STBCFG01 datasheet(16/37 Pages) STMICROELECTRONICS

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Operation description

STBCFG01

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DocID026474 Rev 3

When the battery is deeply discharged (VCELL+ < VTRK, VTRK = 2 V) the device is in trickle

charge mode and charges the battery in linear mode with a low current (ITRK = 45 mA) up to

the trickle charge threshold.

As soon as the battery voltage enters the pre-charge range (VTRK < VCELL+ < VPRE, VPRE = 3

V) the device starts the switch mode charging and increases the charging current up to the

pre-charge current level (IPRE) to make the system voltage rise quickly up to a level which

allows the system to wake up.

The typical value for the pre-charge current is 450 mA but this value can be decreased to

100 mA through the I²C compatible interface.

A 45 minute (typ.) safety timer is active during both trickle charge and pre-charge.

When the battery voltage is above the pre-charge threshold, the STBCFG01 enters fast

charge mode and increases the charging current up to IFAST value. The fast charge

current can be programmed through the I²C compatible interface between 550 mA and 1.2

A in 100 mA steps.

A soft-start function makes the battery current increase smoothly when the charging current

changes.

The constant voltage mode enters when the battery voltage reaches the programmable

floating voltage threshold (VFLOAT, 3.60 V to 4.70 V in 20 mV steps).

In constant voltage mode, the charging current tapers down the termination current

threshold and then the charging process stops. The termination current is programmable

from 50 mA to 300 mA in 25 mA steps.

A 360 minute (typ.) safety timer is active when the fast charge starts.

The charger can be disabled pulling high the charger enable input (CENn) and is

automatically stopped in automatic shutdown conditions (ASD, VDCIN - VBAT < VASD).

Figure 4: CC/CV charging cycle

5.1.1

Input current limit

The STBCFG01 implements a programmable input current limitation to prevent the battery

charger from exceeding DCIN voltage source current capability. The current limit can be

programmed through I²C to the following maximum values: 100 mA, 500 mA, 800 mA, 1.2

A. A “no limit” option is also available.

5.1.2

Dynamic input current limit (DICL)

Independently from the chosen input current limit, a dynamic input current limit loop can

also be enabled through the I²C compatible interface (DICL_en bit). When DICL is active,

an analog loop limits the input current when the input voltage drops to a programmable

threshold (VDICL = 4.0 V to 4.75 V in 250 mV steps).

STBCFG01 Datasheet(PDF) 16 Page - STMicroelectronics