DS2777 MAXIM [Maxim Integrated Products], DS2777 Datasheet - Page 25

• Manufacturer Part Number: DS2777
• Description: 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication
• Manufacturer: MAXIM [Maxim Integrated Products]

The Status register contains bits that report the device status. All bits are set internally. The CHGTF, AEF, SEF,
LEARNF, and VER bits are read-only. The UVF and PORF bits can be cleared by writing a 0 to the bit locations.
Bit 7: Charge-Termination Flag (CHGTF). CHGTF is set to indicate that the average of the voltages on V
V
ciently long enough to detect a fully charged condition. CHGTF is cleared when RARC is less than 90%. CHGTF is
read-only.
Bit 6: Active-Empty Flag (AEF). AEF is set to indicate that the battery is at or below the active-empty point. AEF is
set when the average of the voltages on V
greater than 5%. AEF is read-only.
Bit 5: Standby-Empty Flag (SEF). SEF is set to indicate RSRC is less than 10%. SEF is cleared when RSRC is
greater than 15%. SEF is read-only.
Bit 4: Learn Flag (LEARNF). LEARNF indicates that the current-charge cycle can be used to learn the battery
capacity. LEARNF is set when the active-empty point is detected. This occurs when the average of the voltages on
V
greater in magnitude than the IAE threshold. See the Active-Empty Point Detect section for additional information.
LEARNF is cleared when any of the following occur:
LEARNF is read-only.
Bit 3 and 0: Reserved.
Bit 2: Undervoltage Flag (UVF). UVF is set to indicate that the average of the voltages on V
V
Writing UVF to 0 is effective only when the average of the voltages on V
otherwise, UV remains set due to the persistent undervoltage condition. UVF is set on power-up.
Bit 1: Power-On Reset Flag (PORF). PORF is set to indicate initial power-up. PORF is not cleared internally. The
user must write this flag value to a 0 to use it to indicate subsequent power-up events. If PORF indicates a power-on
reset, the ACR could be misaligned with the actual battery state of charge. The system can request a charge to full
to synchronize the ACR with the battery charge state. PORF is read/write to 0.
IN2
IN1
UV
1) Learn cycle completes (CHGTF set).
2) Current register value becomes negative indicating discharge current flow.
3) ACR = 0.
4) ACR value is written or recalled from EEPROM.
5) Sleep mode is entered.
CHGTF
and must be written to 0 to allow subsequent undervoltage events to be reported. UVF is not cleared internally.
BIT 7
and the Average Current register values have persisted above the VCHG and below the IMIN thresholds suffi-
and V
Protector and Optional SHA-1 Authentication
IN2
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with
drops below the VAE threshold and the two previous current register values were negative and
______________________________________________________________________________________
BIT 6
AEF
BIT 5
SEF
IN1
and V
LEARNF
BIT 4
IN2
is less than the VAE threshold. AEF is cleared when RARC is
BIT 3
X
IN1
and V
BIT 2
UVF
Status Register Format
IN2
is greater than or equal to V
Status Register (01h)
IN1
PORF
BIT 1
and V
IN2
is less than
BIT 0
X
IN1
and
UV
25
,