SLVSH18 December   2024 TPS4HC120-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1.     6
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 SNS Timing Characteristics
    7. 5.7 Switching Characteristics
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Pin Current and Voltage Conventions
      2. 6.3.2 Low Power Mode
      3. 6.3.3 Accurate Current Sense
      4. 6.3.4 Adjustable Current Limit
      5. 6.3.5 Inductive-Load Switching-Off Clamp
      6. 6.3.6 Fault Detection and Reporting
        1. 6.3.6.1 Diagnostic Enable Function
        2. 6.3.6.2 Multiplexing of Current Sense
        3. 6.3.6.3 FAULT Reporting
        4. 6.3.6.4 Fault Table
      7. 6.3.7 Full Diagnostics
        1. 6.3.7.1 Short-to-GND and Overload Detection
        2. 6.3.7.2 Open-Load Detection
          1. 6.3.7.2.1 Channel On
          2. 6.3.7.2.2 Channel Off
        3. 6.3.7.3 Short-to-Battery Detection
        4. 6.3.7.4 Reverse-Polarity and Battery Protection
        5. 6.3.7.5 Thermal Fault Detection
          1. 6.3.7.5.1 Thermal Protection Behavior
      8. 6.3.8 Full Protections
        1. 6.3.8.1 UVLO Protection
        2. 6.3.8.2 Loss of GND Protection
        3. 6.3.8.3 Loss of Power Supply Protection
        4. 6.3.8.4 Reverse Polarity Protection
        5. 6.3.8.5 Protection for MCU I/Os
    4. 6.4 Device Functional Modes
      1. 6.4.1 Working Mode
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curves
    3. 7.3 EMC Transient Disturbances Test
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
      2. 7.5.2 Layout Examples
        1. 7.5.2.1 Without a GND Network
        2. 7.5.2.2 With a GND Network
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.4 Adjustable Current Limit

A high-accuracy adjustable current limit allows higher reliability, which protects the power supply and wires during short circuit or power up by being programed to an acceptable level. Also, current limiting can save system costs by reducing PCB traces, connector size, capacity of the preceding power stage and possibly reducing wire gauge.

Current limit offers protection from over-stressing to the load and integrated power FET. the current limit regulates the output current to the set value, asserts the FLT pin, and pulls up the SNS pin to VSNSFH if the device is set up to output that channel on the SNS pin.

  • The device can be programmed to different current limit values through an external resistor on the ILIM pin. There are 10 current limit settings which can be set based on resistors values in Table 6-1. ≤1% tolerance resistors should be used for RILIM resistor.
    Table 6-1 Current Limit Setting Through External Resistor
    ALLOWED RESISTOR VALUE(1) ILIM THRESHOLD
    57.6kΩ 250mA
    43.2kΩ 500mA
    31.6kΩ 750mA
    23.2kΩ 1A
    16.5kΩ 1.25A
    9.76kΩ 1.5A
    4.87kΩ 1.75A
    2.49kΩ 2A
    Short to GND (<1.1kΩ) 2.25A
    Open (>60 kΩ) 5A
Note: Any resistor settings that are not listed in this table can be interpreted as one of the adjacent levels, which is not a recommended configuration.

To set a different inrush current limit and steady state current limit, the current limit resistor can be changed dynamically when the device is ON. MOSFET based control scheme can be adopted for changing the current limit on the fly. However, the components and the layout at ILIM pin need to be considered carefully to minimize the capacitance at the pin. Any capacitance ≥ 100pF at ILIM pin might affect the current limit functionality. MOSFET with low input capacitance needs to be selected for dynamic current limit.

A current limit event occurs when IOUTx reaches the regulation threshold level, ICL. When IOUT reaches the current limit threshold, ICL, the device can remain enabled and limit IOUTx to ICL. When the device remains enabled (and limits IOUT), thermal shutdown may be triggered due to the high amount of power dissipation in the FET. The regulation loop response when the device is enabled into a short circuit is shown in Figure 6-7. Please note that the current may peak at a higher value (ICL_ENPS) than the regulation threshold (ICL).

When an over-current event occurs, the current limit must respond quickly in order to limit the peak current seen on short circuits (both hot and enabling into a short). The peak has to be limited to ensure that the supply does not droop for a given amount of supply capacitance. This is especially important in applications where the device is powered from a DC/DC instead of car battery.

TPS4HC120-Q1 Enable Into Short Current Limit Figure 6-7 Enable Into Short Current Limit

However, a higher (ICL_LINPK) output current than the current limit regulation loop threshold (ICL) may be available from the switch during an overload condition before the current limitation is applied.

TPS4HC120-Q1 Linear Peak From Soft Short Figure 6-8 Linear Peak From Soft Short

The device applies a strong pulldown to limit the current during the short circuit event while the switch is enabled. The current will then drop down to zero before the current limit regulation loop engages and the switch turn-on and the behavior will be similar to the enable into a short circuit case.

TPS4HC120-Q1 Hot Short Event Figure 6-9 Hot Short Event