LTC2943IDD-1#PBF - ANALOG DEVICES

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Typical applicaTion

FeaTures DescripTion

1A Multicell Battery Gas

Gauge with Temperature,

Voltage and Current Measurement

The LT C

2943-1 measures battery charge state, battery

voltage, battery current and its own temperature in portable

product applications. The wide input voltage range allows

use with multicell batteries up to 20V. A precision coulomb

counter integrates current through a sense resistor between

the battery’s positive terminal and the load or charger.

Voltage, current and temperature are measured with an

internal 14-bit No Latency ΔΣ™ ADC. The measurements

are stored in internal registers accessible via the onboard

I2C/SMBus Interface.

The LTC2943-1 features programmable high and low

thresholds for all four measured quantities. If a pro-

grammed threshold is exceeded, the device communicates

an alert using either the SMBus alert protocol or by setting

a flag in the internal status register.

Total Charge Error vs Current Sense

applicaTions

n Measures Accumulated Battery Charge and Discharge

n 3.6V to 20V Operating Range for Multiple Cells

n Integrated 50mΩ High Side Sense Resistor

n ±1A Current Sense Range

n 14-Bit ADC Measures Voltage, Current and

Temperature

n 1% Voltage, Current and Charge Accuracy

n High Side Sense

n General Purpose Measurements for Any Battery

Chemistry and Capacity

n I2C/SMBus Interface

n Configurable Alert Output/Charge Complete Input

n Quiescent Current Less Than 120µA

n Small 8-Lead 3mm × 3mm DFN Package

n Power Tools

n Portable Medical Equipment

n Video Cameras

L, LT , LT C , LT M , Linear Technology and the Linear logo are registered trademarks and

No Latency ΔΣ and PowerPath are trademarks of Linear Technology Corporation. All other

trademarks are the property of their respective owners. Protected by U.S. Patent, 8390363.

SENSE+

ALCC

SDA

SCL

LTC2943-1

CHARGER

2k2k 2k

LOAD

MULTICELL

LI-ION

29431 TA01a

SENSE–

GND

1µF

VDD

3.3V

µP

VSENSE+ = 10V

SENSE

| (mA)

100

–2.0

–1.5

–1.0

–0.5

0.5

1.0

1.5

2.0

CHARGE ERROR (%)

29431 TA01b

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

pin conFiguraTionabsoluTe MaxiMuM raTings

(Notes 1, 2)

TOP VIEW

DD PACKAGE

8-LEAD (3mm × 3mm) PLASTIC DFN

1SENSE+

GND

SCL

SENSE–

GND

ALCC

SDA

TJMAX = 150°C, θJA = 53.4°C/W

EXPOSED PAD (PIN 9) PCB GND CONNECTION OPTIONAL

elecTrical characTerisTics

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Power Requirements

VSENSE+Supply Voltage 3.6 20 V

ISUPPLY Supply Current (Note 3) Battery Gas Gauge On, ADC Sleep

Battery Gas Gauge On, ADC On

Shutdown

650

120

750

µA

VUVLO Undervoltage Lockout Threshold VSENSE+ Falling l3.0 3.3 3.6 V

Coulomb Counter

ISENSE Sense Current l±1 A

RSENSE Internal Sense Resistance 50 mΩ

RFP Pin-to-Pin Resistance from SENSE+

to SENSE–(Note 8) 50 74 100 mΩ

qLSB Charge LSB (Note 4) Prescaler M = 4096(Default) 0.4 mAh

TCE Total Charge Error (Note 5) 0.2A ≤ |ISENSE–| ≤ 1A DC

0.2A ≤ |ISENSE–| ≤ 1A DC, 0°C to 70°C

0.02A ≤ |ISENSE–| ≤ 1A DC (Note 8)

±1

±1.5

±3.5

VOSE Effective Differential Offset Current

(Note 9)

ISENSE ≥ 10mA, VSENSE+ = 10V l100 200 µA

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. (Note 2)

orDer inForMaTion

Supply Voltage (SENSE+) ........................... –0.3V to 24V

SCL, SDA, ALCC Voltage .............................. –0.3V to 6V

Sense Current (into SENSE–) ....................................±2A

Operating Ambient Temperature Range

LTC2943C-1 ............................................ 0°C to 70°C

LTC2943I-1 .........................................–40°C to 85°C

Storage Temperature Range .................. –65°C to 150°C

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC2943CDD-1#PBF LTC2943CDD-1#TRPBF LGQN 8-Lead (3mm × 3mm) Plastic DFN 0°C to 70°C

LTC2943IDD-1#PBF LTC2943IDD-1#TRPBF LGQN 8-Lead (3mm × 3mm) Plastic DFN –40°C to 85°C

Consult LT C Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through

designated sales channels with #TRMPBF suffix.

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

elecTrical characTerisTics

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Voltage Measurement ADC

Resolution (No Missing Codes) (Note 8) l14 Bits

VFS(V) Full-Scale Voltage Conversion 23.6 V

ΔVLSB Quantization Step of 14-Bit Voltage

ADC

(Note 6) 1.44 mV

TUEVVoltage Total Unadjusted Error

1.3

GainVVoltage Gain Accuracy l1.3 %

INLVIntegral Nonlinearity VSENSE+ > 5V l±1 ±4 LSB

3.6V ≤ VSENSE+ ≤ 5V l±8 LSB

TCONV(V) Voltage Conversion Time l48 ms

Current Measurement ADC

Resolution (No Missing Codes) (Note 8) l12 Bits

VFS(I) Full-Scale Current Conversion l±1.3 A

VSENSE Sense Voltage Differential Input

Range

VSENSE+ – VSENSE–l±1 A

ΔILSB Quantization Step of 12-Bit Current

ADC

(Note 6) 317.4 µA

GainICurrent Gain Accuracy

0°C to 70°C

–40°C to 85°C

1.3

VOS(I) Offset ±1 ±10 LSB

INLIIntegral Nonlinearity l±1 ±4 LSB

TCONV(I) Current Conversion Time l8 ms

Temperature Measurement ADC

Resolution (No Missing Codes) (Note 8) l11 Bits

TFS Full-Scale Temperature 510 K

ΔTLSB Quantization Step of 11-Bit

Temperature ADC

(Note 6) 0.25 K

TUETTemperature Total Unadjusted Error ±3 K

TCONV(T) Temperature Conversion Time l8 ms

Digital Inputs and Digital Outputs

VITH(HV) Logic Input Threshold VSENSE+ ≥ 5V l0.8 2.2 V

VITH(LV)3.6V < VSENSE+ < 5V 0.45 1.8 V

VOL Low Level Output Voltage, ALCC,

SDA

I = 3mA, VSENSE+ ≥ 5V l0.4 V

IIN Input Leakage, ALCC, SCL, SDA VIN = 5V l±1 µA

CIN Input Capacitance, ALCC, SCL, SDA (Note 8) l10 pF

tPCC Minimum Charge Complete (CC)

