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041202
FEATURES
Integrated charge controller supporting both
rechargeable lithium and NiMH battery
technologies
Available in two configurations:
Internal 25m
W current-sense resistor
External user-selectable sense resistor
Current measurement:
15-bit bidirectional measurement
Internal sense resistor configuration:
62.5
mA LSB and 2A
dynamic range
External sense resistor configuration:
1.56
mV LSB and 51.2mV dynamic range
Current accumulation
Internal sense resistor: 0.25mAh LSB
External sense resistor: 6.25
mVh LSB
Voltage measurement with 4.88mV resolution
Temperature measurement using integrated
sensor with 0.125C resolution
40 bytes of lockable EEPROM
16 bytes of general-purpose SRAM
42-day timer
Dallas 1-Wire
interface with 64-bit ID
1.8V logic levels
Low power consumption:
Active current:
80
mA typical
Sleep current:
0.5
mA typical
PIN ASSIGNMENT
PIN DESCRIPTION
UV
Battery Undervoltage Detect Output
CC
Charge Control Output
VCH Charge Supply Input
SNS
Sense Resistor Connection
IS2
Current-Sense Input
IS1
Current-Sense Input
VSS
Device Ground
DQ
Data Input/Output
VIN
Voltage Sense Input
VDD Power Supply Input
NC
No Connect
ORDERING INFORMATION
ORDERING NUMBER
MARKING DESCRIPTION
DS2770AE
D2770EA
TSSOP, Ext. Sense Res., 4.1V Charge Voltage
DS2770BE
D2770EB
TSSOP, Ext. Sense Res., 4.2V Charge Voltage
DS2770AE/T&R
D2770EA
DS2770AE on Tape & Reel
DS2770BE/T&R
D2770EB
DS2770BE on Tape & Reel
DS2770AE-025
2770EAR
TSSOP, 25m
W Sense Res., 4.1V Charge Voltage
DS2770BE-025
2770EBR
TSSOP, 25m
W Sense Res., 4.2V Charge Voltage
DS2770AE-025/T&R
2770EAR
DS2770AE-025 on Tape & Reel
DS2770BE-025/T&R
2770EBR
DS2770BE-025 on Tape & Reel
DS2770
Battery Monitor and Charge Controller
www.maxim-ic.com
DS2770
16-Pin TSSOP
UV
VDD
VIN
DQ
VSS
VSS
VSS
NC
IS1
IS2
SNS
SNS
1
2
2
3
2
1
4
5
6
7
8
16
15
14
13
12
11
10
9
SNS
NC
VCH
CC
1-Wire is a registered trademark of Dallas Semiconductor.
DS2770
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DESCRIPTION
The DS2770 battery monitor and charge controller performs several functions needed for thorough
battery maintenance. When used in conjunction with the host system's processor, a battery-pack resident
DS2770 may be utilized for applications that include charging, remaining capacity estimation, safety
monitoring, and nonvolatile (NV) parametric storage.
The DS2770 provides a unique ID, a digital temperature sensor, an analog-to-digital converter (ADC) that
measures battery voltage and current, an integrated current accumulator that keeps a running total of all
current entering and leaving the battery, an elapsed time meter, NV memory for storage of important
parameters, and an integrated charge controller supporting rechargeable lithium (including lithium-ion
and lithium-ion polymer) and nickel metal hydride (NiMH) batteries. Current measurement can be
accomplished through the use of an integrated 25m
W sense resistor or through an external sense resistor.
The resolution of the current, voltage, and temperature measurements is sufficient for process monitoring
applications such as battery-charge control and safety. The charge-control technique is user-selectable to
support either pulse charge for rechargeable lithium or dT/dt termination for NiMH. Additionally,
programmable charge timers and low-battery recovery are provided for safety and convenience.
Information is sent to/from the DS2770 over a 1-Wire interface so that only one wire (and ground) needs
to be connected from a processor to a DS2770. This means that DS2770-equipped battery packs need
only four output connectors: battery power, charge source, ground, and the 1-Wire interface. Each device
has a factory-programmed 64-bit net address that allows it to be individually addressed by the host
system.
Two types of memory are provided on the DS2770 for battery information storage: 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 and becomes ROM when locked to provide
additional security for unchanging battery data. SRAM provides inexpensive storage for temporary data.
DS2770
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BLOCK DIAGRAM Figure 1
1-WIRE
INTERFACE
AND
ADDRESS
THERMAL
SENSE
MUX
VOLTAGE
REFERENCE
ADC
LOCKABLE EEPROM
SRAM
TEMPERATURE
VOLTAGE
CURRENT
ACCUM CURRENT
TIMER
STATUS/CONTROL
REGISTERS AND
USER MEMORY
TIMEBASE
25mW
VSS
SNS
DQ
VIN
IS1
IS2
CHARGE CONTROL
CC
UV
VCH
ADC
CHIP GROUND
Internal sense resistor configuration only
DS2770
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DETAILED PIN DESCRIPTION Table 1
PIN
SYMBOL
DESCRIPTION
1
UV
Battery Undervoltage Detect Output:
This pin allows charge of the
battery at a reduced rate when the battery cell voltage is less than the low
battery voltage threshold, V
LB
.
2
CC
Charge Control Output:
Charge of the battery is controlled through this
pin when battery cell voltage is greater than or equal to V
LB
.
3
VCH
Charge Supply Input:
The charge source is connected to this pin and is
measured by the DS2770 to determine if a charge source is present.
4, 5, 6
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.
8
IS2
Current-Sense Input:
This pin is internally connected to SNS through a
10k
W resistor. Connect a 0.1mF capacitor between IS2 and IS1 to
complete a lowpass filter.
9
IS1
Current-Sense Input:
This pin is internally connected to VSS through a
10k
W resistor. Connect a 0.1mF capacitor between IS1 and IS2 to
complete a lowpass filter.
11, 12, 13
VSS
Device Ground:
Connect directly to the negative terminal of the battery
cell. For the external sense resistor configuration, connect the sense
resistor between VSS and SNS.
14
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 pull-
down for sensing disconnection.
15
VIN
Voltage Sense Input:
The voltage on the battery cell is monitored via this
input pin.
16
VDD
Power Supply Input:
Input supply voltage for the DS2770 (2.7V to
5.5V)
7, 10
NC
Do not connect.
DS2770
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APPLICATION EXAMPLE Figure 2
VDD
FMMT718
4403
UV
CC
VCH
SNS
SNS
SNS
IS2
NC
VIN
DQ
VSS
VSS
VSS
NC
IS1
Lithium
Protection
Circuit
4.7k
W
1k
W
1k
W
100
W
150
W
0.1
mF
0.1
mF
360
W
0.1
mF
R
SNS
(1)
150
W
PACK+
CHARGE
SOURCE
PACK-
DATA
R
SNS-INT
(2)
10
K
W
10
K
W
Voltage
Sense
DS2770
VSS
SNS
IS2
IS1
5.1V
1 -- R
SNS
is present for external sense resistor configuration only.
2 -- R
SNS-INT
is present for internal sense resistor configuration only.
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