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Battery Management - Gas Gauge Forum
bq20z65 circuit design difficulties
attached hereby is a compressed rar file, comprising of 4 images and i have the following doubts concernig the circuit design as referenced to those images :
image name :-bq29330 : The pack- of bq29330 (ie SRN pin) is also connected to a "low power ground ". Is this the control ground in my terminology ? if yes then i am driving a inductive load on the battery (dc motor) which gives a back emf ,wont it affect my control circuit ics ,since there is no isolation ?AND WHAT IF I AM USING ONLY ONE BATTERY, I AM DRIVING THE CONTROL CIRCUIT VIA A STEP DOWN REGULATOR.
img chassis ground : As marked in the image, i couldnt understand where exactly shoud i connect these grounds.
img sense resistor : same as img bq29330.
img pres pin : One end of the diode is floating , is it to be connected somewhere ?
thanks in advance.
Sorry, can't open RAR file. Please use a standard office or pdf format.
i ve changed the file to .doc, plz reply at the earliest, i am stranded until your reply.
Sorry, don't understand your question regarding control circuit grounds and back emf. Are you refering to the battery manager, or some other control circuits?
The low power ground system in the the battery manager electronics should be connected to the point where the SRN sense line meets the sense resistor.
The ESD ground is (ideally) a star connection at the PACK - connector pin.
The unused diode is not connected.
For a good understanding of these issues, refer to chapters 17, 18, 19 of the bq20z70/90 application book. You can find it here:
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