LTC4015_15 Datasheet, PDF (22/76 Pages) Linear Technology – Multichemistry Buck Battery Charger Controller with Digital Telemetry System

LTC4015
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. Minimum input voltage, UVCL (VIN_UVCL_SETTING)
4. Maximum input current (IIN_LIMIT_SETTING)
The user can program the target values only with the I²C
port. The LTC4015 uses the target values as a starting point,
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
register is read only. In the case of the UVCL register,
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
Constant-Voltage CV_TIMER (0x31) MAX_CV_TIME
State Time
(0x1D)
Maximum Total MAX_CHARGE_ MAX_CHARGE_
Charge Time
TIMER (0x30) TIME (0x1E)
Maximum
Absorb Charge
Time
ABSORB_TIMER MAX_ABSORB_
(0x32)
TIME (0x2B)
Maximum
Equalize Charge
Time
EQUALIZE_ EQUALIZE_TIME
TIMER (0x33)
(0x2D)
APPLICABLE
CHEMISTRIES
Lithium
Chemistries
Lithium
Chemistries
LiFeP04,
Lead-Acid
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
cleared once set to 0x534D). Once armed, ship mode takes
The Target and Actual Registers as Well as the DAC Size are Shown Below:
FUNCTION
TARGET VALUE REGISTER
NAME
HEX ADDRESS
(SIZE)
DEFAULT
Input Current Limit IIN_LIMIT_SETTING
0x15(5:0)
0x3F
Battery Charge Voltage VCHARGE_SETTING
0x1B(5:0)¹
0x3F
Minimum Input Voltage VIN_UVCL_SETTING
0x16(8:0)
0xFF
(UVCL)
Battery Charge Current ICHARGE_TARGET
0x1A(4:0)
0x1F
1 _{Lithium chemistries = 5b (4:0), lead-acid chemistry = 6b (5:0)}
ACTUAL VALUE REGISTER
NAME
HEX ADDRESS
(SIZE)
DEFAULT
IIN_LIMIT_DAC
0x46(5:0)
0x3F
VCHARGE_DAC
0x45(5:0)
0x3F
Scaled by External
Resistors
ICHARGE_DAC
0x44(4:0)
0x1F
4015f
22
For more information www.linear.com/LTC4015