DS2762BE+ ,High-Precision Li+ Battery Monitor with Alertsapplications including remaining Internal 25m Sense Resistor capacity estimation, safety monitori ..
DS2762BE+025 ,High-Precision Li+ Battery Monitor with AlertsAPPLICATIONS V V SS IS1 INPROBE PDAs E Cell Phones/Smartphones V PIO ..
DS2762K ,Li+battery monitor evaluation kit DS2762K Li+ Battery Monitor Evaluation Kit
DS2764A ,High-Precision Li+ Battery Monitor with 2-Wire InterfaceELECTRICAL CHARACTERISTICS (2.5V V 5.5V, T = -20°C to +70°C.) DD A PARAMETER SYMBOL CONDITIONS ..
DS2764B ,High-Precision Li+ Battery Monitor with 2-Wire InterfaceFEATURES The DS2764 high-precision Li+ battery monitor is a Li+ Safety Circuit data-acquisition, ..
DS2764BE ,High-Precision Li+ Battery Monitor with 2-Wire Interfaceapplications. This low-power device integrates Undervoltage Protection precise temperature, voltage ..
EA2-12 ,COMPACT AND LIGHTWEIGHTAPPLICATIONSElectronic switching systems, PBX, key telephone systems, automatic test equipment and ..
EA2-12NU ,COMPACT AND LIGHTWEIGHTFEATURESª Low power consumptionª Compact and light weightª 2 form c contact arrangementª Low magnet ..
EA2-12S ,COMPACT AND LIGHTWEIGHTFEATURESª Low power consumptionª Compact and light weightª 2 form c contact arrangementª Low magnet ..
EA2-12TNU ,COMPACT AND LIGHTWEIGHTAPPLICATIONSElectronic switching systems, PBX, key telephone systems, automatic test equipment and ..
EA2-4.5NU ,COMPACT AND LIGHTWEIGHTAPPLICATIONSElectronic switching systems, PBX, key telephone systems, automatic test equipment and ..
EA2-4.5T ,COMPACT AND LIGHTWEIGHTDATA SHEETMINIATURE SIGNAL RELAYEA2 SERIESCOMPACT AND LIGHTWEIGHTDESCRIPTIONThe EA2 series has red ..
DS2762BE+-DS2762BE+025
High-Precision Li+ Battery Monitor with Alerts
GENERAL DESCRIPTION The DS2762 high-precision Li+ battery monitor is a
data-acquisition, information-storage, and safety-
protection device tailored for cost-sensitive battery
pack applications. This low-power device integrates
precise temperature, voltage, and current
measurement, nonvolatile (NV) data storage, and Li+
protection into the small footprint of either a TSSOP
package or flip-chip package. The DS2762 is a key
component in applications including remaining
capacity estimation, safety monitoring, and battery-
specific data storage.
PIN CONFIGURATIONS
FEATURES Li+ Safety Circuit Overvoltage Protection
Overcurrent/Short-Circuit Protection
Undervoltage Protection
Host Alerted When Accumulated Current or
Temperature Exceeds User-Selectable Limits 0V Battery Recovery Charge Available in Two Configurations: Internal 25m Sense Resistor
External User-Selectable Sense Resistor
Current Measurement 12-Bit Bidirectional Measurement
Internal Sense Resistor Configuration:
0.625mA LSB and ±1.9A Dynamic Range
External Sense Resistor Configuration:
15.625V LSB and ±64mV Dynamic Range
Current Accumulation: Internal Sense Resistor: 0.25mAhr LSB
External Sense Resistor: 6.25Vhr LSB
Voltage Measurement with 4.88mV Resolution Temperature Measurement Using Integrated
Sensor with 0.125°C Resolution System Power Management and Control
Feature Support 32 Bytes of Lockable EEPROM 16 Bytes of General-Purpose SRAM Dallas 1-Wire® Interface with Unique 64-Bit
Device Address Low-Power Consumption: Active Current: 60A typ, 90A max
Sleep Current: 1A typ, 2A max
APPLICATIONS PDAs
Cell Phones/Smartphones
Digital Cameras
ORDERING INFORMATION
PART TEMP RANGE PIN-PACKAGE DS2762BE+ -20°C to +70°C 16 TSSOP
Selector Guide appears at end of data sheet, for additional
options.
