Texas Instruments BQ25120F3A, Manual

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readable with 2% increments with ±1.5% accuracy between 60% and 100% of VBATREG using the VBMON_TH
registers. Reading the value during charge is possible, but for the most accurate battery voltage indication, it is
recommended to disable charge, initiate a read, and then re-enable charge.
A typical discharge profile for a Li-Ion battery is shown in Table 9-2 . The specific battery to be used in the
application should be fully characterized to determine the thresholds that will indicate the appropriate battery
status to the user. Two typical examples are shown below, assuming the VBMON reading is taken with no load
on the battery.
This function enables a simple 5-bar status indicator with the following typical performance with different
VBATREG settings:
Table 9-2. Discharge Profile for a Li-Ion Battery
VBATREG BATTERY FULL
95% to 65%
REMAINING CAPACITY
65% to 35%
REMAINING CAPACITY
35% to 5%
REMAINING CAPACITY
BATTERY EMPTY
4.35 V VBMON > 90% VBMON = 88% VBMON = 86% VBMON = 84% VBMON < 82%
4.2 V VBMON > 98% VBMON = 94% or 96% VBMON = 90% or 92% VBMON = 86% or 88% VBMON < 84%
D
E
C
O
D
E
R
S 3
S 2
S 1
S 0
- 2 % BAT TAP
- 4 % BAT TAP
- 6 % BAT TAP
- 8 % BAT TAP
- 10 % BAT TAP
VREF
90 % VB
80 % VB
70 % VB
60 % VB
VB = 0 . 8 VBAT
V
BG
U
A
G
E
_
T
H<
2
:0
>
Figure 9-3. Voltage Battery Monitor
9.3.5 Sleep Mode
The device enters the low-power sleep mode if the voltage IN falls below the sleep-mode entry threshold and
V
IN
is higher than the undervoltage lockout threshold. In sleep mode, the input is isolated from the connected
battery. This feature prevents draining the battery during the absence of V
IN
. When V
IN
< V
(BAT)
+ V
SLP
, the
device turns the battery discharge FET on, sends a 128-µs pulse on the INT output, and the FAULT bits of the
register are update over I
2
C. Once V
IN
> V
(BAT)
+ V
SLP
, the device initiates a new charge cycle. The FAULT bits
are not cleared until they are read over I
2
C and the sleep condition no longer exists. It is not recommended to do
a battery connection or plug in when V
UVLO
< VIN < V
BAT
+ V
SLP
as it may cause higher quiescent current to be
drained form the battery.
BQ25120F3A
SLUSDI4A – OCTOBER 2018 – REVISED APRIL 2021
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