STBCFG01 datasheet(19/37 Pages) STMICROELECTRONICS

19 / 37 page

STBCFG01

Operation description

DocID026474 Rev 3

19/37

The device also features an output overvoltage protection which turns off OTG boost if the

output voltage rises above VBUSOVP. If the overvoltage lasts for more than tVBUSOVP, OTG

boost is disabled and an alarm is generated.

Together with the standard cycle-by-cycle current limit for the inductor peak current, the

STBCFG01 also implements an average battery current limitation to avoid excessive

battery voltage drop during peaks in system current consumption. When the average boost

input current reaches the programmed limit (IBATLIM = 350 mA, 450 mA, 550 mA, 950 mA),

OTG boost is disabled and an alarm is generated.

5.3

LDO regulator

The STBCFG01 integrates a 4.85 V, 50 mA LDO regulator which is active when DCIN

voltage is higher than VINMIN and lower then VINMAX. LDO is also active when the battery is

not connected and in OTG mode, while it is turned off in automatic shutdown conditions

(VDCIN - VCELL+ < VASD). LDO function can be disabled through I²C and its output is

protected against short-circuit.

5.4

Pre-bias

In order to allow proper functionality with input sources not integrating the necessary

minimum load to provide a valid voltage, the STBCFG01 integrates an automatic pre-bias

circuit: if the input voltage (VDCIN) is above the input OVP threshold but lower than the pre-

bias OVP threshold (VINOVP < VDCIN < VINOVP_PB) a pre-bias current is applied to DCIN to

attempt reducing the input voltage down to a valid level. During the charging cycle, if the

pre-bias current has been activated, it is kept on only during trickle charge and taper

charge. The pre-bias current is also turned off in automatic shutdown conditions (ASD).

The pre-bias current is active only if the input voltage is in the activation range for at least

tPBD (5 ms typ.). The pre-bias function can be disabled through I²C.

Figure 8: Pre-bias enable strategy

STBCFG01 데이터시트(PDF) 19 Page - STMicroelectronics