DS2762
High-Precision Li+ Battery Monitor With Alerts
TOP VIEW VIN
VDD
PIO
VSS
VSS
VSS
PS
IS1
TSSOP IS2
SNS
SNS3
SNS
PLS
1-Wire is registered trademark of Dallas Semiconductor.
FLIP CHIP (top view – bumps on bottom)
PLS DC DQ
CC IS2
VIN IS1
VDD PIO PS
SNS
VSS
1 2 3 4
SNS
PROBE
VSS
PROBE
DS2762 High-Precision Li+ Battery Monitor With Alerts
ABSOLUTE MAXIMUM RATINGS Voltage Range on PLS and CC Pin, Relative to VSS -0.3V to +18V
Voltage Range on PIO Pin, Relative to VSS -0.3V to +12V
Voltage Range on Any Other Pin, Relative to VSS -0.3V to +6V
Continuous Internal Sense Resistor Current 2.5A
Pulsed Internal Sense Resistor Current 50A for <100µs/s, <1000 pulses
Operating Temperature Range -40°C to +85°C
Storage Temperature Range -55°C to +125°C
Soldering Temperature See IPC/JEDEC J-STD-020A Specification
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is
not implied. Exposure to the absolute maximum rating conditions for extended periods may affect device.
RECOMMENDED DC OPERATING CONDITIONS (2.5V VDD 5.5V, TA = -20°C to +70°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage VDD (Note 1) 2.5 5.5 V
Data Pin DQ (Note 1) -0.3 +5.5 V
DC ELECTRICAL CHARACTERISTICS (2.5V VDD 5.5V, TA = -20°C to +70°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Active Current IACTIVE DQ = VDD, normal operation 60 90 A
Sleep Mode Current ISLEEP DQ = 0V, no activity, PS floating 1 2 A
Input Logic High: DQ, PIO VIH (Note 1) 1.5 V
Input Logic High: PS VIH (Note 1) VDD - 0.2V V
Input Logic Low: DQ, PIO VIL (Note 1) 0.4 V
Input Logic Low: PS VIL (Note 1) 0.2 V
Output Logic High: CC VOH IOH = -0.1mA (Note 1) VPLS - 0.4V V
Output Logic High: DC VOH IOH = -0.1mA (Note 1) VDD - 0.4V V
Output Logic Low: CC, DC VOL IOL = 0.1mA (Note 1) 0.4 V
Output Logic Low: DQ, PIO VOL IOL = 4mA (Note 1) 0.4 V
DQ Pulldown Current IPD 1 A
Input Resistance: VIN RIN 5 M
Internal Current-Sense Resistor RSNS +25°C 20 25 30 m
DS2762 High-Precision Li+ Battery Monitor With Alerts
ELECTRICAL CHARACTERISTICS: PROTECTION CIRCUITRY (2.5V VDD 5.5V, TA = 0°C to +50°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 4.325 4.350 4.375 Overvoltage Detect VOV (Notes 1, 2)
4.250 4.275 4.300
Charge Enable VCE (Note 1) 4.10 4.15 4.20 V
Undervoltage Detect VUV (Note 1) 2.5 2.6 2.7 V
Overcurrent Detect IOC (Note 3) 1.8 1.9 2.0 A
Overcurrent Detect VOC (Note 1, 4) 45 47.5 50 mV
Short-Circuit Detect ISC (Note 3) 5.0 8.0 11 A
Short-Circuit Detect VSC (Note 1) 150 200 250 mV
Overvoltage Delay tOVD 0.8 1 1.2 s
Undervoltage Delay tUVD 90 100 110 ms
Overcurrent Delay tOCD 5 10 20 ms
Short-Circuit Delay tSCD 160 200 240 s
Test Threshold VTP 0.5 1.0 1.5 V
Test Current ITST 10 20 40 A
Recovery Charge Current IRC (Note 5) 0.5 1 2 mA
DS2762 High-Precision Li+ Battery Monitor With Alerts
ELECTRICAL CHARACTERISTICS: TEMPERATURE, VOLTAGE, CURRENT (2.5V VDD 5.5V, TA = -20°C to +50°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Temperature Resolution TLSB 0.125 C
Temperature Full-Scale Magnitude TFS 127 C
Temperature Error TERR (Note 6) 3 C
Voltage Resolution VLSB 4.88 mV
Voltage Full-Scale Magnitude VFS 4.75 V
Voltage Offset Error VOERR (Note 7) 1 LSB
Voltage Gain Error VGERR 5 %
(Note 3) 0.625 mA
Current Resolution ILSB
(Note 4) 15.625 V
(Notes 3, 4) 1.9 2.56 A
Current Full-Scale Magnitude IFS
(Note 8) 64 mV
Current Offset Error IOERR (Note 9) 1 LSB
(Notes 3, 10, 14) 3
