DS2784G+ Maxim Integrated Products, DS2784G+ Datasheet - Page 25

• Manufacturer Part Number: DS2784G+
• Description: IC FUEL GAUGE STND-ALONE 14-TDFN
• Manufacturer: Maxim Integrated Products

Specifications of DS2784G+

• Function: Fuel, Gas Gauge/Monitor
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 2.5 V ~ 4.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 14-TDFN
• Product: Fuel Gauges
• Operating Supply Voltage: 2.5 V to 4.6 V
• Supply Current: 85 uA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Charge Safety Timers: Yes
• Mounting Style: SMD/SMT
• Temperature Monitoring: Yes
• Uvlo Start Threshold: 2.4 V
• Uvlo Stop Threshold: 2.5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ACR Housekeeping
The ACR value is adjusted occasionally to maintain the coulomb count within the model curve boundaries. When
the battery is charged to full (CHGTF set), the ACR is set equal to the age scaled full lookup value at the present
temperature. If a learn cycle is in progress, correction of the ACR value occurs after the age scalar (AS) is updated.
When an empty condition is detected (LEARNF and/or AEF set), the ACR adjustment is conditional:
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Full Detect
Full detection occurs when the voltage (V) readings remain continuously above the charge voltage (VCHG)
threshold for the duration of two average current (IAVG) readings, and both IAVG readings are below terminating
current (IMIN). The two consecutive IAVG readings must also be positive and nonzero (> 16 LSB). This ensures
that removing the battery from the charger does not result in a false detection of full. Full detect sets the charge to
full (CHGTF) bit in the status register.
Active-Empty Point Detect
Active-empty point detection occurs when the voltage register drops below the VAE threshold AND the two
previous current readings are above IAE. This captures the event of the battery reaching the active-empty point.
Note that the two previous current readings must be negative and greater in magnitude than IAE, that is, a larger
discharge current than specified by the IAE threshold. Qualifying the voltage level with the discharge rate ensures
that the active-empty point is not detected at loads much lighter than those used to construct the model. Also, the
active-empty point must not be detected when a deep discharge at a very light load is followed by a load greater
than IAE. Either case would cause a learn cycle on the following charge to include part of the standby capacity in
the measurement of the active capacity. Active-empty point detection sets the learn flag (LEARNF) bit in the status
register. Do not confuse the active-empty point with the active-empty flag. The active-empty flag is set only when
the VAE threshold is passed.
STATUS REGISTER FORMAT
The status register contains bits that report the device status. All bits are set internally. The CHGTF, AEF, SEF, and
LEARNF bits are read only. The UVF and PORF bits can be cleared by writing a zero to the bit locations.
CHGTF—Charge-Termination Flag. CHGTF is set to indicate that the voltage and average current register values
have persisted above the VCHG and below the IMIN thresholds sufficiently long to detect a fully charged condition.
CHGTF is cleared when RARC is less than 90%. CHGTF is read only.
AEF—Active-Empty Flag. AEF is set to indicate that the battery is at or below the active-empty point. AEF is set
when the voltage register value is less than the VAE threshold. AEF is cleared when RARC is greater than 5%.
AEF is read only.
SEF—Standby-Empty Flag. SEF is set to indicate RSRC is less than 10%. SEF is cleared when RSRC is greater
than 15%. SEF is read only.
If the AEF is set and the LEARNF is not set, then the active-empty point was not detected. The battery is likely
below the active-empty capacity of the model. The ACR is set to the active-empty model value at present temp
only if it is greater than the active-empty model value at present temp.
If the AEF is set, the LEARNF is not set, and the ACR is below the active-empty model value at present temp
the ACR is NOT updated.
If the LEARNF is set, then the battery is at the active-empty point and the ACR is set to the active-empty model
value.
CHGTF
BIT 7
BIT 6
AEF
BIT 5
SEF
LEARNF
BIT 4
ADDRESS 01h
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BIT 3
X
BIT 2
UVF
PORF
BIT 1
BIT 0
X