Am I missing something here or being stupid ?

I tried using a LM66100 (Low IQ Ideal Diode With Input Polarity Protection) for reverse battery protection, but when I reversed the connection there was smoke and now the device no longer works when the polarity is correct (VOUT is zero).

I am trying to implement reverse battery protection with bidirectional current, so the battery can be charged via USB...




The datasheet even shows a diagram where the input has reverse polairty...





I first tested it with correct polarity as shown in the diagram below and checked that VOUT = VIN...





I then swapped VIN and GND (CE was left connected to battery negative) as shown in the diagram below...




As soon as I did this I saw smoke so immediately disconnected it.

In both tests, VOUT was left floating.

So I don't understand why the device failed when I reversed the battery polarity, or have I misunderstood something ?

 

Perhaps the reversal that you made was not the one it was made to protect against.OR maybe leaving the "CE" connection connected was the problem.
Did you read any data sheet on the product?? or any application information??
WHAT was the source of that device?? What supplier, and what brand??
I have seen product ads that steer me away from the product as fast as I can leave.

 

Perhaps the reversal that you made was not the one it was made to protect against.OR maybe leaving the "CE" connection connected was the problem.
Did you read any data sheet on the product?? or any application information??
WHAT was the source of that device?? What supplier, and what brand??
I have seen product ads that steer me away from the product as fast as I can leave.

Yes I read the datasheet and it does say "The LM66100 also comes with reverse polarity protection (RPP) that can protect the
device from a miswired input, such as a reversed battery"

The datasheet is in the following link...

https://www.ti.com/lit/ds/symlink/lm66100.pdf

Its a Texas Instruments device and I bought it from a reputable company (Digikey).

Regarding the CE pin, the datasheet says. "Active-low chip enable. Can be connected to VOUT for reverse current protection. Do not leave floating."

So CE must be connected. The application circuit is shown in Figure 12 in my original post.

I don't want the reverse current protection, as this would prevent the charger IC from charging the battery. This is why I need reverse polarity protection with bidirectional current.

 

So CE must be connected

Yes.
But when the battery would be incorrectly reversed, /CE would go the battery positive as shown in the data sheet Figure 12, not battery negative as you show in your bottom diagram.

 

I have used this device for reverse input protection, and for that the example circuit you shared works ok.

However, my design did not have an alternate power supply providing power to the Vout pin (the charger)

Perhaps consider the alternate circuit where the two devices are used to select between two power supplies (details on the datasheet)?

 

Thanks all

The problem seemed to be down to the CE pin (as crutschow suggested) and the fact I had a GND connection between the battery negative and a fuel gauge IC (MAX17048). This is shown in the diagram below and the fault occurred when I reversed the polarity....





Below is the fix that now works using a new device (although battery charging does not seem to work)...