TMDSCNCD280049C: TMDSCNCD280049C

Hello,

REAGAN RONALD COLIN COOPER said:

I have followed the recommendations provided in the 4.5 Evaluation of the Internal DC/DC Converter, but there appears to be some confusion regarding the PGA-GND configuration resistors. According to the Hardware References on page 12/21 (link: www.ti.com/.../spruic4d.pdf, resistors R55-R59 should be populated as they serve as the PGA-GND configurations in the context of an internal DC/DC converter.

If you want to evaluate the internal DC/DC converter, follow the steps in the user guide.

To enable the internal DC/DC converter: • R18 and R19 must be unpopulated. • R21 and R22 must be populated with a 0-Ω resistor. • C19 must be populated with a 2.2-µF X5R/X7R capacitor. • C20 and C21 must each be populated with a 10-µF X5R/X7R capacitor.

I am not sure what is your confusion with R55-59. These have nothing to do with the DC/DC converter. Perhaps you can clarify your question?

REAGAN RONALD COLIN COOPER said:

However, what about R7, R17, R21, R22, and R28? The MCU009B(001)_BOM specifies that these designators should remain unpopulated since the system was operating in VREG mode.

You can refer to the board schematic for details on all of these.

- R7 connects GPIO-18 to the HSEC header pin 89

- R17 connects the MCU X1 pin to GND

- R21/R22 are used to enable the DC/DC converter (see above)

- R28 is used to disable internal VREG

I would suggest you leave all these as default. 

REAGAN RONALD COLIN COOPER said:

Could you provide some insight into this? After implementing these changes, can the TMDSCNCD280049C still function in VREG mode through code configuration, or will it be restricted to operating solely in DC/DC converter mode? Does it have the capability to automatically switch between VREG and internal DC/DC converter mode?

As described in the F280049c datasheet:

The internal DC-DC regulator offers increased efficiency over the LDO for converting 3.3 V to 1.2 V. The internal DC-DC regulator is supplied by the VDDIO_SW pin and generates the 1.2 V required to power the VDD pins. To use the internal switching regulator, the core domain must power up initially using the internal LDO VREG supply (tie the VREGENZ pin low to VSS) and then transition to the DC-DC regulator through application software by setting the DCDCEN bit in the DCDCCTL register. VREGENZ must still be kept low after transition since it controls both the DC-DC and LDO. Tying VREGENZ high disables both the DC-DC and LDO. The DC-DC regulator also requires external components (inductor, input capacitance, and output capacitance).

Hello Gus Martinez,

By grouping R7, R17, R28, R55, R56, R57, R58, and R59 in the same category as R21 and R22 in the MCU009B(001)_BOM, I thought they all must be populated with a 0-Ω resistor when the TMDSCNCD280049C is used in DC-DC Converter mode, however, thank you for clarifying that NOT all of them should be populated.

In the case of resistors R55-R59, I thought the PGAs are expected to be referenced to ground by the baseboard since it is now used for internal DC-DC Converter PGA-GND configuration, right? My understanding with relation to the MCU might be wrong, therefore, I can unpopulate resistors R55-R59 if they have nothing to do with the TMDSCNCD280049C internal DC-DC Converter.

Lastly for the software, I can only get TMDSCNCD280049M, not TMDSCNCD280049C. Kindly assist how I can get the TMDSCNCD280049C code.

Regards,

Reagan Ronald Colin Cooper
Coperlom Industries Engineering Service

Apologies, I do not see what R55-R59 have to do with the DC-DC converter. From schematics you can see that these resistors just set the GND reference for the PGAs, but they do not have anything to do with the DC-DC converter.

For software examples, you can get these from c2000ware.

https://www.ti.com/tool/C2000WARE 

C:\ti\c2000\C2000Ware_5_02_00_00\driverlib\f28004x\examples

Hi Gus Martinez,

We can set this forum to resolved Thank you for your patience and assistance.