LTC4015_15 Datasheet, PDF (62/76 Pages) Linear Technology – Multichemistry Buck Battery Charger Controller with Digital Telemetry System

LTC4015
DETAILED Register Descriptions
IIN_LIMIT_SETTING (Sub-Address 0x15, Bits 5:0, R/W)
These 6 bits control the target input current limit setting. The input current will be regulated to a maximum value given
by (IIN_LIMIT_SETTING + 1) • 500µV/R_SNSI.
VIN_UVCL_SETTING (Sub-Address 0x16, Bits 7:0, R/W)
These 8 bits control the UVCLFB regulation loop servo voltage. The UVCLFB regulation voltage is given by (VIN_UVCL_
SETTING + 1) • 4.6875mV. By default, this register is set to full-scale (0xFF), corresponding to 1.2V at UVCLFB pin. If
enabled, the maximum power point tracking (MPPT) algorithm directly manipulates VIN_UVCL_SETTING.
ARM_SHIP_MODE (Sub-Address 0x19, Bits 15:0, R/W)
Setting this register to 0x534D (ASCII for SM) arms LTC4015’s low power ship mode. The only allowed values for
this register are 0x0000 and 0x534D, and once armed, ship mode cannot be disarmed (writing ARM_SHIP_MODE=0
does not disarm ship mode). Ship mode does not take effect until V_IN drops below approximately 1V. See the section
Low Power Ship Mode.
CHARGER SETTING REGISTER DESCRIPTIONS (Sub-Addresses 0x1A through 0x2E)
Registers which control the primary charging parameters, such as charge voltage and charge current are only writ-
able when the CHEMn pins are configured for a programmable chemistry algorithm (Li-Ion-Prog, LiFePO₄-Prog, or
Lead-Acid-Prog). If the CHEMn pins are configured for a fixed chemistry algorithm (Li-Ion-Fixed-4.2, Li-Ion-Fixed-4.1,
Li-Ion-fixed-4.0, LiFePO₄-Fixed-3.6, LiFePO₄-Fixed-3.8/3.6, or Lead-Acid-Fixed) the LTC4015 ignores writes to these
registers. See the section Chemistry Selection for more information about configuring the CHEMn pins.
ICHARGE_TARGET (Sub-Address 0x1A, bits 4:0, Fixed: R, Programmable: R/W)
This register controls the target charge current regulation servo level for lead-acid batteries or if en_jeita=0 for lithium
chemistries. For lithium chemistries, if en_jeita=1 (default) ICHARGE_TARGET is controlled by ICHARGE_JEITA_n
(see the section JEITA Temperature Controlled Charging). The charge current regulation servo level is generally given
by (ICHARGE_TARGET + 1) × 1mV/R_SNSB, except during Li-Ion precondition charge phase when the charge current
regulation servo level is reduced by approximately a factor of 10 (rounded down to an increment of 1mV/R_SNSB).
VCHARGE_SETTING (Sub-Address 0x1B, bits 5:0, Fixed: R, Programmable: R/W)
This register controls the charge voltage regulation servo level.
For Li-Ion batteries, only the lower five bits (4:0) are active, and the charge voltage level is given by (VCHARGE_
SETTING/80.0 + 3.8125)V/cell. If en_jeita=1, VCHARGE_SETTING is controlled by vcharge_jeita_n (see the section
JEITA Temperature Qualified Charging). To maintain inherent over charge protection, the maximum Li-Ion charge
voltage level is 4.2V/cell.
For LiFePO₄ batteries, only the lower five bits (4:0) are active, and the charge voltage level is given by (VCHARGE_
SETTING/80.0 + 3.4125)V/cell. If en_jeita=1, VCHARGE_SETTING is controlled by vcharge_jeita_n (see the section
JEITA Temperature Qualified Charging). To maintain inherent over-charge protection, the maximum LiFePO₄ charge
voltage level is 3.8V/cell.
For lead-acid batteries, if en_lead_acid_temp_comp=1, the charge voltage level is given by (VCHARGE_SETTING/105.0
+ 2.0)V/cell at 25°C when a thermistor with a b value of 3490k is used. See the section Lead-Acid Temperature
Compensated Charging for more information. If en_lead_acid_temp_comp=1, the value of VCHARGE_SETTING is
limited to a maximum setting of 35, which corresponds to 2.333V/cell. If en_lead_acid_temp_comp=0, the charge
voltage level is given by (VCHARGE_SETTING/105.0 + 2.0)V/cell, regardless of temperature. To maintain inherent over
charge protection, the maximum lead-acid charge voltage level is 2.6 V/cell.
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