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| Single cell lipo protection circuit with replaceable battery design help |
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| amyk:
See section 12 of the datasheet. The Rds(on) of the MOSFETs sets the current limit. |
| vis321:
Thanks for your help, So ok, after reading into more how to IC detects and samples for over current discharge and all that. As well as much better availability. I am going to try and fit in the bq297002 still. which has a UVP of 2.8v and a OCD of 0.160 V. Given that my boost converter takes upto almost 10 amps on when a new cell is inserted. I figure a 10-12 or so amp cut off limit could be safe? in the datasheet on page 20, In the example, for 5a, they give an upper limit of 7a, they use the bq29700 which has a 0.100v cut off. So 100 mV/7A = 14.3 Ohm (would need for RDS on?). Also few clip snap shots of the scope when a new cell is inserted, I used 3 1.5 ohm resistor in parallel for a quick test,(0.333 Ohm), and after a little ohms law I got almost 10A (9.369A), for roughly 50 uS, ODC protection kicks in, OCD delay is 16 ms... So For my application lets take the bq297002, OCD of 0.160v, I calculated about 16 mOhm for my application. (at 10 amps, 160/10). So I should be on the scope out for a low RDS on mosfet of around 16 mOhm? with a low of like 3v or lower(2.5v? lowest). And most likely will need to double up on the mofest (2 output and 2 input) to get my 10 amps of current? Any suggestions on mosfets? For example I was looking into CSD16301Q2, might be a bit over kill: http://www.ti.com/general/docs/suppproductinfo.tsp?distId=10&gotoUrl=http%3A%2F%2Fwww.ti.com%2Flit%2Fgpn%2Fcsd16301q2 Few other FET's I was looking at as well. Alpha and Omega: AON2406 http://aosmd.com/res/data_sheets/AON2406.pdf Rhom RQ6E080AJTCR https://www.rohm.com/datasheet/RQ6E080AJ/rq6e080aj-e RF6E065BNTCR https://www.rohm.com/datasheet/RF6E065BN/rf6e065bntcr-e RF4E100AJTCR https://www.rohm.com/datasheet/RF4E100AJ |
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