TPS7A80: Start-up time with 1nF of C_NR

MINKYUNG KIM

Part Number: TPS7A80

Hi team,

Could you help me to clarify the start-up time with CNR at 10nF? I understand the operation with quick-start switch,

With CNR at 10nF the datasheet shows a typical of 1.6ms, but it doesn't match with the equation (1), 76,000*10nF = 760 us. The datasheet notes 'whichever is smaller' in terms of equation (1). So would it be 760us? Or is it 1.6ms due to RC delay?

If my customer sets CNR at 22nF, tSTR would be 76,000 * 22n = 1.672ms. And if my customer sets CNR at 10nF, tSTR would be 1.6ms as well?

Thank you for your response.

over 3 years ago

0 Kyle Van Renterghem over 3 years ago

TI__Genius 13085 points

Hi,

You are correct the startup equation has an error in it the constant before the Cnr variable. The constant should be 170,000 which better aligns with the figure you referenced (shown below).

0 MINKYUNG KIM over 3 years ago in reply to Kyle Van Renterghem

Expert 1250 points

Thank you for clarification, Kyle. I will follow the Figure 24, not the equation.

Does your team have any action on the move to update the DS regarding this error?

0 Kyle Van Renterghem over 3 years ago in reply to MINKYUNG KIM

TI__Genius 13085 points

Hi,

Right now all our datasheets are in the process of migrating to a new technical documentation system so we will make this change when we are able to but it could be ~6 months due to the backlog.

Power management

Power management forum

TPS7A80: Start-up time with 1nF of C_NR