dallas semiconductor DS2760 service manual

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www.dalsemi.com

C

V

PRELIMINARY

DS2760

High Precision Li-Ion Battery Monito

FEATURES

 Li-Ion safety circuit

- Overvoltage protection

- Overcurrent/short circuit protection

- Undervoltage protection

 Available in two configurations:

- Internal 25 mΩ sense resistor

- External user-selectable sense resistor

 Current measurement

- 12-bit bi-directional measurement

- Internal sense resistor configuration:

0.625 mA LSB and ±1.8A dynamic range

- External sense resistor configuration:

15.625 µV LSB and ±64 mV dynamic range

 Current accumulation

- Internal sense resistor: 0.25 mAhr LSB

- External sense resistor: 6.25 µVhr LSB

 Voltage measurement with 4.88 mV 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

device address

 Low power consumption:

- Active current: 80 µA max

- Sleep current: 2 µA max

®

interface with unique 64-bit

PIN ASSIGNMENT

CC VIN

1

1
2

2

PLS

3

2

DC
SNS
SNS
SNS

4
5
6

DQ

7

IS2

8

DS2760

16-Pin TSSOP Package

16
15
14
13
12
11
10

PLS CC VIN VDD
VDD
PIO
VSS
VSS
VSS
PS
IS1

9

DC NC NC NC PIO

SNS

NC N

Probe

SNS

DQ IS2 IS1 PS

DS2760

Flip-Chip Packaging

PIN DESCRIPTION

- Charge control output

CC

- Discharge control output

DC

DQ - Data input/output
PIO - Programmable I/O pin
PLS - Battery pack positive terminal input

- Power switch sense input

PS

VIN - Voltage sense input
VDD- Power supply input (2.5V-5.5V)
VSS - Device ground
SNS - Sense resistor connection
IS1 - Current sense input
IS2 - Current sense input
NC - Not connected
SNS Probe – Do not connect
VSS Probe – Do not connect

SS

VSS

1 of 25 092000

DS2760

ORDERING INFORMATION

DS2760E TSSOP, External Sense

Res., 4.35V V

OV

DS2760EA TSSOP, External Sense

Res., 4.275V V

OV

DS2760T DS2760E on Tape & Reel
DS2760TA DS2760EA on Tape &

Reel

DS2760E-025 TSSOP, 25 mΩ Sense

Res., 4.35V V

OV

DS2760EA-025 TSSOP, 25 mΩ Sense

Res., 4.275V V

OV

DS2760T-025 DS2760E-025 in Tape &

Reel

DS2760TA-025 DS2760EA-025 in Tape

& Reel

DS2760X Flipchip, Ext. Sense Res.,

T&R, 4.35V V

OV

DS2760XA Flipchip, Ext. Sense Res.,

T&R, 4.275V V

OV

DS2760X-025 Flipchip, 25 mΩ Sense

Res., T&R, 4.35V V

OV

DS2760XA-025 Flipchip, 25 mΩ Sense

Res., T&R, 4.275V V

OV

DESCRIPTION

The DS2760 High Precision Li-Ion 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 data storage, and Li-Ion protection
into the small footprint of either a TSSOP package or flip-chip. The DS2760 is a key component in
applications including remaining capacity estimation, safety monitoring, and battery-specific data storage.

Via its 1-Wire interface, the DS2760 gives the host system read/write access to status and control
registers, instrumentation registers, and general purpose data storage. Each device has a factory­programmed 64-bit net address which allows it to be individually addressed by the host system,
supporting multi-battery operation.

The DS2760 is capable of performing temperature, voltage and current measurement to a resolution
sufficient to support process monitoring applications such as battery charge control, remaining cap acity
estimation, and safety monitoring. Temperature is measured using an on-chip sensor, eliminating the need
for a separate thermistor. Bi-directional current measurement and accumulation are accomplished using
either an internal 25 mΩ sense resistor or an external device. The DS2760 also features a pro grammable
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 DS2760 for battery information storage: EEPROM, lockable
EEPROM and SRAM. EEPROM memory saves important battery data in true nonvolatile memory that
is unaffected by severe battery depletion, accidental shorts or ESD events. Lock able EEPROM becomes
ROM when locked to provide additional security for unchanging battery data. SRAM provides
inexpensive storage for temporary data.

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BLOCK DIAGRAM – Figure 1

Y

DS2760

DQ

VIN

IS1
IS2

PLS

PS

SNS

THERMAL

SENSE

+

1-WIRE

INTERFACE

ADDRESS

MUX

-

AND

LOCKABLE EEPROM

VOLTAGE

REFERENCE

ADC

ACCUM. CURRENT

STATUS / CONTROL

LI-ION PROTECTION

internal sense resistor configuration only

25 mΩ

REGISTERS AND

USER MEMOR

SRAM

TEMPERATURE

VOLTAGE

CURRENT

chip ground

TIMEBASE

PIO

CC
DC

VSS

IS2 IS1

3 of 25

DETAILED PIN DESCRIPTION – Table 1

SYMBOL DESCRIPTION

DS2760

CC

Charge Protection Control Output. Controls an external p-channel high-side charge
protection FET.

