DS2760 Dallas Semiconducotr, DS2760 Datasheet - Page 6

• Manufacturer Part Number: DS2760
• Description: High Precision Li-Ion Battery Monitor
• Manufacturer: Dallas Semiconducotr

POWER MODES
The DS2760 has two power modes: Active and Sleep. While in Active Mode, the DS2760 continually
measures current, voltage and temperature to provide data to the host system and to support current
accumulation and Li-ion safety monitoring. In Sleep Mode, the DS2760 ceases these activities. The
DS2760 enters Sleep Mode when either of the following conditions occurs:
The DS2760 returns to Active Mode when any of the following occurs:
The DS2760 defaults to Active Mode when power is first applied.
LI-ION PROTECTION CIRCUITRY
During Active Mode, the DS2760 constantly monitors cell voltage and current to protect the battery from
overcharge (overvoltage), overdischarge (undervoltage) and excessive charge and discharge currents
(overcurrent, short circuit). Conditions and DS2760 responses are described in the sections below and
summarized in Table 2 and Figure 3.
LI-ION PROTECTION CONDITIONS AND DS2760 RESPONSES – Table 2
V
references current delivered from pin SNS.
(1) for the internal sense resistor configuration, the overcurrent thresholds are expressed in terms of
(2) with test current I
(3) with test current I
Overvoltage. If the voltage of the cell exceeds overvoltage threshold V
overvoltage delay t
Protection Register. When the cell voltage falls below charge enable threshold V
charge FET back on (unless another protection condition prevents it). Discharging remains enabled
during overvoltage.
Overcurrent, Discharge
Short Circuit
Condition
Name
Overvoltage
Undervoltage
Overcurrent, Charge
IS
current: I
= V
IS1
– V
the PMOD bit in the Status Register has been set to 1 and the DQ line is low for
longer than 2 seconds (pack disconnection)
the voltage on VIN drops below undervoltage threshold V
the pack is disabled through the issuance of a SWAP command (SWEN bit =1)
the PMOD bit has been set to 1 and the SWEN bit is set to 0 and the DQ line is pulled
high (pack connection)
the
the voltage on PLS becomes greater than the voltage on VIN (charger connection) with the
SWEN bit set to 0
the pack is enabled through the issuance of a SWAP command (SWEN bit =1)
SNS
IS2
PS
. Logic high = V
> I
pin is pulled low (power switch)
OC
OVD
TST
TST
for charge direction and I
, the DS2760 shuts off the external charge FET and sets the OV flag in the
current flowing from PLS to VSS (pull-down on PLS)
current flowing from VDD to PLS (pull-up on PLS)
V
V
V
Threshold
V
V
IS
IS
SNS
IN
IN
PLS
< -V
> V
> V
< V
> V
for
OC
OC
OV
UV
SC
(1)
(1)
CC
and VDD for
Delay
t
t
t
t
t
OVD
UVD
OCD
OCD
SCD
Activation
SNS
6 of 25
< -I
OC
for discharge direction
DC
CC
CC
Sleep Mode
Response
.
DC
DC
CC
,
,
All voltages are with respect to VSS. I
DC
DC
high
high
high
high,
high
UV
for t
UVD
OV
for a period longer than
(cell depletion)
CE
V
V
V
(charger connected)
, the DS2760 turns the
PLS
PLS
PLS
V
Threshold
V
< VDD - V
> VDD - V
> VDD - V
PLS
Release
IN
< V
> VDD
CE
TP
TP
TP
DS2760
(2)
(3)
(3)
SNS