Current Gain Error IGERR
(Note 4) 1
(Note 3) 0.25 mAhr
Accumulated Current Resolution qCA
(Note 4) 6.25 µVhr
Current Sampling Frequency fSAMP 1456 Hz
tERR1 (Note 11) 1 3 %
Internal Timebase Accuracy
tERR2 (Note 11) 6.5 %
EEPROM RELIABILITY SPECIFICATION (2.5V VDD 5.5V, TA = -20C to +70C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Copy to EEPROM Time tEEC 2 10 ms
EEPROM Copy Endurance NEEC (Note 12) 25,000 cycles
DS2762 High-Precision Li+ Battery Monitor With Alerts
ELECTRICAL CHARACTERISTICS: 1-WIRE INTERFACE (2.5V VDD 5.5V, TA = -20C to +70C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Time Slot tSLOT 60 120 s
Recovery Time tREC 1 s
Write 0 Low Time tLOW0 60 120 s
Write 1 Low Time tLOW1 1 15 s
Read Data Valid tRDV 15 s
Reset Time High tRSTH 480 s
Reset Time Low tRSTL 480 960 s
Presence Detect High tPDH 15 60 s
Presence Detect Low tPDL 60 240 s
SWAP Timing Pulse Width tSWL 0.2 120 s
SWAP Timing Pulse Falling Edge to DC
Release tSWOFF (Note 13) 0 1 s
SWAP Timing Pulse Rising Edge to DC
Engage tSWON (Note 13) 0 1 s
DQ Capacitance CDQ 60 pF
Note 1: All voltages are referenced to VSS.
Note 2: See the Selector Guide section to determine the corresponding part number for each VOV value.
Note 3: Internal current-sense resistor configuration.
Note 4: External current-sense resistor configuration.
Note 5: Test conditions are PLS = 4.1V, VDD = 2.5V. Maximum current for conditions of PLS = 15V, VDD = 0V is 10mA.
Note 6: Self-heating due to output pin loading and sense resistor power dissipation can alter the reading from ambient conditions.
Note 7: Voltage offset measurement is with respect to VOV at +25°C.
Note 8: The current register supports measurement magnitudes up to 2.56A using the internal sense resistor option and 64mV with the
external resistor option. Compensation of the internal sense resistor value for process and temperature variation can reduce the
maximum reportable magnitude to 1.9A.
Note 9: Current offset error null to ±1LSB typically requires 3.5s in-system calibration by user.
Note 10: Current gain error specification applies to gain error in converting the voltage difference at IS1 and IS2, and excludes any error
remaining after the DS2762 compensates for the internal sense resistor’s temperature coefficient of 3700ppm/C to an accuracy
of 500ppm/C. The DS2762 does not compensate for external sense resistor characteristics, and any error terms arising from
the use of an external sense resistor should be taken into account when calculating total current measurement error.
Note 11: Typical value for tERR1 is specified at 3.6V and +25C, max value is specified for 0°C to +50°C. Max value for tERR2 is specified
for -20°C to +70°C.
Note 12: Four-year data retention at +70C.
Note 13: Typical load capacitance on DC and CC is 1000pF.
Note 14: Error at time of shipment from Dallas Semiconductor is 3% max. Board mounting processes may cause the current gain error
to widen to as much as 10% for devices with the internal sense resistor option. Contact factory for on-board recalibration
procedure for devices with the internal sense resistor option to improve accuracy.
DS2762 High-Precision Li+ Battery Monitor With Alerts
PIN DESCRIPTION
PIN
TSSOP FLIP
CHIP
SYMBOL FUNCTION 1 C1 CC
Charge Protection Control Output. Controls an external P-channel high-side charge protection FET.
