SNVSAT9 June   2017 LM25145

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1. 6.1 Wettable Flanks
  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 Switching Characteristics
    7. 7.7 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  Input Range (VIN)
      2. 8.3.2  Output Voltage Setpoint and Accuracy (FB)
      3. 8.3.3  High-Voltage Bias Supply Regulator (VCC)
      4. 8.3.4  Precision Enable (EN/UVLO)
      5. 8.3.5  Power Good Monitor (PGOOD)
      6. 8.3.6  Switching Frequency (RT, SYNCIN)
        1. 8.3.6.1 Frequency Adjust
        2. 8.3.6.2 Clock Synchronization
      7. 8.3.7  Configurable Soft-Start (SS/TRK)
        1. 8.3.7.1 Tracking
      8. 8.3.8  Voltage-Mode Control (COMP)
      9. 8.3.9  Gate Drivers (LO, HO)
      10. 8.3.10 Current Sensing and Overcurrent Protection (ILIM)
      11. 8.3.11 OCP Duty Cycle Limiter
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Standby Mode
      3. 8.4.3 Active Mode
      4. 8.4.4 Diode Emulation Mode
      5. 8.4.5 Thermal Shutdown
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Design and Implementation
      2. 9.1.2 Power Train Components
        1. 9.1.2.1 Inductor
        2. 9.1.2.2 Output Capacitors
        3. 9.1.2.3 Input Capacitors
        4. 9.1.2.4 Power MOSFETs
      3. 9.1.3 Control Loop Compensation
      4. 9.1.4 EMI Filter Design
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1 - 20-A High-Efficiency Synchronous Buck Regulator for Telecom Power Applications
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Custom Design With WEBENCH® Tools
        4. 9.2.1.4 Application Curves
      2. 9.2.2 Design 2 - High Density, 12-V, 8-A Rail With LDO Low-Noise Auxiliary Output for Industrial Applications
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Application Curves
      3. 9.2.3 Design 3 - Powering a Multicore DSP From a 24-V Rail
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Power Stage Layout
      2. 11.1.2 Gate Drive Layout
      3. 11.1.3 PWM Controller Layout
      4. 11.1.4 Thermal Design and Layout
      5. 11.1.5 Ground Plane Design
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
      2. 12.1.2 Development Support
      3. 12.1.3 Custom Design With WEBENCH® Tools
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
        1. 12.2.1.1 PCB Layout Resources
        2. 12.2.1.2 Thermal Design Resources
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Community Resources
    6. 12.6 Trademarks
    7. 12.7 Electrostatic Discharge Caution
    8. 12.8 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

7 Specifications

7.1 Absolute Maximum Ratings

Over the recommended operating junction temperature range of –40°C to 125°C (unless otherwise noted).(1)
MIN MAX UNIT
Input voltages VIN –0.3 45 V
SW –1 45
SW (20-ns transient) –5 45
ILIM –1 45
EN/UVLO –0.3 45
VCC –0.3 14
FB, COMP, SS/TRK, RT –0.3 6
SYNCIN –0.3 14
Output voltages BST –0.3 60 V
BST to VCC 45
BST to SW –0.3 14
VCC to BST (20-ns transient) 7
LO (20-ns transient) –3
PGOOD –0.3 14
Operating junction temperature, TJ 150 °C
Storage temperature, Tstg –55 150 °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.

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) ±1000
(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 the recommended operating junction temperature range of –40°C to 125°C (unless otherwise noted).(1)
MIN NOM MAX UNIT
VI Input voltages VIN 6 42 V
SW –1 42
ILIM –1 42
External VCC bias rail 8 13
EN/UVLO 0 42
VO Output voltages BST –0.3 55 V
BST to VCC 42
BST to SW 5 13
PGOOD 13
ISINK, ISRC Sink/source currents SYNCOUT –1 1 mA
PGOOD 2
TJ Operating junction temperature –40 125 °C
(1) Recommended Operating Conditions are conditions under which the device is intended to be functional. For specifications and test conditions, see Electrical Characteristics.

7.4 Thermal Information

THERMAL METRIC(1) LM25145 UNIT
RGY (VQFN)
20 PINS
RθJA Junction-to-ambient thermal resistance 36.8 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 28 °C/W
RθJB Junction-to-board thermal resistance 11.8 °C/W
ψJT Junction-to-top characterization parameter 0.4 °C/W
ψJB Junction-to-board characterization parameter 11.7 °C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance 2.1 °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report.

