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PDF DS2755 Data sheet ( Hoja de datos )
| Número de pieza | DS2755 | |
| Descripción | High-Accuracy Battery Fuel Gauge | |
| Fabricantes | Dallas Semiconductor | |
| Logotipo |  |
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www.maxim-ic.com
DS2755
High-Accuracy Battery
Fuel Gauge with Snapshot
FEATURES
Snapshot Mode Allows Instantaneous Power
Measurement
Accurate Current Measurement for Coulomb
Counting (Current Accumulation)
- 2% ±4μV over ±64mV Input Range
- 2% ±200μA over ±3.2A Range Using a 20mΩ
Sense Resistor
Current Measurement
- 9-Bit Bidirectional Snapshot Measurement
- 12-Bit Bidirectional Average Updated Every
88ms
- 15-Bit Bidirectional Average Updated Every 2.8s
Voltage Measurement
- 9-Bit Snapshot Measurement
- 10-Bit Measurement Updated Every 4ms
Temperature Measurement
- 10-Bit Measurement, 0.125°C Resolution Using
Integrated Sensor
Host Alerted When Accumulated Current or
Temperature Exceeds User-Selectable Limits
96 Bytes of Lockable EEPROM
8 Bytes of General-Purpose SRAM
Dallas 1-Wire® Interface with Unique 64-Bit
Device Address with Standard 16kbps or
Overdrive 142kbps Timing
3mm Dimension of 8-Pin TSSOP Package Allows
Mounting on Side of Thin Prismatic Li+ and
Li+/Polymer Cells
APPLICATIONS
Cell Phones
Digital Cameras
Smartphones
PDAs
Portable Consumer Products
PIN CONFIGURATION
VIN 1
VSS 22
PIO 3
VDD 42
8 DQ
7 SNS
6 IS2
5 IS1
DS2755E
8-Pin TSSOP Package
DESCRIPTION
The DS2755 high-precision battery fuel gauge is a
data-acquisition and information-storage device
tailored for cost-sensitive and space-constrained 1-
cell Li+/polymer battery-pack applications. The
DS2755 provides the key hardware components
required to accurately estimate remaining capacity by
integrating low-power, precision measurements of
temperature, voltage, current, and current
accumulation, as well as nonvolatile (NV) data
storage, into the small footprint of a 3.0mm x 4.4mm
8-pin TSSOP package.
Through its 1-Wire interface, the DS2755 gives the
host system read/write access to status and control
registers, instrumentation registers, and general-
purpose data storage. Each device has a unique
factory-programmed 64-bit net address that allows it
to be individually addressed by the host system,
supporting multibattery operation.
ORDERING INFORMATION
PART
DS2755E+
DS2755E+T&R
MARKING
2755
2755
TEMP RANGE
-20°C to +70°C
-20°C to +70°C
1-Wire is a registered trademark of Dallas Semiconductor.
DESCRIPTION
8-Pin TSSOP, Lead Free
DS2755E+ on Tape-and-Reel
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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020507
1 page  
Figure 2. FUNCTIONAL DIAGRAM
DS2755: High-Accuracy Battery Fuel Gauge with Snapshot
DQ
THERMAL
SENSE
VIN
IS2
1-WIRE
INTERFACE
AND
ROM ID
VOLTAGE
REFERENCE
M
U ADC
X
-+
LOCKABLE EEPROM
BLOCKS
SRAM
TEMPERATURE
VOLTAGE
CURRENT
ACCUM. CURRENT
COMPARATORS
STATUS / CONTROL
VDD
BIAS
TIMEBASE
PIO
IS1
SNS
chip ground
VSS
DETAILED PIN DESCRIPTION
PIN NAME
DESCRIPTION
1
VIN
Battery voltage sense input. Voltage measurement performed on VIN input and
displayed in Voltage Register.
2
VSS
Device ground and current sense resistor connection. VSS attaches to battery end
of sense resistor.