Pulse Width

1 µs

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

elecTrical characTerisTics

Note 1. Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2. All currents into pins are positive, all voltages are referenced to

GND unless otherwise specified.

Note 3. ISUPPLY = ISENSE+ + ISENSE–. In most operating modes, ISUPPLY is

flowing in SENSE+ pin. Only during ADC conversions, current is flowing in

SENSE– pin as well. Typically, ISENSE– = VSENSE–/150k during ADC voltage

conversion and ISENSE– = 20µA during ADC current conversion.

Note 4. The equivalent charge of an LSB in the accumulated charge

prescaling factor M:

qLSB = 0.4mAh • (M/4096)

See Choosing Coulomb Counter Prescaler M section for more information.

1mAh = 3.6C (Coulombs)

Note 5. Deviation of qLSB from its nominal value.

Note 6. The quantization step of the 14-bit ADC in voltage mode,12-bit

ADC in current mode and 11-bit ADC in temperature mode is not the

same as the LSB of the respective combined 16-bit registers. See Voltage,

Current and Temperature Registers section for more information.

Note 7. CB = Capacitance of one bus line in pF (10pF ≤ CB ≤ 400pF).

Note 8. Guaranteed by design, not subject to test.

Note 9. See Effect of Differential Offset Voltage on Total Charge Error

section.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I2C Timing Characteristics

fSCL(MAX) Maximum SCL Clock Frequency l400 900 kHz

tBUF(MAX) Bus Free Time Between Stop/Start l1.3 µs

tSU(STA(MIN)) Minimum Repeated Start Set-Up

Time

l600 ns

tHD(STA(MIN)) Minimum Hold Time (Repeated)

Start Condition

l600 ns

tSU(STO(MIN)) Minimum Set-Up Time for Stop

Condition

l600 ns

tSU(DAT(MIN)) Minimum Data Setup Time Input l100 ns

THD(DAT(MIN)) Minimum Data Hold Time Input l50 ns

THDDATO Data Hold Time Input Output l0.3 0.9 µs

TOF Data Output Fall Time (Notes 7, 8) l20 + 0.1 • CB300 ns

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C.

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

TiMing DiagraM

Figure 1. Definition of Timing on I2C Bus

SDA

SCL

29431 TD01

tHD(STA)

START

CONDITION

tSU(DAT) tHD(DAT0)

tHD(DAT1) tHD(STA) tSU(STO)

tSU(STA)

STOP

CONDITION

START

CONDITION

REPEATED START

CONDITION

tBUF

Typical perForMance characTerisTics

Supply Current vs Supply Voltage

Shutdown Supply Current vs

Supply Voltage

Voltage Measurement ADC

Gain Error vs Temperature

Total Charge Error vs Sense

Current

Total Charge Error vs Supply

Voltage

Total Charge Error vs

Temperature

VSENSE+ = 10V

SENSE

| (mA)

100

–2.0

–1.5

–1.0

–0.5

0.5

1.0

1.5

2.0

CHARGE ERROR (%)

29431 G01

ISENSE = 200mA

TEMPERATURE (°C)

–50

–25

100

–1.00

–0.75

–0.50

–0.25

0.25

0.50

0.75

1.00

CHARGE ERROR (%)

29431 G03

ISENSE = 1mA

85°C

25°C

–40°C

SENSE

+ (V)

100

110

120

SUPPLY

(µA)

29431 G04

85°C

25°C

–40°C

SENSE

+ (V)

SUPPLY

(µA)

29431 G05

SENSE

= 200mA

SENSE

= 1A

VSENSE+ (V)

–1.00

–0.75

–0.50

–0.25

0.25

0.50

0.75

1.00

CHARGE ERROR (%)

29431 G02

TEMPERATURE (°C)

–50

–25

100

–1.00

–0.75

–0.50

–0.25

0.25

0.50

0.75

1.00

GAIN ERROR (%)

29431 G06

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Current Measurement ADC

Integral Nonlinearity

Current Measurement ADC

Gain Error vs Temperature

Voltage Measurement ADC

Integral Nonlinearity

= –40°C

= 25°C

SENSE

– (V)

–4

–3

–2

–1

INL (LSB)

29431 G07

= 85°C

TEMPERATURE (°C)

–50

–25

100

–1.00

–0.75

–0.50

–0.25

0.25

0.50

0.75

1.00

GAIN ERROR (%)

29431 G08

TA = –40°C

TA = 85°C

SENSE

(mA)

–1000

–750

–500

–250

250

500

750

1000

–4

–3

–2

–1

INL (LSB)

29431 G09

TA = 25°C

Typical perForMance characTerisTics

Current Measurement Noise

Voltage Measurement Noise

Temperature Error vs Temperature

VSENSE+ = 5V

TEMPERATURE (°C)

–50

–25

100

–2.0

–1.5

–1.0

–0.5

0.5

1.0

1.5

2.0

TEMPERATURE ERROR (°C)

29431 G10

VSENSE+ = 20V

VSENSE+ = 10V

N = 800

LSB

–2

–1

100

200

300

400

500

600

700

800

900

NUMBER OF READINGS

29431 G11

N = 800

LSB

–3

–2

–1

100

150

200

250

300

350

400

450

NUMBER OF READINGS

29431 G12

Sense Resistor Stability

kHOURS

–3.0

∆R/R

(%)

–2.0

–1.0

–2.5

–1.5

–0.5

10 20 30 40

29431 G13

500

ACCELERATED LOAD LIFE TEST

DATA SCALED TO TAMB = 85°C,

ISENSE = 1A CONDITIONS

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

pin FuncTions

SENSE+ (Pin 1): Positive Current Sense Input and Power

Supply. Connect to the load and battery charger output.

