Argail
Newbie level 4
Hi, I'm looking for building a custom protection circuit for rechargeable lithium ion polymer batteries.
The three protection offered by the standard PCM are :
- overcharge voltage
- over discharge current
- cut-off voltage
Assuming, the charge voltage is regulated and controlled by the charger IC, the over discharge current is limited by the LDO with short circuit protection, the only thing which is not protected is the cut-off voltage.
What I'm thinking is to use a "simple" nanopower voltage comparator (or uC supervisor) which will directly drive a FET for th on/off function, should you think this protection will work and be sufficient?
For example the AS1927 from austrianmicrosytem has a very low quiscent current (400nA max, much lower than the 6uA of the standard PCM).
The supervisor is active down to 1V, if I use a load switch like the Vishay Sip4282A which has a valid input from 1.5V to 5.5V, I should not use external pull down or pull up for forcing the output signal to 0V if the input voltage on the AS1927 is below 1V?
The battery will be a 80mAh (low capacity, so I have to spare the maximum energy I can) with a maximum discharge current of 0.5C.
The three protection offered by the standard PCM are :
- overcharge voltage
- over discharge current
- cut-off voltage
Assuming, the charge voltage is regulated and controlled by the charger IC, the over discharge current is limited by the LDO with short circuit protection, the only thing which is not protected is the cut-off voltage.
What I'm thinking is to use a "simple" nanopower voltage comparator (or uC supervisor) which will directly drive a FET for th on/off function, should you think this protection will work and be sufficient?
For example the AS1927 from austrianmicrosytem has a very low quiscent current (400nA max, much lower than the 6uA of the standard PCM).
The supervisor is active down to 1V, if I use a load switch like the Vishay Sip4282A which has a valid input from 1.5V to 5.5V, I should not use external pull down or pull up for forcing the output signal to 0V if the input voltage on the AS1927 is below 1V?
The battery will be a 80mAh (low capacity, so I have to spare the maximum energy I can) with a maximum discharge current of 0.5C.
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