3 PIO General purpose programmable I/O pin or optional interrupt output.
4 VDD Input supply: +2.5V to +5.5V input range. Bypass VDD to VSS with 0.1μF.
5 IS1 Current sense filter input 1
6 IS2 Current sense filter input 2
7 SNS Sense resistor connection. SNS attaches to pack end of current sense resistor.
8
DQ
Serial interface data I/O pin. Bidirection data transmit and receive at 16kbps or
143kbps. Optional interrupt output.
POWER MODES
The DS2755 has two power modes: Active and Sleep. While in Active mode, the DS2755 continuously measures
current, voltage and temperature. Current accumulation and monitoring for under voltage also occur continuously in
Active mode. In Sleep mode, the DS2755 ceases these activities. The DS2755 enters Sleep mode when PMOD =
1 AND either of the following occur:
the DQ line is low for longer than tSLEEP (minimum 2.1s)
(DQ low used indicate that the pack has been disconnected or that the host system is signaling the
DS2755 to enter Sleep mode.)
the UVEN bit in the Status Register is set to 1 AND the voltage on VIN drops below undervoltage threshold VUV for
tUVD
The DS2755 returns to Active mode when the DQ line is pulled from a low-to-high state and the voltage on VIN is
above VUV. The factory default for the DS2755 is UVEN = PMOD = 0. The DS2755 defaults to Active mode when
power is first applied.
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5 Page 
DS2755: High-Accuracy Battery Fuel Gauge with Snapshot
rising edge of the DQ high to low to high pulse. The Snapshot mode can be abandoned by sending a 1-Wire Reset
instead of the synchronization pulse. The rising edge DQ trigger is formed by the first data bit after issuing the Sync
Function command. A full byte can be issued, but the rising edge of the first bit sets the trigger point. [[The SNAP
bit is set after the rising edge trigger: timing is not critical and could be several 100μs later since it cannot be read
quickly via 1-Wire]]. If a 1-wire reset is issued instead of a data bit, then the Snapshot is abandoned (SNAP bit not
set).]
The Snapshot Synchronization Timing in Figure 10 illustrates the timing of the Snapshot current and voltage
sample apertures relative to the DQ rising edge trigger and one timeslot GSM power amp load pulse. In the
diagram, tSAMP = 1/ fSAMP.= 1456-1 = 687μs. The current and voltage measurements are taken 343μs apart but
within a single GSM timeslot.
Figure 10. SNAPSHOT SYNCHRONIZATION TIMING
MEMORY
The DS2755 has a 256-byte linear address space with registers for instrumentation, status, and control in the lower
32 bytes, with lockable EEPROM and SRAM memory occupying portions of the remaining address space. All
EEPROM and SRAM memory is general-purpose except addresses 31h and 33h, which should be written with the
default values for the Status Register and Accumulation Bias Register, respectively. When the MSB of any two-
byte register is read, the MSB and LSB values are latched and held for the duration of the Read Data command.
This prevents updates during the read to ensure synchronization between the two register bytes. For consistent
results, always read the MSB and the LSB of a two-byte register during the same Read Data command sequence.
In describing register control and status bits, the terms set and clear refer to internal operations which manipulate
bit values. The terms read and write refer to 1-Wire access to the bit values. Several bits are set internally but
require the host system to write them to a 0 value.
EEPROM memory is shadowed by RAM to eliminate programming delays between writes and to allow the data to
be verified by the host system before being copied to EEPROM. The Read Data and Write Data protocols to/from
EEPROM memory addresses access the shadow RAM. The Recall Data function command transfers data from the
EEPROM to the shadow RAM. The Copy Data function command transfers data from the shadow RAM to the
EEPROM and requires tEEC to complete programming of the EEPROM cells. In unlocked EEPROM blocks, writing
data updates shadow RAM. In locked EEPROM blocks, the Write Data command is ignored. The Copy Data
function command copies the contents of shadow RAM to EEPROM in an unlocked block of EEPROM but has no
effect on locked blocks. The Recall Data function command copies the contents of a block of EEPROM to shadow
RAM regardless of whether the block is locked or not.
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| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet DS2755.PDF ] | |
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