Questions about AM437x and TPS65218

Hi g.f.

g.f. said:

1. To run the AM437x in Nitro(OPP), the typical voltage is 1.325V. But TPS65218 can't output 1.325V. The closest voltage which TPS65218 can output are 1.320V or 1.330V. Both voltage satisfies the specification of AM437x, but which voltage should be chosen?

The AM437X Datasheet Rev. A specifies a range from 1.272V to 1.378V (1.325V typical) for Nitro mode. So either of these voltages will do. This will be taken care of by Linux power management.

g.f. said:

2. Question about the following AM437x Power Supply pins. *CAP_VDDS1P8V_IOLDO (BALL Number:D6) *VDDS3P3V_IOLDO (BALL Number:F8) What should be connected to these two power supply pins? In the GP EVM, CAP_VDDS1P8V_IOLDO is unconnected and VDDS3P3V_IOLDO is connected to the GND. But in the Industrial EVM(IDK), it seem that CAP_VDDS1P8V_IOLDO is connected to VDDS pins and 3.3V is supplied to VDDS3P3V_IOLDO.

These pins are input and output from the AM437X internal 1.8V LDO. When TPS65218 is used the internal LDO is not needed so these pins should be connected as in the GP EVM.

g.f. said:

3. In the schematic of GP EVM and IDK, the following pins are separated from other VDDS/VDD_CORE and is processed. Is this means the following pins need some special processing? *AD8 pin (VDDS) *AD9 pin (VDD_CORE) *AD12 pin (VDSS) In GP EVM and IDK, Ferrite Beads is connected to AD12 pin but it is not connected to other VDDS pins. And in IDK, decoupling capacitor(0.01uF) is connected to AD8 pin and AD9 pin but it isn't connected to other VDDS and VDD_CORE pin.

These pins should be connected as follows: AD8 and AD12 to VDDS, AD9 to VDD_CORE, as documented in the AM437X Datasheet Rev. A.

Yes, this is correct. http://www.ti.com/lit/ug/slvuaa9/slvuaa9.pdf is the relevant document for using TPS65218 with AM437X. The AM437X internal LDO usage is covered in this document: http://www.ti.com/lit/ug/slvuab1/slvuab1.pdf