2 B1 PLS
Battery Pack Positive Terminal Input. The DS2762 monitors the pack plus terminal through PLS to detect overcurrent and overload conditions, as well as the presence of a
charge source. Additionally, a charge path to recover a deeply depleted cell is provided
from PLS to VDD. In sleep mode (with SWEN = 0), any capacitance or voltage source
connected to PLS is discharged internally to VSS through 200µA (nominal) to assure
reliable detection of a valid charge source. For details of other internal connections to
PLS and associated conditions see the Li+ Protection Circuitry section.
3 B2 DC
Discharge Protection Control Output. Controls an external P-channel high-side discharge protection FET.
4, 5, 6 A3 SNS
Sense Resistor Connection. Connect to the negative terminal of the battery pack. In the internal sense resistor configuration, the sense resistor is connected between VSS
and SNS.
7 B4 DQ
Data Input/Out. 1-Wire data line. Open-drain output driver. Connect this pin to the DATA terminal of the battery pack. Pin has an internal 1A pulldown for sensing disconnection.
8 C4 IS2
Current-Sense Input. This pin is internally connected to SNS through a 4.7k resistor. 9 D4 IS1
Current-Sense Input. This pin is internally connected to VSS through a 4.7k resistor. Connect a 0.1F capacitor between IS1 and IS2 to complete a lowpass input filter.
10 E4 PS
Power Switch Sense Input. The device wakes up from sleep mode when it senses the closure of a switch to VSS on this pin. Pin has an internal 1A pullup to VDD.
11, 12, 13 F3 VSS
Device Ground. Connect directly to the negative terminal of the Li+ cell. For the external sense resistor configuration, connect the sense resistor between VSS and SNS.
14 E2 PIO
Programmable I/O Pin. Can be configured to be used to control and monitor user-
defined external circuitry or as an interrupt output to alert the host when preset current
accumulator or temperature limits are exceeded. Open drain to VSS.
15 E1 VDD
Power-Supply Input. Connect to the positive terminal of the Li+ cell through a decoupling network.
16 D1 VIN
Voltage Sense Input. The voltage of the Li+ cell is monitored through this input pin. This pin has a weak pullup to VDD.
— C2 SNS
Probe Do not connect.
— D2 VSS
Probe Do not connect.
DS2762 High-Precision Li+ Battery Monitor With Alerts
Figure 1. Block Diagram
DETAILED DESCRIPTION The DS2762 high-precision Li+ battery monitor is a data-acquisition, information-storage, and safety-protection
device tailored for cost-sensitive battery pack applications. This low-power device integrates precise temperature,
voltage, and current measurement, nonvolatile (NV) data storage, and Li+ protection into the small footprint of
either a TSSOP package or flip-chip package. The DS2762 is a key component in applications including remaining
capacity estimation, safety monitoring, and battery-specific data storage.
Through its 1-Wire interface, the DS2762 gives the host system read/write access to status and control registers,
instrumentation registers, and general-purpose data storage. Each device has a unique factory-programmed 64-bit
net address that allows it to be individually addressed by the host system, supporting multibattery operation.
The DS2762 is capable of performing temperature, voltage, and current measurement to a resolution sufficient to
support process monitoring applications such as battery charge control, remaining capacity estimation, and safety
monitoring. Temperature is measured using an on-chip sensor, eliminating the need for a separate thermistor.
Bidirectional current measurement and accumulation are accomplished using either an internal 25m sense
resistor or an external device. The DS2762 also features a programmable I/O pin that allows the host system to
sense and control other electronics in the pack, including switches, vibration motors, speakers, and LEDs. This pin
may also be used to alert the host when preset accumulated current or temperature limits are exceeded.
Three types of memory are provided on the DS2762 for battery information storage: EEPROM, lockable EEPROM,
and SRAM. EEPROM memory saves important battery data in true NV memory that is unaffected by severe battery
depletion, accidental shorts, or ESD events. Lockable EEPROM becomes ROM when locked to provide additional
security for unchanging battery data. SRAM provides inexpensive storage for temporary data.
