SLUSFM1 December   2024 TPS4812-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  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 Switching Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Charge Pump and Gate Driver Output (VS, GATE, BST, SRC)
      2. 8.3.2 Capacitive Load Driving
        1. 8.3.2.1 Using Low-Power Bypass FET (G Drive) for Load Capacitor Charging
        2. 8.3.2.2 Using Main FET (GATE Drive) Gate Slew Rate Control
      3. 8.3.3 Overcurrent and Short-Circuit Protection
        1. 8.3.3.1 I2t-Based Overcurrent Protection
          1. 8.3.3.1.1 I2t-Based Overcurrent Protection With Auto-Retry
          2. 8.3.3.1.2 I2t-Based Overcurrent Protection With Latch-Off
        2. 8.3.3.2 Short-Circuit Protection
      4. 8.3.4 Analog Current Monitor Output (IMON)
      5. 8.3.5 NTC-Based Temperature Sensing (TMP) and Analog Monitor Output (ITMPO)
      6. 8.3.6 Fault Indication and Diagnosis (FLT)
      7. 8.3.7 Reverse Polarity Protection
      8. 8.3.8 Undervoltage Protection (UVLO)
    4. 8.4 Device Functional Modes
      1. 8.4.1 State Diagram
      2. 8.4.2 State Transition Timing Diagram
      3. 8.4.3 Power Down
      4. 8.4.4 Shutdown Mode
      5. 8.4.5 Low Power Mode (LPM)
      6. 8.4.6 Active Mode (AM)
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application 1: Driving Power at all times (PAAT) Loads With Automatic Load Wakeup
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
    3. 9.3 Typical Application 2: Driving Power at all times (PAAT) Loads With Automatic Load Wakeup and Output Bulk Capacitor Charging
      1. 9.3.1 Design Requirements
      2. 9.3.2 External Component Selection
      3. 9.3.3 Application Curves
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
      2. 9.5.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RGE|23
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.3.4 Analog Current Monitor Output (IMON)

TPS4812-Q1 features an accurate analog load current monitor output (IMON) with adjustable gain (ON in active mode and load wakeup only). The current source at IMON terminal is configured to be proportional to the current flowing through the RSNS current sense resistor. This current can be converted to a voltage using a resistor RIMON from IMON terminal to GND pins.

This voltage, computed using following equation, can be used as a means of monitoring current flow through the system.

Use Equation 15 to calculate the V(IMON) for TPS48120-Q1 variant with I2t enabled.

Equation 15. V(IMON) = (VSNS + V(VOS_SET)) × 0.9 × RIMONRSET

Use Equation 16 to calculate the V(IMON) for TPS48121-Q1 variant with I2t disabled.

Equation 16. V(IMON) = (VSNS + V(VOS_SET)) × RIMONRSET

Where,

VSNS = ILOAD × RSNS,

V(OS_SET) is the input referred offset (±140µV) of the current sense amplifier (VSNS to V(IMON) scaling),

0.9 is the current mirror factor between the current sense amplifier and the IMON pass FET.

The maximum voltage range for monitoring the current (V(IMONmax)) is limited to minimum([V(VS) – 0.5V], 5.5V)

to ensure linear output. This puts limitation on maximum value of RIMON resistor. The IMON pin has an internal clamp of 6.5V (typical).

Accuracy of the current mirror factor is <±1%. Use the following equation to calculate the overall accuracy of V(IMON).

Equation 17. % V(IMON) = V(OS_SET)VSNS × 100

TPS4812-Q1 features bi-directional current sensing (across CS1+ and CS1–) and monitoring using IMON output to get magnitude of scaled voltage across RSNS (VSNS) and open drain I_DIR output pin indicating direction of current.

I_DIR output is pulled high if current is flowing in forward direction whereas I_DIR is pulled low for reverse current as shown in below figure.

TPS4812-Q1 TPS4812-Q1 Bi-directional Current Monitoring Timing DiagramFigure 8-11 TPS4812-Q1 Bi-directional Current Monitoring Timing Diagram