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, VEN/UVLO = 1.5 V, RRT = 25 kΩ unless otherwise stated.(1)(2)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
INPUT SUPPLY
VIN Operating input voltage range 6 42 V
IQ-RUN Operating input current, not switching VEN/UVLO = 1.5 V, VSS/TRK = 0 V 1.8 2.1 mA
IQ-STBY Standby input current VEN/UVLO = 1 V 1.75 2 mA
IQ-SDN Shutdown input current VEN/UVLO = 0 V, VVCC < 1 V 13.5 16 µA
VCC REGULATOR
VVCC VCC regulation voltage VSS/TRK = 0 V, 9 V ≤ VVIN ≤ 42 V,
0 mA < IVCC ≤ 20 mA		 7.3 7.5 7.7 V
VVCC-LDO VIN to VCC dropout voltage VVIN = 6 V, VSS/TRK = 0 V, IVCC = 20 mA 0.25 0.63 V
ISC-LDO VCC short-circuit current VSS/TRK = 0 V, VVCC = 0 V 40 50 70 mA
VVCC-UV VCC undervoltage threshold VVCC rising 4.8 4.93 5.2 V
VVCC-UVH VCC undervoltage hysteresis Rising threshold – falling threshold 0.26 V
VVCC-EXT Minimum external bias supply voltage Voltage required to disable VCC regulator 8 V
IVCC External VCC input current, not switching VSS/TRK = 0 V, VVCC = 13 V 2.1 mA
ENABLE AND INPUT UVLO
VSDN Shutdown to standby threshold VEN/UVLO rising 0.42 V
VSDN-HYS Shutdown threshold hysteresis EN/UVLO rising – falling threshold 50 mV
VEN Standby to operating threshold VEN/UVLO rising 1.164 1.2 1.236 V
IEN-HYS Standby to operating hysteresis current VEN/UVLO = 1.5 V 9 10 11 µA
ERROR AMPLIFIER
VREF FB reference voltage FB connected to COMP 792 800 808 mV
IFB-BIAS FB input bias current VFB = 0.8 V –0.1 0.1 µA
VCOMP-OH COMP output high voltage VFB = 0 V, COMP sourcing 1 mA 5 V
VCOMP-OL COMP output low voltage COMP sinking 1 mA 0.3 V
AVOL DC gain 94 dB
GBW Unity gain bandwidth 6.5 MHz
SOFT-START AND VOLTAGE TRACKING
ISS SS/TRK capacitor charging current VSS/TRK = 0 V 8.5 10 12 µA
RSS SS/TRK discharge FET resistance VEN/UVLO = 1 V, VSS/TRK = 0.1 V 11 Ω
VSS-FB SS/TRK to FB offset –15 15 mV
VSS-CLAMP SS/TRK clamp voltage VSS/TRK – VFB, VFB = 0.8 V 115 mV
POWER GOOD INDICATOR
PGUTH FB upper threshold for PGOOD high to low % of VREF, VFB rising 106% 108% 110%
PGLTH FB lower threshold for PGOOD high to low % of VREF, VFB falling 90% 92% 94%
PGHYS_U PGOOD upper threshold hysteresis % of VREF 3%
PGHYS_L PGOOD lower threshold hysteresis % of VREF 2%
TPG-RISE PGOOD rising filter FB to PGOOD rising edge 25 µs
TPG-FALL PGOOD falling filter FB to PGOOD falling edge 25 µs
VPG-OL PGOOD low state output voltage VFB = 0.9 V, IPGOOD = 2 mA 150 mV
IPG-OH PGOOD high state leakage current VFB = 0.8 V, VPGOOD = 13 V 100 nA
OSCILLATOR
FSW1 Oscillator Frequency – 1 RRT = 100 kΩ 100 kHz
FSW2 Oscillator Frequency – 2 RRT = 25 kΩ 380 400 420 kHz
FSW3 Oscillator Frequency – 3 RRT = 12.5 kΩ 780 kHz
SYNCHRONIZATION INPUT AND OUTPUT
FSYNC SYNCIN external clock frequency range % of nominal frequency set by RRT –20% +50%
VSYNC-IH Minimum SYNCIN input logic high 2 V
VSYNC-IL Maximum SYNCIN input logic low 0.8 V
RSYNCIN SYNCIN input resistance VSYNCIN = 3 V 20 kΩ
TSYNCI-PW SYNCIN input minimum pulsewidth Minimum high state or low state duration 50 ns
VSYNCO-OH SYNCOUT high state output voltage ISYNCOUT = –1 mA (sourcing) 3 V
VSYNCO-OL SYNCOUT low state output voltage ISYNCOUT = 1 mA (sinking) 0.4 V
TSYNCOUT Delay from HO rising to SYNCOUT leading edge VSYNCIN = 0 V, TS = 1/FSW,
