LTC6803HG-2#TRPBF Linear Technology, LTC6803HG-2#TRPBF Datasheet - Page 29

• Manufacturer Part Number: LTC6803HG-2#TRPBF
• Manufacturer: Linear Technology
• Type: Battery Monitoringr

Specifications of LTC6803HG-2#TRPBF

• Battery Type: Li-Ion
• Operating Supply Voltage (min): 4V
• Operating Temp Range: -40C to 125C
• Package Type: SSOP
• Mounting: Surface Mount
• Pin Count: 44
• Operating Temperature Classification: Automotive
• Lead Free Status / Rohs Status: Compliant

APPLICATIONS INFORMATION
between C2 and C4 after several cycles of measuring cells
B3 and B4. Thus the measurements for B3 and B4 may
indicate a valid cell voltage when in fact the exact state of
B3 and B4 is unknown.
To reliably detect an open connection, the command
STOWAD is provided. With this command, two 100µA
current sources are connected to the ADC inputs and
turned on during all cell conversions. Referring again to
Figure 10, with the STOWAD command, the C3 pin will be
pulled down by the 100µA current source during the B3
cell measurement AND during the B4 cell measurement.
This will tend to decrease the B3 measurement result and
B4
B3
+
+
+
+
+
B4
B3
+
+
+
+
+
Figure 10. Open Connection with RC Filtering
C
C
F4
F3
Figure 9. Open Connection
18
20
22
24
1
C4
C3
C2
C1
V
–
18
20
22
24
1
MUX
C4
C3
C2
C1
V
–
MUX
100µA
LTC6803-4
100µA
680324 F09
LTC6803-4
680324 F10
increase the B4 measurement result relative to the normal
STCVAD command. The biggest change is observed in the
B4 measurement when C3 is open. So, the best method to
detect an open wire at input C3 is to look for an increase
in the value of battery connected between inputs C3 and
C4 (battery B4).
The following algorithm can be used to detect an open
connection to cell pin Cn:
1. Issue a STOWAD command (with 100µA sources
2. Issue a RDCV command and store all cell measurements
3. Issue the 2nd STOWAD command (with 100µA sources
4. Issue the 2nd RDCV command and store all cell mea-
5. For battery cells, if CELLA(1) < 0 or CELLB(1) < 0, V
The 200mV threshold is chosen to provide tolerance for
measurement errors. For a system with the capacitor con-
nected to Cn larger than 0.5µF , repeating step 3 several
times will discharge the external capacitor enough to meet
the criteria.
If the top C pin is open yet V
best way to detect an open connection to the top C pin
is by comparing the sum of all cell measurements using
the STCVAD command to an auxiliary measurement of
the sum of all the cells, using a method similar to that
shown in Figure 19. A significantly lower result for the
sum of all 12 cells suggests an open connection to the
top C pin, provided it was already determined that no
other C pin is open.
connected).
into array CELLA(n).
connected).
surements into array CELLB(n).
must be open.
If CELLA(12) < 0 or CELLB(12) < 0, C12 must be open.
For n = 2 to 11, if CELLB(n+1) – CELLA(n+1) > 200mV,
or CELLB(n+1) reaches the full scale of 5.375V, then
Cn is open.
LTC6803-2/LTC6803-4
+
is still connected, then the
29
680324f
–