DS2761
High-Precision Li+ Battery Monitor
www.maxim-ic.com
FEATURES
§
Lithium-Ion (Li+) Safety Circuit
- Overvoltage Protection
- Overcurrent/Short-Circuit Protection
- Undervoltage Protection
Zero Volt Battery Recovery Charge
Available in Two Configurations:
- Internal 25mW 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:
15.625mV LSB and ±64mV Dynamic
Range
Current Accumulation:
- Internal Sense Resistor: 0.25mAhr LSB
- External Sense Resistor: 6.25mVhr 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: 60mA typ, 90mA max
- Sleep Current:
1mA typ, 2mA max
PIN CONFIGURATION
CC
PLS
DC
SNS
SNS
SNS
DQ
IS2
1
2
3
2
4
5
6
7
8
16
15
14
13
12
11
10
9
V
IN
V
DD
PIO
V
SS
V
SS
V
SS
PS
IS1
1
2
3
SNS
4
A
DQ
IS2
IS1
PS
PLS DC
CC
VIN
SNS
Probe
VSS
Probe
B
C
D
E
§
§
§
VDD PIO
VSS
F
DS2761
16-Pin TSSOP Package
DS2761
Flip-Chip Packaging*
Top View
PIN DESCRIPTION
- Charge Control Output
- Discharge Control Output
DQ - Data Input/Output
PIO - Programmable I/O Pin
PLS - Battery Pack Positive Terminal Input
PS
- Power Switch Sense Input
V
IN
- Voltage-Sense Input
V
DD
- Power-Supply Input (2.5V to 5.5V)
V
SS
- Device Ground
SNS - Sense Resistor Connection
IS1 - Current-Sense Input
IS2 - Current-Sense Input
SNS Probe
- Do Not Connect
- Do Not Connect
V
SS
Probe
CC
DC
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* Mechanical drawing for the 16-pin TSSOP and DS2761 flip-chip package can be found at:
http://pdfserv.maxim-ic.com/arpdf/Packages/16tssop.pdf
http://pdfserv.maxim-ic.com/arpdf/Packages/chips/2761x.pdf
1-Wire is a registered trademark of Dallas Semiconductor.
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072303
DS2761
ORDERING INFORMATION
PART
DS2761AE
DS2761BE
DS2761AE/T&R
DS2761BE/T&R
DS2761AE-025
DS2761BE-025
DS2761AE-025/T&R
DS2761BE-025/T&R
DS2761AX-025/T&R
DS2761BX-025/T&R
DS2761AX/T&R
DS2761BX/T&R
MARKING
D2761EA
D2761EB
D2761EA
D2761EB
2761A25
2761B25
2761A25
2761B25
DS2761AR
DS2761BR
DS2761A
DS2761B
DESCRIPTION
TSSOP, External Sense Resistor, 4.275V V
OV
TSSOP, External Sense Resistor, 4.35V V
OV
DS2761AE on Tape-and-Reel
DS2761BE on Tape-and-Reel
TSSOP, 25mW Sense Resistor, 4.275V V
OV
TSSOP, 25mW Sense Resistor, 4.35V V
OV
DS2761AE-025 in Tape-and-Reel
DS2761BE-025 in Tape-and-Reel
Flip-Chip, 25mW Sense Resistor, Tape-and-Reel, 4.275V V
OV
Flip-Chip, 25mW Sense Resistor, Tape-and-Reel, 4.35V V
OV
Flip-Chip, External Sense Resistor, Tape-and-Reel, 4.275V V
OV
Flip-Chip, External Sense Resistor, Tape-and-Reel, 4.35V V
OV
Note: Additional V
OV
options are available, contact Maxim/Dallas Semiconductor sales.
DESCRIPTION
The DS2761 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 DS2761 is a key component
in applications including remaining capacity estimation, safety monitoring, and battery-specific data
storage.
Through its 1-Wire interface, the DS2761 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 DS2761 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 25mW sense resistor or an external device. The DS2761 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.
Three types of memory are provided on the DS2761 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.
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DS2761
Figure 1. BLOCK DIAGRAM
DQ
1-WIRE
INTERFACE
AND
ADDRESS
THERMAL
SENSE
VOLTAGE
REFERENCE
MUX
ADC
REGISTERS AND
USER MEMORY
LOCKABLE EEPROM
SRAM
TEMPERATURE
VOLTAGE
CURRENT
ACCUM. CURRENT
STATUS / CONTROL
LI-ION PROTECTION
TIMEBASE
PIO
CC
DC
V
IN
IS1
IS2
PLS
PS
+
-
INTERNAL SENSE RESISTOR CONFIGURATION ONLY
25mW
SNS
CHIP GROUND
V
SS
IS2
IS1
TEST CURRENT AND RECOVERY CHARGE DETAIL
I
RC
PLS
V
DD
I
TST
I
TST
V
SS
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DS2761
Table 1. DETAILED PIN DESCRIPTION
SYMBOL
CC
DC
TSSOP
1
3
7
FLIP
CHIP
C1
B2
B4
DESCRIPTION
Charge Protection Control Output.
Controls an external p-channel
high-side charge protection FET.
Discharge Protection Control Output.
Controls an external p-channel
high-side discharge protection FET.
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
1mA pull-down for sensing disconnection.
Programmable I/O Pin.
Used to control and monitor user-defined
external circuitry. Open drain to VSS.
Battery Pack Positive Terminal Input.
The DS2761 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 V
DD
. In sleep
mode (with SWEN = 0), any capacitance or voltage source connected to
PLS is discharged internally to V
SS
through 200mA (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.
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 1mA pull-up to V
DD
.
Voltage Sense Input.
The voltage of the Li+ cell is monitored via this
input pin. This pin has a weak pullup to V
DD
.
Power Supply Input.
Connect to the positive terminal of the Li+ cell
through a decoupling network.
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.
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.
Current Sense Input.
This pin is internally connected to VSS through a
4.7kW resistor. Connect a 0.1mF capacitor between IS1 and IS2 to
complete a low-pass input filter.
Current Sense Input.
This pin is internally connected to SNS through a
4.7kW resistor.
Do Not Connect.
Do Not Connect.
DQ
PIO
PLS
14
2
E2
B1
PS
10
E4
VIN
V
DD
VSS
SNS
16
15
13,14,
15
4,5,6
D1
E1
F3
A3
IS1
9
D4
IS2
SNS
Probe
VSS
Probe
8
N/A
N/A
C4
C2
D2
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DS2761
Figure 2. APPLICATION EXAMPLE
102 x 2
PACK+
BAT+
1k
W
1k
W
DS2761
CC
PLS
DC
SNS
SNS
SNS
DQ
IS2
V
IN
V
DD
PIO
V
SS
V
SS
V
SS
PS
IS1
104
1k
W
150
W
150
W
104
150
W
DATA
102
PS
4.7k
W
PACK-
R
SNS
(1)
BAT-
R
SNS-INT
SNS
4.7KW
(2)
V
SS
4.7KW
R
KS
IS2
R
KS
IS1
voltage
sense
DS2761
1) R
SNS
is present for external sense resistor configurations only.
2) R
SNS-INT
is present for internal sense resistor configurations only.
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