LTC4162EUFD-FST#PBF datasheet(28/52 Pages) AD

28 / 52 page

LTC4162-F

Rev A

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OPERATION

Absorb (Rapid) Charging

The LTC162 can optionally perform an accelerated ab-

sorb, or rapid, charge phase if vabsorb_delta is greater

than zero. During the absorb phase the battery terminal

voltage is allowed to rise vabsorb_delta above the normal

constant_voltagelevelforuptoadefaultmax_absorb_time

of 900 seconds or 15 minutes. Note that depending on

batterystateofcharge,chargecurrentandseriesresistance

the battery terminal voltage may not necessarily reach

the increased absorb voltage during the tabsorbtimer

period. The vabsorb_delta default of 0 inhibits the rapid

charging phase.

Low Power Ship Mode

The LTC4162 can reduce its already low battery-only

standby current to about 2.8µA in a special mode designed

for shipment and storage. Ship mode is armed by setting

arm_ship_mode to arm. It does not take effect, however,

until the input voltage VIN drops below approximately 1V.

Uponreturnoftheinputvoltageaboveapproximately1Vthe

LTC4162wakesfromshipmode.Thedecisiontoremainout

of ship mode is latched once the internal voltage reference

is re-biased and VIN is detected as having reached about

4.2V (vin_gt_4p2v). In ship mode, the VCC2P5 2.5V logic

LDO and the INTVCC 5V system LDO are deactivated and,

along with them, all logic and communications with the

I2C port. Consequently, no settings or state information

will persist through a ship mode cycle.

Oscillator Synchronization

The SYNC pin is available to synchronize the switching

battery charger to an external clock for optimum noise

immunity. To use the SYNC pin, use the RT pin to set

the frequency of the internal oscillator to the frequency

expected by the SYNC signal. If no signal is present at

SYNC, the internal oscillator will run normally. If a signal

within the required tolerance range appears at SYNC, the

internal oscillator will detect it and synchronize with it. To

avoid a long or short cycle, synchronization won't occur

until the internal oscillator and external signals coincide.

Therefore, synchronization may take several thousand

cycles (milliseconds) to occur. If SYNC is not used, it

should just be grounded.

Under Voltage Lockout Circuits/suspend_charger/

System Faults

Various supply monitor circuits, as well as suspend_char-

ger, can disable charging. If the voltage at VIN falls below

BATSENS+ (i.e. not vin_gt_vbat), or thermal_shutdown

(die temperature above ~150°C), no_rt resistor, not

intvcc_gt_2p8v, not vin_gt_4p2v, or a CELLS0/1 pins

cell_count_err, the LTC4162 suspends charging and

reports charger_suspended. In the absence of any of the

above fault conditions, charging is re-enabled when VIN

rises VIN_DUVLO above the BATSENS+ voltage.

LTC4162 Lithium Iron Phosphate Variants

The LTC4162-FAD is fully programmable and follows the

descriptions given thus far but there are two other variants

available as well. Each of these three versions is available

with and without solar panel maximum power tracking

enabled by default.

The other LTC4162 lithium iron phosphate variants are:

LTC4162-FST

LTC4162-FFS

The LTC4162-FST is identical to the LTC4162-FAD but,

for improved safety, the JEITA values as well as v_re-

charge_lifepo4, vabsorb_delta and max_absorb_time are

not writable.

The LTC4162-FFS variant enables the absorb_charge

(rapid) feature by having a default vabsorb_delta of 16

representing 200mV/cell_count above the normal charg-

ing voltage. In the LTC4162-FFS variant the JEITA values,

v_recharge_lifepo4,vabsorb_deltaandmax_absorb_time

are also not writable.

LTC4162EUFD-FST#PBF Datasheet(PDF) 28 Page - Analog Devices

LTC4162EUFD-FST#PBF Datasheet(HTML) 28 Page - Analog Devices

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