LTC4015 datasheet(22/76 Pages) LINER

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LTC4015

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OPERATION

ICL, UVCL, ICHARGE and VCHARGE DACS

The LTC4015 has four DAC’s for setting target values of:

1. Maximum battery charge voltage (VCHARGE_

SETTING)

2. Maximum battery charge current (ICHARGE_

TARGET)

3. Minimuminputvoltage,UVCL(VIN_UVCL_SETTING)

4. Maximum input current (IIN_LIMIT_SETTING)

The user can program the target values only with the I2C

port.TheLTC4015usesthetargetvaluesasastartingpoint,

the charging algorithms calculate the actual values to be

applied to the DACs to support functions such as Li-Ion

precharge, absorb and equalize charge voltage adders,

MPPT, lead-acid charge voltage temperature compensa-

tion, and charger soft starting.

The target value register is read/write, the actual value

minimum input voltage is scaled by external resistors.

For further information see the Register Description and

Battery Charging sections.

JEITA temperature controlled charging does not use

VCHARGE_SETTING or ICHARGE_TARGET for setting

target values, see JEITA Temperature Controlled Charging

section for further information.

Charging Timers

There are a total of four timers in the LTC4015 used in the

charging algorithms. Timers are 16-bit, and measure time

in seconds. 216 = 65535 seconds or 18.2 hours maximum.

Each timer has current value (read only) and a timeout

value (read/write):

TIMED

PARAMETER

CURRENT

VALUE

TIMEOUT

VALUE

APPLICABLE

CHEMISTRIES

Constant-Voltage

State Time

CV_TIMER (0x31) MAX_CV_TIME

(0x1D)

Lithium

Chemistries

Maximum Total

Charge Time

MAX_CHARGE_

TIMER (0x30)

MAX_CHARGE_

TIME (0x1E)

Lithium

Chemistries

Maximum

Absorb Charge

Time

ABSORB_TIMER

(0x32)

MAX_ABSORB_

TIME (0x2B)

LiFeP04,

Lead-Acid

Maximum

Equalize Charge

Time

EQUALIZE_

TIMER (0x33)

EQUALIZE_TIME

(0x2D)

Lead-Acid

Low Power Ship Mode

The LTC4015 can reduce its already low standby current

to approximately 5μA in a special mode designed for

shipment and storage. Ship mode is armed by setting the

ARM_SHIP_MODE register to 0x534D (ASCII for SM) via

the serial port. Note that once armed, ship mode cannot

be disarmed (the ARM_SHIP_MODE register cannot be

clearedoncesetto0x534D).Oncearmed,shipmodetakes

The Target and Actual Registers as Well as the DAC Size are Shown Below:

FUNCTION

TARGET VALUE REGISTER

ACTUAL VALUE REGISTER

NAME

HEX ADDRESS

(SIZE)

DEFAULT

NAME

HEX ADDRESS

(SIZE)

DEFAULT

Input Current Limit

IIN_LIMIT_SETTING

0x15(5:0)

0x3F

IIN_LIMIT_DAC

0x46(5:0)

0x3F

Battery Charge Voltage

VCHARGE_SETTING

0x1B(5:0)1

0x3F

VCHARGE_DAC

0x45(5:0)

0x3F

Minimum Input Voltage

(UVCL)

VIN_UVCL_SETTING

0x16(8:0)

0xFF

Scaled by External

Resistors

Battery Charge Current

ICHARGE_TARGET

0x1A(4:0)

0x1F

ICHARGE_DAC

0x44(4:0)

0x1F

1 Lithium chemistries = 5b (4:0), lead-acid chemistry = 6b (5:0)

LTC4015 Datasheet(PDF) 22 Page - Linear Technology

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