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Smart Power Switches Forum Discussions

deycart
Level 1
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First reply posted First question asked Welcome!

On page 7 of the datasheet note 4) "Slew rate limitation can be achieved by means of using a series resistor for the small signal driver or in series in the input path. A series resistor RIN in the input path is also required for reverse operation at Vbb≤-16V. See also Figure 14."

Figure 14 is about reverse battery protection and has nothing about limiting the slew rate. How do I select Rin to limit the slew rate?

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1 Solution
G_Anshika
Moderator
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250 sign-ins 25 likes received 5 likes given

Hello,

Considering input slew rate as per question, the factors it may depend on the components connected to IN pin. The resistor Rbb is internally present to limit the slew rate as per range given in datasheet.


Annotation 2022-12-16 120427.png

If you want to incorporate more limitation on slew rate, the additional Rin resistor is suggested.  Rin has also a different purpose to serve, for reverse battery protection. 

Annotation 2022-12-16 115745.png

Hence, the value of RIN is to be decided by the following formula.

There is no timing related formula available. 

Best Regards,
Anshika

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G_Anshika
Moderator
Moderator
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250 sign-ins 25 likes received 5 likes given

Hello,

You can use the following formula to calculate the value of RIN.
Given in the datasheet, RIS = 1kohm and the range of Vbb.

G_Anshika_0-1670926595437.png

Best Regards,
Anshika

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That formula is already in the datasheet and has do do with limiting the current when designing the reverse polarity protection and is not what I asked for.

I want the formula to calculate Rin to limit the SLEW RATE.

deycart_0-1670935598667.png

The formula provided uses no timing information so how can you use it for slew limiting?

 

 

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G_Anshika
Moderator
Moderator
Moderator
250 sign-ins 25 likes received 5 likes given

Hello,

Considering input slew rate as per question, the factors it may depend on the components connected to IN pin. The resistor Rbb is internally present to limit the slew rate as per range given in datasheet.


Annotation 2022-12-16 120427.png

If you want to incorporate more limitation on slew rate, the additional Rin resistor is suggested.  Rin has also a different purpose to serve, for reverse battery protection. 

Annotation 2022-12-16 115745.png

Hence, the value of RIN is to be decided by the following formula.

There is no timing related formula available. 

Best Regards,
Anshika

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