TPS54325: The time needs to turn off Vo after EN became low level

Hung Ching Hsu

Part Number: TPS54325

Hi Team,

My customer is asking following questions. Could you kindly help? Thanks.

1. I think "EN" pin controls output voltage, how long is the time needs to turn off Vo after EN became low level(lower than 0.4V)?

2. Table 2. in p.12 of datasheet have C8+C9(uF), is this a typo of C7+C8(uF)? We can see C7+C8(uF) from figure 4. in p.11.

Regards,

over 2 years ago

0 Tahar Allag over 2 years ago

TI__Mastermind 29640 points

Hello Jo,

Typically, there is about 200us (Typ) delay from the time the EN is low to the time the switching is off. Then there is time that it takes for the VOUT to fall to 0V, that depends on VOUT, COUT, LOUT and the load conditions.
Yes, that is a typo, C7 and C8 are COUT according to figure 4..

Thanks!

Tahar

0 Hung Ching Hsu over 2 years ago in reply to Tahar Allag

TI__Expert 3086 points

Hi Tahar,

Thank you for the reply!

Is there any formula that customer can estimate the time needed for VOUT to fall to 0V?

Tahar Allag said:
Then there is time that it takes for the VOUT to fall to 0V, that depends on VOUT, COUT, LOUT and the load conditions.

Thanks.

Regards,

+1 Tahar Allag over 2 years ago in reply to Hung Ching Hsu

TI__Mastermind 29640 points

Hello Jo,

there is no format per say, but that is typically an RC element to allow the external COUT to discharge thru resistive load. After the device stops switching, the COUT charge will hold VOUT until the charge in COUT is depleted. If there is a strong resistive load, that will be depleted fast, if the resistive element is not present, then the COUT will take longer to bleed out.

thanks

Tahar

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TPS54325: The time needs to turn off Vo after EN became low level