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I was referencing the datasheet for BQ24040 Texas Instrument IC and could not understand the following statement and what does it actually mean. I am new to this. Can some one explain what does it mean.

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This is on page '4' in the datasheet. Reference datasheet can be found here: http://www.ti.com/lit/ds/symlink/bq24040.pdf

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  • \$\begingroup\$ Ipgm is the programmed current, I believe. \$\endgroup\$
    – DKNguyen
    Commented May 7, 2020 at 15:30
  • \$\begingroup\$ I was wondering if 'Ipgm' is equal to fast charge current ? \$\endgroup\$
    – Ravi
    Commented May 7, 2020 at 15:40

2 Answers 2

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When charging, the charging is terminated when charging current has dropped to I/10, i.e. the battery is full.

When battery is really low on charge, it is slowly charged at I/5 before it is safe to charge it with full current.

These are achieved with 2k resistor.

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  • \$\begingroup\$ Is the 'I' in 'I/5' the Ipgm ? Is 'Ipgm' the fast charge current ? \$\endgroup\$
    – Ravi
    Commented May 7, 2020 at 15:40
  • \$\begingroup\$ search for the word fast in the document \$\endgroup\$
    – jsotola
    Commented May 7, 2020 at 16:03
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Expected range of programming resistor is 1k to 10kΩ (2k: Ipgm/10 for term; Ipgm/5 for precharge)

Iset = CC then CV then cutoff= Fast Charge mode =Ipgm
Ipre = 2*Iterm.
term.=cutoff
2 kΩ = 10% cutoff = 20% precharge

Some use 5% for slightly more capacity yet more ageing.

This is a user tradeoff choice, as is Depth of discharge >50%.

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