BQ26501_16 Datasheet, PDF (20/33 Pages) Texas Instruments – HANDHELD APPLICATIONS

bq26501
Not Recommended For New Designs
ą
SLUS586B − OCTOBER 2003 − REVISED MARCH 2004
APPLICATION INFORMATION
Temperature Compensation Constants (TCOMP) or ID1 – Address 0x7F
This register is used to set the compensation coefficients for temperature. These coefficients are applied to the
discharge rate compensated available charge (CACD) to more accurately predict capacity available at cold
temperature.
NAME
BIT 7
TCGN[3]
BIT 6
TCGN[2]
BIT 5
TCGN[1]
BIT 4
TCGN[0]
BIT 3
TOFF[3]
BIT 2
TOFF[2]
BIT 1
TOFF[1]
BIT 0
TOFF[0]
MODE
REGISTER
TCGN[3]
TCGN[2]
TCGN[1]
TCGN[0]
TOFF[3]
TOFF[2]
TOFF[1]
TOFF[0]
DESCRIPTION
Temperature compensation gain. Used to set the slope of the compensation as a percentage of design capacity
(DC) decrease per °C. The equation for programming the value is:
TCGN[3:0] = 10.24 × design temp compensation gain % DC/°C
Temperature compensation offset. Used to set the offset of the compensation. The temperature threshold is also
used as the cold temperature disqualification for learning cycle even if TCGN=0. The equation for programming
the value is:
TOFF[3:0] = design temp compensation offset (°K) − 273
Temperature compensation, TCMP, is computed from these coefficients as follows:
TCMP + TCGN
ILMD
(273 ) TOFF * T)
4
(12)
where T is the temperature in °K and T < 273 + TOFF. TCMP = 0 if T ≥ 273 + TOFF. CACT is then computed
as follows:
CACT + CACD * (TCMP * TCMPADJ)
(13)
where TEMPADJ is the value of TCMP at EDV1 or is equal to zero, depending on whether the EDV1 condition
or full condition respectively, occurred last.
If PKCFG[0]=1, the device assumes a fixed value of 0x7C for TCOMP, giving a temperature compensation gain
of 0.68% DC/°C with an offset of 12°C. This frees the EEPROM location of 0x7F for a user-defined identification
byte, ID1.
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