ltc6803g-3 Linear Technology Corporation, ltc6803g-3 Datasheet - Page 30

• Manufacturer Part Number: ltc6803g-3
• Description: Ltc6803-1/ltc6803-3 - Multicell Battery Stack Monitor
• Manufacturer: Linear Technology Corporation

LTC6803-1/LTC6803-3
APPLICATIONS INFORMATION
Table 15. LTC6803-1/LTC6803-3 Failure Mechanism Effect Analysis
SCENARIO
Cell input open-circuit (random).
Cell input open-circuit (random).
Disconnection of a harness
between a group of battery cells
and the IC (in a system of stacked
groups).
Data link disconnection between
stacked LTC6803 units.
Cell-pack integrity, break between
stacked units.
Cell-pack integrity, break between
stacked units.
Cell-pack integrity, break within
stacked unit.
Cell-pack integrity, break within
stacked unit.
30
NEXT HIGHER GROUP
NEXT LOWER GROUP
EFFECT
Power-up sequence at IC inputs.
Differential input voltage overstress.
Loss of supply connection to the IC.
Break of "daisy-chain" communication (no stress to
ICs). Communication will be lost to devices above the
disconnection. The devices below the disconnection
are still able to communicate and perform all functions,
however, the polling feature is disabled.
Daisy-chain voltage reversal up to full stack potential
during pack discharge.
Daisy-chain positive overstress during charging.
Cell input reverse overstress during discharge.
Cell input positive overstress during charge.
OF 7 CELLS
OF 7 CELLS
+
+
+
+
+
+
+
Figure 13. Monitoring 7 Cells with the LTC6803-1/LTC6803-3
100
V
C12
S12
C11
S11
C10
S10
C9
S9
C8
S8
C7
S7
C6
S6
C5
S5
C4
S4
C3
S3
C2
S2
C1
S1
V
+
–
LTC6803-1
NEXT HIGHER GROUP
NEXT LOWER GROUP
OF 7 CELLS
OF 7 CELLS
+
+
+
+
+
+
+
DESIGN MITIGATION
Clamp diodes at each pin to V
alternate power path.
Zener diodes across each cell voltage input pair (within IC)
limits stress.
Separate power may be supplied by a local supply.
All units above the disconnection will enter standby mode
within 2 seconds of disconnect. Discharge switches are
disabled in standby mode.
Use series protection diodes with top-port I/O connections
(RS07J for up to 600V). Use isolated data link at bottom-
most data port.
Add redundant current path link. See Figure 14.
Add parallel Schottky diodes across each cell for load-
path redundancy. Diode and connections must handle full
operating current of stack, will limit stress on IC.
Add SCR across each cell for charge-path redundancy. SCR
and connections must handle full charging current of stack,
will limit stress on IC by selection of trigger Zener.
100
V
C12
S12
C11
S11
C10
S10
C9
S9
C8
S8
C7
S7
C6
S6
C5
S5
C4
S4
C3
S3
C2
S2
C1
S1
C0
V
+
–
LTC6803-3
680313 F13
+
and V
–
(within IC) provide
680313f