L9963E datasheet(66/184 Pages) STMICROELECTRONICS

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Direct conversion of the voltage VBATT_MONITOR at VBAT pin through internal resistive divider (within

the VBAT Conversion step of the Voltage Conversion Routine). The result is compared to the

VBAT_CRITICAL_OV_TH or VBAT_CRITICAL_UV_TH fixed thresholds. This diagnostic is mainly intended to protect

the IC against AMR violation on VBAT pin. It can also be used as a redundant coherency check with the

arithmetic sum of cells.

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Continuous sense of the VBAT pin voltage with a VBAT_UV/OV comparator, featuring fixed thresholds

(VBAT_OV_WARNING (COMP) and VBAT_UV_WARNING (COMP)). It is used as an “over voltage warning” or an

“under voltage warning”. This diagnostic is intended to provide a fast reaction against transient overvoltage

and undervoltage events.

This UV/OV comparator is always enabled in order to guarantee a continuous safety check on VBAT voltage.

Refer to Table 40 for the electrical parameters.

4.11.2.1

VBAT over-voltage

The aim of this diagnostic is to detect a dangerous increase of battery voltage in order to protect the circuitry

connected to VBAT.

If VBAT > VBAT_OV_WARNING (COMP) (for a time longer than TVBAT_FILT) or VBATT_SUM > VBAT_OV (SUM) or

VBATT_MONITOR > VBAT_CRITICAL_OV_TH the over-voltage fault is directly reported in registers and notified to the

microcontroller with 3 dedicated flags, according to the Fault communication procedure.

In case of VBAT overvoltage detection during voltage conversion routine (violation of VBAT_OV (SUM) or

VBAT_CRITICAL_OV_TH).

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Corresponding fault flag is set and latched into register VSUM_OV or VBATTCRIT_OV

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Fault is propagated through the FAULT Line

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Voltage conversion routine goes into Configuration Override

In case of VBAT overvoltage detection through the analog comparator (VBAT_OV_WARNING):

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Corresponding fault flag is set and latched into register VBATT_WRN_OV

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Fault is propagated through the FAULT Line

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Voltage conversion routine is not involved, since this diagnostic is not part of the routine steps

For further details see Section 4.12 Voltage conversion routine.

4.11.2.2

VBAT under-voltage

The aim of this diagnostic is to detect a decrease of battery voltage in order to notify this fault that may cause

system malfunctions.

If VBAT < VBAT_UV_WARNING (COMP) (for a time longer than TVBAT_FILT) or VBATT_SUM < VBAT_UV (SUM) or

VBATT_MONITOR < VBAT_CRITICAL_UV_TH the under-voltage fault is reported in the register and notified to the

microcontroller with 3 dedicated flags, according to the Fault communication procedure.

In case of VBAT undervoltage detection during voltage conversion routine (violation of VBAT_UV (SUM) or

VBAT_CRITICAL_UV_TH):

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Corresponding fault flag is set and latched into register VSUM_UV or VBATTCRIT_UV

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Fault is propagated through the FAULT Line

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Balance is stopped on the whole stack

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Voltage conversion routine goes into Configuration Override

In case of VBAT undervoltage detection through the analog comparator (VBAT_UV_WARNING):

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Corresponding fault flag is set and latched into register VBATT_WRN_UV

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Fault is propagated through the FAULT Line

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Voltage conversion routine is not involved, since this diagnostic is not part of the routine steps

In case of VBAT pin loss, the internal resistive divider will pull-down VBAT to GND, thus causing VBAT UV failure

and, eventually, POR.

For further details see Section 4.12 Voltage conversion routine.

L9963E

Safety and diagnostic features

DS13636 - Rev 12

page 66/184

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