PCM-072/phyCORE-AM64xx System on Module
L-860e.A0
© PHYTEC America L.L.C. 2022
38
B13
X_PGOOD
O
3.3V
SOM/PMIC Power Good Status Output
1
:
The voltage level for this signal is configurable for 1.8V or 3.3V. The default voltage level is listed here, but always check the actual jumper setting for the applicable
SOM configuration. Refer to section
for details
5.4 Power Sequencing
It is mandatory to avoid driving the I/O pins of the phyCORE-AM64xx SOM when the SOM is not fully powered up.
Prematurely driving the pins may cause current to flow through the I/O pins before the processor is properly powered,
potentially resulting in damage or unknown behavior after power-up or reset. Therefore, the peripheral carrier board
power should be switched on/enabled by the X_PGOOD signal to avoid powering external peripherals and circuits that
directly interface with the phyCORE-AM64xx SOM I/Os until their respective voltage domains are powered. X_PGOOD is
a 3.3V level signal that is driven high once the PMIC has finished its power sequencing and the SOM has been powered
on. This should be used to sequence the baseboard power supplies (3.3V, 1.8V, etc.). This ensures that the I/O domains
on the SOM are powered before any external circuits or peripherals drive power to the processor pins. To accomplish this,
it is recommended to integrate load switches to turn on the peripheral voltage rails after the SOM has finished powering
up or use VDD_3V3_OUT to power the peripherals. An example of this is shown in the reference circuit below.
Figure 17. Carrier board power reference circuit
