TMS320F28069: Clock Requirement Document

Part Number: TMS320F28069
Other Parts Discussed in Thread: TMDSCNCD28069, C2000WARE

Hi Team,

We have some strange issue going on with our TMS320F28069UPZPS after enabling external clock. Few boards work well with external clock but majority have problem after enabling external clock.

Issue description:

internal clock: ok, can communication works
external clock as reference, PLL:30MHz*6/2, internal oscillator on: board periodically resets
Comment: in a very specific configuraiton (delay removed, adc-calibration removed, debugger connected, slowly stepping, the board was once running)

Can you please provide clock requirement document , if there is one additional to the information on datasheet and review below information and let us know if we are not following something here?

Datasheet: TMS320F2806x Microcontrollers datasheet (Rev. J) (ti.com)

External Crystal used: ECS-300-20-3X-EN-TR (ECS Inc) , Supplier part # XC1801CT-ND.

Regards,

Ramon

over 2 years ago

0 MatthewPate over 2 years ago

TI__Guru 71785 points

Ramon,

I've copied a section from the F2806x datasheet, but the max input frequency for a crystal is capped at 20MHz. This is the reason you are having issues with 30MHz X-tal as you mentioned; the internal feedback circuit can't oscillate at this speed.

There are two alternatives; change the X-tal to 20MHz(you can still get 90MHz C2000 with PLL x9/2) or switch to a canned oscillator(X1 connection only), which does support up to 30MHz. This would bypass the oscillation circuit.

Best,

Matthew

0 RJ over 2 years ago in reply to MatthewPate

TI__Intellectual 2550 points

Hey Matt,

Can you provide us a 20Mz Crystal part number (from Demo board , or experiments that we might have done and concluded best crystal and its tuning condition for this DSP) which your team has tested already , So that we don’t need to engage into crystal tuning activity.

0 MatthewPate over 2 years ago in reply to RJ

TI__Guru 71785 points

We use this part from Abracon on the TMDSCNCD28069 eval board: https://www.digikey.com/en/products/detail/abracon-llc/ABM3B-20-000MHZ-10-1-U-T/687825?WT.z_se_ps=1&s=N4IgTCBcDaIMwAYEFoAcYCMAWZHkDkAREAXQF8g

Schematic and BOM are here: C:\ti\c2000\C2000Ware_4_00_00_00\boards\controlCARDs\TMDSCNCD28069\R1_1\

Best,
Matthew

0 RJ over 2 years ago in reply to MatthewPate

TI__Intellectual 2550 points

Matt,

I cannot access schematic. Can you share the entire working clock design, including any resistors , Capacitors CL1, CL2 . this is because we want to save clock tuning time by using same (known working) design from ti