SNVS593J October   2008  – November 2014 LM25085 , LM25085-Q1

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 Handling Ratings - LM25085
    3. 6.3 Handling Ratings - LM25085-Q1
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Electrical Characteristics
    7. 6.7 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  Regulation Control Circuit
      2. 7.3.2  On-Time Timer
      3. 7.3.3  Shutdown
      4. 7.3.4  Current Limiting
      5. 7.3.5  Current Limit Off-Time
      6. 7.3.6  VCC Regulator
      7. 7.3.7  PGATE Driver Output
      8. 7.3.8  P-Channel MOSFET Selection
      9. 7.3.9  Soft-Start
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Standby Mode with VIN <4.5 V
      2. 7.4.2 RT Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  RFB1 and RFB2
        2. 8.2.2.2  RT, PFET
        3. 8.2.2.3  L1
        4. 8.2.2.4  RSEN, RADJ
        5. 8.2.2.5  COUT
        6. 8.2.2.6  R3, C1, C2
        7. 8.2.2.7  Alternate Output Ripple Configurations
          1. 8.2.2.7.1 Reduced Ripple Configuration
          2. 8.2.2.7.2 Lowest Cost Configuration
        8. 8.2.2.8  CIN, CBYP
        9. 8.2.2.9  D1
        10. 8.2.2.10 CVCC
        11. 8.2.2.11 IC Power Dissipation
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    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 Related Links
    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

See (1)(1) MIN MAX UNIT
VIN to GND -0.3 45 V
ISEN to GND -3 VIN + 0.3 V
ADJ to GND -0.3 VIN + 0.3 V
RT, FB to GND -0.3 7 V
VIN to VCC, VIN to PGATE -0.3 10 V
(1) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications.

6.2 Handling Ratings - LM25085

MIN MAX UNIT
Tstg Storage temperature range -65 150 °C
V(ESD) Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins(1) 2 kV
Charged device model (CDM), per JEDEC specification JESD22-C101, all pins(2) 750 V
(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 Handling Ratings - LM25085-Q1

MIN MAX UNIT
Tstg Storage temperature range -65 150 °C
V(ESD) Electrostatic discharge Human body model (HBM), per AEC Q100-002(1) 2 kV
Charged device model (CDM), per AEC Q100-011 Corner pins 1, 4, 5, 8 750 V
Other pins 750
(1) AEC Q100-002 indicates HBM stressing is done in accordance with the ANSI/ESDA/JEDEC JS-001 specification.

6.4 Recommended Operating Conditions

Over operating free-air temperature range (unless otherwise noted)
MIN MAX UNIT
VIN Voltage 4.5 42 V
Junction Temperature −40 125 °C

6.5 Thermal Information

THERMAL METRIC(1) LM25085 LM25085 / Q-1 LM25085 UNIT
VSSOP HVSSOP-PowerPAD WSON
8 PINS 8 PINS 8 PINS
RθJA Junction-to-ambient thermal resistance 153 54.1 44.8 °C/W
RθJC Junction-to-case (top) thermal resistance 52.5 49.1 39.4
RθJB Junction-to-board thermal resistance 71.9 26.7 11.6
ψJT Junction-to-top characterization parameter 4.6 1.3 0.3
ψJB Junction-to-board characterization parameter 70.8 26.5 11.6
RθJC(bot) Junction-to-case (bottom) thermal resistance 29 3.6 5.0
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

