TPS63900: The actual impact of cfg resister error

Kazuki Kuramochi

Part Number: TPS63900

Hello Expert,

I have question for this device's cfg feature.
Datasheet recommend to use the resister that has resistance error within 3% including all factor.
Then, I'd like to know about actual concern when I use the resister that violate this required accuracy. Would you tell me it?
For example, there is risk to configure unexpected value or it cannot configure.(e.g, I want to configure output voltage as 2.8V using 10kohm resister but output become 1 step smaller value (2.7V). Or become completely different value).

Best regards,
Kazuki Kuramochi

over 4 years ago

0 Tao Zhang over 4 years ago

TI__Mastermind 32350 points

Hi kazuki-san,

we concern wrong value will get during start up with a bad accuracy resister, than the configuration register state will go wrong.

For your example, output will keep 2.8V or one step smaller, but not be a completely value.

Regards

Tao

0 Kazuki Kuramochi over 4 years ago in reply to Tao Zhang

TI__Genius 10525 points

Hi Tao-san,

Thank you for your swift reply.
This is just confirmation but I'd like to know about detail of wrong state.
Is there the other wrong state from bad accuracy resister except configuring one step smaller or larger value?

Best regards,
Kazuki Kuramochi

0 Tao Zhang over 4 years ago in reply to Kazuki Kuramochi

TI__Mastermind 32350 points

Hi kazuki-san,

I remember I did a similar test before and I have not seen other wrong state but one step value with bad resister.

Regards

Tao

0 Kazuki Kuramochi over 4 years ago in reply to Tao Zhang

TI__Genius 10525 points

Tao-san,

I have quick question.
Lowest resister is used 0ohm but highest resister is 36.5kohm.
Then would you tell me what will happen when we use the resister with a resistance value greater than the recommended error range against 36.5k ohm?(I expected it is just applied the setting when I use 36.5kohm.)

Best regards,
Kazuki Kuramochi

0 Tao Zhang over 4 years ago in reply to Kazuki Kuramochi

TI__Mastermind 32350 points

Hi kazuki-san,

If voltage at CFG PIN is larger than some value when start up, it will keep maxmum 5V output.(e.g, CFG resister is larger than 36.5K, 5V output will keep even CFG PIN is floating.)

Regards

Tao

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TPS63900: The actual impact of cfg resister error