DS2770
Battery Monitor and
Charge Controller
www.maxim-ic.com
§
Integrated charge controller supporting both
rechargeable lithium and NiMH battery
technologies
§
Available in two configurations:
– Internal 25mW current-sense resistor
– External user-selectable sense resistor
§
Current measurement:
– 15-bit bidirectional measurement
– Internal sense resistor configuration:
62.5mA LSB and
±2A
dynamic range
– External sense resistor configuration:
1.56mV LSB and
±51.2mV
dynamic range
§
Current accumulation
– Internal sense resistor: 0.25mAh LSB
– External sense resistor: 6.25mVh LSB
§
Voltage measurement with 4.88mV resolution
§
Temperature measurement using integrated
sensor with 0.125°C resolution
§
40 bytes of lockable EEPROM
§
16 bytes of general-purpose SRAM
§
42-day timer
§
Dallas 1-Wire
â
interface with 64-bit ID
§
1.8V logic levels
§
Low power consumption:
– Active current:
80mA typical
– Sleep current:
0.5mA typical
FEATURES
PIN ASSIGNMENT
UV
CC
VCH
SNS
SNS
SNS
NC
IS2
1
2
3
2
4
5
6
7
8
16
15
14
13
12
11
10
9
VDD
VIN
DQ
VSS
VSS
VSS
NC
IS1
DS2770
16-Pin TSSOP
PIN DESCRIPTION
UV
CC
VCH
SNS
IS2
IS1
VSS
DQ
VIN
VDD
NC
– Battery-Undervoltage Detect Output
– Charge-Control Output
– Charge-Supply Input
– Sense Resistor Connection
– Current-Sense Input
– Current-Sense Input
– Device Ground
– Data Input/Output
– Voltage-Sense Input
– Power Supply Input
– No Connect
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.
Description continued on page 2.
1-Wire is a registered trademark of Dallas Semiconductor.
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052605
DS2770
ORDERING INFORMATION
ORDERING NUMBER
DS2770AE+
DS2770BE+
DS2770AE+T&R
DS2770BE+T&R
DS2770AE+025
DS2770BE+025
DS2770AE+025/T&R
DS2770BE+025/T&R
DS2770AE
DS2770BE
DS2770AE/T&R
DS2770BE/T&R
DS2770AE-025
DS2770BE-025
DS2770AE-025/T&R
DS2770BE-025/T&R
MARKING
D2770EA
D2770EB
D2770EA
D2770EB
2770EAR
2770EBR
2770EAR
2770EBR
D2770EA
D2770EB
D2770EA
D2770EB
2770EAR
2770EBR
2770EAR
2770EBR
DESCRIPTION
TSSOP, Ext. Sense Res., 4.1V Charge Voltage, Lead-Free
TSSOP, Ext. Sense Res., 4.2V Charge Voltage, Lead-Free
DS2770AE+ on Tape and Reel, Lead-Free
DS2770BE+ on Tape and Reel, Lead-Free
TSSOP, 25mΩ Sense Res., 4.1V Charge Voltage, Lead-Free
TSSOP, 25mΩ Sense Res., 4.2V Charge Voltage, Lead-Free
DS2770AE+025 on Tape and Reel, Lead-Free
DS2770BE+025 on Tape and Reel, Lead-Free
TSSOP, Ext. Sense Res., 4.1V Charge Voltage
TSSOP, Ext. Sense Res., 4.2V Charge Voltage
DS2770AE on Tape and Reel
DS2770BE on Tape and Reel
TSSOP, 25mΩ Sense Res., 4.1V Charge Voltage
TSSOP, 25mΩ Sense Res., 4.2V Charge Voltage
DS2770AE-025 on Tape and Reel
DS2770BE-025 on Tape and Reel
DESCRIPTION (CONTD.)
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 25mW 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.
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DS2770
BLOCK DIAGRAM
Figure 1
DQ
1-WIRE
INTERFACE
AND
ADDRESS
THERMAL
SENSE
MUX
VOLTAGE
REFERENCE
ADC
ADC
REGISTERS AND
USER MEMORY
LOCKABLE EEPROM
SRAM
TEMPERATURE
VOLTAGE
CURRENT
ACCUM CURRENT
TIMER
STATUS/CONTROL
CHARGE CONTROL
CC
UV
TIMEBASE
VIN
IS1
IS2
VCH
Internal sense resistor configuration only
25m
W
SNS
CHIP GROUND
VSS
3 of 27
DS2770
DETAILED PIN DESCRIPTION
Table 1
PIN
1
SYMBOL
DESCRIPTION
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
.
Charge Control Output:
Charge of the battery is controlled through this
pin when battery cell voltage is greater than or equal to V
LB
.
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.
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 SNS through a
10k
W
resistor. Connect a 0.1
m
F capacitor between IS2 and IS1 to
complete a lowpass filter.
Current-Sense Input:
This pin is internally connected to VSS through a
10k
W
resistor. Connect a 0.1
m
F capacitor between IS1 and IS2 to
complete a lowpass filter.
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.
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.
Voltage Sense Input:
The voltage on the battery cell is monitored via this
input pin.
Power Supply Input:
Input supply voltage for the DS2770 (2.7V to
5.5V)
Do not connect.
UV
2
3
4, 5, 6
CC
VCH
SNS
8
IS2
9
IS1
11, 12, 13
VSS
14
DQ
15
16
7, 10
VIN
VDD
NC
4 of 27
DS2770
APPLICATION EXAMPLE
Figure 2
PACK+
CHARGE
SOURCE
FMMT718
4403
360W
150W
100W
1kW
4.7kW
1kW
0.1mF
UV
CC
VCH
SNS
SNS
SNS
NC
IS2
VDD
VIN
DQ
VSS
VSS
VSS
NC
IS1
0.1mF
5.1V
Lithium
Protection
Circuit
0.1mF
PACK-
DATA
150W
R
SNS(1)
DS2770
SNS
10K
W
R
SNS-INT (2)
10K
W
VSS
IS2
Voltage
Sense
IS1
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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