Datasheet

LTC6803-2/LTC6803-4
35
680324fa
APPLICATIONS INFORMATION
SUPPLY DECOUPLING IF BATTERY-STACK POWERED
As shown in Figure 21, the LTC6803-4 can have filtering
on both V
+
and V
–
, so differential bypassing to the cell
group potentials is recommended. The Zener suppresses
overvoltages from reaching the IC supply pins. A small
ferrite-bead inductor provides protection for the Zener, par-
ticularly from energetic ESD strikes. Since the LTC6803-2
cannot have a series resistance to V
–
, additional Schottky
diodes are needed to prevent ESD-induced reverse-supply
(substrate) currents to flow.
ADVANTAGES OF KELVIN CONNECTION ON C0
The V
–
trace resistance can cause an observable voltage
drop between the negative end of the bottom battery
cell and V
–
pin of LTC6803. This voltage drop will add to
the measurement error of the bottom cell voltage. The
LTC6803-4 separates C0 from V
–
, allowing Kelvin con-
nection on C0 as shown in Figure 22. Voltage drop on the
V
–
trace will not affect the bottom cell voltage measure-
ment. The Kelvin connection will also allow RC filtering
on V
–
as shown in Figure 21.
Figure 21. Supply Decoupling
Figure 22. Kelvin Connection on C0 Improving
Bottom Cell Voltage Measurement Accuracy
CELLGROUP
+
CELLGROUP
–
CMHZ5265B BAT46W
100Ω
100nF
V
+
V
–
BLM31PG330SN1L
LTC6803-2 Configuration
CELLGROUP
+
CELLGROUP
–
CMHZ5265B
100Ω
100Ω
100nF
680324 F21
V
+
V
–
BLM31PG330SN1L
LTC6803-4 Configuration
I
SUPPLY
68034 F20
BATTERY
STACK
R
+
+
+
+
C1
C0
V
–
LTC6803-4