Rainbow-electronics DS2788 Manual do Utilizador descarregar pdf (Página 8)

DS2788

Temperature Measurement

The DS2788 uses an integrated temperature sensor to

measure battery temperature with a resolution of

0.125°C. Temperature measurements are updated

every 440ms and placed in the Temperature (TEMP)

format of the Temperature register.

Current Measurement

In the ACTIVE mode of operation, the DS2788 continu-

ally measures the current flow into and out of the bat-

tery by measuring the voltage drop across a low-value

current-sense resistor, R

SNS

. The voltage-sense range

between SNS and V

is ±51.2mV. The input linearly

converts peak signal amplitudes up to 102.4mV as long

as the continuous signal level (average over the con-

version cycle period) does not exceed ±51.2mV. The

ADC samples the input differentially at 18.6kHz and

updates the Current (CURRENT) register at the com-

pletion of each conversion cycle.

The Current register is updated every 3.515s with the

current conversion result in two’s complement form.

Charge currents above the maximum register value are

reported at the maximum value (7FFFh = +51.2mV).

Discharge currents below the minimum register value

are reported at the minimum value (8000h = -51.2mV).

Stand-Alone Fuel-Gauge IC with

LED Display Drivers

8 _______________________________________________________________________________________

TEMP READ ONLY

MSB—ADDRESS 0Ah LSB—ADDRESS 0Bh

S 2

X X X X X

MSb LSb MSb LSb

“S”: SIGN BIT(S), “X”: RESERVED UNITS: 0.125°C

Figure 4. Temperature Register Format

CURRENT READ ONLY

MSB—ADDRESS 0Eh LSB—ADDRESS 0Fh

S 2

MSb LSb MSb LSb

“S”: SIGN BIT(S) UNITS: 1.562 5µV/R

SNS

Figure 5. Current Register Format

CURRENT RESOLUTION (1 LSB)

SNS

- V

SNS

20m 15m 10m 5m

1.5625µV 78.13µA 104.2µA 156.3µA 312.5µA

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 29 30

LED Display Drivers 1

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