6.6 Electrical Characteristics

Typical values correspond to TJ = 25°C. Minimum and maximum limits apply over –40°C to 125°C junction temperature range, unless otherwise stated. VIN = 24V, RT = 100kΩ unless otherwise stated. (See (5)).
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VIN PIN
IIN Operating Current Non-Switching, FB = 1.4V (3) 1.25 1.75 mA
IQ Shutdown Current RT = 0V (3) 175 300 µA
VCC REGULATOR (2)
VCC(reg) VIN - VCC Vin = 9V, FB = 1.4V, ICC = 0mA 6.9 7.7 8.5 V
Vin = 9V, FB = 1.4V, ICC = 20mA 7.7 V
Vin = 42V, FB = 1.4V, ICC = 0mA 7.7 V
UVLOVcc VCC Under-Voltage Lock-Out Threshold VCC Increasing 3.8 V
UVLOVcc Hysteresis VCC Decreasing 260 mV
VCC(CL) VCC Current Limit FB = 1.4V 20 40 mA
PGATE PIN
VPGATE(HI) PGATE High Voltage PGATE Pin = Open VIN -0.1 VIN V
VPGATE(LO) PGATE Low Voltage PGATE Pin = Open VCC VCC+0.1 V
VPGATE(HI)4.5 PGATE High Voltage at Vin = 4.5V PGATE Pin = Open VIN -0.1 VIN V
VPGATE(LO)4.5 PGATE Low Voltage at Vin = 4.5V PGATE Pin = Open VCC VCC+0.1 V
IPGATE Driver Output Source Current VIN = 12V, PGATE = VIN - 3.5V 1.75 A
Driver Output Sink Current VIN = 12V, PGATE = VIN - 3.5V 1.5 A
RPGATE Driver Output Resistance Source current = 500mA 2.3 Ω
Sink current = 500mA 2.3 Ω
CURRENT LIMIT DETECTION
IADJ ADJUST Pin Current Source VADJ = 22.5V 32 40 48 µA
VCL OFFSET Current Limit Comparator Offset VADJ = 22.5V, VADJ - VISEN -9 0 9 mV
RT PIN
RTSD Shutdown Threshold RT Pin Voltage Rising 0.73 V
RTHYS Shutdown Threshold Hysteresis 50 mV
ON-TIME
tON – 1 On-Time VIN = 4.5V, RT = 100kΩ 3.5 5 7.15 µs
tON – 2 VIN = 24V, RT = 100kΩ 560 720 870 ns
tON - 3 VIN = 42V, RT = 100kΩ 329 415 500 ns
tON - 4 Minimum On-Time in Current Limit (4) VIN = 24V, 25mV Overdrive at ISEN 55 140 235 ns
OFF-TIME
tOFF(CL1) Off-Time (Current Limit) (4) VIN = 12V, VFB = 0V 5.35 7.9 10.84 µs
tOFF(CL2) VIN = 12V, VFB = 1V 1.42 1.9 3.03 µs
tOFF(CL3) VIN = 24V, VFB = 0V 8.9 13 17.7 µs
tOFF(CL4) VIN = 24V, VFB = 1V 2.22 3.2 4.68 µs
REGULATION AND OVER-VOLTAGE COMPARATORS (FB PIN)
VREF FB Regulation Threshold 1.225 1.25 1.275 V
VOV FB Over-Voltage Threshold Measured With Respect to VREF 350 mV
IFB FB Bias Current 10 nA
SOFT-START FUNCTION
tSS Soft-Start Time 1.4 2.5 4.3 ms
THERMAL SHUTDOWN
TSD Junction Shutdown Temperature Junction Temperature Rising 170 °C
THYS Junction Shutdown Hysteresis 20 °C
(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is intended to be functional. For specifications and test conditions, see the Electrical Characteristics.
(2) VCC provides self bias for the internal gate drive.
(3) Operating current and shutdown current do not include the current in the RT resistor.
(4) The tolerance of the minimum on-time (tON-4) and the current limit off-times (tOFF(CL1) through (tOFF(CL4)) track each other over process and temperature variations. A device which has an on-time at the high end of the range will have an off-time that is at the high end of its range.
(5) All hot and cold limits are specified by correlating the electrical characteristics to process and temperature variations and applying statistical process control.

6.7 Typical Characteristics

Unless otherwise specified the following conditions apply: TJ = 25°C, VIN = 24V.
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Figure 1. Efficiency (Circuit Of LM25085 Typical Application)
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Figure 3. Shutdown Current vs. VIN
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Figure 5. VCC vs. ICC
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Figure 7. Off-Time vs. VIN And VFB
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Figure 9. Adj Pin Current vs. VIN
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Figure 11. Shutdown Current vs. Temperature
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Figure 13. On-Time vs. Temperature
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Figure 15. Off-Time vs. Temperature
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Figure 17. Adj Pin Current vs. Temperature
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Figure 19. Feedback Reference Voltage vs. Temperature
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Figure 21. Rt Pin Shutdown Threshold vs. Temperature
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Figure 2. Input Operating Current vs. VIN
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Figure 4. VCC vs. VIN
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Figure 6. On-Time vs. RT And VIN
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Figure 8. Voltage At The Rt Pin
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Figure 10. Input Operating Current vs. Temperature
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Figure 12. Vcc vs. Temperature
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Figure 14. Minimum On-Time vs. Temperature
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Figure 16. Current Limit Comparator Offset vs. Temperature
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Figure 18. Pgate Driver Output Resistance vs. Temperature
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Figure 20. Soft-Start Time vs. Temperature