MAX11080 Datasheet, PDF (21/27 Pages) Maxim Integrated Products – 12-Channel, High-Voltage Battery-Pack Fault Monitor

12-Channel, High-Voltage Battery-Pack
Fault Monitor
tion for this test-mode compare level. If all comparators
can detect the internally generated overvoltage test
event, part operation continues. If any comparator fails
to detect the internally generated overvoltage test
event, a fault is signaled using the ALRM_L pin. The
device must be power cycled to retest the comparators
and attempt to clear this fault condition.
Failure Mode and Effects Analysis
High-voltage battery-pack systems can be subjected to
severe stresses during in-service fault conditions and
could experience similar conditions during the manu-
facturing and assembly process. The MAX11080 is
designed with high regard to these potential states.
Open and short circuits at the package level must be
readily detected for fault diagnosis and should be toler-
ated whenever possible. A number of circuits are
employed within the MAX11080 specifically to detect
such conditions and progress to a known device state.
Table 3 summarizes other conditions typical in a normal
manufacturing process along with their effect on the
MAX11080 device.
See Table 4 for the FEMA analysis of the MAX11080. If
the cell voltage is within the monitor range, the heart-
beatsignal on the ALRML resumes once the fault condi-
tion (either open or short) is removed, unless specified.
Table 3. System Fault Modes
CONDITION
EFFECT
PCB or IC package open or short circuit— Refer to the pin-level FMEA analysis
no stack load
spreadsheet available from the factory
DESIGN RECOMMENDATION
The built-in features of the MAX11080
should ensure low FMEA risk in most
cases.
Random connection of cells to IC—
no stack load
No effect
The series resistors on the cell inputs of
the MAX11080 as well as the internal
design ensure protection against random
power supply or ground connections.
Random connection of modules—
no stack load
No effect
Each module is referenced to its neighbor,
so no special connection order is
necessary.
Random connect/disconnect of
communication bus—no stack load;
AC- or DC-coupled
Communication from host to the first break
in the daisy-chain bus
The level-shifted interface design of the
MAX11080 ensures that the SHDN, GND_U,
and ALRM_ communication bus can be
connected at any time with no load.
Random connect/disconnect of
communication bus—with stack load;
AC- or DC-coupled
Communication from host to the first break
in the daisy-chain bus
The level-shifted interface design of the
MAX11080 ensures that the SHDN, GND_U,
ALRM_ communication bus can be
connected at any time as long as the
power bus is properly connected.
Connect/disconnect module interconnect No effect for DC- or AC-coupled
(bus bar)—no stack load
communication bus
A break in the power bus does not cause
a problem as long as there is no load on
the stack.
Removal/fault of module interconnect
(bus bar)—with stack load
No effect for AC-coupled communication
bus; device damage for DC-coupled bus
An AC-coupled bus with isolation on the
SHDN pin or a redundant bus-bar
connection should be used to protect
against this case.
Removal/fault of module interconnect
(bus bar)—with stack under charge
No effect for AC-coupled communication
bus; device damage for DC-coupled bus
An AC-coupled bus with isolation on the
SHDN pin or a redundant bus-bar
connection should be used to protect
against this case.
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