Let’s take mobile device charging as an example. How do we design a reverse current protection scheme? If you are unfamiliar with reverse current protection, please refer to “What is Reverse Current?”.
Modern mobile devices have many power supply methods, such as the common TYPE-C DC 5V, internal battery pack power supply 4.2V, or power adapter power supply.
In the second case, when TYPE-C power supply, a MOSFET is used as an electronic switch to block reverse current by controlling the MOSFET’s on/off state.
Circuit Principle:
TYPE-C Independent 5V input via MOSFET AO3401A, at this time, the power supply is not connected, so point A is 0V. The voltage is connected to the gate of Q1 through a 1kΩ resistor R2. To ensure that Q1 conducts stably at 0V, a 10kΩ resistor R1 is also added to pull it to GND. At this point, the current flows through Q1 to the 10uF filter capacitor C6, supplying power to the downstream load. If current flows through the downstream load, Q1 will be cut off, and no current will flow through Q1.
Regarding MOSFET, DigiKey offers many different MOSFETs with various parameters, making it easy to select the appropriate MOSFET based on your circuit requirements.
The advantages of this solution are low voltage drop, low internal resistance, low heat generation, near-ideal diode, and high cost-effectiveness, but it requires more external circuitry compared to diode circuits.
Reverse current protection methods vary. Based on circuit current, efficiency, and cost, we’ll share three reverse current protection solutions:
- Reverse Current Protection - Diode
- Reverse Current Protection - MOSFET
- Reverse Current Protection - Ideal Diode
- Reverse Current Protection - Simultaneous Use of Diode + MOSFET + Ideal Diode
Related Parts: