SLVSGL6A July   2022  – December 2022 TPS1HC30-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 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 SNS Timing Characteristics
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Accurate Current Sense
      2. 8.3.2 Programmable Current Limit
        1. 8.3.2.1 Capacitive Charging
      3. 8.3.3 Inductive-Load Switching-Off Clamp
      4. 8.3.4 Full Protections and Diagnostics
        1. 8.3.4.1  Short-Circuit and Overload Protection
        2. 8.3.4.2  Open-Load and Short-to-Battery Detection
        3. 8.3.4.3  Short-to-Battery Detection
        4. 8.3.4.4  Reverse-Polarity and Battery Protection
        5. 8.3.4.5  Latch-Off Mode
        6. 8.3.4.6  Thermal Protection Behavior
        7. 8.3.4.7  UVLO Protection
        8. 8.3.4.8  Loss of GND Protection
        9. 8.3.4.9  Loss of Power Supply Protection
        10. 8.3.4.10 Reverse Current Protection
        11. 8.3.4.11 Protection for MCU I/Os
      5. 8.3.5 Diagnostic Enable Function
    4. 8.4 Device Functional Modes
      1. 8.4.1 Working Mode
  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 Dynamically Changing Current Limit
        2. 9.2.2.2 EMC Transient Disturbances Test
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
        1. 9.4.2.1 Without a GND Network
        2. 9.4.2.2 With a GND Network
      3. 9.4.3 Thermal Considerations
  10. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.2 Programmable Current Limit

A high-accuracy current limit allows higher reliability, which protects the power supply during short circuit or power up. Also, a current limit can save system costs by reducing PCB traces, connector size, and the capacity of the preceding power stage.

Current limit offers protection from over-stressing to the load and integrated power FET. Current limit holds the current at the set value, and pulls up the SNS pin to VSNSFH and asserts the FLT pin as diagnostic reports. The three current-limit thresholds are:

  • External programmable current limit – An external resistor, RILIM, is used to set the channel current limit. When the current through the device exceeds ICL (current limit threshold), a closed loop steps in immediately. VGS voltage regulates accordingly, leading to the VDS voltage regulation. When the closed loop is set up, the current is clamped at the set value. The external programmable current limit provides the capability to set the current-limit value by application.

    Additionally, this value can be dynamically changed by changing the resistance on the ILIM pin. This information can be seen in the Applications section.

  • Internal current limit: ILIM pin shorted to ground – If the external current limit is out of range on the lower end or the ILIM pin is shorted to ground, the internal current limit is fixed and typically 12 A. To use the internal current limit for large-current applications, tie the ILIM pin directly to the device GND.
  • Internal current limit: ILIM pin open – If the external resistor is out of range on the higher end or the ILIM pin is open, the current limit reverts to 6 A or half the current limit range. This level is still above the nominal operation for the device to operate in DC STEADY state, but is low enough that if a pin fault occurs and the RILIM opens up, the current does not default to the highest rating and put additional stress on the power supply.

Both the internal current limit (Ilim,nom) and external programmable current limit are always active when VBB is powered and EN is high. The lower value one (of ILIM and the external programmable current limit) is applied as the actual current limit. The typical deglitch time for the current limit to assert is 2.5 µs.

Note that if a GND network is used (which leads to the level shift between the device GND and board GND), the ILIM pin must be connected with device GND. Use Equation 2 to calculate RILIM.

Equation 2. RILIM = KCL / ILIM

For better protection from a "hot short" condition (when VBB is high, channel is on, and a short to GND happens suddenly), an overcurrent protection, OVCR, circuit is triggered that makes sure to limit the maximum current the device allows to go through. With this OVCR, the device is protected during "hot short" events.

For more information about the current limiting feature, see the Short-Circuit and Overload Protection section.

Current Limit Accuracy Across VDS

The TPS1HC30-Q1 has very tight accuracy of the current limit regulation level across the full range of currents and temperature. This accuracy is defined at several defined RILIM values, 7.15 kΩ, 25 kΩ, and 71.5 kΩ specified in the Electrical Characteristics at VDS = 3 V. However, as VDS (VBB – VOUT) increases , the current regulation value also slightly increases. Taking a typical device, at the 3 different current limits ranges specified, sweeping the VDS voltage, and plotting the regulation value gives the graphs below.

Figure 8-4 Current Limit Regulation With Varying VDS, RILIM = 25 kΩ
Figure 8-5 Current Limit Regulation With Varying VDS, RILIM = 71.5 kΩ
Figure 8-6 Current Limit Regulation With Varying VDS, RILIM = 7.15 kΩ

Using a point during the regulation time of each of the different RILIM settings, the graph can be normalized to the specification in the electrical characteristics of VDS = 3 V which results in graph below.

Figure 8-7 Current Limit Regulation Percentage Change With Varying VDS

Using this figure, the current limit regulation value can be estimated for any current limit value desired based on the VDS value seen in the application. These graphs were taken on a typical device and should be used as reference when accounting for current limit tolerances. As an example see table below for regulation values based on setting the current limit close to the maximum load current. Note that RILIM tolerances are not factored into analysis below.

Max Load Current for Application RILIM KCL Minimum Current Limit (at VDS = 3 V) Short Circuit Regulation value at VBB = VDS = 18 V
1.5 A 47.5 kΩ 92.4 A × kΩ 1.53 A (1.94 A -21%) 2.5 A, +11%
3 A 25 kΩ 90 A × kΩ 3.06 A (3.6 A - 15%) 4.6A, +13%
6A 11.3 kΩ 88.2A × kΩ 6.03 A (7.8 A - 23%) 10.6 A, +11%