Analog Devices LTC2941 Datasheet
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Analog Devices LTC2941 Datasheet

Analog Devices LTC2941 Datasheet

Battery gas gauge with i2c interface
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FEATURES
Indicates Accumulated Battery Charge
n
and Discharge
High Accuracy Analog Integration
n
High Side Sense
n
1% Charge Accuracy
n
±50mV Sense Voltage Range
n
2
SMBus/I
C Interface
n
Configurable Alert Output/Charge Complete Input
n
2.7V to 5.5V Operating Range
n
Quiescent Current Less Than 100µA
n
Small 6-Pin 2mm × 3mm DFN and 8-Lead
n
MSOP Packages
APPLICATIONS
Low Power Handheld Products
n
Cellular Phones
n
MP3 Player
n
Cameras
n
GPS
n
TYPICAL APPLICATION
CHARGER
SENSE
LTC2941
AL/CC
2
I
C/SMBus
SDA
SENSE
TO HOST
SCL
GND
Document Feedback
Battery Gas Gauge with I
LOAD
0.1µF
+
R
SENSE
100m
–
+
1-CELL
Li-Ion
2941 TA01a
For more information
DESCRIPTION
The
LTC
2941
measures battery charge state in battery-
®
supplied handheld PC and portable product applications.
Its operating range is perfectly suited for single-cell Li-Ion
batteries. A precision coulomb counter integrates current
through a sense resistor between the battery's positive
terminal and the load or charger. The measured charge
is stored in internal registers. An SMBus/I
accesses and configures the device.
The LTC2941 features programmable high and low
thresholds for accumulated charge. If a threshold is
exceeded, the device communicates an alert using either
the SMBus alert protocol or by setting a flag in the inter-
nal status register.
The LTC2941 requires only a single low value external
sense resistor to set the current range.
All registered trademarks and trademarks are the property of their respective owners.
Total Charge Error vs
Differential Sense Voltage
2.0
V
= 3.6V
SENSE +
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
0.1
1
www.analog.com
LTC2941
2
C Interface
2
C interface
10
100
V
(mV)
SENSE
2941 TA01b
Rev. C
1

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Summary of Contents for Analog Devices LTC2941

  • Page 1 MSOP Packages the SMBus alert protocol or by setting a flag in the inter- nal status register. APPLICATIONS The LTC2941 requires only a single low value external sense resistor to set the current range. Low Power Handheld Products Cellular Phones All registered trademarks and trademarks are the property of their respective owners.

  • Page 2: Absolute Maximum Ratings

    LTC2941 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Supply Voltage (SENSE ) ......–0.3V to 6V Operating Ambient Temperature Range SCL, SDA, AL/CC ......... –0.3V to 6V LTC2941C ..........0°C to 70°C – SENSE ........–0.3V to (V + 0.3V) LTC2941I..........–40°C to 85°C SENSE + Storage Temperature Range ....

  • Page 3: Electrical Characteristics

    LTC2941 ELECTRICAL CHARACTERISTICS denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25°C. (Note 2) SYMBOL PARAMETER CONDITIONS UNITS Power Requirements Supply Voltage SENSE + Supply Current (Note 3) Device On µA...

  • Page 4: Timing Diagram

    LTC2941 ELECTRICAL CHARACTERISTICS denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25°C. (Note 2) SYMBOL PARAMETER CONDITIONS UNITS Minimum Data Set-Up Time Input SU,DAT(MIN) Minimum Data Hold Time Input µs HD,DATI(MIN) Data Hold Time Output µs...

  • Page 5: Typical Performance Characteristics

    LTC2941 TYPICAL PERFORMANCE CHARACTERISTICS Total Charge Error Total Charge Error vs Differential Sense Voltage vs Supply Voltage Total Charge Error vs Temperature 1.00 1.00 0.75 0.75 0.50 0.50 0.25 0.25 –0.25 –0.25 –1 –0.50 –0.50 –2 –0.75 = –50mV –0.75 = 2.7V...

