TMS320F280039C: VDD 1.2V power supply design problem

Rhea Gao

Tool/software:

Hi,

a. Currently, the customer's system power supply has 1.2V power supply, and I want to know whether the system's 1.2V power supply needs to be connected to the F280039C VDD 1.2V port, or only need to add a decoupling capacitor in the VDD port?

b. The F280039C can generate 1.2V voltage inside. Does the system 1.2V voltage connected to VDD affect the use?

over 1 year ago

0 MatthewPate over 1 year ago

TI__Guru* 84900 points

Rhea,

This device has support for internal VREG, to generate the 1.2V supply internally.

For those devices with a VREGENZ pin, if this pin is grounded, then the internal VREG will be enabled and 1.2V will be sourced in internally. In this mode the customer must place external bulk caps with values set forth in the DS https://www.ti.com/document-viewer/TMS320F280039C/datasheet#GUID-9D2CEBE2-4430-4F99-87A2-C07098C07FA3/GUID-B83B02EC-3DA8-4AB8-9AA7-13DA2A4304AC

If VREGENZ pin is tied to VDDIO, then internal VREG will be disabled, and the customer will need to supply the 1.2V from an external voltage source along with appropriate decaps for that source.

I believe there is a pinout of this device with no VREGENZ pin, in that device VREG is always on/enabled.

Best,

Matthew

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TMS320F280039C: VDD 1.2V power supply design problem