SLVSH18B December   2024  – July 2025 TPS4HC120-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 Timing Characteristics, SNS
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Pin Current and Voltage Conventions
      2. 7.3.2 Low Power Mode
        1. 7.3.2.1 Entry into LPM
        2. 7.3.2.2 During LPM
        3. 7.3.2.3 Exiting LPM
      3. 7.3.3 Accurate Current Sense
      4. 7.3.4 Adjustable Current Limit
      5. 7.3.5 Inductive-Load Switching-Off Clamp
      6. 7.3.6 Fault Detection and Reporting
        1. 7.3.6.1 Diagnostic Enable Function
        2. 7.3.6.2 Multiplexing of Current Sense
        3. 7.3.6.3 FAULT Reporting
        4. 7.3.6.4 Fault Table
      7. 7.3.7 Full Diagnostics
        1. 7.3.7.1 Short-to-GND and Overload Detection
        2. 7.3.7.2 Open-Load Detection
          1. 7.3.7.2.1 Channel On
          2. 7.3.7.2.2 Channel Off
        3. 7.3.7.3 Short-to-Battery Detection
        4. 7.3.7.4 Reverse-Polarity and Battery Protection
        5. 7.3.7.5 Thermal Fault Detection
          1. 7.3.7.5.1 Thermal Protection Behavior
      8. 7.3.8 Full Protections
        1. 7.3.8.1 UVLO Protection
        2. 7.3.8.2 Loss of GND Protection
        3. 7.3.8.3 Loss of Power Supply Protection
        4. 7.3.8.4 Reverse Polarity Protection
        5. 7.3.8.5 Protection for MCU I/Os
    4. 7.4 Device Functional Modes
      1. 7.4.1 Working Modes
        1. 7.4.1.1 SLEEP
        2. 7.4.1.2 DIAGNOSTIC
        3. 7.4.1.3 ACTIVE
        4. 7.4.1.4 STANDBY DELAY
        5. 7.4.1.5 LOW POWER MODE
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 EMC Transient Disturbances Test
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Examples
        1. 8.4.2.1 Without a GND Network
        2. 8.4.2.2 With a GND Network
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • DGQ|28
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.4 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 help 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 are set based on resistors values in Table 7-1. Tolerance resistors ≤ 1% are recommended for the RILIM resistor.

Table 7-1 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 (> 60kΩ) 5A
(1) Interpret any resistor settings that are not listed in this table as one of the adjacent levels, which are not recommended configurations.

To set a different inrush current limit and steady state current limit, the current limit resistor is able to change dynamically when the device is on. Adopt the MOSFET-based control scheme to change the current limit on the fly. However, carefully consider the components and the layout at ILIM pin to minimize the capacitance at the pin. Any capacitance ≥ 100pF at ILIM pin possibly affects the current limit functionality. Select a MOSFET with low input capacitance for the 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 is able to remain enabled and limit IOUTx to ICL. When the device remains enabled (and limits IOUT), thermal shutdown potentially triggers due to the high amount of power dissipation in the FET. Figure 7-7 shows the regulation loop response when the device is enabled into a short circuit. The figure shows the scenario with the auto-retry version listed in Section 4. The LATCH version latches off after the first thermal shutdown. Be aware that the current peak is able to be at a higher value (ICL_ENPS) than the regulation threshold (ICL).

When an overcurrent event occurs, the current limit must respond quickly to limit the peak current seen on short circuits (both hot and enabling into a short). Limit the peak so that the supply does not droop for a given amount of supply capacitance. This peak limiting 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 (Auto-Retry Version)Figure 7-7 Enable Into Short Current Limit (Auto-Retry Version)

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

TPS4HC120-Q1 Linear Peak From Soft Short (Auto-Retry Version)Figure 7-8 Linear Peak From Soft Short (Auto-Retry Version)

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

TPS4HC120-Q1 Hot Short Event (Auto-Retry Version)Figure 7-9 Hot Short Event (Auto-Retry Version)