MAXIM DS2782 Technical data

Standalone Fuel Gauge IC

DS2782

www.maxim-ic.com

GENERAL DESCRIPTION

The DS2782 measures voltage, temperature and current, and estimates available capacity for rechargeable lithium ion and lithium-ion polymer batteries. Cell characteristics and application parameters used in the calculations are stored in onchip EEPROM. The available capacity registers report a conservative estimate of the amount of charge that can be removed given the current temperature, discharge rate, stored charge and application parameters. Capacity estimation reported in mAh remaining and percentage of full.

PIN CONFIGURATION

APPLICATIONS

Digital Still Cameras

Sub-Notebook Computers

Handheld PC Data Terminals

3G Multimedia Wireless Handsets

TYPICAL OPERATING CIRCUIT

FEATURES

 Precision Voltage, Temperature, and Current

Measurement System

 Accurate Stable Internal Time Base  Absolute and Relative Capacity Estimated from

Coulomb Count, Discharge Rate, Temperature and Battery Cell Characteristics

 Accurate Warning of Low Battery Conditions  Automatic Backup of Coulomb Count and Age

Estimation to Nonvolatile (NV) EEPROM

 Gain and Tempco Calibration Allows the Use of

Low-Cost Sense Resistors

 24-Byte User EEPROM or 16-Byte User

EEPROM and Unique 64-bit ID

 Industry 2-Wire Interface with Programmable

Slave Address

 Tiny TSSOP-8 and TDFN-10 Packages Embed

Easily in Thin Prismatic Cell packs

ORDERING INFORMATION

PART MARKING PACKAGE INFORMATION

DS2782E+ 2782+ Lead-Free TSSOP-8 DS2782E+T&R 2782+ DS2782E+, Tape-and-Reel DS2782G+ 2782+ Lead-Free 3mm x 4mm TDFN-10 DS2782G+T&R 2782+ DS2782G+, Tape-and-Reel

Note: To order devices with the unique 64-bit ID option, contact Maxim/Dallas Semiconductor sales.

Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata

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050907

DS2782: Standalone Fuel Gauge IC

ABSOLUTE MAXIMUM RATINGS

Voltage Range on Any Pin Relative to V Voltage on V

Relative to VSS -0.3V to VDD+0.3

Operating Temperature Range -40°C to +85°C Storage Temperature Range Soldering Temperature

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.

-55°C to +125°C

See IPC/JEDEC J-STD-020 Specification

-0.3V to +6.0V

RECOMMENDED DC OPERATING CHARACTERISTICS

(VDD = 2.5V to 5.5V; TA = -20°C to +70°C, unless otherwise noted. Typical values are at TA = +25°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage VDD (Note 1) +2.5 +5.5 V SDA, SCL, PIO Voltage Range

DC ELECTRICAL CHARACTERISTICS

(VDD = 2.5V to 5.5V; TA = -20°C to +70°C, unless otherwise noted. Typical values are at TA = +25°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

(Note 1) -0.3 +5.5 V

ACTIVE Current I

SLEEP Mode Current I

Input Logic High: SDA, SCL, PIO Input Logic Low: SDA, SCL, PIO

ACTIVE

SLEEP

2.5V ≤ VDD ≤ 4.2V 65 95 µA

105

2.5V ≤ VDD ≤ 4.2V 1 3 µA

(Note 1) 1.5 V

(Note 1) 0.6 V

Output Logic Low: SDA, PIO VOL IOL = 4mA (Note 1) 0.4 V Pulldown Current:

SDA, SCL, PIO

VIN Input Resistance RIN 15

Bus Low to Sleep time

Undervoltage SLEEP Threshold

SLEEP

, V

SDA

0.4V

SCL

PIO

0.2 µA

MΩ SDA, SCL < V (Note 2)

