BQ2063_15 Datasheet, PDF (11/60 Pages) Texas Instruments – SBS v1.1-COMPLIANT Li-ION GAS-GAUGE IC

Not Recommended For New Designs
bq2063
SBS v1.1ĆCOMPLIANT LiĆION GASĆGAUGE IC
WITH PROTECTOR INTERFACE
SLUS468E− MAY 2001 − REVISED APRIL 2002
Table 2. bq2063 Register Functions (Continued)
FUNCTION
SerialNumber
Reserved
ManufacturerName
DeviceName
DeviceChemistry
ManufacturerData
Pack Status
Pack Configuration
VCELL4
VCELL3
VCELL2
VCELL1
COMMAND CODE
SMBus
HDQ16
0x1c
0x1c
0x1d-0x1f 0x1d−0x1f
0x20
0x20−0x25
0x21
0x28−0x2b
0x22
0x30−0x32
0x23
0x38−0x3b
0x2f (LSB) 0x2f (LSB)
0x2f (MSB) 0x2f (MSB)
0x3c
0x3c
0x3d
0x3d
0x3e
0x3e
0x3f
0x3f
ACCESS
(SMBus)
read
—
read
read
read
read
read/write
read/write
read/write
read/write
read/write
read/write
UNITS
integer
—
string
string
string
string
NA
NA
mV
mV
mV
mV
self-discharge
The bq2063 estimates the self-discharge of the battery to maintain an accurate measure of the battery capacity
during periods of inactivity. The algorithm for self-discharge estimation takes a programmed estimate for the
expected self-discharge rate at 25°C stored in EEPROM and makes a fixed reduction to RM of an amount equal
to RemainingCapacity( )/256. The bq2063 makes the fixed reduction at a varying time interval that is adjusted
to achieve the desired self-discharge rate. This method maintains a constant granularity of 0.39% for each
self-discharge adjustment, which may be performed multiple times per day, instead of once per day with a
potentially large reduction.
The self-discharge estimation rate for 25°C is doubled for each 10 degrees above 25°C or halved for each 10
degrees below 25°C. The following table shows the relation of the self-discharge estimation at a given
temperature to the rate programmed for 25°C (Y% per day).
Table 3. Self-Discharge for Rate Programmed
TEMPERATURE
(°C)
Temp < 10
10 ≤ Temp <20
20 ≤ Temp <30
30 ≤ Temp <40
40 ≤ Temp <50
50 ≤ Temp <60
60 ≤ Temp <70
70≤ Temp
SELF-DISCHARGE RATE
1/4 Y% per day
1/2 Y% per day
Y% per day
2Y% per day
4Y% per day
8Y% per day
16Y% per day
32Y% per day
The interval at which RM is reduced is given by the following equation, where n is the appropriate factor of 2
(n = 1/4, 1/2,1, 2, . . . ):
Self-Discharge
Update
Time
+
256
640
•n•
• 13500
(Y% per
day)
seconds
(2)
Example: If T = 35°C (n = 2) and programmed self-discharge rate Y is 2.5% per day at 25°C, the bq2063 reduces
RM by RM/256 (0.39%) every
640 • 13500
256 • 2 • 2.5
+ 6750 seconds
(3)
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