TPS7A69-Q1: Consequences of connecting the NC pin to Gnd

Part Number: TPS7A69-Q1
Other Parts Discussed in Thread: TPS7A66-Q1, TPS7B84-Q1, TPS7B85-Q1

Hi,

We are currently proposing the TPS7A69-Q1 as a p-p alternative to one of the competition part (CP).

One major difference is that the #CP has an additional feature to adjust the reset either by connecting to a resistor divider circuit or by grounding it on Pin 3. Whereas TPS7A69-Q1 has an NC on pin-3 which is internally not connected.

Question: Are there any consequences of connecting the NC to Gnd or a resistor-divider network?

The customer requires minimum or no changes in the design to choose the TI part as an alternative. Looking forward to your insights.

Best Regards,

Madhurya

over 4 years ago

+1 Jason Song over 4 years ago

TI__Mastermind 23361 points

Hi Madhurya,

The NC pin can be connected to GND or a resistor network because there is no internal connection. But the DNC pin needs to be floating.

Regards,

Jason Song

0 MK over 4 years ago in reply to Jason Song

TI__Intellectual 1650 points

Hi Jason,

Thank you for the confirmation! The TPS7A69-Q1 does not have DNC pin whereas TPS7A66-Q1 does. I shall keep note of this and share it with the customer!

Best Regards,

Madhurya

0 MK over 4 years ago in reply to Jason Song

TI__Intellectual 1650 points

Hi Jason,

If SI and SO pins are not utilized, what is the correct way to connect it?

Can SO pin be left floating and SI connected to the output?

Does it have any issues/risks?

Best Regards,

Madhurya

+1 Jason Song over 4 years ago in reply to MK

TI__Mastermind 23361 points

Here is the description of the SO pin from the datasheet:

Sense output. This open-drain pin must connect to VOUT via an external resistor. VSO is logic level low when VSI falls below the sense-low threshold.

SO pin can be left floating with SI connecting to the output. SI pin's maximum voltage is rated up to Vin.

If not utilized, the preferred way is to ground SI and leave SO floating or grounded.

0 MK over 4 years ago in reply to Jason Song

TI__Intellectual 1650 points

Hi Jason,

Thank you for the info! Adding a few other queries-

Does the TPS7A69 have an exposed thermal pad? ( Looks like the competition part has a exposed thermal pad and so does the 8-Pin HVSSOP version TPS7A66)
Does a thermal pad provide better thermal resistance? (Comparing TPS7A66 vs TPS7A69)

Best Regards,

Madhurya

0 Jason Song over 4 years ago in reply to MK

TI__Mastermind 23361 points

Hi Madhurya

Having an exposed thermal pad will certainly improve thermal performance and as you have noticed, the TPS7A66-Q1 does have an exposed thermal pad but the TPS7A69-Q1 does not.

Regards,
Jason

0 MK over 4 years ago in reply to Jason Song

TI__Intellectual 1650 points

Hi Jason,

Thank you! Adding to this, the key factor with having an exposed pad would also imply RθJC(bot) Junction-to-case (bottom) thermal resistance along with other thermal resistances are lesser!

Since the customer prefers a better thermal resistance, I recommend the TPS7A66-Q1 and other LDO options TPS7B85-Q1 or TPS7B84-Q1 with an exposed thermal pad.

Best Regards,

Madhurya

0 Jason Song over 4 years ago in reply to MK

TI__Mastermind 23361 points

Yes, I agree with your assessment and your recommendations.

0 MK over 4 years ago in reply to Jason Song

TI__Intellectual 1650 points

Thanks for the affirmation!

0 Jason Song over 4 years ago in reply to MK

TI__Mastermind 23361 points

You are welcome!

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TPS7A69-Q1: Consequences of connecting the NC pin to Gnd