BQ27750: Technical Reference Manual Update?

Andrew,

For this device we are making lots of TRM updates and corrections and A newer revision of the TRM should be available soon. In the meantime here are some answers to your questions

1) All of the following bits serve no purpose in this FW and the feature is not included
EMSHUT_PEXIT_DIS, EMSHUT_EXIT_COMM, EMSHUT_EXIT_VPACK, PWR_SAVE_VSHUT
2) SLP_ACCUM - This will add charge accumulated in sleep mode to the passed charge counter
3) SLEEPWKCHG - Device will exit sleep mode on entrance to charge mode
4) [SMOOTH]: A change in temperature or current rate can cause a significant change in Remaining
Capacity (RemCap) and Full Charge Capacity (FCC), resulting in a jump or drop in the Relative State-of-
Charge (RSOC). This function provides an option to prevent an RSOC jump or drop during charge and
discharge.
If a jump or drop of RSOC occurs, the device examines the amount of RSOC jump or drop versus the
expected end point (that is, the charge termination for the charging condition or the EDV for the discharge
condition) and automatically smooths the change of RSOC, and always converges with the filtered (or
smoothed) value to the actual charge termination or EDV point. The actual and filtered values are always
available. The [SMOOTH] flag selects either the actual or filtered values are returned by the SBS
commands.
[RELAX_JUMP_OK] and [RELAX_SMOOTH_OK]: When the battery enters RELAX mode from CHARGE
or DISCHARGE mode, the transient voltage may change to RSOC as the battery goes into its RELAX
state. Once the battery is in RELAX mode, a change in temperature or self-discharge may also cause a
change in RSOC.
If [RELAX_JUMP_OK] = 1, this allows the RSOC jump to occur during RELAX mode. Otherwise, RSOC
holds constant during RELAX mode and any RSOC jump will be passed into the onset of the charge or
discharge phase.
If [RELAX_SMOOTH_OK] = 1, this allows the amount of the RSOC jump to be smoothed out over a
period of Smooth Relax Time. Otherwise, the additional RSOC jump amount will be passed into the
onset of charge or discharge phase.
If both flags are set to 1, the [RELAX_JUMP_OK] = 1 takes higher priority and the RSOC jump is allowed
during RELAX mode.
5) Fast QMax Update Conditions
The Fast QMax update conditions are very similar to the QMax update conditions with the following
differences:
• Instead of taking two OCV readings for QMax update, Fast QMax update requires only one OCV
reading, AND
• The battery pack should discharge below 10% RSOC.
The differences in requirements allow the Fast QMax feature to have a QMax update at the end of
discharge (given one OCV reading is already available and discharge below 10% RSOC) without a longer
relax time after a discharge event. Typically, it can take up to 5 hours in a discharge state to ensure the
dV/dt < 4 μV/s condition is satisfied. The Temperature, Delta Capacity, Voltage, and Offset Error
requirements for QMax update are still required for the Fast QMax update.
This feature is particularly useful for reducing production QMax learning cycle time or for an application
that is mostly in charge or discharge stage with infrequent relaxation. Setting IT Gauging
Configuration[FAST_QMAX_LRN] = 1 enables Fast QMax during production learning only (that is,
Update Status = 6). When setting IT Gauging Configuration[FAST_QMAX_FLD] = 1, Fast QMax is
enabled when Impedance Track is enabled and Update Status ≥ 6.
6) IMAXRESEN - This will include the set Reserve capacity in the IMAX calcualation
7) I2C Gauging Configuration
[LOCK0]: After a discharge event, cell voltage will usually recover to a slightly higher voltage during
RELAX state. A new OCV reading during this time can result in a slightly higher state-of-charge. This flag
provides an option to keep RemainingCapacity() and RelativeStateOfCharge() jumping back during
relaxation after 0% and FD are reached during discharge.
[RSOC_HOLD]: An IT simulation will run at the onset of discharge. If charge terminates at a low
temperature and a discharge occurs at a higher temperature, the difference in temperature could cause a
small rise of RSOC for a short period of time at the beginning of discharge. This flag option prevents
RSOC rises during discharge. RSOC will be held until the calculated value falls below the actual state.
[RSOC_HOLD] should not be used when [SMOOTH] is set.
[RSOCL]: When set, RSOC will be held at 99% until charge termination is detected. See Section 4.6 for
details.
[TAMB_SYNC_SIM] When T-Ambient sync command is used this will also trigger a gauging simulation similar to if a grid point was reached.
8) IT Gauging Ext
Bit0: DSG_0_SMOOTH_OK—Enable for smoothing to 0% in
DISCHARGE mode. If enabled, this smoothing option must be used in
conjunction with Term Smooth Start Cell V Delta, Term Smooth
Time, and Term Smooth Final Cell V Delta. If not configured
properly, this smoothing option can result in causing
RemainingCapacity() to 0 mAh early.
0 = Disabled
1 = Enabled (default)
Bit 1: CHG_100_SMOOTH_OK—Enable for smoothing to 100% in
CHARGE mode during charge termination
0 = Disabled
1 = Enabled (default)
Bit 2: AMB_PRED—Enable for ambient temperature prediction in
modes other than RELAX
0 = Disabled (default)
1 = Enabled
Bit 3: THERM_IV—Enable for holding battery heat constant near the
end of an IT simulation. This helps prevent overestimation of
temperature towards the end of discharge, and applies to SOH
simulations
0 = Disabled
1 = Enabled (default)
Bit 4: THERM_SAT—Enable for using measured cell temperature for
simulated temperature within IT simulations occurring near termination
in a sustained discharge (when thermal saturation is reached). This
behavior does NOT apply to SOH simulations
0 = Disabled
1 = Enabled (default)

I know this is a lot and not displayed super well. please let me know if i need to make something more clear.

Thanks,
Eric Vos