DC

Discharge Protection Control Output. Controls an external p-channel high-side
discharge protection FET.

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 1 µA pull-down for sensing
disconnection.

PIO

Programmable I/O Pin. Used to control and monitor user-defined external circuitry.
Open drain to VSS.

PLS

Battery Pack Positive Terminal Input. The device monitors the state of the battery
pack’s positive terminal through this pin in order to detect events such as the attachment
of a charger or the removal of a short circuit.

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 1 µA pull-up.

VIN Voltage Sense Input. The voltage of the Li-Ion cell is monitored via this input pin.

VDD

Power Supply Input. Connect to the positive terminal of the Li-Ion cell through a
decoupling network.

VSS

Device Ground. Connect directly to the negative terminal of the Li-Ion cell. For the
external sense resistor configuration, connect the sense resistor between VSS and SNS.

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.

IS1

IS2

Current Sense Input. This pin is internally connected to VSS through a 4.7 kΩ resistor.
Connect a 0.1µF capacitor between IS1 and IS2 to complete a low-pass input filter.

Current Sense Input. This pin is internally connected to SNS through a 4.7 kΩ resistor.

4 of 25

APPLICATION EXAMPLE – Figure 2

0

(1)

(2)

102

DS2760

PACK+

DATA

PACK-

1

1 kΩ

150Ω

150

2

BAT+

1 kΩ

1kΩ

150Ω

DS2760

CC
PLS
DC
SNS
SNS

Ω

SNS
DQ
IS2

VIN

VDD

PIO
VSS
VSS
VSS

PS

IS1

104

104

BAT-

R

SENS

DS2760

SNS

VSS

1 – R
2 – R

is present for external sense resistor configurations only

SENS
SENSINT

is present for internal sense resistor configurations only

R

R

KS

IS2 IS1

SENSINT

4.7 kΩ

voltage

R

KS

4.7 kΩ

sense

5 of 25

DS2760

POWER MODES

The DS2760 has two power modes: Active and Sleep. While in Active Mode, the DS2760 continually
measures current, voltage and temperature to provide data to the host system and to support current
accumulation and Li-ion safety monitoring. In Sleep Mode, the DS2760 ceases these activities. The
DS2760 enters Sleep Mode when either 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 2 seconds (pack disconnection)

• the voltage on VIN drops below undervoltage threshold VUV for t

• the pack is disabled through the issuance of a SWAP command (SWEN bit =1)

The DS2760 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 DS2760 defaults to Active Mode when power is first applied.

(cell depletion)

UVD

LI-ION PROTECTION CIRCUITRY

During Active Mode, the DS2760 constantly monitors cell voltage and current to protect the batte ry from
overcharge (overvoltage), overdischarge (undervoltage) and excessive charge and discharge currents
(overcurrent, short circuit). Conditions and DS2760 responses are described in the sections below and
summarized in Table 2 and Figure 3.

LI-ION PROTECTION CONDITIONS AND DS2760 RESPONSES – Table 2

ActivationCondition

Name

Overvoltage V
Undervoltage V

Threshold Delay Response

IN
IN

> V
< V

OV
UV

t

OVD

t

UVD

CC

CC, DC

high

high,

Sleep Mode

Overcurrent, Charge V
Overcurrent, Discharge V
Short Circuit V

VIS = V

IS1

– V

. Logic high = V

IS2

IS

IS

SNS

< -V

PLS

(1)

> V

> V

OC

OC

(1)

SC

t

OCD

t

OCD

t

SCD

for CC and VDD for

CC, DC

DC

.

high

high

DC

high

DC

All voltages are with respect to VSS. I

references current delivered from pin SNS.
(1) for the internal sense resistor configuration, the overcurrent thresholds are expressed in terms of

current: I
(2) with test current I
(3) with test current I

> IOC for charge direction and I

SNS

current flowing from PLS to VSS (pull-down on PLS)

TST

current flowing from VDD to PLS (pull-up on PLS)

TST

< -IOC for discharge direction

SNS

Release

Threshold

V

< V

IN

CE

V

> VDD

PLS

(charger connected)
V

< VDD - V

PLS

V

> VDD - V

PLS

V

> VDD - V

PLS

TP
TP
TP

(2)
(3)
(3)

SNS

Overvoltage. If the voltage of the cell exceeds overvoltage threshold VOV for a period longer than
overvoltage delay t

, the DS2760 shuts off the external charge FET and sets the OV flag in the

OVD

Protection Register. When the cell voltage falls below charge enable threshold VCE, the DS2760 turns the
charge FET back on (unless another protection condition prevents it). Discharging remains enabled
during overvoltage.

