STBC02 Datasheet, PDF (28/39 Pages) STMicroelectronics – Automatic power path management

Operation description
STBC02
8
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.
28/39
DocID029261 Rev 2