Rainbow-electronics DS2788 Manuel d'utilisateur

General DescriptionThe DS2788 measures voltage, temperature, and cur-rent, and estimates available capacity for rechargeablelithium-ion (Li+) and Li+

DS2788current-sense resistors. RSGAIN is an 11-bit valuestored in 2 bytes of the parameter EEPROM memoryblock. The RSGAIN value adjusts the gain from

Current BlankingThe current blanking feature modifies the current mea-surement result prior to being accumulated in the ACR.Current blanking occurs co

DS2788Capacity Estimation AlgorithmRemaining capacity estimation uses real-time mea-sured values and stored parameters describing the cellcharacterist

curves named full, active empty, and standby empty.Each model curve is constructed with five line seg-ments, numbered 1 through 5. Above +50°C, the se

DS2788Active Empty: The active empty curve defines the tem-perature variation in the empty point of the dischargeprofile based on a high-level load cu

Application ParametersIn addition to cell model characteristics, several appli-cation parameters are needed to detect the full andempty points, as wel

DS2788continue uninterrupted until the battery is charged tofull. Upon detecting full, LEARNF is cleared, the charge-to-full (CHGTF) flag is set, and

The Status register contains bits that report the devicestatus. The bits can be set internally by the DS2788.The CHGTF, AEF, SEF, LEARNF, and VER bits

DS2788All Control register bits are read and write accessible.The Control register is recalled from parameter EEPROM memory at power-up. Register bit

Fuel-Gauge DisplayThe DS2788 provides five open-drain drivers capableof sinking 30mA. These can be used to directly driveeither 4 or 5 LEDs to display

DS2788Stand-Alone Fuel-Gauge IC withLED Display Drivers2 _______________________________________________________________________________________ABSOLU

DS2788The EEPROM register provides access control of theEEPROM blocks. EEPROM blocks can be locked to pre-vent alteration of data within the block. Lo

MemoryThe DS2788 has a 256-byte linear memory space withregisters for instrumentation, status, and control, as wellas EEPROM memory blocks to store pa

DS2788Stand-Alone Fuel-Gauge IC withLED Display Drivers22 ______________________________________________________________________________________Table

1-Wire Bus SystemThe 1-Wire bus is a system that has a single bus mas-ter and one or more slaves. A multidrop bus is a 1-Wirebus with multiple slaves.

DS2788separate output and input pins can be connectedtogether.The 1-Wire bus must have a pullup resistor at the bus-master end of the bus. For short l

Match Net Address [55h]. This command allows thebus master to specifically address one DS2788 on the1-Wire bus. Only the addressed DS2788 responds toa

DS2788Copy Data [48h, XX]. This command copies the con-tents of the EEPROM shadow RAM to EEPROM cells forthe EEPROM block containing address XX. Copy

DS2788Stand-Alone Fuel-Gauge IC withLED Display Drivers______________________________________________________________________________________ 27DS2788

DS27881-Wire SignalingThe 1-Wire bus requires strict signaling protocols toensure data integrity. The four protocols used by theDS2788 are as follows:

DS2788Stand-Alone Fuel-Gauge IC withLED Display Drivers______________________________________________________________________________________ 29RESIST

DS2788Stand-Alone Fuel-Gauge IC withLED Display Drivers_______________________________________________________________________________________ 3ELECTR

DS2788Stand-Alone Fuel-Gauge IC withLED Display DriversMaxim cannot assume responsibility for use of any circuitry other than circuitry entirely embod

DS2788Stand-Alone Fuel-Gauge IC withLED Display Drivers4 _______________________________________________________________________________________Note 1

DS2788Stand-Alone Fuel-Gauge IC withLED Display Drivers_______________________________________________________________________________________ 5Pin De

DS2788Detailed DescriptionThe DS2788 operates directly from 2.5V to 5.5V andsupports single-cell Li+ battery packs. As shown inFigure 2, the DS2788 ac

nection or system shutdown, in which no charge or dis-charge current flows. A PMOD SLEEP condition transi-tions back to ACTIVE mode when DQ is pulled

DS2788Temperature MeasurementThe DS2788 uses an integrated temperature sensor tomeasure battery temperature with a resolution of0.125°C. Temperature m

Average Current MeasurementThe Average Current (IAVG) register reports an aver-age current level over the preceding 28 seconds. Theregister value is u