We are using the TPS65910A3 to power the AM3358. One of the connections between the two devices is the PMIC_PWR_EN that could be connected to the PWRHOLD input of the PMIC.
We are a bit confused how to power-off the combination.
I see two possibilities:
1- If I have read the technical manual of the AM335X MPU (SPRUH73G) correctly, the PMIC_PWR_EN output is either always '1', or controlled by ALARM2 event (page 3651). In case PMIC_PWR_EN is controlled by ALARM2, then an ALARM2 event will generate a ON->OFF transition in the PMIC.
2- The PMIC_PWR_EN is also mentioned in an earlier post on this forum (http://e2e.ti.com/support/arm/sitara_arm/f/791/p/239414/837970.aspx#837970),
"When you disconnect the signal PMIC_POWER_EN (Ball C6 on ZCZ package) you should pullup PWRHOLD (pin 1 on TPS65910) to the VDDIO voltage of the PMIC through a 10kOhm resistor. Check the Starter Kit schematics (http://processors.wiki.ti.com/index.php/AM335x_StarterKit_Board_Design_Files)."
In this schematic the PWRHOLD is connected to VAUX33. However, in the TPS65910x Schematic Checklist (SWCA139B) is noted: "If control is not required, then can be tied to VRTC".
In this case the device can be powered off by writing the DEV_OFF bit to register 0x31 of the PMIC.
Questions:
A- Does someone know if there are any drawbacks for using method 2 with respect to method 1?
B- To which voltage must the PWRHOLD be tied in method 2? VAUX33 or VRTC?