VSENSE+ operating range is 3.6V to 20V. SENSE+ is also

an input to the ADC during current measurement. Bypass

to GND with a 1µF capacitor located as close to pin 1 and

pin 2 as possible.

GND (Pin 2, Pin 3, Pin 7): Device Ground. Connect directly

to the negative battery terminal.

SCL (Pin 4): Serial Bus Clock Input. SCL is internally pulled

up with 50µA (Typ) above its logic input high threshold

to about 2V (Typ).

SDA (Pin 5): Serial Bus Data Input and Output. SDA is

internally pulled up with 50µA (Typ) above its logic input

high threshold to about 2V (Typ).

ALCC (Pin 6): Alert Output or Charge Complete Input.

Configured either as an SMBus alert output or charge

complete input by control register bits B[2:1]. At power-up,

the pin defaults to alert mode conforming to the SMBus

alert response protocol. It behaves as an open-drain logic

output that pulls to GND when any threshold register value

is exceeded. When configured as a charge complete input,

connect to the charge complete output from the battery

charger circuit. A low level at CC sets the value of the

accumulated charge (registers C, D) to FFFFh.

SENSE– (Pin 8): Negative Current Sense Input. Connect

SENSE– to the positive battery terminal. Current from/

into this pin must not exceed 1A in normal operation.

SENSE– is also an input to the ADC during voltage and

current measurement.

Exposed Pad (Pin 9): Exposed pad may be left open or

connected to device ground (GND).

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

block DiagraM

VSUPPLY

RSENSE

50mΩ

RBOND

12mΩ

COULOMB COUNTER

LTC2943-1

29431 BD

REFERENCE

GENERATOR

TEMPERATURE

SENSOR

ACCUMULATED

CHARGE

OSCILLATOR

F = 10kHz

CLK

I2C/

SMBUS

AL ALCC

SCL

SDA

REF

CLKREF+

REF–

ADC

DATA AND

CONTROL

REGISTERS

MUX

SENSE–

SENSE+

GND

RBOND

12mΩ

operaTion

Overview

The LTC2943-1 is a battery gas gauge designed for use

with multicell batteries with terminal voltages from 3.6V

to 20V. It measures battery charge and discharge, battery

voltage, current and its own temperature.

A precision analog coulomb counter integrates current

through a sense resistor between the battery’s positive

terminal and the load or charger. Battery voltage, battery

current and silicon temperature are measured with an

internal ADC.

The integrated, temperature compensated sense resistor

offers board space savings and superior change measure-

ment accuracy in applications with currents up to 1A.

Coulomb Counter

Charge is the time integral of current. The LTC2943-1

measures charge by monitoring the voltage developed

across an internal sense resistor. The differential voltage

is applied to an auto-zeroed differential analog integrator

to infer charge.

When the integrator output ramps to REFHI or REFLO

levels, switches S1, S2, S3 and S4 toggle to reverse the

ramp direction (Figure 2). By observing the condition of

the switches and the ramp direction, polarity is determined.

This approach also significantly lowers the impact on offset

of the analog integrator as described in the Differential

Offset Voltage section.

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

operaTion

A programmable prescaler effectively increases integration

time by a factor M programmable from 1 to 4096. At each

underflow or overflow of the prescaler, the accumulated

charge register (ACR) value is incremented or decremented

one count. The value of accumulated charge is read via

the I2C interface.

Voltage, Current and Temperature ADC

The LTC2943-1 includes a 14-bit No Latency ΔΣ analog-

to-digital converter, with internal clock and voltage refer-

ence circuits.

The ADC can be used to monitor the battery voltage at

SENSE– or the battery current flowing through the sense

resistor or to convert the output of the on-chip tempera-

ture sensor.

Conversion of voltage, current and temperature are trig-

gered by programming the control register via the I2C

interface. The LTC2943-1 includes a scan mode where

Figure 2. Coulomb Counter Section of the LTC2943-1

voltage, current and temperature conversion measure-

ments are executed every 10 seconds. At the end of each

conversion the corresponding registers are updated and

the converter goes to sleep to minimize quiescent current.

The temperature sensor generates a voltage proportional

to temperature with a slope of 2mV/K resulting in a volt-

age of 600mV at 27°C.

Power-Up Sequence

When SENSE+ rises above a threshold of approximately

3.3V, the LTC2943-1 generates an internal power-on reset

(POR) signal and sets all registers to their default state. In

the default state, the coulomb counter is active while the

voltage, current and temperature ADC is switched off. The

accumulated charge register is set to mid-scale (7FFFh),

all low threshold registers are set to 0000h and all high

threshold registers are set to FFFFh. The alert mode is

enabled and the coulomb counter prescaling factor M is

set to 4096.

LOAD

CHARGER

RSENSE

BATTERY

IBAT

–

RBOND

REFHI

REFLO

VCC

SENSE+

SENSE–

GND

POLARITY

DETECTION

CONTROL

LOGIC

PRESCALER ACR

29431 F02

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Internal Registers

The LTC2943-1 register map is shown in Table 1. The

LTC2943-1 integrates current through a sense resistor,

measures battery voltage, current and temperature and

stores the results in internal 16-bit registers accessible

via I2C. High and low limits can be programmed for each

measured quantity. The LTC2943-1 continuously monitors

these limits and sets a flag in the status register when a

limit is exceeded. If the alert mode is enabled, the ALCC

pin pulls low.