1-Wire
INTERFACE
AND
ADDRESS
THERMAL
SENSE
MUX
VOLTAGE
REFERENCE
ADC
REGISTERS AND
USER MEMORY
25m
CHIP GROUND
LOCKABLE EEPROM
SRAM
TEMPERATURE
VOLTAGE
CURRENT
ACCUM. CURRENT
STATUS/CONTROL
Li+ PROTECTION
VIN
IS1
IS2
SNS
IS2IS1
VSS
CC
DC
PLS
PIO
TIMEBASE
INTERNAL SENSE RESISTOR
CONFIGURATION ONLY
DS2762
DS2762 High-Precision Li+ Battery Monitor With Alerts
Figure 2. Application Example SNS
DS2762
VSS
IS2IS1
VOLTAGESENSE
RSNS-INT
(NOTE 2)
RKS RKS
CC
PLS
DC
SNS
SNS
SNS
DQ
IS2
VIN
VDD
PIO
VSS
VSS
VSS
PS
IS1
DS2762
104
102 x 2
PACK+
PACK-
DATA
150
1501k
150
1k 1k
102
BAT+
BAT-
RSNS
(NOTE 1)
PS
4.7k
PIO
NOTE 1: RSNS IS PRESENT FOR EXTERNAL SENSE RESISTOR CONFIGURATIONS ONLY.
NOTE 2: RSNS-INT IS PRESENT FOR INTERNAL SENSE RESISTOR CONFIGURATIONS ONLY.
DS2762 High-Precision Li+ Battery Monitor With Alerts
POWER MODES The DS2762 has two power modes: active and sleep. While in active mode, the DS2762 continually measures
current, voltage, and temperature to provide data to the host system and to support current accumulation and Li+
safety monitoring. In sleep mode, the DS2762 ceases these activities. The DS2762 enters sleep mode when any of
the following conditions occurs: The PMOD bit in the Status Register has been set to 1 and the DQ line is low for longer than 2s (pack
disconnection). The voltage on VIN drops below undervoltage threshold VUV for tUVD (cell depletion). The pack is disabled through the issuance of a SWAP command (SWEN bit = 1).
The DS2762 returns to active mode when any of the following occurs: 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 PS pin is pulled low (power switch). 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).
The DS2762 defaults to active mode when power is first applied.
Li+ PROTECTION CIRCUITRY During active mode, the DS2762 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 DS2762 responses are described in the following sections and summarized in Table 1 and
Figure 3.
Table 1. Li+ Protection Conditions and DS2762 Responses
ACTIVATION
CONDITION THRESHOLD DELAY RESPONSE RELEASE THRESHOLD Overvoltage VIN > VOV tOVD CC high VIN < VCE, or
VIS ≤ -2mV
Undervoltage VIN < VUV tUVD CC, DC high,
Sleep Mode
VPLS > VDD (1)
(charger connected)
Overcurrent, Charge VIS > VOC(2) tOCD CC, DC high VPLS < VDD - VTP (3)
Overcurrent, Discharge VIS < -VOC(2) tOCD DC high VPLS > VDD - VTP (4)
Short Circuit VSNS > VSC tSCD DC high VPLS > VDD - VTP (4)
VIS = VIS1 - VIS2. Logic high = VPLS for CC and VDD for DC. All voltages are with respect to VSS. ISNS references current delivered from pin SNS.
Note 1: If VDD < 2.2V, release is delayed until the recovery charge current (IRC) passed from PLS to VDD charges the battery and allows VDD
to exceed 2.2V.
Note 2: For the internal sense resistor configuration, the overcurrent thresholds are expressed in terms of current: ISNS > IOC for charge
direction and ISNS < -IOC for discharge direction.
Note 3: With test current ITST flowing from PLS to VSS (pulldown on PLS).
Note 4: With test current ITST flowing from VDD to PLS (pullup on PLS).
Overvoltage. If the cell voltage on VIN exceeds the overvoltage threshold, VOV, for a period longer than overvoltage delay, tOVD, the DS2762 shuts off the external charge FET and sets the OV flag in the protection register. When the
cell voltage falls below charge enable threshold VCE, the DS2762 turns the charge FET back on (unless another
protection condition prevents it). Discharging remains enabled during overvoltage, and the DS2762 re-enables the
charge FET before VIN < VCE if a discharge current of -80mA (VIS ≤ -2mV) or less is detected.
DS2762 High-Precision Li+ Battery Monitor With Alerts
register, and enters sleep mode. The DS2762 provides a current-limited (IRC) recovery charge path from PLS to
VDD to gently charge severely depleted cells. The recovery path is enabled when 0 VDD < 3V (typ). Once VDD
reaches 3V (typ), the DS2762 returns to normal operation, awaiting connection of a charger to turn on the charge
FET and pull out of sleep mode.
