Datasheet

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°Cor>60°C, then CFC is
driven low.
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.
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.
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
.
9
bq2050H
Symbol Parameter Typical Maximum Units Notes
INL
Integrated non-linearity
error
±
2
±
4
%
Add 0.1% per °C above or below 25°C
and 1% per volt above or below 4.25V.
INR
Integrated non-
repeatability error
±
1
±
2
%
Measurement repeatability given
similar operating conditions.
Table 6. bq2050H Current-Sensing Errors
FG2050H3.eps
Charger
P STAT
Charge
Control
Discharge
Control
CFC
R
LOAD
R
S
SR
V
SS
bq2050H
Figure 3. bq2050H Pack Supervision