MXL7704 (Raspberry Pi)

The MXL7704 is a programmable quadruple step-down DC/DC converter that is used in the following Raspberry Pi models:


 * Raspberry Pi 3 (A+ and B+) (MXL7704-R3 version)
 * Raspberry Pi 4 (all) (MXL7704-P4 version)

Common cause of failure
If the Pi's 5V pin is shorted to the neighboring 3.3V pin, the MXL7704 will try to clamp the voltage on the 3.3V line. This destroys the MXL7704 chip, leaving the 3.3V line permanently shorted to GND.

Configuring
The MXL7704 chip can be configured via an I2C interface. The I2C address depends on the version of the chip:

Despite having a different I2C address, the R3 version of the chip will be correctly recognized by the OS if it's installed in a Raspberry Pi 4.

Note that any changes made to the configuration are not permanently stored. Every time the chip is powered off, its default configuration is restored. Different versions of the chip have different default configurations:

Here's the meaning of the two default configurations (for more info, see the datasheet linked at the bottom of the page):

The following pads can be used to acces the I2C interface: