SNVS902A October   2012  – October 2015 TPS92640 , TPS92641

PRODUCTION DATA.  

  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  Controlled On-Time Architecture
      2. 7.3.2  Switching Frequency
      3. 7.3.3  Average LED Current
      4. 7.3.4  Analog Dimming and True-Zero Operation
      5. 7.3.5  Undervoltage Lockout (UVLO)
      6. 7.3.6  PWM Dimming Using the UDIM Pin
      7. 7.3.7  External Shunt FET PWM Dimming
      8. 7.3.8  VCC Regulation and Start-up
      9. 7.3.9  Precision Reference
      10. 7.3.10 Control Loop Compensation
      11. 7.3.11 Overcurrent Protection
      12. 7.3.12 Overvoltage Protection (OVP)
      13. 7.3.13 Boot Undervoltage Lockout (UVLO)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Low Power Shutdown Using the UDIM Pin
      2. 7.4.2 Thermal Shutdown
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Switching Frequency
      2. 8.1.2 LED Ripple Current
      3. 8.1.3 Buck Converters Without Output Capacitor
      4. 8.1.4 Input Capacitor
      5. 8.1.5 NFETs
    2. 8.2 Typical Applications
      1. 8.2.1 TPS92640: Design Procedure
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Set Output Voltage Feedback Ratio
          2. 8.2.1.2.2 Set Switching Frequency
          3. 8.2.1.2.3 Set Average LED Current
          4. 8.2.1.2.4 Set Inductor Ripple Current
          5. 8.2.1.2.5 Set LED Ripple Current and Determine Output Capacitance, COUT
          6. 8.2.1.2.6 Choose N-Channel MOSFETs
          7. 8.2.1.2.7 Choose Input Capacitance
          8. 8.2.1.2.8 Set the Turnon Voltage and Undervoltage Lockout Hysteresis
      2. 8.2.2 TPS92640 - PWM Dimming Application
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Calculate Operating Points
          2. 8.2.2.2.2 Output Voltage Feedback
          3. 8.2.2.2.3 Switching Frequency
          4. 8.2.2.2.4 Set the Feedback Reference and LED Current
          5. 8.2.2.2.5 Calculate the Inductor Value
          6. 8.2.2.2.6 Calculate the Output Capacitor Value
          7. 8.2.2.2.7 Calculate the MOSFET Parameters
          8. 8.2.2.2.8 Calculate the Minimum Input Capacitance
          9. 8.2.2.2.9 Undervoltage Lockout and Hysteresis
        3. 8.2.2.3 Application Curve
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 EMI and Noise Considerations
  11. 11Device and Documentation Support
    1. 11.1 Related Links
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)
MIN MAX UNIT
VIN, UDIM, SW –0.3 90 V
–1 mA
BOOT –0.3 98.5 V
HG –0.3 90 V
–2.5 (Pulse < 100 ns) V
LG, SDRV, CS –0.3 +VCC V
–2.5 (Pulse < 100 ns) V
VCC + 2.5 (Pulse < 100 ns) V
VCC –0.3 15 V
VREF, RON, COMP, VOUT, IADJ, SDIM –0.3 6 V
–200 200 µA
GND –0.3 0.3 V
–2.5 (Pulse < 100 ns) 2.5 (Pulse < 100 ns) V
Continuous power dissipation Internally Limited
Maximum lead temperature (soldering and reflow) (2) 260 °C
Maximum junction temperature –40 125 °C
Storage temperature –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) Refer to TI’s packaging website for more detailed information and mounting techniques.

6.2 ESD Ratings

VALUE UNIT
TPS92640 PWP PACKAGE
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
TPS92641 PWP PACKAGE
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.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN NOM MAX UNIT
VIN Input voltage 7 85 V
TJ Junction temperature –40 125 °C

6.4 Thermal Information

THERMAL METRIC(1) TPS92640 TPS92641 UNIT
PWP (HTSSOP) PWP (HTSSOP)
14 PINS 16 PINS
RθJA Junction-to-ambient thermal resistance 40.1 38.7 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 24.6 22.7 °C/W
RθJB Junction-to-board thermal resistance 20.9 16.5 °C/W
ψJT Junction-to-top characterization parameter 0.6 0.6 °C/W
ψJB Junction-to-board characterization parameter 20.7 16.3 °C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance 2.5 1.7 °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953.

6.5 Electrical Characteristics

Unless otherwise specified VIN = 24 V. Typical specifications apply for TA = TJ = 25°C.
PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT
START-UP REGULATOR (VCC, VIN)
VCCREG VCC Regulation ICC = 10 mA, VIN = 24 V, 85 V 7.86 8.5 9.14 V
ICCLIM VCC Current Limit VCC = 0 V 48 63 78 mA
IQ Quiescent Current VUDIM = 3 V,
Static VIN = 7 V, 24 V, 85 V		 2 3 mA
ISD Shutdown Current VUDIM = 0 V 100 µA
VCC-UV VCC UVLO Threshold VCC increasing 5.04 5.9 V
VCC decreasing 4.5 4.9
VCC-HYS VCC UVLO Hysteresis 0.17 V
REFERENCE VOLTAGE (VREF)
VREF Reference Voltage No Load, VIN = 7 V, 24 V, 85 V 2.97 3.03 3.09 V
IVREFLIM Current Limit VREF = 0 V 1.3 2.1 2.9 mA
ERROR AMPLIFIER (CS, COMP)
VCSREF CS Reference Voltage With respect to GND VIADJ/10 V
VCSREF-OFF Error Amp Input Offset Voltage –600 0 600 µV
ICOMP COMP Sink Current 85 µA
COMP Source Current 110 µA
gM-CS Transconductance 500 µA/V
Linear Input Range See (3) ±125 mV
Transconductance Bandwidth –6-dB unloaded response(3) 400 kHz
TIMERS / OVERVOLTAGE PROTECTION (RON, VOUT)
tOFF-MIN Minimum Off-time CS = 0 V 230 ns
tON-MIN Minimum On-time 235 ns
tON Programmed On-time VVOUT = 2 V, RON = 25 kΩ, CON = 1 nF 2.08 µs
RRON RON Pulldown Resistance 35 120 Ω
tCL Current Limit Off-time 270 µs
tD-ON RON Thresh - HG Falling Delay 25 ns
VTH-OVP VOUT Overvoltage Threshold VOUT rising 2.85 3.05 3.25 V
VHYS-OVP VOUT Overvoltage Hysteresis 0.13 V
GATE DRIVER (HG, LG, BOOT, SW)
RSRC-LG LG Sourcing Resistance LG = High 1.5 6 Ω
RSNK-LG LG Sinking Resistance LG = Low 1 4.5 Ω
RSRC-HG HG Sourcing Resistance HG = High 3.9 6 Ω
RSNK-HG HG Sinking Resistance HG = Low 1.1 4.5 Ω
VTH-BOOT BOOT UVLO Threshold BOOT-SW rising 1.9 3.4 4.5 V
VHYS-BOOT BOOT UVLO Hysteresis BOOT-SW falling 1.8 V
TD-HL HG to LG deadtime HG fall to LG rise 60 ns
TD-LH LG to HG deadtime LG fall to HG rise 60 ns
PWM DIMMING (SDIM, SDRV) (TPS92641 only)
RSRC-DDRV SDRV Sourcing Resistance SDRV = High 5.6 30 Ω
tSDIM-RIS SDIM to SDRV Rising Delay SDIM rising 68 100 ns
tSDIM -FALL SDIM to SDRV Falling Delay SDIM falling 29 70 ns
VSDIM-RIS SDIM Rising Threshold SDIM rising 1.29 1.74 V
VSDIM -FALL SDIM Falling Threshold SDIM falling 0.5 V
RSDIM-PU SDIM Pullup Resistance 90 kΩ
ANALOG ADJUST (IADJ)
VADJ-MAX IADJ Clamp Voltage 2.46 2.54 2.62 V
RADJ IADJ Input Impedance 1 MΩ
UNDERVOLTAGE / PWM (UDIM)
VTH-UDIM UDIM Start-up Threshold UDIM rising 1.21 1.276 1.342 V
IHYS-UDIM UDIM Hysteresis Current 12 21 30 µA
tUDIM-RIS UDIM to HG/LG Rising Delay UDIM rising 168 260 ns
tUDIM-FALL UDIM to HG/LG Falling Delay UDIM falling 174 280 ns
VUDIM-LP UDIM Low Power Threshold 370 mV
TUDIM-DET UDIM Shutdown Detect Timer UDIM falling 8.5 13 ms
THERMAL SHUTDOWN
TSD Thermal Shutdown Threshold See (3) 165 °C
THYS Thermal Shutdown Hysteresis See (3) 20 °C
(1) All limits specified at room temperature (TYP values) and at temperature extremes (MIN/MAX values). All room temperature limits are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
(2) Typical numbers are at 25°C and represent the most likely norm.
(3) These electrical parameters are specified by design, and are not verified by test.

6.6 Typical Characteristics

Unless otherwise stated, –40°C ≤ TA = TJ ≤ 125°C, VIN = 24 V, VIADJ= 2 V, ILED = 1 A, CVCC = 2.2 μF, CCOMP = 0.47 μF
TPS92640 TPS92641 C001_SNVS902.png
Figure 1. Quescient Current, IQ vs Input Voltage, VIN
TPS92640 TPS92641 C003_SNVS902.png
Figure 3. Start-Up Regulator, VCC vs Input Voltage, VIN
TPS92640 TPS92641 C005_SNVS902.png
Figure 5. Minimum On-time, tON_MIN vs Input Voltage, VIN
TPS92640 TPS92641 C007_SNVS902.png
Figure 7. LED Current, ILED vs Input Voltage, VIN
TPS92640 TPS92641 C009_SNVS902.png
Figure 9. Converter Switching Frequency, fSW vs Input Voltage, VIN
TPS92640 TPS92641 SS_Waveform.gif
Figure 11. Waveforms of Steady-State Operation
TPS92640 TPS92641 C002_SNVS902.png
Figure 2. Shutdown Current, ISDvs Input Voltage , VIN
TPS92640 TPS92641 C004_SNVS902.png
Figure 4. Reference Voltage, VREF vs Input Voltage, VIN
TPS92640 TPS92641 C006_SNVS902.png
Figure 6. Minimum Off-time, tOFF_MIN vs Input Voltage, VIN
TPS92640 TPS92641 C008_SNVS902.png
Figure 8. Conversion Efficiency, η vs Input Voltage, VIN
TPS92640 TPS92641 PU_Waveform.gif
Figure 10. Waveforms of Power-Up Transient
TPS92640 TPS92641 UDIM_Waveform.gif
Figure 12. Waveforms of UDIM Operation (DDIM = 0.5)