BQ2050H_15 Datasheet, PDF (9/30 Pages) Texas Instruments – Low-Cost Lithium Ion Power Gauge™ IC

Not Recommended For New Designs
bq2050H
Table 6. bq2050H Current-Sensing Errors
Symbol
INL
INR
Parameter
Integrated non-linearity
error
Integrated non-
repeatability error
Typical
±2
±1
Maximum
±4
±2
Units
%
%
Notes
Add 0.1% per °C above or below 25°C
and 1% per volt above or below 4.25V.
Measurement repeatability given
similar operating conditions.
trol FET signal and can quickly determine if the protector
circuit is operating properly during charge.
Register 15h, NMCV, is used to set the maximum bat-
tery voltage for the battery stack. If V_SB > NMCV or the
battery temperature is < 0°C or > 60°C, then CFC is
driven low.
A Capacity Inaccurate counter (CPI) is maintained and
incremented each time a valid charge occurs (qualified
by NAC; see the CPI register description). It is reset
whenever LMD is updated from the DCR. The counter
does not wrap around but stops counting at 255. The ca-
pacity inaccurate flag (CI) is set if LMD has not been
updated following 64 valid charges.
Error Summary
Capacity Inaccurate
The LMD is susceptible to error on initialization or if no
updates occur. On initialization, the LMD value in-
cludes the error between the programmed full capacity
and the actual capacity. This error is present until a
valid discharge occurs and LMD is updated (see the
DCR description). The other cause of LMD error is bat-
tery wear-out. As the battery ages, the measured capac-
ity must be adjusted to account for changes in actual
battery capacity.
Current-Sensing Error
Table 6 shows the non-linearity and non-repeatability
errors associated with the bq2050H current sensing.
Table 7 illustrates the current-sensing error as a func-
tion of V_OS. A digital filter prevents charge and dis-
charge counts to the NAC register when V_SRO is be-
tween V_SRQ and V_SRD.
Discharge
Control
Charge
Control
RS
PSTAT
bq2050H
CFC
SR
VSS
Charger
RLOAD
FG2050H3.eps
Figure 3. bq2050H Pack Supervision
9