Table 1. Register Map

ADDRESS NAME REGISTER DESCRIPTION R/W DEFAULT

00h A Status R See Table 2

01h B Control R/W 3Ch

02h C Accumulated Charge MSB R/W 7Fh

03h D Accumulated Charge LSB R/W FFh

04h E Charge Threshold High MSB R/W FFh

05h F Charge Threshold High LSB R/W FFh

06h G Charge Threshold Low MSB R/W 00h

07h H Charge Threshold Low LSB R/W 00h

08h I Voltage MSB R 00h

09h J Voltage LSB R 00h

0Ah K Voltage Threshold High MSB R/W FFh

0Bh L Voltage Threshold High LSB R/W FFh

0Ch M Voltage Threshold Low MSB R/W 00h

0Dh N Voltage Threshold Low LSB R/W 00h

0Eh O Current MSB R 00h

0Fh P Current LSB R 00h

10h Q Current Threshold High MSB R/W FFh

11h R Current Threshold High LSB R/W FFh

12h S Current Threshold Low MSB R/W 00h

13h T Current Threshold Low LSB R/W 00h

14h U Temperature MSB R 00h

15h V Temperature LSB R 00h

16h W Temperature Threshold High R/W FFh

17h X Temperature Threshold Low R/W 00h

R = Read, W = Write

applicaTions inForMaTion

The status of the charge, voltage, current and temperature

alerts is reported in the status register shown in Table 2.

Table 2. Status Register (A)

BIT NAME OPERATION DEFAULT

A[7] Reserved

A[6] Current Alert Indicates one of the current

limits was exceeded 0

A[5]

Accumulated

Charge

Overflow/

Underflow

Indicates that the value of the

ACR hit either top or bottom 0

A[4] Temperature

Alert

Indicates one of the

temperature limits was

exceeded

A[3] Charge Alert

High

Indicates that the ACR value

exceeded the charge threshold

high limit

A[2] Charge Alert

Low

Indicates that the ACR value

exceeded the charge threshold

low limit

A[1] Voltage Alert Indicates one of the voltage

limits was exceeded 0

A[0] Undervoltage

Lockout Alert

Indicates recovery from

undervoltage. If set to 1, a

UVLO has occurred and the

contents of the registers are

uncertain

After each voltage, current or temperature conversion, the

conversion result is compared to the respective threshold

registers. If a value in the threshold registers is exceeded,

the corresponding bit A[6], A[4] or A[1] is set.

The accumulated charge register (ACR) is compared to

the charge thresholds every time the analog integrator

increments or decrements the prescaler. If the ACR value

exceeds the threshold register values, the corresponding

bit A[3] or A[2] are set. Bit A[5] is set if the accumulated

charge registers (ACR) overflows or underflows. At each

overflow or underflow, the ACR rolls over and resumes

integration.

The undervoltage lockout (UVLO) bit of the status register

A[0] is set if, during operation, the voltage on the SENSE+

pin drops below 3.5V without reaching the POR level. The

analog parts of the coulomb counter are switched off while

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the digital register values are retained. After recovery of the

supply voltage the coulomb counter resumes integrating

with the stored value in the accumulated charge registers

but it has missed any charge flowing while SENSE+ < 3.5V.

All status register bits are cleared after being read by the

host, but might be reasserted after the next temperature,

voltage or current conversion or charge integration, if the

corresponding alert condition is still fulfilled.

Control Register (B)

The operation of the LTC2943-1 is controlled by program-

ming the control register. Table 3 shows the organization

of the 8-bit control register B[7:0].

Table 3. Control Register B

BIT NAME OPERATION DEFAULT

B[7:6] ADC Mode [11] Automatic Mode:

continuously performing

voltage, current and temperature

conversions

[10] Scan Mode: performing

voltage, current and temperature

conversion every 10s

[01] Manual Mode: performing

single conversions of voltage,

current and temperature then

sleep

[00] Sleep

[00]

B[5:3] Prescaler M Sets coulomb counter prescaling

factor M between 1 and 4096.

Default is 4096.

Maximum value is limited to 4096

[111]

B[5:3] M

000 1

001 4

010 16

011 64

100 256

101 1024

110 4096

111 4096

BIT NAME OPERATION DEFAULT

B[2:1] ALCC

Configure

Configures the ALCC pin

[10] Alert Mode.

Alert functionality enabled. Pin

becomes logic output

[01] Charge Complete Mode. Pin

becomes logic input and accepts

charge complete inverted signal

(e.g., from a charger) to set

accumulated charge register (C,D)

to FFFFh

[00] ALCC pin disabled

[11] Not allowed

[10]

B[0] Shutdown Shut down analog section to

reduce ISUPPLY

[0]

Power Down B[0]

Setting B[0] to 1 shuts down the analog parts of the

LTC2943-1, reducing the current consumption to less than

15μA (typical). The circuitry managing I2C communica-

tion remains operating and the values in the registers are

retained. Note that any charge flowing while B[0] is 1 is

not measured and any charge information below 1LSB of

the accumulated charge register is lost.

Alert/Charge Complete Configuration B[2:1]

The ALCC pin is a dual function pin configured by the

control register. By setting bits B[2:1] to [10] (default),

the ALCC pin is configured as an alert pin following the

SMBus protocol. In this configuration, the ALCC is pulled

low if one of the four measured quantities (charge, voltage,

current, temperature) exceeds its high or low threshold or

if the value of the accumulated charge register overflows

or underflows. An alert response procedure started by the

master resets the alert at the ALCC pin. If the configura-

tion of the ALCC pin is changed while it is pulled low due

to an alert condition, the part will continue to pull ALCC

low until a successful alert response procedure (ARA) has

been issued by the master. For further information see the

Alert Response Protocol section.

Setting the control bits B[2:1] to [01] configures the

ALCC pin as a digital input. In this mode, a low input on

the ALCC pin indicates to the LTC2943-1 that the battery

is full and the accumulated charge register is set to its

maximum, value FFFFh.

applicaTions inForMaTion

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

If neither the alert nor the charge complete functionality

is desired, bits B[2:1] should be set to [00]. The ALCC

pin is then disabled and should be tied to the supply of

the I2C bus with a 10k resistor.

Avoid setting B[2:1] to [11] as it enables the alert and the

charge complete modes simultaneously.

Choosing Coulomb Prescaler M B[5:3]

If the battery capacity (QBAT) is small compared to the

maximum current (IMAX) the prescaler value M should

be changed from its default value (4096).

In these applications with a small battery but a high

maximum current, qLSB can get quite large with respect

to the battery capacity. For example, if the battery capacity

is 100mAh and the maximum current is 1A, the default

value M = 4096 leads to:

qLSB = 0.4mAh

The battery capacity then corresponds to only 250 qLSB

and less than 0.5% of the accumulated charge register

is utilized.