2.2 s

(Note 1) 2.40 2.45 2.50 V

ELECTRICAL CHARACTERISTICS: TEMPERATURE, VOLTAGE, CURRENT

(VCC = 2.5V to 5.5V; TA = -20°C to +70°C, unless otherwise noted. Typical values are at TA = +25°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Temperature Resolution T

Temperature Error T

Voltage Resolution V

Voltage Full-Scale VFS 0 4.992 V

0.125 °C

LSB

±3 °C

ERR

4.88 mV

LSB

Voltage Error V

Current Resolution I

±50 mV

ERR

1.56 µV

LSB

Current Full-Scale IFS ±51.2 mV

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PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Current Gain Error I

Current Offset Error I

(Note 3) ±1

GERR

≤ +70°C,

≤ 4.2V

OERR

0°C ≤ T

2.5V ≤ V (Note 5)

≤ +70°C,

≤ 4.2V

= VSS, (Notes 4, 5)

Accumulated Current Offset q

OERR

0°C ≤ T

2.5V ≤ V V

SNS

VDD = 3.8V, TA = +25°C ±1

Timebase Error t

ERR

0°C ≤ TA ≤ +70°C,

2.5V ≤ VDD ≤ 4.2V

±3

ELECTRICAL CHARACTERISTICS: 2-WIRE INTERFACE

(2.5V ≤ VDD ≤ 5.5V, TA = -20°C to +70°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DS2782: Standalone Fuel Gauge IC

% Full-

Scale

- 7.82 + 12.5 µV

- 188 + 0

±2

µVhr/

day

SCL Clock Frequency

Bus Free Time Between a STOP and START Condition

Hold Time (Repeated) START Condition

Low Period of SCL Clock

High Period of SCL Clock

Setup Time for a Repeated START Condition

Data Hold Time

Data Setup Time

Rise Time of Both SDA and SCL Signals

Fall Time of Both SDA and SCL Signals

Setup Time for STOP Condition

Spike Pulse Widths Suppressed by Input Filter

Capacitive Load for Each Bus Line

SCL, SDA Input Capacitance C

(Note 6) 0 400 KHz

SCL

1.3 µs

BUF

HD:STA

LOW

HIGH

SU:STA

HD:DAT

SU:DAT

SU:STO

(Note 11) 400 pF

BIN

(Note 7) 0.6 µs

1.3 µs

0.6 µs

(Note 8, 9) 0 0.9 µs

(Note 8) 100 ns

20 + 0.1C

0.6 µs

(Note 10) 0 50 ns

300 ns

60 pF

EEPROM RELIABILITY SPECIFICATION

(VCC = 2.5V to 5.5V; TA = -20°C to +70°C, unless otherwise noted. Typical values are at TA = +25°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

EEPROM Copy Time t

EEPROM Copy Endurance N

10 ms

EEC

TA = +50°C 50,000 cycles

EEC

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DS2782: Standalone Fuel Gauge IC

Note 1: All voltages are referenced to V Note 2: To properly enter sleep mode the application should hold the bus low for longer than the maximum t

SLEEP

Note 3: Factory calibrated accuracy. Higher accuracy can be achieved by in-system calibration by the user. Note 4: Accumulation bias register set to 00h. Note 5: Parameters guaranteed by design. Note 6: Timing must be fast enough to prevent the DS2782 from entering sleep mode due to bus low for period >

SLEEP.

Note 7: f Note 8: The maximum t

must meet the minimum clock low time plus the rise/fall times.

SCL

has only to be met if the device does not stretch the LOW period (t

HD:DAT

) of the SCL

LOW

signal.

Note 9: This device internally provides a hold time of at least 300 ns for the SDA signal (referred to the VIHmin of

the SCL signal) to bridge the undefined region of the falling edge of SCL.

Note 10: Filters on SDA and SCL suppress noise spikes at the input buffers and delay the sampling instant. Note 11: C

– total capacitance of one bus line in pF.

