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Power Management ICs Forum Discussions

NXTY_Fujioka
Level 2
First solution authored 5 replies posted 10 sign-ins
Level 2

Hi sir, 

In addition to the CoolMOS, a MOSFET is built in series inside the CoolSET. (Q1 in the attached figure)

At startup, Vcc is charged via primary transformer Lp → CoolMOS → internal diode D1.

At this time, the other MOSFET inside is turned off, which I believe prevents current leakage to the CS pin.

Soft-start is initiated when Vcc exceeds the turn-on threshold, but will Q1 be fully ON from the time of soft start operation?

NXTY_Fujioka_0-1657518030182.png

BR

Yuki Fujioka

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1 Solution
Guruprasad_A
Moderator
Moderator 10 solutions authored 5 solutions authored First like received
Moderator

Hi @NXTY_Fujioka ,

Thanks for posting in Infineon community.

In the Vcc voltage and current at startup curve. (ICE5xRxxxxxZ).

Guruprasad_A_0-1657533620985.png

 At t1, Vcc voltage exceeds the Vcc turn on threshold Vcc_on. IC starts to operate with soft start and Q1 is turned on. t2 onwards output voltage rises close to regulation. Axillary winding starts to charge the Vcc capacitor.

Please feel free to reach out to us if you need further clarification on this topic.

Regards,

Guruprasad A

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2 Replies
Guruprasad_A
Moderator
Moderator 10 solutions authored 5 solutions authored First like received
Moderator

Hi @NXTY_Fujioka ,

Thanks for posting in Infineon community.

In the Vcc voltage and current at startup curve. (ICE5xRxxxxxZ).

Guruprasad_A_0-1657533620985.png

 At t1, Vcc voltage exceeds the Vcc turn on threshold Vcc_on. IC starts to operate with soft start and Q1 is turned on. t2 onwards output voltage rises close to regulation. Axillary winding starts to charge the Vcc capacitor.

Please feel free to reach out to us if you need further clarification on this topic.

Regards,

Guruprasad A

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NXTY_Fujioka
Level 2
First solution authored 5 replies posted 10 sign-ins
Level 2

Hi 

I understood that Q1 is fully on during soft-start.
Thank you for your answer.

BR

Yuki Fujioka

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