To preserve digital resolution in this case, the LTC2943-1

includes a programmable prescaler. Lowering the prescaler

factor M reduces qLSB to better match the accumulated

charge register to the capacity of the battery. The prescaling

factor M can be chosen between 1 and its default value

of 4096. The charge LSB then becomes:

qLSB = 0.4mAh•

4096

To use as much of the range of the accumulated charge

chosen for a given battery capacity QBAT and a sense

resistor RSENSE as:

M≥ 4096 •

BAT

•0.4mAh

M can be set to 1, 4, 16, ... 4096 by programming B[5:3]

of the control register as M = 22•(4 • B[5] + 2 • B[4] + B[3]) .

The default value is 4096.

In the above example of a 100mAh battery, the prescaler

should be programmed to M = 64. The qLSB is then 6.25μAh

and the battery capacity corresponds to 16000 qLSBs.

ADC Mode B[7:6]

The LTC2943-1 features an ADC which measures either

voltage on SENSE– (battery voltage), current through

SENSE+ and SENSE– (battery current) or temperature via

an internal temperature sensor. The reference voltage and

clock for the ADC are generated internally.

The ADC has four different modes of operation as shown

in Table 3. These modes are controlled by bits B[7:6] of

the control register. At power-up, bits B[7:6] are set to

[00] and the ADC is in sleep mode.

A single conversion of the three measured quantities

is initiated by setting the bit B[7:6] to [01]. After three

conversions (voltage, current and temperature), the ADC

resets B[7:6] to [00] and goes back to sleep.

The LTC2943-1 is set to scan mode by setting B[7:6] to

[10]. In scan mode the ADC converts voltage, current,

then temperature, then sleeps for approximately 10 sec-

onds. It then reawakens automatically and repeats the

three conversions. The chip remains in scan mode until

reprogrammed by the host.

Programming B[7:6] to [11] sets the chip into automatic

mode where the ADC continuously performs voltage,

current and temperature conversions. The chip stays in

automatic mode until reprogrammed by the host.

Programming B[7:6] to [00] puts the ADC to sleep. If

control bits B[7:6] change within a conversion, the ADC

will complete the running cycle of conversions before

entering the newly selected mode.

A conversion of voltage requires 33ms (typical), and cur-

rent and temperature conversions are completed in 4.5ms

(typical). At the end of each conversion, the corresponding

registers are updated. If the converted quantity exceeds

the values programmed in the threshold registers, a flag

is set in the status register and the ALCC pin is pulled low

(if alert mode is enabled).

applicaTions inForMaTion

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Alert Thresholds Registers (E,F,G,H,K,L,M,N,Q,R,S,

T,W,X)

For each of the measured quantities (battery charge, volt-

age, current and temperature) the LTC2943-1 features

high and low threshold registers. At power-up, the high

thresholds are set to FFFFh while the low thresholds are set

to 0000h, with the effect of disabling them. All thresholds

can be programmed to a desired value via I2C. As soon as

a measured quantity exceeds the high threshold or falls

below the low threshold, the LTC2943-1 sets the cor-

responding flag in the status register and pulls the ALCC

pin low if alert mode is enabled via bits B[2:1].

Accumulated Charge Register (C,D)

The coulomb counting circuitry in the LTC2943-1 integrates

current through the sense resistor. The result of this charge

integration is stored in the 16-bit accumulated charge reg-

ister (registers C, D). As the LTC2943-1 does not know the

actual battery status at power-up, the accumulated charge

the status of the battery, the accumulated charge (C[7:0]

D[7:0]) can be either programmed to the correct value via

I2C or it can be set after charging to FFFFh (full) by pulling

the ALCC pin low if charge complete mode is enabled via

bits B[2:1]. Note that before writing to the accumulated

charge registers, the analog section should be temporarily

shut down by setting B[0] to 1. In order to avoid a change

in the accumulated charge registers between reading MSBs

C[7:0] and LSBs D[7:0], it is recommended to read them

sequentially as shown in Figure 9.

Voltage Registers (I,J) and Voltage Threshold

Registers (K,L,M,N)

The result of the 14-bit ADC conversion of the voltage at

SENSE– is stored in the voltage registers (I, J).

From the result of the 16-bit voltage registers I[7:0]J[7:0]

the measured voltage can be calculated as:

VSENSE–=23.6V •

RESULT

FFFF

=23.6V •

RESULT

DEC

65535

Example 1: a register value I[7:0] = B0h and J[7:0] = 1Ch

corresponds to a voltage on SENSE– of:

VSENSE–=23.6V •

B01C

FFFF

=23.6V •

45084

DEC

65535 ≈16.235V

Example 2: To set a low level threshold for the battery

voltage of 7.2V, register M should be programmed to 4Eh

and register N to 1Ah.

Current Registers (O,P) and Current Threshold

Registers (Q,R,S,T)

The result of the current conversion is stored in the cur-

rent registers (O,P).

As the ADC resolution is 12 bits in current mode, the

lowest four bits of the combined current registers (O, P)

are always zero.

The ADC measures battery current by converting the volt-

age, VSENSE, across the sense resistor RSENSE. Depending

on whether the battery is being charged or discharged, the

measured voltage drop on RSENSE is positive or negative.

The result is stored in registers O and P in excess –32767

representation. O[7:0] = FFh, P[7:0] = FFh corresponds to

the full-scale positive current 1.3A. While O[7:0] = 00h,

P[7:0] = 00h corresponds to the full-scale negative current

–1.3A. The battery current can be obtained from the two

byte register O[7:0]P[7:0] and the value of the chosen

sense resistor RSENSE:

IBAT =1.3A •RESULTh– 7FFFh

7FFFh









=

1.3A •RESULTDEC – 32767

32767











Positive current is measured when the battery is charg-

ing and negative current is measured when the battery is

discharging.

applicaTions inForMaTion

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Example 1: a register value of O[7:0] = A8h P[7:0] = 40h

together with a sense resistor RSENSE = 50mΩ corresponds

to a battery current:

IBAT =1.3A •A840h– 7FFFh

7FFFh









=

1.3A •43072– 32767

32767









≈ 314.5mA

The positive current result indicates that the battery is

being charged.

