Rainbow-electronics DS2784 Manual do Utilizador descarregar pdf (Página 19)

DS2784: 1-Cell Stand-Alone Fuel Gauge IC with Li+ Protector and SHA-1 Authentication

model curve are stored in the cell parameter EEPROM block as ppm/°C. The breakpoint temperatures of each

segment are stored there also (see Application Note 3584: Storing Battery Fuel Gauge Parameters in DS2780 for

more details on how values are stored). An example of data stored in this manner is shown in Table 6.

able 6. Example Cell Characterization Table (Normalized to +40°C) T

19 of 38

anufacturer’s Rated Cell Capacity: 1000mAh

Charge Voltage: 4.2V Termination Current: 50mA

Active Empty (V): 3.0V Active Empty (I): 300mA

Sense Resistor: 0.020Ω

TBP12 TBP23 TBP34

Segment

Breakpoint

-12°C 0°C 18°C

+40

Seg. 1 Seg. 2 Seg. 3 Seg. 4

°C

ominal

(mAh)

ppm/°C ppm/°C ppm/°C ppm/°C

Full 1051 3601 3113 1163 854

Active Empty 2380 1099 671 305

Standby Empty 1404 427 244 183

Figure 4. Lookup Function Diagram

PPLICATION PARAMETERS

everal application parameters are needed to detect the full and empty

ense Resistor Prime (R

SNSP

[1/Ω])—R

SNSP

stores the value of the sense resistor for use in computing the absolute

SNSP

= 1/R

SNS

(units of mhos; 1/Ω)

harge Voltage (VCHG)—VCHG stores the charge voltage threshold used to detect a fully charged state. The

See Result Registers section for a description of these registers.

CELL MODEL

PARAMETERS

(EEPROM)

TEMPERATURE

LOOKUP

FUNCTION

FULL(T)

AE(T)

SE(T)

In addition to cell model characteristics, s

points, as well as calculate results in mAh units.

capacity results. The resistance is stored as a 1-byte conductance value with units of mhos (1/Ω). R

SNSP

supports

resistor values of 1Ω to 3.922mΩ. R

SNS

is located in the parameter EEPROM block.

voltage is stored as a 1-byte value with units of 19.5mV and can range from 0V to 4.978V. VCHG should be set

marginally less than the cell voltage at the end of the charge cycle to ensure reliable charge termination detection.

VCHG is located in the parameter EEPROM block.

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 37 38

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