UCD3138128A: UCD3138 family Reset

Manu Abraham

Part Number: UCD3138128A
Other Parts Discussed in Thread: UCD3138, TIDA-00705, TIDA-00653, PMP4320A, UCD3138064A, UCD3138128, UCD3138A64A, UCD3138A64, UCD3138A, , UCD3138CC64EVM-030

Hi,

slua779a UCD3138 Family - Practical Design Guideline states the following:

"The RESET pin must have one at least 2.2-μF low ESL capacitor locally decoupled with DGND plane or
SGND plane. As shown in Figure 2-1, this capacitor must be placed very close to the device RESET pin."

Looked at the following TI designs:

PMP11432: no capacitor

TIDA-00705: uses a 100n capacitor

TIDA-00653: uses a 100n capacitor

PMP4320A: uses a 100n capacitor

and so on. Am I missing something here ?

Thanks,

Manu

over 6 years ago

0 Yitzhak Bolurian over 6 years ago

TI__Mastermind 18370 points

For best results please follow Section 3.4:

Recommendation for RC Time Constant of nRESET Pin for UCD3138A, UCD3138064A, UCD3138A64, UCD3138128, UCD3138A64A, and UD3138128A

in the application note:

www.ti.com/.../slua779a.pdf

Regards,

0 Manu Abraham over 6 years ago in reply to Yitzhak Bolurian

Genius 3510 points

Thanks for pointing it out. That almost clears it up.

I have settled with a bare bones schematic to get the UCD3138128A up. Attached schematic.

That includes the change to the RESET. Also, I have tried to incorporate the XDS100v2 JTAG interface.

First question, would be whether the following connection to the XDS100v2 is okay, or does it need any changes.

Another question that comes across is the JTAG RST. Is the RESET as used in the schematic okay ?

The next question is about the serial port, whether that can also be used as described above ?

Any thing else that you seem incorrect in the above schematic ?

Thanks,

Manu

0 Yitzhak Bolurian over 6 years ago in reply to Manu Abraham

TI__Mastermind 18370 points

One of us will get back to you with a response soon.

0 Sean Xu over 6 years ago in reply to Yitzhak Bolurian

TI__Genius 14580 points

The cap used for RESET pin can be large, such ass 2.2uF. Also, other caps used for each V33D and V33DIO can be as large as 2.2uF + 10nF, instead of 100nF.

0 Manu Abraham over 6 years ago in reply to Sean Xu

Genius 3510 points

Hi Sean / Yitzhak,

Modified the decoupling caps and the Reset capacitor, as shown.

What do you think about the XDS100v2 interface ?

Thanks,

Manu

0 Yitzhak Bolurian over 6 years ago in reply to Manu Abraham

TI__Mastermind 18370 points

The JTAG pins require pull up resistors:

Also I do not believe that pin #10 (Main Chip Reset) should be connected as a JTAG test-reset pin.

Regards,

0 Manu Abraham over 6 years ago in reply to Yitzhak Bolurian

Genius 3510 points

Will remove the Reset pin connection to JTAG.

It would be nice, if you could clarify a bit more.

Do all the pins require pullups ?
And what value pullups are recommended ?
PMP11432 pulls up TMS alone, using 1k5 resistors
UCD3138CC64EVM-030 pulls up TMS, TDI, TDO using 10k resistors . TCK is untouched.

Thanks,
Manu

0 Yitzhak Bolurian over 6 years ago in reply to Manu Abraham

TI__Mastermind 18370 points

Yes, 10 KOhm resistors should be used. None should be left floating.
TCK can be pulled high or low (Low is the default as per JTAG standard).

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0517a/Cjaeccji.html

Regards,

0 Manu Abraham over 6 years ago in reply to Yitzhak Bolurian

Genius 3510 points

That clears up the cloud.

Thanks,
Manu

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UCD3138128A: UCD3138 family Reset