SLUAAN7A April   2023  – November 2024 TPS1211-Q1 , TPS4811-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1TPS1211-Q1 High Side Switch Controller Overview
  5. 2System Design Examples with Reverse Battery Protection
    1. 2.1 Design 1: Power Distribution Box
    2. 2.2 Design 2: Body Motors Load Driving
    3. 2.3 Design 3: Heater Load Driving
      1. 2.3.1 Reverse Battery Protection with MOSFET OFF
      2. 2.3.2 Reverse Battery Protection with MOSFET ON
  6. 3Summary
  7. 4References
  8. 5Revision History

2.3.2 Reverse Battery Protection with MOSFET ON

Turning the MOSFET Q1 ON during input, the reverse-battery condition address the challenges mentioned in Section 2.3.1. Figure 2-7 shows the TPS12110-Q1 application circuit to turn ON the MOSFET Q1 during reverse battery condition.

TPS12110-Q1 Application Schematic for Driving PTC Heater Load with MOSFET ON During Reverse Battery ConditionFigure 2-7 TPS12110-Q1 Application Schematic for Driving PTC Heater Load with MOSFET ON During Reverse Battery Condition

With the application circuit shown in Figure 2-7, the MOSFET Q1 can be turned on during input reverse battery condition. During input reverse battery condition, the source of the MOSFET Q1 follows the input reverse voltage. D5, R3, R4 path conducts during this condition and turns on Q4. This, then turns off Q3. Q3 is a signal N-FET to disconnect the source of the Q1 to device SRC pin during input reverse battery condition. R6, R5, D4 path conducts and turns ON Q2. The anode of the D1 gets connected to GND through Q2. GATE voltage of Q1 gets pulled to VF of D1 (-1V) and SOURCE terminal to negative VIN minus body diode drop of Q1 (-14V+1V = -13V). This results in VGS drive of -1V-(-13V) = 12V turning on the MOSFET Q1 and load current conducts through the MOSFET of the RDSON of the Q1.

The TPS1211-Q1 gets protected by disconnecting the GND with the help of D2. D3 is placed on the top side of the IMON resistor. With this placement, the IMON signal does not include the D3 voltage drop.

During the normal operation at positive VIN levels, Q2 and Q4 gets turned OFF. Q3 is turned on by the BST drive from TPS1211-Q1 connecting the source of the MOSFET Q1 to the SRC terminal of the TPS1211-Q1. Diode D1 gets disconnected from the GND.

Figure 2-8 shows the waveform of the above application circuit during the -14 V automotive reverse battery test. As shown, the MOSFET Q1 turns on as the gate to source is at approximately12 V level during this test. The following bill of material components were used.

  • D1, D2, D3, D4, D5 = BAS40H,115
  • Q2 = MMBT3906WT1G
  • Q3 = PMV60ENEAR
  • Q4 = MMBT3904WT1G
  • R1, R4, R6 = 10kΩ
  • R2 = 100kΩ
  • R3, R5 = 1kΩ
Performance Graph Showing Reverse Battery Protection with MOSFET ONFigure 2-8 Performance Graph Showing Reverse Battery Protection with MOSFET ON