MSP430F6779A: Capacitors with MCU MSP430F6779A

Vasu Khwanyuen

Intellectual 535 points

Part Number: MSP430F6779A

Hi TI Support,

I suspect about connect capacitor with pin MCU of MSP430F6779A.

Which pin of the mcu if there is no connection to a capacitor? It will cause the mcu to not start-up.

Using 100-Pin PZ Package

Data sheet

TI_msp430f6779a.pdf

Best Regards,

Vasu Khwanyuen

over 2 years ago

0 Luke Ledbetter over 2 years ago

TI__Mastermind 26890 points

Hi Vasu,

Below is the table from the Datasheet on the Auxiliary supplies and the recommended capacitors.

Below is the schematic snippet from the Implementation of a Three-Phase Electronics Watt-Hour Meter which helps show the implementation. The 4.7uF caps are the bulk capacitors for dips and spikes in current and the 100nF capacitors are the decoupling caps for high frequency noise.

VCORE must have the 0.47 uF capacitor for device operation.

A 4.7uF capacitor is also recommended on the LCDCAP pin when the charge pump is enabled.

Regards,
Luke

0 Vasu Khwanyuen over 2 years ago in reply to Luke Ledbetter

Intellectual 535 points

From data sheet, How about these C that use 4.7uF, does it has any affect to MCU operation? In case less than 4.23uF (4.7 -10%)

Best Regards,

Vasu Khwanyuen

0 Luke Ledbetter over 2 years ago in reply to Vasu Khwanyuen

TI__Mastermind 26890 points

Hi Vasu,

For the power supply capacitors, they are typical recommended values so the 10% tolerance is acceptable. For the LCD capacitor the minimum value is 4.7uF so I recommend you select a capacitor where the minimum value will be met with the tolerance taken into consideration.

Regards,
Luke

0 Vasu Khwanyuen over 2 years ago in reply to Luke Ledbetter

Intellectual 535 points

And case use capacitors more 10 uF (Over recommend) I'm not sure occur affect to MCU operation?

Detail in data sheet not have description about impact from use over 10 uF

Best Regards,

Vasu Khwanyuen

0 Luke Ledbetter over 2 years ago in reply to Vasu Khwanyuen

TI__Mastermind 26890 points

Hi Vasu,

We don't list the impact here so we don't have test information. From my perspective there could be timing issues and failure on the LCD operation due to the increased capacitor value.

Regards,
Luke

0 Vasu Khwanyuen over 2 years ago in reply to Luke Ledbetter

Intellectual 535 points

Hi, I have a question about Cvsys

This capacitor, Is there a chance that the voltage will come in more than 6.3 v?

Best Regards,

Vasu Khwanyuen

0 Luke Ledbetter over 2 years ago in reply to Vasu Khwanyuen

TI__Mastermind 26890 points

Hi Vasu,

The recommended voltage around the MCU should only be 3.6V, if you're seeing larger than that there may be multiple power sources causing this. Below are the maximum ratings, if you exceed these values the device can be damaged.

I would inspect where in your design you have ties that could be causing multiple power sources to be connected. (There are 4 total Cvsys capacitors one at each VDSYS1, VDSYS2, VASYS1, VASYS2 if you are using all the possible power sources)

Regards,
Luke

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MSP430F6779A: Capacitors with MCU MSP430F6779A