LTC4012 datasheet(42/48 Pages) AD

42 / 48 page

LTC4162-S

Rev B

For more information www.analog.com

Symbol Name

Command

Code

Access

Bit

Range

Default Description

thermistor_voltage

0x40

[15:0]

SignednumberthatindicatestheA/DmeasurementfortheNTCpinvoltage.Thethermistor

value can be determined by the expression RNTC = RNTCBIAS × thermistor_voltage

/ (21829 - thermistor_voltage). Recall that the thermistor has a negative temperature

coefficientsohighertemperaturesmakelowerthermistor_voltagereadingsandvice-versa.

Enum: open_thermistor = 21684

bsr

0x41

[15:0]

Indicates the A/D measurement for the battery resistance. The battery resistance

measurement is proportional to the battery charge current setting resistor, RSNSB, and

can be computed in Ω from: BSR = N × bsr × RSNSB / 250 where N is 1, 2, 3 or 4 for

a 6V, 12V, 18V or 24V battery respectively as set by the CELLS0/CELLS1 pins. If the

charge current, ibat, is below icharge_over_10, bsr_questionable will be set.

CHEM_CELLS_REG

0x43

[11:0]

Programmed battery chemistry

chem

[11:8]

Indicates the chemistry of the battery being charged. For additional safety, application

softwarecantestthisvaluetoensurethatthecorrectversionoftheLTC4162(LTC4162-L,

LTC4162-F or LTC4162-S) is populated on the circuit board.

Enums: LTC4162_LAD = 0,

LTC4162_L42 = 1,

LTC4162_L41 = 2,

LTC4162_L40 = 3,

LTC4162_FAD = 4,

LTC4162_FFS = 5,

LTC4162_FST = 6,

LTC4162_SST = 8,

LTC4162_SAD = 9

cell_count

[3:0]

Indicates the cell count value detected by the CELLS0 and CELLS1 pin strapping. The

LTC4162 uses a cell_count value of 2 for each group of 3 physical (2V) cells (i.e. 6V

cell_count = 2, 12V cell_count = 4, 18V cell_count = 6 and 24V cell_count = 8). cell_count

always indicates 0 when the battery charger is not enabled such as when there is no

input power available.

Enums: Unknown = 0,

6V Battery = 2,

12V Battery = 4,

18V Battery = 6,

24V Battery = 8

icharge_dac

0x44

[4:0]

Indicates the actual charge current setting applied to the charge current digital to analog

converter. icharge_dac is ramped up/down to implement digital soft-start/stop. The

LTC4162 sets the value of icharge_dac based on charger_state. Recall that the charge

current is regulated by controlling the voltage across an external current sense resistor

RSNSB. The servo voltage is given by (icharge_dac + 1) × 1mV. The charge current

servo level is thus given by (icharge_dac + 1) × 1mV/RSNSB.

vcharge_dac

0x45

[5:0]

This is the actual battery voltage setting applied to the charge voltage digital to

analog converter. The LTC4162 sets the value of vcharge_dac based charger_state,

thermistor_voltage, and charger settings including vcharge_setting, vabsorb_delta,

v_equalize_delta and en_sla_temp_comp. The charge voltage setting can be computed

from N × (vcharge_dac × 28.571mV + 6.0V) where N is 1 for a 6V battery, 2 for a 12V

battery, 3 for an 18V battery, 4 for a 24V battery and vcharge_setting ranges from 0 to 63.

iin_limit_dac

0x46

[5:0]

Indicatestheactualinputcurrentlimit.Theiin_limit_dacwillfollowthevalueprogrammed

in iin_limit_target. The input current will be regulated to a maximum value given by

(iin_limit_dac + 1) × 500µV / RSNSI.

vbat_filt

0x47

[15:0]

Signed number that is a digitally filtered version of the A/D measurement of vbat. The

value is based on the A/D value, vbat, which has a scaling factor of 384.8µV/LSB for each

multiple of 6V chosen by the CELLS0/CELLS1 pins. To compute the total battery voltage

multiply this value by 1, 2, 3 or 4 representing a 6V, 12V 18V or 24V battery respectively.

LTC4012 Datasheet(PDF) 42 Page - Analog Devices

LTC4012 Datasheet(HTML) 42 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

Datasheet Download

Link URL