  • Page 6: Pin Functions

    SMBus alert response protocol. It behaves as an BLOCK DIAGRAM SUPPLY SENSE ACCUMULATED BIDIRECTIONAL PRESCALER CHARGE INTEGRATOR – SENSE REGISTER AL/CC SMBus INTERNAL INTERNAL REFERENCE OSCILLATOR STATUS/ GENERATOR CONTROL REGISTER 2941 F02 Figure 2. Block Diagram of the LTC2941 Rev. C For more information www.analog.com...

  • Page 7: Operation

    A programmable prescaler is incremented or decre- mented every time the integrator changes ramp direc- The LTC2941 is a battery gas gauge device designed for tion. The prescaler effectively increases integration time use with single Li-Ion cells and other battery types with by a factor M programmable from 1 to 128.

  • Page 8: Applications Information

    LTC2941 APPLICATIONS INFORMATION C/SMBus Interface Status Register (A) The LTC2941 communicates with a bus master using a Table  2 shows the details of the status register 2-wire interface compatible with I C and SMBus. The 7-bit (address 00h): hard-coded I C address of LTC2941 is 1100100.
  • Page 9 Programming the last bit B[0] of the control register to 1 Note that the counting process does not roll over, but sim- sets the analog parts of the LTC2941 in power down and ply stops at FFFFh or 0000h until the direction is reversed.
  • Page 10 A. the battery capacity (Q ) is very large compared to To preserve digital resolution in this case, the LTC2941 the maximum current (I includes a programmable prescaler. Lowering the pres- caler factor M allows reducing q to better match the >...
  • Page 11 In addition to transmitters and receivers, devices can also be classified as masters or slaves when perform- and D. As the LTC2941 does not know the actual battery status after initial power-up, the accumulated charge is ing data transfers. A master is the device which initiates set to mid-scale (7FFFh).
  • Page 12 1100100 and and data transfer begins between a master and a slave. As the R/W bit set to zero, as shown in Figure 7. The LTC2941 data is transferred over I C in groups of nine bits (eight...
  • Page 13 7-bit ARA bus address (0001100) In a system where several slaves share a common inter- followed by the read bit (R) = 1. If the LTC2941 is assert- rupt line, the master can use the alert response address...
  • Page 14 C bus arbitration. If the inaccuracy. Use a 4-wire Kelvin sense connection for the LTC2941 is sending a 1 and reads a 0 on the SDA pin on sense resistor, locating the LTC2941 close to the resis- the rising edge of SCL, it assumes another device with a –...

  • Page 15: Package Description

    LTC2941 PACKAGE DESCRIPTION DCB Package 6-Lead Plastic DFN (2mm × 3mm) (Reference LTC DWG # 05-08-1715 Rev A) 0.70 ±0.05 1.65 ±0.05 3.55 ±0.05 (2 SIDES) 2.15 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 1.35 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115...
  • Page 16 LTC2941 PACKAGE DESCRIPTION MS8E Package 8-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1662 Rev K) BOTTOM VIEW OF EXPOSED PAD OPTION 1.88 (.074) 0.29 1.88 ±0.102 1.68 0.889 ±0.127 (.074 ±.004) (.066) (.035 ±.005) 0.05 REF DETAIL “B”...

  • Page 17: Revision History

    Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications For more information www.analog.com subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

  • Page 18: Typical Application

    C Battery Gas Gauge with Integrated 50mΩ Sense Pin Compatible with LTC2942-1 Resistor LTC2942 C Battery Gas Gauge with Voltage and Temperature 14-Bit ∑∆-ADC, Pin Compatible with LTC2941 Measurement LTC2942-1 C Battery Gas Gauge with Voltage and Temperature 14-Bit ∑∆-ADC, Pin Compatible with LTC2941-1 Measurement;...

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