STBC02BJR datasheet(28/39 Pages) STMICROELECTRONICS

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Operation description

STBC02

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DocID029261 Rev 2

Operation description

The STBC02 is a power management IC integrating a battery charger with an embedded

power path function, a 150 mA low quiescent LDO, a smart reset/watchdog, two SPDT load

switches and a protection circuit module (PCM) to prevent the battery from being damaged.

When powered off from a single-cell Li-Ion or Li-Poly battery, and after having performed all

the safety checks, the STBC02 starts charging the battery using a constant-current and

constant-voltage algorithm.

The embedded power path allows simultaneously the battery to be charged and the overall

system to be supplied.

By contrast, when the input voltage is outside the above valid range, the battery supplies

the LDO as well as every load connected to SYS.

The STBC02 also protects the battery in case of:



Overcharge



Over-discharge



Charge overcurrent



Discharge overcurrent

If a fault condition is detected when the input voltage is valid (VUVLO<VIN<VINOVP), the CHG

pin starts toggling, signaling the fault.

The device can also be in shutdown mode (shutdown IBAT<100 nA) maximizing the battery

life of the end-product during its shelf life.

8.1

Power-on

When the STBC02 is in shutdown mode, any load connected to LDO and to SYS is not

supplied.

An applied valid input voltage (VUVLO < VIN < VINOVP) for at least 250 ms, regardless the

presence of a battery or if the battery is fully depleted, allows the loads connected to SYS

and LDO to be supplied, thus enabling proper system operations.

The CEN pin must be left floating or tied high (LDO level) during the power-on for proper

operations. The STBC02 can be also turned on when VIN is outside the valid range, below

the conditions that the battery has at least a remaining charge of 3 V and the wake-up input

is properly triggered. The STBC02 features an UVLO circuit that prevents oscillations if the

input voltage source is unstable. The CEN pin must be left floating or tied to a high level

(LDO) when the STBC02 is powered.

8.2

Battery charger

The STBC02 allows single-cell Li-Ion and Li-Poly battery chemistry to be charged up to a

4.45 V using a CC/CV charging algorithm. The charging cycle starts when a valid input

voltage source (VUVLO < VIN < VINOVP) is detected and signaled by the CHG pin toggling from

a high impedance state to a low logic level.

If the battery is deeply discharged (the battery voltage is lower than VPRE), the STBC02

charger enters the pre-charge phase and starts charging in constant-current mode with the

pre-charge current (IPRE) set. In case the battery voltage does not reach the VPRE threshold

within the tPRE time, the charging process is stopped and a fault is signaled.

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