DS2780 Maxim Integrated Products, DS2780 Datasheet - Page 6

• Manufacturer Part Number: DS2780
• Description: Stand-Alone Fuel Gauge IC
• Manufacturer: Maxim Integrated Products

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Figure 2. Multicell Application Example
POWER MODES
The DS2780 has two power modes: ACTIVE and SLEEP. On initial power up, the DS2780 defaults to ACTIVE
mode. While in ACTIVE mode, the DS2780 is fully functional with measurements and capacity estimation
continuously updated. In SLEEP mode, the DS2780 conserves power by disabling measurement and capacity
estimation functions, but preserves register contents. SLEEP mode is entered under two different conditions and
an enable bit for each condition makes entry into SLEEP optional. SLEEP mode can be enabled using the Power
Mode (PMOD) bit or the Under Voltage Enable (UVEN) bit.
The PMOD type SLEEP is entered if the PMOD bit is set AND DQ is low for t
DQ low for t
current will flow. A PMOD SLEEP condition transitions back to ACTIVE mode when DQ is pulled high.
The second option for entering SLEEP is an under voltage condition. When the UVEN bit is set, the DS2780
transitions to SLEEP if the voltage on VIN is less than V
logic level for t
battery should be minimized. UVEN type SLEEP relieves the battery of the I
resumes.
NOTE: PMOD and UVEN SLEEP features must be disabled when a battery is charged on an external charger that
does not connect to the DQ pin. PMOD SLEEP can be used if the charger pulls DQ high. UVEN SLEEP can be
used if the charger toggles DQ. The DS2780 remains in SLEEP and therefore does not measure or accumulate
current when a battery is charged on a charger that failures properly drive DQ.
INITIATING COMMUNICATION IN SLEEP
When beginning communication with a DS2780 in PMOD SLEEP, DQ must be pulled up first and then a 1-Wire
Reset pulse must be issued by the master. In UVEN SLEEP, the procedure depends on the state of DQ when
UVEN SLEEP was entered. If DQ was low, DQ must be pulled up and then a 1-Wire Reset pulse must be issued
by the master as with PMOD SLEEP. If DQ was high when UVEN SLEEP was entered, then the DS2780 is
prepared to receive a 1-Wire reset from the master. In the first two cases with DQ low during SLEEP, the DS2780
does not respond to the first rising edge of DQ with a presence pulse.
PK+
DATA
PIO
PK-
(1) Components improve IEC1004 Air/Contact ESD compliance
SLEEP
SLEEP
150
can be used to detect a pack disconnection or system shutdown, in which no charge or discharge
150
. An under-voltage condition occurs when a pack is fully discharged, where loading on the
(1)
(1)
0.1uF
DQ
PIO
SNS
DS2780
MAX1615
RSNS
6 of 27
VDD
OVD
VSS
VIN
SLEEP
4.7uF
(2.45V nominal) AND DQ is stable at a low or high
0.1uF
500
ACTIVE
DS2780 Stand-Alone Fuel Gauge IC
(n * R)
SLEEP
R
load until communication on DQ
(2s nominal). The condition of
Multi-Cell
Battery
Li-Ion
Protection
Circuit