Overcurrent, Charge Direction. The voltage difference between the IS1 pin and the IS2 pin (VIS = VIS1 - VIS2) is the filtered voltage drop across the current-sense resistor. If VIS exceeds overcurrent threshold VOC for a period longer
than overcurrent delay tOCD, the DS2762 shuts off both external FETs and sets the COC flag in the protection
register. The charge current path is not re-established until the voltage on the PLS pin drops below VDD - VTP. The
DS2762 provides a test current of value ITST from PLS to VSS to pull PLS down to detect the removal of the
offending charge current source.
Overcurrent, Discharge Direction. If VIS is less than -VOC for a period longer than tOCD, the DS2762 shuts off the external discharge FET and sets the DOC flag in the protection register. The discharge current path is not re-
established until the voltage on PLS rises above VDD - VTP. The DS2762 provides a test current of value ITST from
VDD to PLS to pull PLS up to detect the removal of the offending low-impedance load.
Short Circuit. If the voltage on the SNS pin with respect to VSS exceeds short-circuit threshold VSC for a period
longer than short-circuit delay tSCD, the DS2762 shuts off the external discharge FET and sets the DOC flag in the
protection register. The discharge current path is not re-established until the voltage on PLS rises above VDD - VTP.
The DS2762 provides a test current of value ITST from VDD to PLS to pull PLS up to detect the removal of the short
circuit.
Figure 3. Li+ Protection Circuitry Example Waveforms
Summary. All of the protection conditions described above are ORed together to affect the CC and DC outputs. DC = (Undervoltage) or (Overcurrent, Either Direction) or (Short Circuit) or (Protection Register Bit DE = 0)
or (Sleep Mode)
CC = (Overvoltage) or (Undervoltage) or (Overcurrent, Charge Direction) or (Protection Register bit CE = 0)
SLEEP
MODE
VOV
VCE
VUV
VCELL
VIS
CHARGE
DISCHARGE
-VSC
VOC
-VOC
0
tSCDtOCD
tOCD
tUVD
tOVDVPLS
VDD
ACTIVE
VSS
VSS
INACTIVE
tOVD
(NOTE 1)
NOTE 1: TO ALLOW THE DEVICE TO REACT QUICKLY TO SHORT CIRCUITS, DETECTION OCCURS ON THE SNS PIN RATHER THAN ON THE FILTERED IS1 AND IS2 PINS. THE ACTUAL SHORT-CIRCUIT DETECT CONDITION IS VSNS> VSC.
DS2762 High-Precision Li+ Battery Monitor With Alerts
CURRENT MEASUREMENT In active mode, the DS2762 continually measures the current flow into and out of the battery by measuring the
voltage drop across a current-sense resistor. The DS2762 is available in two configurations: 1) internal 25m
current-sense resistor and 2) external user-selectable sense resistor. In either configuration, the DS2762 considers
the voltage difference between pins IS1 and IS2 (VIS = VIS1 - VIS2) to be the filtered voltage drop across the sense
resistor. A positive VIS value indicates current is flowing into the battery (charging), while a negative VIS value
indicates current is flowing out of the battery (discharging).
VIS is measured with a signed resolution of 12 bits. The current register is updated in two’s-complement format
every 88ms with an average of 128 readings. Currents outside the register range are reported at the range limit.
Figure 4 shows the format of the current register.
For the internal sense resistor configuration, the DS2762 maintains the current register in units of amps, with a
resolution of 0.625mA and full-scale range of no less than 1.9A (see Note 7 on IFS spec for more details). The
DS2762 automatically compensates for internal sense resistor process variations and temperature effects when
reporting current.
For the external sense resistor configuration, the DS2762 writes the measured VIS voltage to the current register,
with a 15.625V resolution and a full-scale 64mV range.
Figure 4. Current Register Format MSB—Address 0E LSB—Address 0F
S 211 210 29 28 27 26 25 24 23 22 21 20 X X X
MSb LSb MSb LSb
Units: 0.625mA for Internal Sense Resistor
15.625V for External Sense Resistor
CURRENT ACCUMULATOR The current accumulator facilitates remaining capacity estimation by tracking the net current flow into and out of the
battery. Current flow into the battery increments the current accumulator while current flow out of the battery
decrements it. Data is maintained in the current accumulator in two’s-complement format. Figure 5 shows the
format of the current accumulator.
