STBC02 datasheet(33/39 Pages) STMICROELECTRONICS

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STBC02

Operation description

DocID029261 Rev 2

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8.8

Floating voltage adjustment

The STBC02 features a floating voltage adjustment, controlled via SWIRE, allowing the

battery floating voltage (four steps of 50 mV each) to be changed. Due to multiple battery

charging processes and the aging of the battery, the floating voltage of the battery can

change and be reduced. The floating voltage adjustment feature brings the floating voltage

level back to the original nominal value. For safety reasons, the battery voltage overcharge

threshold level (VOCHG) is linked to any floating voltage set. By default this feature is

disabled and moreover, as no state is stored in any memory, every shutdown or shipping

mode event resets the floating voltage at the default value.

8.9

Input overcurrent protection

When the STBC02 is powered off from a valid input voltage source, a current limitation

circuit prevents the input current from increasing in an uncontrolled manner in case of

excessive load. In fact, when VSYS is lower than VILIMSCTH, the input current is limited so to

have a reduced power dissipation. As soon as VSYS increases over VILIMSCTH, the input

current limit value is increased to IINLIM.

8.10

SYS short-circuit protection, LDO current limitation

In battery mode condition, if a short-circuit on the SYS pin happens, the STBC02 is turned

off (no deglitch). This short-circuit protection occurs until the SYS voltage drops below

VSCSYS.

If the LDO output is in a short-circuit condition, the maximum delivered current is limited

to ISC.

8.11

IN overvoltage protection

Should the input voltage source temporarily be VIN>VINOVP (for example due to a poorly

regulated voltage source), then the STBC02 is powered off from the battery, thus any load

connected to SYS is protected.

As soon as the input voltage source goes back within a valid input range

(VUVLO<VIN<VINOVP), the STBC02 is then powered off again from VIN.

8.12

Shutdown mode

A proper SWIRE sequence forces the STBC02 to enter in shutdown mode (low power); the

current sunk from the battery is reduced to less than 50 nA. Both SYS and LDO pins are

not supplied. Normal operating condition is restored either by connecting a valid input

voltage source (VUVLO<VIN<VINOVP) for at least tPW-VIN or by connecting the WAKE-UP pin to

VBAT for at least tPW-WA.

8.13

Watchdog function

The watchdog function can be enabled by SWIRE commands (#27 enabled, #26 disabled).

The watchdog pulse is generated on nRESET pin.

8.14

Thermal shutdown

The STBC02 is fully protected against overheating. During the charging process, if a

TWRN< TSD temperature level is detected, a warning is signaled via the CHG output

(toggling at 14.2 Hz).When in this condition, the programmed IPRE and IFAST are temporary

halved. In case of a further temperature increase (up to TSD) the STBC02 turns off, thus

stopping the charging process. This condition is latched and normal operation can be

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