鉃?/div>
Designed for battery pack inte-
gration
General Description
The bq2945 Gas Gauge IC With
SMBus Interface is intended for
battery-pack or in-system installa-
tion to maintain an accurate record
of available battery charge. The
bq2945 directly supports capacity
monitoring for NiCd, NiMH, and
Li-Ion battery chemistries.
The bq2945 uses the System Man-
agement Bus v1.0 (SMBus) protocol
and supports the Smart Battery
Data (SBData) commands. The
bq2945 also supports the SBData
charge control functions. Battery
state-of-charge, remaining capacity,
remaining time, and chemistry are
av a i l a b le ov e r t h e s e r i a l l in k .
Battery-charge state can be directly
indicated using a five-segment LED
display to graphically depict battery
full-to-empty in 20% increments.
The bq2945 estimates battery self-
discharge based on an internal
timer and temperature sensor and
user-programmable rate informa-
tion stored in external EEPROM.
The bq2945 also automatically re-
calibrates or 鈥渓earns鈥?battery capac-
ity in the full course of a discharge
cycle from full to empty.
The bq2945 may operate directly
from three nickel chemistry cells.
With the REF output and an exter-
nal transistor, a simple, inexpensive
regulator can be built to provide V
CC
for other battery cell configurations.
An external EEPROM programs
initial values into the bq2945 and is
necessary for proper operation.
-
-
Low operating current
Complete circuit can fit on less
than 戮 square inch of PCB
space
鉃?/div>
Supports SBS charge control
commands for NiCd, NiMH, and
Li-Ion
鉃?/div>
Drives a five-segment LED dis-
play for remaining capacity
indication
鉃?/div>
16-pin narrow SOIC
Pin Connections
Pin Names
V
CC
LED
1
3.0鈥?.5V
LED segment 1/
EEPROM clock
LED segment 2/
EEPROM data
LED segment 3
LED segment 4
LED segment 5
Control pin 1
System ground
SR
DISP
SB
CP
2
SMBD
SMBC
REF
V
OUT
Sense resistor input
Display control input
Battery sense input
Control pin 2
SMBus data input/output
SMBus clock
Voltage reference output
EEPROM supply output
VCC
LED1/ESCL
LED2/ESDA
LED3
LED4
LED5
CP1
VSS
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
VOUT
REF
SMBC
SMBD
CP2
SB
DISP
SR
LED
2
LED
3
LED
4
LED
5
CP
1
V
SS
16-Pin Narrow SOIC
PN294501.eps
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