Parasitic diod

Alexander Marusyak

Other Parts Discussed in Thread: BQ24725A

Hello everyone.
Who can explain me transistor Q5 necessity in chip bq24725A.
page 28 Figure 18 in datasheet if "Pack+" connected with "System" net
through parasitic diod in transistor Q3 (it not pictured but have)

Thanks.

over 9 years ago

0 Jing Zou over 9 years ago

TI__Mastermind 20570 points

This FET is used to control the discharge path from the battery to the system load.

0 Alexander Marusyak over 9 years ago

Prodigy 20 points

Yes you are right.
This is writen in TRM but ,what control you are talking about if SYS connected through diod ALWAYS.
Control by Q3 offer disconnect Pack+ from SYS and charging it through Q5 from external source. It also supplied to SYS when Pack disconnected from SYS.

Best regards.

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Parasitic diod