The values in the threshold register for the current mode

Q,R,S,T are also expressed in excess –32767 representa-

tion in the same manner as the current conversion result.

The alert after a current measurement is set if the result

is higher than the value stored in the high threshold reg-

isters Q,R or lower than the value stored in the low value

registers S,T.

Example 2: In an application, the user wants to get an alert

if the absolute current through the sense resistor, exceeds

1A. This is achieved by setting the upper threshold IHIGH

in register [Q,R] to 1A and the lower threshold ILOW in

IHIGH(DEC) =1A

1.3A •32767









+32767= 57972

ILOW (DEC) =–1A

1.3A•32767









+ 32767=7562

Leading the user to set Q[7:0] = E2h, R[7:0] = 74h for the

high threshold and S[7:0] = 1Dh and T[7:0] = 8Ah for the

low threshold.

Temperature Registers (U,V) and Temperature

Threshold Registers (W,X)

As the ADC resolution is 11 bits in temperature mode, the

lowest five bits of the combined temperature registers

(U, V) are always zero.

The actual temperature can be obtained from the two byte

T =510K •RESULTh

FFFF

=510K •

RESULT

DEC

65535

Example: a register value of U[7:0] = 96h, V[7:0] = 96h

corresponds to ~300K or ~27°C

A high temperature limit of 60°C is programmed by setting

of the 11 bits temperature result are checked.

Effect of Differential Offset Voltage on Total Charge

Error

In battery gas gauges, an important parameter is the

differential offset (IOS) of the circuitry monitoring the bat-

tery charge. Many coulomb counter devices perform an

analog to digital conversion of ISENSE and accumulate the

conversion results to infer charge. In such an architecture,

the differential offset IOS causes relative charge error of

IOS/ISENSE. For small ISENSE values IOS can be the main

source of error.

The LTC2943-1 performs the tracking of the charge with

an analog integrator. This approach allows to continuously

monitor the battery charge and significantly lowers the

error due to differential offset. The relative charge error

due to offset (CEOV) can be expressed by:

CEOV =IOS

SENSE











As an example, at a 20mA input signal, a differential volt-

age offset VOS = 20µV results in a 2% error using digital

integration, whereas the error is only 0.04% (a factor of

50 times smaller!) using the analog integration approach

of LTC2943-1.

applicaTions inForMaTion

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

The reduction of the impact of the offset in LTC2943-1 can

be explained by its integration scheme depicted in Figure 2.

While positive offset accelerates the up ramping of the

integrator output from REFLO to REFHI, it slows the down

ramping from REFHI to REFLO thus the effect is largely

canceled as depicted below.

I2C Protocol

The LTC2943-1 uses an I2C/SMBus-compatible 2-wire

interface supporting multiple devices on a single bus.

Connected devices can only pull the bus lines low and

must never drive the bus high. The bus wires are externally

connected to a positive supply voltage via current sources

or pull-up resistors. When the bus is idle, all bus lines are

high. Data on the I2C bus can be transferred at rates of

up to 100kbit/s in standard mode and up to 400kbit/s in

fast mode.

Each device on the I2C/SMbus is recognized by a unique

address stored in that device and can operate as either a

transmitter or receiver, depending on the function of the

device. In addition to transmitters and receivers, devices

can also be classified as masters or slaves when perform-

ing data transfers. A master is the device which initiates a

data transfer on the bus and generates the clock signals

to permit that transfer. At the same time any device ad-

dressed is considered a slave. The LTC2943-1 always

acts as a slave.

Figure 3 shows an overview of the data transmission on

the I2C bus.

Start and Stop Conditions

When the bus is idle, both SCL and SDA must be high. A

bus master signals the beginning of a transmission with

a START condition by transitioning SDA from high to low

while SCL is high. When the master has finished com-

applicaTions inForMaTion

Figure 3. Data Transfer Over I2C or SMBus

For input signals with an absolute value smaller than the

offset of the internal op amp, the LTC2943-1 stops inte-

grating and does not integrate its own offset.

I2C/SMBus Interface

The LTC2943-1 communicates with a bus master using a

2-wire interface compatible with I2C and SMBus. The 7-bit

hard coded I2C address of the LTC2943-1 is 1100100.

The LTC2943-1 is a slave only device. The serial clock

line (SCL) is input only while the serial data line (SDA) is

bidirectional. The device supports I2C standard and fast

mode. For more details refer to the I2C Protocol section.

29431 F0B

INTEGRATOR

OUTPUT

REFHI

REFLO

TIME

WITH OFFSET

WITHOUT OFFSET

FASTER

UP RAMPING

SLOWER

DOWN RAMPING

SCL

SDA

START

CONDITION

STOP

CONDITION

ADDRESS R/W ACK DATA ACK DATA ACK

1 - 7 8 9

29431 F03

a6 - a0 b7 - b0 b7 - b0

1 - 7 8 9 1 - 7 8 9

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Figure 4. Writing FCh to the LTC2943-1 Control Register (B)

municating with the slave, it issues a STOP condition by

transitioning SDA from low to high while SCL is high. The

bus is then free for another transmission. When the bus

is in use, it stays busy if a repeated START (Sr) is gener-

ated instead of a STOP condition. The repeated START

(Sr) conditions are functionally identical to the START (S).

Write Protocol

The master begins a write operation with a START con-

dition followed by the seven bit slave address 1100100

and the R/W bit set to zero, as shown in Figure 4. The

LTC2943-1 acknowledges this by pulling SDA low and

the master sends a command byte which indicates which

internal register the master is to write. The LTC2943-1

acknowledges and latches the command byte into its

internal register address pointer. The master delivers the

data byte, the LTC2943-1 acknowledges once more and

latches the data into the desired register. The transmission

is ended when the master sends a STOP condition. If the

applicaTions inForMaTion

master continues by sending a second data byte instead

of a stop, the LTC2943-1 acknowledges again, increments

its address pointer and latches the second data byte in the

following register, as shown in Figure 5.

