Addressing the Issue of Increased Loss in Reverse Polarity Protection Diodes

Units such as ECUs operate using power supplied by a battery, but there is a risk of accidentally connecting the battery with reversed polarity.
If the battery is connected in reverse, current flows in the opposite direction, which can damage the unit. To prevent this, protective measures are put in place.
Because diodes only allow current to flow in one direction, a typical solution is to connect a diode in series between the battery and the unit for reverse polarity protection.
However, during normal operation, current constantly flows through this diode, which leads to continuous power loss calculated as the diode's forward voltage (Vf) multiplied by the current (Iin). Figure 1
In recent years, current consumption in units like ECUs has been increasing. As a result, diode losses have also grown, leading to problems such as diode heating and reduced overall system efficiency.

Solving the Problem with Ideal Diode Controllers MAX16171 / MAX16141

To address this issue, we introduce the ideal diode controllers MAX16171 and MAX16141, developed by the former Maxim.
These controllers replace the traditional reverse polarity protection diode by controlling the ON/OFF state of a MOSFET, preventing reverse current flow and resolving the associated issues.
While the MOSFET also conducts current during normal operation and incurs some loss, this loss—calculated as Rdson multiplied by the current (Iin)—is significantly lower than that of a diode, leading to reduced heat generation and improved system efficiency. Figure 1

Figure 1. Comparing Reverse Polarity Protection Diodes and Ideal Diodes

The MAX16171 provides an inexpensive replacement for reverse polarity diodes using a single FET. In contrast, the MAX16141 utilizes two FETs in a back-to-back configuration. This configuration offers a more robust replacement, providing protection against forward overcurrent and overvoltage in addition to reverse polarity protection.

Table 1. Comparison Table by Solution

To address this issue, we introduce the ideal diode controllers MAX16171 and MAX16141, developed by the former Maxim.
These controllers replace the traditional reverse polarity protection diode by controlling the ON/OFF state of a MOSFET, preventing reverse current flow and resolving the associated issues.
While the MOSFET also conducts current during normal operation and incurs some loss, this loss—calculated as Rdson multiplied by the current (Iin)—is significantly lower than that of a diode, leading to reduced heat generation and improved system efficiency. Figure 1