FSW set by RRT		 TS/2 – 140 ns
TSYNCIN Delay from SYNCIN leading edge to HO rising 50% to 50% 150 ns
BOOTSTRAP DIODE AND UNDERVOLTAGE THRESHOLD
VBST-FWD Diode forward voltage, VCC to BST VCC to BST, BST pin sourcing 20 mA 0.75 0.9 V
IQ-BST BST to SW quiescent current, not switching VSS/TRK = 0 V, VSW = 24 V, VBST = 30 V 80 µA
VBST-UV BST to SW undervoltage detection VBST – VSW falling 3.4 V
VBST-HYS BST to SW undervoltage hysteresis VBST – VSW rising 0.42 V
PWM CONTROL
TON(MIN) Minimum controllable on-time VBST – VSW = 7 V, HO 50% to 50% 40 60 ns
TOFF(MIN) Minimum off-time VBST – VSW = 7 V, HO 50% to 50% 140 200 ns
DC100kHz Maximum duty cycle FSW = 100 kHz, 6 V ≤ VVIN ≤ 42 V 98% 99%
DC400kHz FSW = 400 kHz, 6 V ≤ VVIN ≤ 42 V 90% 94%
VRAMP(min) Ramp valley voltage (COMP at 0% duty cycle) 300 mV
kFF PWM feedforward gain (VIN / VRAMP) 6 V ≤ VVIN ≤ 42 V 15 V/V
OVERCURRENT PROTECT (OCP) – VALLEY CURRENT LIMITING
IRS ILIM source current, RSENSE mode Low voltage detected at ILIM 90 100 110 µA
IRDSON ILIM source current, RDS(on) mode SW voltage detected at ILIM, TJ = 25°C 180 200 220 µA
IRSTC ILIM current tempco RDS-ON mode 4500 ppm/°C
IRDSONTC ILIM current tempco RSENSE mode 0 ppm/°C
VILIM-TH ILIM comparator threshold at ILIM –8 –2 3.5 mV
SHORT-CIRCUIT PROTECT (SCP) – DUTY CYCLE CLAMP
VCLAMP-OS Clamp offset voltage – no current limiting CLAMP to COMP steady state offset voltage 0.2 + VVIN/75 V
VCLAMP-MIN Minimum clamp voltage CLAMP voltage with continuous current limiting 0.3 + VVIN/150 V
HICCUP MODE FAULT PROTECTION
CHICC-DEL Hiccup mode activation delay Clock cycles with current limiting before hiccup off-time activated 128 cycles
CHICCUP Hiccup mode off-time after activation Clock cycles with no switching followed by SS/TRK release 8192 cycles
DIODE EMULATION
VZCD-SS Zero-cross detect (ZCD) soft-start ramp ZCD threshold measured at SW pin
50 clock cycles after first HO pulse		 0 mV
VZCD-DIS Zero-cross detect disable threshold (CCM) ZCD threshold measured at SW pin
1000 clock cycles after first HO pulse		 200 mV
VDEM-TH Diode emulation zero-cross threshold Measured at SW with VSW rising –5 0 5 mV
GATE DRIVERS
RHO-UP HO high-state resistance, HO to BST VBST – VSW = 7 V, IHO = –100 mA 1.5 Ω
RHO-DOWN HO low-state resistance, HO to SW VBST – VSW = 7 V, IHO = 100 mA 0.9 Ω
RLO-UP LO high-state resistance, LO to VCC VBST – VSW = 7 V, ILO = –100 mA 1.5 Ω
RLO-DOWN LO low-state resistance, LO to PGND VBST – VSW = 7 V, ILO = 100 mA 0.9 Ω
IHOH, ILOH HO, LO source current VBST – VSW = 7 V, HO = SW, LO = AGND 2.3 A
IHOL, ILOL HO, LO sink current VBST – VSW = 7 V, HO = BST, LO = VCC 3.5 A
THERMAL SHUTDOWN
TSD Thermal shutdown threshold TJ rising 175 °C
TSD-HYS Thermal shutdown hysteresis 20 °C
(1) All minimum and maximum limits are specified by correlating the electrical characteristics to process and temperature variations and applying statistical process control.
(2) The junction temperature (TJ in °C) is calculated from the ambient temperature (TA in °C) and power dissipation (PD in Watts) as follows: TJ = TA + (PD • RθJA) where RθJA (in °C/W) is the package thermal impedance provided in Thermal Information.

