PS501 Datasheet, PDF (22/42 Pages) Microchip Technology – Single Chip Field Reprogrammable Battery Manager

PS501
8.1.12 AverageCurrent (0x0b)
Returns a one-minute rolling average based on at least
60 samples of the current being supplied (or accepted)
through the battery’s terminals (mA).
8.1.13 MaxError (0x0c)
Returns the expected margin of error (%) in the State-
Of-Charge calculation. For example, when MaxError
returns 10% and RelativeStateOfCharge returns 50%,
the RelativeStateOfCharge is actually between 50%
and 60%. The MaxError of a battery is expected to
increase until the Smart Battery identifies a condition
that will give it higher confidence in its own accuracy.
For example, when a Smart Battery senses that it has
been fully charged from a fully discharged state, it may
use that information to reset or partially reset MaxError.
The Smart Battery can signal when MaxError has
become too high by setting the CONDITION_FLAG bit
in BatteryMode.
8.1.14 RelativeStateOfCharge (0x0d)
Returns the predicted remaining battery capacity
expressed as a percentage of FullChargeCapacity (%).
8.1.15 AbsoluteStateOfCharge (0x0e)
Returns the predicted remaining battery capacity
expressed as a percentage of DesignCapacity (%).
Note that AbsoluteStateOfCharge can return values
greater than 100%.
8.1.16 RemainingCapacity (0x0f)
Returns the predicted remaining battery capacity. The
RemainingCapacity value is expressed in either current
(mAh) or power (10 mWh), depending on the setting of
the BatteryMode’s CAPACITY_MODE bit.
8.1.17 FullChargeCapacity (0x10)
Returns the predicted pack capacity when it is fully
charged. It is based on either current or power,
depending on the setting of the BatteryMode’s
CAPACITY_MODE bit.
8.1.18 RunTimeToEmpty (0x11)
Returns the predicted remaining battery life at
the present rate of discharge (minutes). The
RunTimeToEmpty value is calculated based on either
current or power, depending on the setting of the
BatteryMode’s CAPACITY_MODE bit. This is an impor-
tant distinction because use of the wrong calculation
mode may result in inaccurate return values.
8.1.19 AverageTimeToEmpty (0x12)
Returns a one-minute rolling average of the
predicted remaining battery life (minutes). The
AverageTimeToEmpty value is calculated based on
either current or power, depending on the setting of the
BatteryMode’s CAPACITY_MODE bit. This is an impor-
tant distinction because use of the wrong calculation
mode may result in inaccurate return values.
8.1.20 AverageTimeToFull (0x13)
Returns a one-minute rolling average of the predicted
remaining time until the Smart Battery reaches full
charge (minutes).
8.1.21 ChargingCurrent (0x14)
Sets the maximum charging current for the Smart
Charger to charge the battery. This can be written to the
Smart Charger from the Smart Battery or requested by
the Smart Charger from the battery.
8.1.22 ChargingVoltage (0x15)
Sets the maximum charging voltage for the Smart
Charger to charge the battery. This can be written to the
Smart Charger from the Smart Battery or requested by
the Smart Charger from the battery.
8.1.23 BatteryStatus (0x16)
Returns the Smart Battery’s status word (flags). Some of the
BatteryStatus flags, like REMAINING_CAPACITY_ALARM
and REMAINING_TIME_ALARM, are calculated based
on either current or power, depending on the setting of
the BatteryMode’s CAPACITY_MODE bit. This is impor-
tant because use of the wrong calculation mode may
result in an inaccurate alarm. The BatteryStatus function
is used by the power management system to get alarm
and status bits, as well as error codes, from the Smart
Battery. This is basically the same information returned
by the SBData AlarmWarning function except that the
AlarmWarning function sets the error code bits all high
before sending the data. Also, information broadcasting
is disabled in the PS501.
Battery Status Bits:
bit 15:
bit 14:
bit 13:
bit 12:
bit 11:
bit 10:
bit 9:
bit 8:
bit 7:
bit 6:
bit 5:
bit 4:
OVER_CHARGED_ALARM
TERMINATE_CHARGE_ALARM
Reserved
OVER_TEMP_ALARM
TERMINATE_DISCHARGE_ALARM
Reserved
REMAINING_CAPACITY_ALARM
REMAINING_TIME_ALARM
INITIALIZED
DISCHARGING
FULLY_CHARGED
FULLY_DISCHARGED
The Host system assumes responsibility for detecting
and responding to Smart Battery alarms by reading the
BatteryStatus to determine if any of the alarm bit flags
are set. At a minimum, this requires the system to poll
the Smart Battery BatteryStatus every 10 seconds at all
times the SMBus is active.
DS21818C-page 22
 2004 Microchip Technology Inc.