LTC4162EUFD-FST#PBF datasheet(25/52 Pages) AD

25 / 52 page

LTC4162-F

Rev A

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OPERATION

be diluted to match it by placing a low drift resistor in

series with the thermistor and increasing the bias resis-

tor accordingly. (see Alternate Thermistors and Biasing

in Applications Information for details). If the application

does not require temperature controlled charging then the

thermistorshouldbereplacedwitharesistorofequalvalue

to bias resistor RNTCBIAS, for example, 100kΩ.

Advanced JEITA Temperature Controlled Charging

A control system is included to provide compliance

with the Japan Electronics and Information Technology

Industries Association guidelines on battery charging by

leaving en_jeita set to its default value of 1. Specifically,

a very flexible multi-point temperature-voltage-current

profile can be programmed into the LTC4162 to ensure

that charging parameters as a function of temperature

are used. Figure 1 and Table 6 illustrate default values

of the JEITA system available in the LTC4162. There are

sevendistincttemperatureregionsprogrammedbythesix

thermistor_voltage based temperature set points jeita_t1

through jeita_t6. For each of the temperature regions, the

charge current and charge voltage can be programmed

within the limits set by (VCSP – VCSN)/RSNSB (charge_cur-

rent_setting) and battery charge voltage (vcharge_set-

ting). When en_jeita is true, The JEITA system writes its

registers, icharge_jeita_2 through icharge_jeita_6 and

vcharge_jeita_2 through vcharge_jeita_6 to charge_cur-

rent_setting and vcharge_setting which are then passed

on to the icharge_dac and vcharge_dac.

Writingvaluestocharge_current_settingandvcharge_set-

ting with en_jeita set is futile as the JEITA system will

overwrite these values every 11ms.

The values for the JEITA registers are shown below. The

bold values in the tables are programmable. The jeita_t1

through jeita_t6 registers determine the thermistor_volt-

age values for the breakpoints between regions. Table 6

lists the default values of the JEITA charging parameters

along with example values of a 10kΩ thermistor with a β

value of 3490K. All of the temperature, voltage and current

settings can be modified for maximum flexibility.

Table 6. Tabular Representation of the JEITA system, Default JEITA Values and β = 3490K Equivalent Temperatures

jeita_region vcharge_jeita

Charge

Voltage

icharge_jeita

Charge

Current

JEITA

Temperature

thermistor_voltage

RNTC

Temp

Charger Off

jeita_t1

16117

28215Ω

0°C

3.60V

16mV/RSNSB

jeita_t2

14113

18290Ω

10°C

3.60V

32mV/RSNSB

jeita_t3

7970

5751Ω

40°C

3.50V

32mV/RSNSB

jeita_t4

7112

4832Ω

45°C

3.50V

16mV/RSNSB

jeita_t5

6325

4080Ω

50°C

3.45V

16mV/RSNSB

jeita_t6

4970

2948Ω

60°C

Charger Off

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