ZHCSCR7A June   2014  – November 2020 TPS2559

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Device Comparison Table
  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 Timing Diagrams
    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 Thermal Sense
      2. 8.3.2 Overcurrent Protection
      3. 8.3.3 FAULT Response
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operation with VIN Undervoltage Lockout (UVLO) Control
      2. 8.4.2 Operation with EN Control
  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 Step-by-Step Design Procedure
        2. 9.2.2.2 Input and Output Capacitance
        3. 9.2.2.3 Programming the Current-Limit Threshold
        4. 9.2.2.4 Design Above a Minimum Current Limit
        5. 9.2.2.5 Design Below a Maximum Current Limit
        6. 9.2.2.6 Accounting for Resistor Tolerance
        7. 9.2.2.7 Power Dissipation and Junction Temperature
        8. 9.2.2.8 Auto-Retry
        9. 9.2.2.9 Two-Level Current-Limit
      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 Receiving Notification of Documentation Updates
    2. 12.2 Support Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

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9.2.2.6 Accounting for Resistor Tolerance

The previous sections described the selection of R(ILIM) given certain application requirements and the importance of understanding the current-limit threshold tolerance. The analysis focused only on the TPS2559 is bounded by an upper and lower tolerance centered on a nominal resistance. The additional RILIM resistance tolerance directly affects the current-limit threshold accuracy at a system level. Table 9-2 lists a process that accounts for worst-case resistor tolerance assuming 1% resistor values.

Step one follows the selection process outlined in the application examples above.

Step two determines the upper and lower resistance bounds of the selected resistor.

Step three uses the upper and lower resistor bounds in the IOS equations to calculate the threshold limits.

It is important to use tighter tolerance resistors, that is, 0.5% or 0.1%, when precision current limiting is desired.

Table 9-2 Common R(ILIM) Resistor Selections
DESIRED NOMINAL
CURRENT LIMIT
(mA)		 IDEAL RESISTOR
(kΩ)		 CLOSEST 1%
RESISTOR
(kΩ)		 RESISTOR TOLERANCE ACTUAL LIMITS
1% LOW
(kΩ)		 1% HIGH
(kΩ)		 IOS MIN
(mA)		 IOS NOM
(mA)		 IOS MAX
(mA)
1250 94.1 93.1 92.2 94 1153 1264 1348
1500 78.4 78.7 77.9 79.5 1372 1495 1588
1750 67.2 66.5 65.8 67.2 1633 1770 1874
2000 58.8 59 58.4 59.6 1847 1995 2107
2250 52.3 52.3 51.8 52.8 2090 2551 2373
2500 47.1 47.5 47 48 2306 2478 2610
2750 42.8 43.2 42.8 43.6 2541 2725 2866
3000 39.2 39.2 38.8 39.6 2805 3003 3155
3250 36.2 36.5 36.1 36.9 3016 3226 3386
3500 33.6 34 33.7 34.3 3241 3463 3633
3750 31.4 31.6 31.3 31.9 3491 3726 3907
4000 29.4 29.4 29.1 29.7 3757 4005 4197
4250 27.7 28 27.7 28.3 3947 4206 4405
4500 26.1 26.1 25.8 26.4 4238 4512 4724
4750 24.8 24.9 24.7 25.1 4445 4730 4950