When the internal sense resistor is used, the DS2762 maintains the current accumulator in units of amp-hours, with
a 0.25mAhrs resolution and full-scale 8.2Ahrs range. When using an external sense resistor, the DS2762
maintains the current accumulator in units of volt-hours, with a 6.25Vhrs resolution and a full-scale 205mVhrs
range.
The current accumulator is a read/write register that can be altered by the host system as needed.
Figure 5. Current Accumulator Format MSB—Address 10 LSB—Address 11
S 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20
MSb LSb MSb LSb
Units: 0.25mAhrs for Internal Sense Resistor
6.25Vhrs for External Sense Resistor
DS2762 High-Precision Li+ Battery Monitor With Alerts
CURRENT OFFSET COMPENSATION Current measurement and current accumulation are internally compensated for offset on a continual basis
minimizing error resulting from variations in device temperature and voltage. Additionally, a constant bias can be
used to alter any other sources of offset. This bias resides in EEPROM address 33h in two’s-complement format
and is subtracted from each current measurement. The current offset bias is applied to the internal and external
sense resistor configurations. The factory default for the current offset bias is 0.
Figure 6. Current Offset Bias Address 33
S 26 25 24 23 22 21 20
MSb LSb
Units: 0.625mA for Internal Sense Resistor
15.625V for External Sense Resistor
VOLTAGE MEASUREMENT The DS2762 continually measures the voltage between pins VIN and VSS over a 0 to 4.75V range. The voltage
register is updated in two’s-complement format every 3.4ms with a 4.88mV resolution. Voltages above the
maximum register value are reported as the maximum value. Figure 7 shows the voltage register format.
Figure 7. Voltage Register Format MSB—Address 0C LSB—Address 0D
S 29 28 27 26 25 24 23 22 21 20 X X X X X
MSb LSb MSb LSb
Units: 4.88mV
TEMPERATURE MEASUREMENT The DS2762 uses an integrated temperature sensor to continually measure battery temperature. Temperature
measurements are placed in the temperature register every 220ms in two’s-complement format with a 0.125°C
resolution over a 127°C range. Figure 8 shows the temperature register format.
Figure 8. Temperature Register Format MSB—Address 18 LSB—Address 19
S 29 28 27 26 25 24 23 22 21 20 X X X X X
MSb LSb MSb LSb
Units: 0.125C
DS2762 High-Precision Li+ Battery Monitor With Alerts
PROGRAMMABLE I/O To use the PIO pin as described in this section, the IE bit (bit 2) of the Status Register must be set to 0.
To use the PIO pin as an output, write the desired output value to the PIO bit in the special feature register. Writing
a 0 to the PIO bit enables the PIO output driver, pulling the PIO pin to VSS. Writing a 1 to the PIO bit disables the
output driver, allowing the PIO pin to be pulled high or used as an input. To sense the value on the PIO pin, read
the PIO bit. The DS2762 turns off the PIO output driver and sets the PIO bit high when in sleep mode or when DQ
is low for more than 2s, regardless of the state of the PMOD bit.
ALARM COMPARATORS The PIO pin can be programmed as an interrupt output (active low) to alert the host system of critical events. To
use the Interrupt feature, the Interrupt Enable (IE) bit (bit 2) of the Status Register must be set to a 1. Interrupt
threshold values can be programmed by the user in the designated SRAM memory registers in the formats and
locations found in Figure 9. Since these thresholds are located in SRAM memory, they must be reprogrammed if a
loss of power to the DS2762 occurs. The PIO line will go low to interrupt the system host and indicate that one of
the following events has occurred: Accumulated Current Current Accumulator Interrupt High Threshold Accumulated Current Current Accumulator Interrupt Low Threshold Temperature Temperature Interrupt High Threshold Temperature Temperature Interrupt Low Threshold
The host may then poll the DS2762 to determine which threshold has been met or exceeded.
Figure 9. Interrupt Threshold Register Formats
Current Accumulator Interrupt High Threshold MSB—Address 80 LSB—Address 81
S 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20
MSb LSb MSb LSb
Units: 0.25mAhrs for Internal Sense Resistor
6.25Vhrs for External Sense Resistor
Current Accumulator Interrupt Low Threshold MSB—Address 82 LSB—Address 83
S 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20
MSb LSb MSb LSb
Units: 0.25mAhrs for Internal Sense Resistor
6.25Vhrs for External Sense Resistor