Figure 1. I2C Bus Timing Diagram

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DS2782: Standalone Fuel Gauge IC

PIN DESCRIPTION

NAME

TSSOP

NC 1 1 Not Connected. Pin not connected internally, float or connect to VSS.

VSS 2 2, 3

VIN 3 4

VDD 4 5

SDA 5 6

SCL 6 7

N.C. — 8 No Connection. (Only present on TDFN package).

TDFN

FUNCTION

Device Ground. Connect directly to the negative terminal of the battery cell.

Connect the sense resistor between VSS and SNS.

Voltage Sense Input. The voltage of the battery cell is monitored through this

input pin.

Power-Supply Input. Connect to the positive terminal of the battery cell through a

decoupling network.

Serial Data Input/Out. 2-Wire data line. Open-drain output driver. Connect this pin

to the DATA terminal of the battery pack. Pin has an internal pull-down (IPD) for sensing disconnection.

Serial Clock Input. 2-Wire clock line. Input only. Connect this pin to the CLOCK

terminal of the battery pack. Pin has an internal pull-down (I

) for sensing

disconnection.

SNS 7 9

PIO 8 10

PAD — PAD

Sense Resistor Connection. Connect to the negative terminal of the battery

pack. Connect the sense resistor between VSS and SNS.

Programmable I/O Pin. Can be configured as input or output to monitor or control

user-defined external circuitry. Output driver is open drain. This pin has a weak internal pulldown (I

Exposed Pad. Connect to VSS or leave floating. (Only present on TDFN

package).

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Figure 2. Block Diagram

VDD

VPOR

PIO

SDA

SCL

2-Wire

Interface

BIAS/VREF Timebase

Status

Control

DS2782: Standalone Fuel Gauge IC

VIN

Temp

Voltage

ADC

EEPROM

Accumulated

Current

SNS VSS

Current ADC

Rate,

Temperature

Compensation

15 bit + sign

DETAILED DESCRIPTION

The DS2782 operates directly from 2.5V to 5.5V and supports single cell Lithium-ion battery packs. As shown in Figure 3, the DS2782 accommodates multicell applications by adding a voltage regulator for VDD and voltage divider for VIN. Nonvolatile storage is provided for cell compensation and application parameters. Host side development of fuel-gauging algorithms is eliminated. On-chip algorithms and convenient status reporting of operating conditions reduce the serial polling required of the host processor.

Additionally, 16 bytes of EEPROM memory are made available for the exclusive use of the host system and/or pack manufacturer. The additional EEPROM memory can be used to facilitate battery lot and date tracking and NV storage of system or battery usage statistics.

Through its 2-Wire interface, the DS2782 gives the host system read/write access to status and control registers, instrumentation registers, and general-purpose data storage. The 7-bit slave address is field programmable, thus allowing up to 128 devices to be distinctly addressed by the host system. A unique, factory programmed 64-bit registration number (8-bit family code + 48-bit serial number + 8-bit CRC) option assures that no two parts are alike and enables absolute traceability.

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Figure 3. Multicell Application Example

Pack+

DS2782: Standalone Fuel Gauge IC

4.7uF0.1uF

SDA

150

SDA

VDD

500

(n * R)

Multi-Cell

Li-Ion

Battery

SCL

Pack-

150

(1) (1)

Protection

Circuit

(1) Components improve IEC1004 Air/Contact ESD compliance

SCL

PIO

SNS

RSNS

VIN

VSS

0.1uF

POWER MODES

The DS2782 has two power modes: ACTIVE and SLEEP. On initial power up, the DS2782 defaults to ACTIVE mode. While in ACTIVE mode, the DS2782 is fully functional with measurements and capacity estimation continuously updated. In SLEEP mode, the DS2782 conserves power by disabling measurement and capacity estimation functions, but preserves register contents. SLEEP mode is entered under two different conditions and an enable bit for each condition makes entry into SLEEP optional. SLEEP mode can be enabled using the Power Mode (PMOD) bit or the Under Voltage Enable (UVEN) bit.

