MAX11080 Datasheet, PDF (13/27 Pages) Maxim Integrated Products – 12-Channel, High-Voltage Battery-Pack Fault Monitor

12-Channel, High-Voltage Battery-Pack
Fault Monitor
referenced voltage is then connected to a set of over-
voltage and undervoltage comparators. The threshold
references for the comparators are set by the UVSEL_
and OVSEL_ input pins. When one of the cell voltages
exceeds V_OV or is below V_UV when V_UV is enabled, the
internal cell out-of-range signal for the given cell is set
and logically ORed with the same signal for the other
cell positions to create an overall out-of-range signal.
When any cells are out-of-range as indicated by the
internal out-of-range signal, an internal current source
begins to charge the capacitor C_DLY connected to the
CD pin. If the voltage at the CD pin reaches V_CD, the
ALRM_L line is set to V_AA (+2.4V minimum as referred to
AGND). Normally, the ALRM_L line is a heartbeat signal
with pulses occurring every 250µs. If all cell voltages
transition from out-of-range to in-range before the volt-
age at pin CD reaches V_CD, an internal switch clamps
the CD pin to GND. This action discharges C_DLY and,
because the delay had not yet expired, no alarm
occurs. Discharging C_DLY ensures that the full delay
time occurs for the next overvoltage or undervoltage
event. Figure 8 summarizes the C_DLY circuit.
V_CELL/(4 x R_SHIFT)
HV
C_N+1
+
V_CELL
R_IN*
40MΩ RSHIFT
TYP
-
C_N
+
V_CELL/4
-
CELLS 2-12
AGND
CELL 1
+
V_CELL
-
6MΩ
TYP
2MΩ
TYP
V_CELL/4
V_OV/4
75mV
HYSTERESIS
75mV
HYSTERESIS
CELL
OUT-OF-RANGE
OUT-OF-RANGE
11
V_UV/4
UNDERVOLTAGE
COMPARATOR
ENABLE
V_SC/4
SHORT-CIRCUIT
DETECTOR
Figure 7. Cell Differential Input and Comparator Block Diagram
CELL OUT-OF-RANGE
1 TO 12
11
V_AA
I_CD
6.1µA
OUT-OF-RANGE
6kΩ
CD
ALARM
V_CD
THRESHOLD
C_DLY
Figure 8. C_DLY Circuit Block Diagram
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