TIDUF43 August   2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Terminology
    2. 1.2 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 TPS1213-Q1 45V, Low IQ, Automotive High-Side Switch Controller With Low-Power Mode and Adjustable Load Wakeup Trigger
      2. 2.3.2 INA296x-Q1 AEC-Q100, –5V to 110V, Bidirectional, 1.1MHz, 8V/μs, Ultra-Precise Current-Sense Amplifier
  9. 3System Design Theory
    1. 3.1 Low-Power Mode Considerations
    2. 3.2 Precharge Circuit Considerations
    3. 3.3 Short-Circuit Protection
    4. 3.4 LM74704-Q1 Enable
    5. 3.5 Headers
      1. 3.5.1 Headers for Configuring INA296B-Q1
      2. 3.5.2 Headers for Configuring TPS1213-Q1
    6. 3.6 Software Considerations
      1. 3.6.1 Fuse Channel Definition
      2. 3.6.2 Software Functions
    7. 3.7 Optional Output TVS Diode
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software
    3. 4.3 Test Setup
    4. 4.4 Test Results
      1. 4.4.1 State Transition
      2. 4.4.2 System IQ in Low-Power Mode
      3. 4.4.3 Precharge Test
      4. 4.4.4 Overcurrent Protection
      5. 4.4.5 PWM Overcurrent
      6. 4.4.6 Short-Circuit Protection
      7. 4.4.7 Thermal Testing
      8. 4.4.8 CISPR-25 Emissions Testing
        1. 4.4.8.1 Conducted Emissions Testing
        2. 4.4.8.2 Radiated Emissions Testing
        3. 4.4.8.3 Summary of Results
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
      3. 5.1.3 PCB Layout Recommendations
        1. 5.1.3.1 Layout Prints
      4. 5.1.4 Altium Project
      5. 5.1.5 Gerber Files
      6. 5.1.6 Assembly Drawings
    2. 5.2 Documentation Support
    3. 5.3 Support Resources
    4. 5.4 Trademarks
  12. 6About the Author

3.1 Low-Power Mode Considerations

All components were selected to consume less than 40μA in low-power mode. This quiescent current is mostly comprised from the TPS1213-Q1, which consumes a low IQ of 35μA when driving the low-power path FET. Since the INA296B-Q1 does not have an enable pin, the TPS22919-Q1 load switch was used to control the state of the INA296B-Q1 in low-power mode. Table 3-2 shows the quiescent current for all devices in low-power mode.

Table 3-1 Component Quiescent Currents
DEVICEIQ (LOW-POWER MODE)
TPS1213-Q135μA
INA296B-Q1N/A
TPS22919-Q10.002μA
TPS7B81-Q12.7μA
LM74704-Q11μA
MSPM0L1306-Q1(Standby Mode)1.4μA

Figure 3-1 shows the TPS1213-Q1 schematic. Because the LM74704-Q1 is disabled in low-power mode, a drop-in output voltage around 0.7V is expected due to the internal FET diode of Q1 conducting.

TIDA-020065 TPS1213-Q1 SchematicFigure 3-1 TPS1213-Q1 Schematic

When selecting the load wakeup trigger threshold, which is 200mA for this design, use Equation 1:

Equation 1. RBYPASS(Ω)=(2μA×RISCP+19mV)ILWU-RDSON_BYPASS

where

  • RISCP (R8) is the resistor selected based on the set short-circuit threshold using Equation 5
  • ILWU is the desired load current wakeup threshold
  • RDSON_BYPASS = 25.8mΩ
  • RBYPASS also helps to limit the current as well as stress on Q3 during power up into short-circuit

Either R4 or R11 can be used for the RBYPASS depending if a high-side or low-side resistor is desired.

For pre-release TPS1213-Q1 silicon, use Equation 2 instead of Equation 1.

Equation 2. RBYPASS(Ω)=(2μA×RISCP+10mV)ILWU-RDSON_BYPASS