Dennis Field / dvk-mx8m-bsb - History

Include boot configuration circuit and notes regarding booting from eMMC (USDHC1) vs SD (USDHC2)

Include UART debug interface/header, using a 74LVC2G241 buffer which is 5V tolerant so that either 3.3V or 5V UART cables could be used

Six pin header used so that either 6-pin fixed, 4-pin, or 3-pin cables can be used. Only RX, TX, and GND are used since Vcc, RTS#, and CTS# is unneeded, the other three pins are NC.

Add UART USB cable options, cheaper to bring out UART pins than to implement USB<->Serial adapter on-board

Include uSD card schematic, add note about testing 1.8V LDO in place of the buck

Use a buck for the 1.8V rail for efficiency, include power line ferrite bead, change main buck-boost output caps to 0805 ones, move the main regulator's input caps to the VIN node, include USB power switch circuit's components

The 1.8V buck has a drop-in: "ST1S12G18R"

Use MIC2876 instead of RT6150A due to several advantages which are noted in the schematic

Figure out 5.0V buck-boost's inductor value, include inductor current calculations

Add PTC Fuse, zener on VCC_PJ, USB PD current-limiting switch, 5V regulator, and make regulators' VINA=VIN (since VIH is 1.2V)

Equation for setting NX5P3090's current limit is included.

Add reset & watchdog, sd power, and BASE_PER_1V8 circuits

Add the board ID EEPROM chip and move the 0Ohm resistor such that the coin cell battery would actually power SOM_SNVS_3V3 when removed and the NC resistor is populated

This re-arrengment of the resistor makes the reference schematic more clear knowing that SOM_VBAT_3V3 is not actually LICELL.