LM25183-Q1: Adding a reverse polarity (connection) diode at the input

Masaru Oinaga

Part Number: LM25183-Q1
Other Parts Discussed in Thread: LM25183

Tool/software:

Hello, Team,

Our customer asked us about whether they need to add a reverse polarity (connection) diode at the input side. Looking at the datasheet, the schematic does not have such diode and this is same for EVM.

Is there a situation where such diode is required, or does the IC does not require such diode by nature because of some function implemented in it?

Please let us know your thoughts.

Best,
Masaru

3 months ago

0 Manuel Alva Hernandez 3 months ago

TI__Genius 15566 points

Masaru, could you please elaborate "diode at the input side". Where exactly is this diode wanted to be connected? Could you provide a drawing/schematic for better understanding?

Thank you

0 Masaru Oinaga 3 months ago in reply to Manuel Alva Hernandez

TI__Expert 4425 points

Hi, Manuel,

What I meant by "input" is the red circle in the below:

Best,
Masaru

+1 Manuel Alva Hernandez 3 months ago in reply to Masaru Oinaga

TI__Genius 15566 points

Masaru,

My guess is that you are suggesting a protection diode between VIN supply voltage at VIN pin to prevent any current flowing to VIN supply side. LM25183 does not require this diode. If by any case a reversed polarity current is loaded at the secondary side, the secondary diodes are prevent any current flowing to the primary side.

Thank you

0 Masaru Oinaga 3 months ago in reply to Manuel Alva Hernandez

TI__Expert 4425 points

Hello, Manuel,

We received additional question from the customer.

Manuel Alva Hernandez said:
LM25183 does not require this diode.

Could you explain in detail about above comment? Is it because the IC itself has a reverse protection component built inside, or the reverse current path does not exist?

Best,
Masaru

+1 Manuel Alva Hernandez 3 months ago in reply to Masaru Oinaga

TI__Genius 15566 points

Reverse current path does not exist. As mentioned earlier, the secondary side diodes prevent any reversed polarity current to flow to the primary side.

Thank you

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LM25183-Q1: Adding a reverse polarity (connection) diode at the input