Taking mobile device charging as an example, how should 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 power 4.2V, or power adapter power.
In the third case, when using independent battery power, the battery power supply is 4.2V, connected to the U1 ideal diode LM66100 input pin. Since the VOUT output is controlled by the CE enable pin… When the voltage at the CE pin is higher than the input voltage, the internal PMOS of the LM66100 is cut off, shutting down the output. When the voltage at the CE pin is relatively low, the internal PMOS is turned on, outputting.
Circuit Principle:
When a 1kΩ resistor R4 is connected to the VOUT terminal (point C), the Zener diode D2 protects the CE pin from damage caused by high voltage or electrostatic discharge. The other two power adapters and TYPE-C are not connected, so the C point potential is 0V. Therefore, CE is 0V, and the LM66100DCK will operate. The output voltage is filtered twice by a 10uF capacitor C2 to power the downstream load.
The LM66100DCK also features Reverse Polarity Protection (RPP), which protects the device from incorrect wiring inputs, such as reversed battery installation.
There are many ideal diodes like the LM66100DCK, such as ADI’s MAX40200 and onsemi’s NCV68061, etc.
The advantages of using an ideal diode solution are comprehensive protection, low voltage drop, low internal resistance, and low heat generation, but the price is slightly higher.
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: