHz IOUT = 0.5 A
Measured on the LM43600PWPEVM with L = 44 µH, COUT = 66 µF, CFF = 33 pF. Input filter Lin = 1 µH Cd = 47 µF CIN4 = 68 µF
Figure 24. Conducted EMI Curve
LM43600 Gen_Curve_Shdn_Current.png
Figure 26. Shutdown Current vs Junction Temperature
LM43600 Gen_Curve_EN_Leakage_Curr.png
Figure 28. Enable Leakage Current vs
Junction Temperature
LM43600 Gen_Curve_FB_Voltage.png
Figure 30. Feedback Voltage vs Junction Temperature
LM43600 Gen_Curve_43601Iq.png
i.
VOUT = 3.3 V FSW = 500 kHz IOUT = 0 A
Figure 32. Operation IQ vs VIN with BIAS Connected to VOUT