Read Protocol

The master begins a read operation with a START condition

followed by the seven bit slave address 1100100 and the

R/W bit set to zero, as shown in Figure 6. The LTC2943-

1 acknowledges and the master sends a command byte

which indicates which internal register the master is to

read. The LTC2943-1 acknowledges and then latches the

command byte into its internal register address pointer.

The master then sends a repeated START condition fol-

lowed by the same seven bit address with the R/W bit

now set to one. The LTC2943-1 acknowledges and sends

the contents of the requested register. The transmission

is ended when the master sends a STOP condition. If

the master acknowledges the transmitted data byte, the

LTC2943-1 increments its address pointer and sends the

contents of the following register as depicted in Figure 7.

Figure 5. Writing F001h to the LTC2943-1 Accumulated

Charge Register (C, D)

Figure 6. Reading the LTC2943-1 Status Register (A)

Figure 7. Reading the LTC2943-1 Voltage Register (I, J)

FROM MASTER TO SLAVE

ADDRESS REGISTER DATA

FROM SLAVE TO MASTER

29431 F04

A: ACKNOWLEDGE (LOW)

A: NOT ACKNOWLEDGE (HIGH)

S: START CONDITION

P: STOP CONDITION

R: READ BIT (HIGH)

W: WRITE BIT (LOW)

A A A

1100100 01h FCh

0 0 0

ADDRESS REGISTER DATA

29431 F05

A A A

1100100 02h F0h 01h

0 0 0 0

DATA A

ADDRESS REGISTER Sr

29431 F06

A A ADDRESS

1100100 00h 1

0 0 1100100 0

01h

DATA

ADDRESS REGISTER Sr

29431 F07

A A ADDRESS

1100100 08h 1

0 0 1100100 0

F1h

DATA

24h

DATA

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Alert Response Protocol

In a system where several slaves share a common interrupt

line, the master can use the alert response address (ARA)

to determine which device initiated the interrupt (Figure 8).

stop pulling down the ALCC pin and will not respond to

further ARA requests until a new Alert event occurs.

Internal Sense Resistor

The internal sense resistor uses proprietary temperature

compensation techniques to reduce the effective tem-

perature coefficient to less than ±50 ppm/K typically.

The effective sense resistance as seen by the coulomb

counter is factory trimmed to 50mΩ. Both measures,

and the lack of thermocouple effects in the sense resis-

tor connections, contribute to the LTC2943-1’s superior

charge measurement accuracy compared to competing

solutions employing a common 1% tolerance, 50ppm/K

tempco discrete current sense resistor.

Like all sense resistors, the integrated sense resistor in

the LTC2943-1 will exhibit minor long-term resistance

shift. The resistance typically drops less than –0.1% per

1000h at 1A current and 85°C ambient temperature; this

outperforms most types of discrete sense resistors except

those of the very high and ultrahigh stability variety. See

the Typical Performance Characteristics for expected

resistor drift performance under worst-case conditions.

Drift will be much slower at lower temperatures. Contact

LT C applications for more information.

For most coulomb counter applications this aging behavior

of the integrated sense resistor is insignificant compared

to the change of battery capacity due to battery aging.

The LTC2943-1 is factory trimmed to optimum accuracy

when new; for applications which require the best possible

coulomb count accuracy over the full product lifetime, the

coulomb counter gain can be adjusted in software. For

instance, if the error contribution of sense resistor drift

must be limited to ±1%, coulomb counts may be biased

high by 1% (use factor 1.01), and maximum operational

temperature and current then must be derated such that

sense resistor drift over product lifetime or calibration

intervals is less than –2%.

Applications employing the standard external resistor

LTC2943 with an external 50mΩ sense resistor may be

upgraded to the pin-compatible LTC2943-1 by removing

the external sense resistor.

The master initiates the ARA procedure with a START

condition and the special 7-bit ARA bus address (0001100)

followed by the read bit (R) = 1. If the LTC2943-1 is as-

serting the ALCC pin in alert mode, it acknowledges and

responds by sending its 7-bit bus address (1100100) and

a 1. While it is sending its address, it monitors the SDA pin

to see if another device is sending an address at the same

time using standard I2C bus arbitration. If the LTC2943-1

is sending a 1 and reads a 0 on the SDA pin on the rising

edge of SCL, it assumes another device with a lower ad-

dress is sending and the LTC2943-1 immediately aborts

its transfer and waits for the next ARA cycle to try again.

If transfer is successfully completed, the LTC2943-1 will

applicaTions inForMaTion

Figure 8. LTC2943-1 Serial Bus SDA Alert Response Protocol

Figure 9. Reading the LTC2943-1 Accumulated Charge

Registers (C, D)

Figure 10. ADC Single Conversion Sequence and Reading

of Voltage Registers (I,J)

S R

ALERT RESPONSE ADDRESS DEVICE ADDRESS

29431 F08

0001100 1100100

0 1

ADDRESS REGISTER S

2943 F09

A A ADDRESS

1100100 02h 1

0 0 1100100 0

80h

DATA

01h

DATA

40ms

ADDRESS REGISTER S

2943 F10

A A ADDRESS

1100100 08h 1

0 0 1100100 0

F1h

DATA

80h

DATA

ADDRESS REGISTER DATA

A A

1100100 01h 4C

0 0

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Voltage Drop Between SENSE+ and SENSE–

The LTC2943-1 is trimmed for an effective internal resis-

tance of 50mΩ , but the total pin-to-pin resistance (RPP),

consisting of the sense resistor in series with pin and bond

wire resistances, is somewhat higher. Assuming a sense

resistor temperature coefficient of about 3900ppm/K,

the total resistance between SENSE+ and SENSE– at a

temperature T is typically:

RPP(T) = RPP(TNOM) [1 + 0.0039(T – TNOM)]

where TNOM = 27°C (or 300K) and RPP(TNOM) is from

the Electrical Characteristics table. This means that the

resistance between SENSE+ and SENSE– may drop by

26% if die temperature changes from 27°C to –40°C

or increase by 23% for a 27°C to 85°C die temperature

change. Ensure that total voltage drop between SENSE+

and SENSE–, caused by maximum peak current flowing

in/out of SENSE–:

VDROP = IPEAK • RPP(TDIE(MAX))

does not exceed the application’s requirements.