The PMOD type SLEEP is entered if the PMOD bit is set AND where both SDA AND in which the bus pull-up voltage, V

SCL low for tSLEEP (2s nominal), is used to detect a pack disconnection or system shutdown

, is not present. PMOD SLEEP assumes that no charge or discharge

PULLUP

a bus low condition occurs. A bus low condition,

current will flow and therefore coulomb counting is not necessary. A system with PMOD SLEEP enabled must ensure that a standalone or cradle charger includes a pull-up on SDA and/or SCL. The DS2782 transitions from PMOD SLEEP to ACTIVE mode when either SDA or SCL is pulled high.

The second option for entering SLEEP is an under voltage condition measured on VIN. When the UVEN bit is set, the DS2782 will transition to SLEEP if the voltage on VIN is less than V is in a bus high or a bus low condition for t

SLEEP. UVEN SLEEP relieves the battery of the DS2782 load until

SLEEP (2.45V nominal) AND the 2-Wire bus

communication resumes to prevent over discharging the battery. The DS2782 transitions from UVEN SLEEP to ACTIVE mode when either SDA or SCL change logic state. The bus master should initiate a transaction after charging of a depleted battery begins.

Note: PMOD and UVEN SLEEP features must be disabled when a battery is charged on an external charger that does not connect to SDA and/or SCL. PMOD SLEEP can be used if the charger pulls the bus high. The DS2782 remains in SLEEP and therefore does not measure or accumulate current when a battery is charged on a charger that fails to properly drive the communication bus.

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DS2782: Standalone Fuel Gauge IC

INITIATING COMMUNICATION IN SLEEP

When beginning communication with a DS2782 in PMOD SLEEP, the bus must be pulled up before a START bit can be issued by the master. In UVEN SLEEP, the procedure depends on the bus state when UVEN SLEEP was entered. If the bus was low, it must be pulled up before a START bit can be issued by the master as required with PMOD SLEEP. If the bus was high when UVEN SLEEP was entered, then the DS2782 is prepared to receive a START bit from the master. A standard procedure of issuing a START – STOP – START when the host system is powered up on the charger input properly initiates communication from both PMOD and UVEN SLEEP modes.

VOLTAGE MEASUREMENT

Battery voltage is measured at the VIN input with respect to VSS over a range of 0V to 4.992V, with a resolution of

4.88mV. The result is updated every 440ms and placed in the VOLTAGE register in two’s compliment form. Voltages above the maximum register value are reported at the maximum value; voltages below the minimum register value are reported at the minimum value. The format of the voltage register is shown in Figure 4.

Figure 4. Voltage Register Format

VOLT

MSB—Address 0Ch LSB—Address 0Dh

S 2

MSb LSb MSb LSb

“S”: sign bit(s), “X”: reserved

VIN is usually connected to the positive terminal of a single cell Lithium-Ion battery via a 1kΩ resistor. The input impedance is sufficiently large (15MΩ) to be connected to a high impedance voltage divider in order to support multiple cell applications. The pack voltage should be divided by the number of series cells to present a single cell average voltage to the VIN input. In Figure 3, the value of R can be up to 1MΩ without incurring significant error due to input loading.

28 27 26 25 24 23 22 21 20 X X X X X

Read Only

Units: 4.88mV

TEMPERATURE MEASUREMENT

The DS2782 uses an integrated temperature sensor to measure battery temperature with a resolution of 0.125°C. Temperature measurements are updated every 440ms and placed in the temperature register in two’s complement form. The format of the temperature register is shown in Figure 5.

Figure 5. Temperature Register Format

TEMP

MSB—Address 0Ah LSB—Address 0Bh

S 2

MSb LSb MSb LSb

“S”: sign bit(s), “X”: reserved

28 27 26 25 24 23 22 21 20 X X X X X

Read Only

Units: 0.125°C

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