BQ24193: What is the expected VSYS when the battery is disconnected?

Southern Engineering

Part Number: BQ24193

Hi,

There are situations in the project where the battery may get physically disconnected. The datasheet explains how VSYS behaves as a function of VBAT, but I have not understood from the given description what VSYS voltage to expect if the battery is disconnected. What value should I expect?

Also, VSYS is described to track 150 mV above VBAT when not charging. VBAT can be set to charge up to 4.4V, yet the maximum VSYS range is stated as 4.35V. How should that be understood? What VSYS voltage should I expect when not charging if the charging voltage is set to for instance 4.35V or 4.4V?

Thanks!

over 5 years ago

0 Jeff F over 5 years ago

TI__Guru**** 165886 points

Hi,

With no battery and charge disabled, VSYS= MINSYS. With no battery and charge enabled, VSYS jumps between MINSYS and VBATREG as the capacitor at BAT is charged, allowed to discharge, repeat.

The max VSYS of 4.35V is a typo. VSYS max is VBATREG+150mV.

Regards,

Jeff

0 Southern Engineering over 5 years ago in reply to Jeff F

Intellectual 715 points

Hi,

Could I then even assume that it in practice stays at VSYS = MINSYS because of the charger not charging due to it thinking that the temperature is sub-zero since the NTC connection to the battery is open/high-Z (when the battery is disconnected)?

Thanks!

0 Jeff F over 5 years ago in reply to Southern Engineering

TI__Guru**** 165886 points

Hi,

yes. If in TS fault and charge is disabled, VSYS=MINSYS.

Regards,

Jeff

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BQ24193: What is the expected VSYS when the battery is disconnected?