Data Sheet

bq27441-G1
SLUSBH1C –NOVEMBER 2013–REVISED DECEMBER 2014 www.ti.com
11 Power Supply Recommendation
11.1 Power Supply Decoupling
The battery connection on the BAT pin is used for two purposes:
• To supply power to the fuel gauge
• To provide an input for voltage measurement of the battery.
A capacitor of value of at least 1 µF should be connected between BAT and V
SS
. The capacitor should be placed
close to the gauge IC and have short traces to both the BAT pin and V
SS
.
The fuel gauge has an integrated LDO with an output on the V
DD
pin of approximately 1.8 V. A capacitor of value
at least 0.47 µF should be connected between the V
DD
pin and V
SS
. The capacitor should be placed close to the
gauge IC and have short traces to both the V
DD
pin and V
SS
.
12 Layout
12.1 Layout Guidelines
• A capacitor of a value of at least 0.47 µF is connected between the V
DD
pin and V
SS
. The capacitor should be
placed close to the gauge IC and have short traces to both the V
DD
pin and V
SS
.
• It is required to have a capacitor of at least 1.0 µF connect between the BAT pin and V
SS
if the connection
between the battery pack and the gauge BAT pin has the potential to pick up noise. The capacitor should be
placed close to the gauge IC and have short traces to both the V
DD
pin and V
SS
.
• If the external pullup resistors on the SCL and SDA lines will be disconnected from the host during low-power
operation, it is recommend to use external 1-MΩ pulldown resistors to V
SS
to avoid floating inputs to the I
2
C
engine.
• The value of the SCL and SDA pullup resistors should take into consideration the pullup voltage and the bus
capacitance. Some recommended values, assuming a bus capacitance of 10 pF, can be seen in Table 4.
Table 4. Recommended Values for SCL and SDA Pullup Resistors
VPU 1.8 V 3.3 V
Range Typical Range Typical
R
PU
400 Ω ≤ R
PU
≤ 37.6 kΩ 10 kΩ 900 Ω ≤ R
PU
≤ 29.2 kΩ 5.1 kΩ
• If the GPOUT pin is not used by the host, the pin should still be pulled up to V
DD
with a 4.7-kΩ or 10-kΩ
resistor.
• If the battery pack thermistor is not connected to the BIN pin, the BIN pin should be pulled down to V
SS
with a
10-kΩ resistor.
• The BIN pin should not be shorted directly to V
DD
or V
SS
.
• The actual device ground is pin 3 (V
SS
).
• The SRP and SRN pins should be Kelvin connected to the R
SENSE
terminals. SRP to the battery pack side of
R
SENSE
and SRN to the system side of the R
SENSE
.
• Kelvin connect the BAT pin to the battery PACKP terminal.
18 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated
Product Folder Links: bq27441-G1