7.6 Switching Characteristics

Over operating free-air temperature range (unless otherwise noted).
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
THO-TR
TLO-TR		 HO, LO rise times VBST – VSW = 7 V, CLOAD = 1 nF, 20% to 80% 7 ns
THO-TF
TLO-TF		 HO, LO fall times VBST – VSW = 7 V, CLOAD = 1 nF, 80% to 20% 4 ns
THO-DT HO turnon dead time VBST – VSW = 7 V, LO off to HO on, 50% to 50% 14 ns
TLO-DT LO turnon dead time VBST – VSW = 7 V, HO off to LO on, 50% to 50% 14 ns

7.7 Typical Characteristics

VVIN = 24 V, RRT = 25 kΩ, SYNCIN tied to VCC, EN/UVLO tied to VIN (unless otherwise noted).
LM25145 D050_snvsat9.gif
VOUT = 5 V
See Figure 46		 VSYNCIN = VVCC FSW = 500 kHz
RRT = 20 kΩ
Figure 1. Efficiency vs Load, CCM
LM25145 D052_snvsat9.gif
VOUT = 12 V
See Figure 57		 VSYNCIN = VVCC FSW = 425 kHz
RRT = 23.7 kΩ
Figure 3. Efficiency vs Load, CCM
LM25145 D043_snvsai4.gif
VOUT = 1.1 V
See Figure 70		 FSW = 300 kHz
RRT = 33.2 kΩ
Figure 5. Efficiency vs Load, CCM
LM25145 D020_snvsai4.gif
Figure 7. TON(min) and TOFF(min) vs Junction Temperature
LM25145 D061_snvsat9.gif
VSW = 0 V VEN/UVLO = 1 V
Figure 9. IQ-STANDBY vs Input Voltage
LM25145 D063_snvsat9.gif
VSW = 0 V HO, LO Open
Figure 11. IQ-OPERATING (Switching) vs Input Voltage
LM25145 D008_snvsai4.gif
Figure 13. ILIM Current Source vs Junction Temperature
LM25145 D030_snvsai4.gif
Figure 15. VCC UVLO Thresholds vs Junction Temperature
LM25145 D028_snvsai4.gif
Figure 17. PGOOD UVP Thresholds vs Junction Temperature
LM25145 D027_snvsai4.gif
Figure 19. EN/UVLO Threshold vs Junction Temperature
LM25145 D011_snvsai4.gif
VSW = 0 V
Figure 21. Oscillator Frequency vs RT Resistance
LM25145 D013_snvsai4.gif
Figure 23. BST Diode Forward Voltage vs Current
LM25145 D015_snvsai4.gif
Figure 25. HO Driver Resistance vs VCC Voltage
LM25145 D065_snvsat9.gif
VSS/TRK = 0 V
Figure 27. VCC Voltage vs Input Voltage
LM25145 D019_snvsai4.gif
VIN = 12 V
Figure 29. VCC vs ICC Characteristic
LM25145 D051_snvsat9.gif
VOUT = 5 V
See Figure 46		 VSYNCIN = 0 V FSW = 500 kHz
RRT = 20 kΩ
Figure 2. Efficiency vs Load, DCM
LM25145 D053_snvsat9.gif
VOUT = 12 V
See Figure 57		 VSYNCIN = 0 V FSW = 425 kHz
RRT = 23.7 kΩ
Figure 4. Efficiency vs Load, DCM
(VOUT Supplies Bias Power to VCC)
LM25145 D024_snvsai4.gif
Figure 6. FB Voltage vs Junction Temperature
LM25145 D060_snvsat9.gif
VSW = 0 V VEN/UVLO = 0 V
Figure 8. IQ-SHD vs Input Voltage
LM25145 D062_snvsat9.gif
VSW = 0 V VEN/UVLO = VVIN VSS/TRK = 0 V
Figure 10. IQ-OPERATING (Nonswitching) vs Input Voltage
LM25145 D064_snvsat9.gif
VSW = 0 V VVCC = VBST = VILIM VFB = 0 V
Figure 12. VIN Quiescent Current With External VCC Applied
LM25145 D009_snvsai4.gif
VSW = 0 V
Figure 14. Dead Time vs Junction Temperature
LM25145 D023_snvsai4.gif
Figure 16. BST UVLO Thresholds vs Junction Temperature
LM25145 D029_snvsai4.gif
Figure 18. PGOOD OVP Thresholds vs Junction Temperature
LM25145 D026_snvsai4.gif
Figure 20. EN Standby Thresholds vs Junction Temperature
LM25145 D010_snvsai4.gif
Figure 22. Oscillator Frequency vs Junction Temperature
LM25145 D014_snvsai4.gif
Figure 24. Gate Driver Peak Current vs VCC Voltage
LM25145 D016_snvsai4.gif
Figure 26. LO Driver Resistance vs VCC Voltage
LM25145 D018_snvsai4.gif
VIN = 6 V
Figure 28. VCC vs ICC Characteristic
LM25145 D022_snvsai4.gif
Figure 30. SS/TRK Current Source vs Junction Temperature