Figure 2-1 shows an example of power distribution box with two-channel outputs VOUT1 and VOUT2. Input power source can be from a battery or a DC-DC. A grouped input reverse battery protection scheme is implemented using LM74500-Q1 reverse polarity protection controller and an external MOSFET Q1.

The output of the LM74500-Q1 reverse battery protection stage is connected to the TPS12110-Q1 high side switch controllers. The TPS12110-Q1 ICs and the loads connected to the outputs gets protected from the input reverse battery condition by the LM74500-Q1 circuit. During input reverse battery condition the LM74500-Q1 controller pulls GATE to SOURCE and the MOSFET Q1 gets turned OFF disconnecting the input battery connection to the downstream TPS12110-Q1 ICs and the loads.

TPS12110-Q1 does not see reverse voltages and therefore does not need any special reverse protection techniques for this section of the system design.

Figure 2-1 Power Distribution Box with Grouped Reverse Battery Protection Using LM74500-Q1 Controller

Figure 2-2 shows an example of a smartFuse based power distribution box system design without input reverse battery protection switch. VOUT1 is an always ON channel to drive power available all time (PAAT) loads such as door locks, power windows, wireless key system ECU, etc. VOUT2 is a switchable channel allowed to turn OFF during vehicle parking state. This channel can be used to drive actuator or heater loads.

Figure 2-2 Power Distribution Box with Reverse Battery Protection using TPS12141-Q1 smartFuse controller

In system architectures based on the load type the reverse battery, protection is done locally on the load side. However, loads such as heaters do not have any reverse battery protection and can result in reverse currents during reverse battery faults. In this scenario, turn on the MOSFETs to prevent damage due to excessive power dissipation due to body diode conduction. The TPS12141-Q1 from TPS1214-Q1 smartFuse controller family has integrated reverse battery protection with MOSFET turn ON feature. The other features of the TPS1214-Q1, such as low IQ LPM mode with automatic load wakeup functionality, adjustable I2T over current protection makes the device an excellent choice for smartFuse system design.

Figure 2-3 shows reverse battery protection performance of TPS12141-Q1 at -14V input. As shown, the MOSFET turns ON with a gate drive level of 12V.

Figure 2-3 Performance Graph Showing Reverse Battery Protection with MOSFET ON with TPS12141-Q1 smartFuse controller