LTC2941CDCB-1#PBF Linear Technology, LTC2941CDCB-1#PBF Datasheet - Page 6

• Manufacturer Part Number: LTC2941CDCB-1#PBF
• Description: IC, BATTERY FUEL GAUGE LI-ION 5.5V DFN-6
• Manufacturer: Linear Technology

Specifications of LTC2941CDCB-1#PBF

• Battery Management Function: Fuel Gauge, Charge Controller
• Battery Type: Li-Ion
• Supply Voltage Range: 2.7V To 5.5V
• Battery Ic Case Style: DFN
• No. Of Pins: 6
• Rohs Compliant: Yes

CHARGER
LTC2941
operaTion
Overview
The LTC2941 is a battery gas gauge device designed for
use with single Li-Ion cells and other battery types with
a terminal voltage between 2.7V and 5.5V. A precision
coulomb counter integrates current through a sense
resistor between the battery’s positive terminal and the
load or charger.
Coulomb Counter
Charge is the time integral of current. The LTC2941 mea-
sures battery current by monitoring the voltage developed
across a sense resistor and then integrates this information
to infer charge. The differential voltage between SENSE
and SENSE
integrator to convert the measured current to charge.
When the integrator output ramps to REFHI or REFLO
levels, switches S1, S2, S3 and S4 toggle to reverse the
ramp direction. By observing the condition of the switches
and the ramp direction, polarity is determined.

BATTERY
R
SENSE
I
BAT
+
–
is applied to an auto-zeroed differential analog
LOAD
1
6
2
SENSE
SENSE
GND
+
–
V
SUPPLY
S1
S2
S3
S4
Figure 3. Coulomb Counter Section of the LTC2941
–
+
REFLO
REFHI
+
A programmable prescaler is incremented or decremented
every time the integrator changes ramp direction. The
prescaler effectively increases integration time by a factor
M programmable from 1 to 128. At each under or overflow
of the prescaler, the accumulated charge is incremented or
decremented one count. The value of accumulated charge
is read via the I
Power-Up Sequence
When V
2.5V, the LTC2941 generates an internal power-on reset
(POR) signal and sets all registers to their default state.
In the default state, the coulomb counter is active. The
accumulated charge is set to mid-scale (7FFFh), the
low threshold registers are set to 0000h and all the high
threshold registers are set to FFFFh. The alert mode is
enabled and the coulomb counter prescaling factor M is
set to 128.
+
–
+
–
SENSE +
DETECTION
CONTROL
POLARITY
2
rises above a threshold of approximately
LOGIC
C interface.
SCALER
PRE-
M
THRESHOLDS
REGISTERS
CONTROL
STATUS
ACR
SMBus
I
2
C/
AL/CC
SDA
SCL
2941fa
2941 F03
5
3
4