6 of 25

DS2760

SC

OC

U

Undervoltage. If the voltage of the cell drops below undervoltage threshold VUV for a period longer than
undervoltage delay t

, the DS2760 shuts off the charge and discharge FETs, sets the UV flag in the

UVD

Protection Register, and enters Sleep Mode.

Overcurrent, Charge Direc tion. The voltage difference between th e IS1 pin and the IS2 pin (V
– V

) is the filtered voltage drop across the current sense resistor. If VIS exceeds overcurrent threshold

IS2

VOC for a period longer than overcurrent delay t

, the DS2760 shuts off both external FETs and sets the

OCD

IS

= V

IS1

COC flag in the Protection Register. The charge current path is not re-established until the voltage on the
PLS pin drops below VDD – V

. The DS2760 provides a test current of value I

TP

from PLS to VSS to

TST

pull PLS down when the offending charge current source has been removed.

Overcurrent, Discharge Direction. If VIS is less than -VOC for a period longer than t

, the DS2760

OCD

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 DS2760 provides
a test current of value I

from VDD to PLS to pull PLS up when the offending low-impedance load has

TST

been removed.

Short Circuit. If the voltage on the SNS pin with respect to VS S exceeds short cir cuit threshold VSC for
a period longer than short circuit delay t

, the DS2760 shuts off the external discharge FET and sets the

SCD

DOC flag in the Protection Register. The discharge current path is not re-established until the voltage on
PLS rises above VDD - VTP. The DS2760 provides a test current of value I

from VDD to PLS to pull

TST

PLS up when the short circuit has been removed.

LITHIUM-ION PROTECTION CIRCUITRY EXAMPLE WAVEFORMS – Figure 3

V

OV

V

CELL

charge

V

discharge

CC

IS

(1)

t

OVD

t

OVD

t

OCD

V
V

V
0

-V

-V

V
VSS

CE

UV

OC

OC

SC

PLS

DC

t

D

t

D

t

VD

Sleep

Mode

(1) To allow the device to react quickly to short circuits, detection is actually done on the SNS pin rather

than on the filtered IS1 and IS2 pins. The actual short circuit detect condition is V

SNS

> VSC.

7 of 25

VDD

VSS

active
inactive

DS2760

r

r

Summary. All of the protection conditions described above are OR'ed together to affect the CC and

DC

outputs.

= (Undervoltage) or (Overcurrent, EITHER Direction) or (Short Circuit) or

DC

(Protection Register bit DE = 0) or (Sleep Mode)

= (Overvoltage) or (Overcurrent, Charge Direction) or (Protection Register bit CE = 0) or

CC

(Sleep Mode)

CURRENT MEASUREMENT

In the Active Mode of operation, the DS2760 continually measures the current flow into and out of the
battery by measuring the voltage drop across a current sense resistor. The DS2760 is available in two
configurations: (1) internal 25 mΩ current sense resistor, and (2) external user-selectable sense resistor. In
either configuration, the DS2760 considers the voltage difference between pins IS1 and IS2 (VIS = V
V

) to be the filtered voltage drop across the sense resistor. A positive VIS value indicat es current is

IS2

flowing into the battery (charging), while a negative VIS value indicates current is flowing out of the
battery (discharging). Note than when an external sense resistor is used, one end of the resistor must be
wired directly to VSS (the negative terminal of the cell) for proper operation of the current measurement
circuitry.

IS1

–

VIS is measured with a signed resolution of 12-bit s. Measurements are placed in the Current Register in
two’s-complement format. Currents outside the range of the register are reported at the limit of the range.
The format of the Current Register is shown in Figure 4.

For the internal sense resistor configuration, the DS2760 maintains the Current Register in units of Amps,
with a resolution of 0.625 mA and full scale range of no less than ±1.8A (see Note 7 on IFS spec for more
details). The DS2760 automatically compensates for internal sense resistor process variations and
temperature effects when reporting current.

For the external sense resistor configuration, the DS2760 writes the measured VIS voltage to the Current
Register, with a resolution of 15.625 µV and a full scale range of ±64 mV.

CURRENT REGISTER FORMAT – Figure 4

MSB—Address 0E LSB—Address 0F

S2112

1029

2827262

MSb LSb MSb LSb

5

2423222120XXX

Units: 0.625 mA for internal sense resisto

15.625 µV for external sense resisto

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’s­complement format. The format of the Current Accumulator is shown in Figure 5.

8 of 25