Limiting Inrush Current

Inrush currents during events like battery insertion or

closure of a mechanical power switch may be substan-

tially higher than peak currents during normal operation.

Extremely large inrush currents may require additional

circuitry to keep currents through the LTC2943-1 sense

resistor below the absolute maximum ratings.

Note that external Schottky clamp diodes between SENSE+

and SENSE– can leak significantly, especially at high tem-

perature, which can cause significant coulomb counter

errors. Preferred solutions to limit inrush current include

active Hot Swap current limiting or connector designs that

include current limiting resistance and staggered pins to

ensure a low impedance connection when the connector

is fully mated.

Power Dissipation

Power dissipation in the RPP resistance when operated

at high currents can increase the die temperature sev-

eral degrees over ambient. Soldering the exposed pad

of the DFN package to a large copper region on the PCB

is recommended for applications operating close to the

specified maximum current and ambient temperature. Die

temperature at a given ISENSE can be estimated by:

TDIE = TAMB + 1.22 • θJA • RPP(MAX) • ISENSE2

where the factor 1.22 approximates the effect of sense

resistor self-heating, RPP(MAX) is the maximum pad-to-

pad resistance at nominal temperature (27°C) and θJA is

the thermal resistance from junction to ambient. The θJA

data given for the DFN package is valid for typical PCB

layouts; more precise θJA data for a particular PCB layout

may be obtained by measuring the voltage VP-P between

SENSE+ and SENSE–, the ambient temperature TAMB, and

the die temperature TDIE, and calculating:

θJA =

DIE

– T

AMB

VP-P •ISENSE

Both TAMB and TDIE temperature may be measured using

the internal temperature sensor included in the LTC2943-1.

ISENSE should be set to zero to measure TAMB, and high

enough during TDIE measurement to achieve a significant

temperature increase over TAMB.

PC Board Layout Suggestions

Keep all traces as short as possible to minimize noise and

inaccuracy. Use wider traces from the resistor to the bat-

tery, load and/or charger (see Figure 11). Put the bypass

capacitor close to SENSE+.

applicaTions inForMaTion

Figure 11. Recommended Layout

LTC2943-1

29431 F11

CHARGER/LOAD TO BATTERY

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

DD Package

8-Lead Plastic DFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1698 Rev C)

3.00 ±0.10

(4 SIDES)

NOTE:

1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION

ON TOP AND BOTTOM OF PACKAGE

0.40 ± 0.10

BOTTOM VIEW—EXPOSED PAD

1.65 ± 0.10

(2 SIDES)

0.75 ±0.05

R = 0.125

TYP

2.38 ±0.10

PIN 1

TOP MARK

(NOTE 6)

0.200 REF

0.00 – 0.05

(DD8) DFN 0509 REV C

0.25 ± 0.05

2.38 ±0.05

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

1.65 ±0.05

(2 SIDES)2.10 ±0.05

0.50

BSC

0.70 ±0.05

3.5 ±0.05

PACKAGE

OUTLINE

0.25 ± 0.05

0.50 BSC

package DescripTion

Please refer to http://www.linear.com/product/LTC2943-1#packaging for the most recent package drawings.

LTC2943-1

29431f

For more information www.linear.com/LTC2943-1

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

 LINEAR TECHNOLOGY CORPORATION 2015

LT 1215 • PRINTED IN USA

relaTeD parTs

Typical applicaTion

PART

NUMBER DESCRIPTION COMMENTS

Battery Gas Gauges

LTC2941 Battery Gas Gauge with I2C Interface 2.7V to 5.5V Operation, 6-Lead (2mm × 3mm) DFN Package

LTC2941-1 1A I2C Battery Gas Gauge with Internal Sense

Resistor

2.7V to 5.5V Operation, 6-Lead (2mm × 3mm) DFN Package

LTC2942 I2C Battery Gas Gauge with Temperature/Voltage

Measurement

2.7V to 5.5V Operation, 14-Bit Δ∑-ADC, 6-Lead (2mm × 3mm) DFN Package

LTC2942-1 1A I2C Battery Gas Gauge with Internal Sense

Resistor and Temperature/Voltage Measurement

2.7V to 5.5V Operation, 14-Bit Δ∑-ADC, 6-Lead (2mm × 3mm) DFN Package

LTC2943 Battery Gas Gauge with I2C Interface and Voltage,

Current and Temperature ADC

3.6V to 20V Operation, 14-Bit Δ∑-ADC, Pin Compatible with LTC2944, LTC2943-1, or

LTC2943, 8-Lead (3mm × 3mm) DFN Package

LTC4150 Coulomb Counter/Battery Gas Gauge 2.7V to 8.5V Operation, 10-Pin MSOP Package

Battery Chargers

LTC4000 High Voltage High Current Controller for Battery

Charging and Power Management

3V to 60V Operation, 28-Lead (4mm × 5mm) QFN or SSOP Packages

LTC4009 High Efficiency, Multi-Chemistry Battery Charger 6V to 28V Operation, 20-Lead (4mm × 4mm) QFN Package

LTC4012 High Efficiency, Multi-Chemistry Battery Charger

with PowerPath™ Control

6V to 28V Operation, 20-Lead (4mm × 4mm) QFN Package

LT3652HV Power T

racking 2A Battery Charger Input Supply Voltage Regulation Loop for Peak Power Tracking, 5V to 34V Operation,

1MHz, 2A Charge Current, 3mm × 3mm DFN-12 and MSOP-12 Packages

LTC1732 Li-Ion Battery Charger 4.5V to 12V Operation, MSOP-10 Package

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTC2943-1

2-Cell 8.4V Linear Charger and Battery Gas Gauge

RPROG*

19.6k

RSENSE

0.25Ω

IBAT = 500mA

= 10V

CTIMER

0.1µF

MBRM120T3

SENSE

DRV

VCC

BAT

PROGTIMER

LTC1732-8.4

SEL

CHRG

ACPR

GND

10µF

Si7135DP

SENSE+

ALCC

SDA

SCL

LTC2943-1

0.5A

LOAD

8.4V

Li-Ion

BATTERY

2943 TA02

SENSE–

GND

1µF

VDD

3.3V

µP

1µF