Author Topic: Jump starting the DW01  (Read 2243 times)

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Offline PeabodyTopic starter

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Jump starting the DW01
« on: July 30, 2022, 05:36:35 pm »
The DW01 is a lithium battery protection chip.  The typical application circuit is attached below.  When a battery is first connected, the protection mosfets may come up in the off state.  One version of the datasheet has this notation:

Note: When a battery is connected to
DW01 for the first time, it may not enter
the normal condition (discharge may
not be enabled). In this case, short the CS
and VSS pins or connect to a charger to
restore to the normal condition.

Some refer to this as "shipping mode".  I participated in a thread on this subject:

https://www.eevblog.com/forum/projects/pain-and-suffering-getting-the-dw01-and-8205a-protection-circuit-work-right/msg1838381/#msg1838381

which didn't really come to a conclusion about how to deal with this "feature".  I think it could be a problem when changing batteries in the field, and would like to find a way to make the chip come up in normal mode (discharge enabled) when the battery is first connected.  So I wondered if anyone else has dealt with this, and if so, how.

Experimenting with the typical TP4056 charger modules which have protection included, I find that they will come up in normal mode if there is no load (other than my meter leads), but with 100R across the output, I have to plug in the charger before it will come up.  After that it runs fine with or without the charger - so long as the battery stays connected.

In the thread referenced above, one participant said he got it to work by reducing C1 from 100nF to 80nF.  But I don't know if he tested various load conditions, and I have no idea how or why this would work.  Another suggestion was to install a capacitor from CS to GND (pin 2 to pin 6), presumably to temporarily ground CS, which the Note suggests might work.  I don't know if anyone has tried this (I haven't).

Anyway, I just wondered if anyone is aware of anything definitive on this - a way to make sure it comes up enabled, or for that matter to make sure it doesn't.  I have one circuit using the typical circuit for this chip that does come up enabled, even with a load, but I don't know why because a second copy doesn't.
 


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