STBC02 datasheet(20/39 Pages) STMICROELECTRONICS

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Functional pin description

STBC02

20/39

DocID029261 Rev 2

6.5

BATSNS, BATSNSFV

Battery voltage sense pin. The BATSNS pin must be connected as close as possible to the

battery positive terminal to ensure the maximum accuracy on the floating voltage and on

the battery voltage protection thresholds. The BATSNSFV pin can be used to fix the VFLOAT

value by connecting a proper external series resistor (to BATSNSFV. The battery floating

voltage can be set up to 4.45 V according to the following equation:

Equation 2:

�� = �� ∗ (1 +

��

1��Ω

) �� = 4.2 ∗ (1 +

��

1��Ω

) ��

Example: to set the battery floating voltage at 4.35 V, refer to the following equation.

Equation 3:

�� = 1��Ω ∗ (

��

4.2��

− 1) = 1��Ω ∗ (

4.35��

4.2��

− 1) = 35.7��Ω

If the BATSNSFV pin is connected to the battery positive terminal, the floating voltage is

set at its 4.2 V default value.

6.6

BAT

External battery connection pin (positive terminal). A 4.7 µF ceramic bypass capacitor must

be connected to GND.

6.7

5 V input supply voltage pin. The STBC02 is powered off from this pin when a valid voltage

source is detected, meaning a voltage higher than VUVLO and lower than VINOVP. A 10 µF

ceramic bypass capacitor must be connected to GND.

6.8

SYS

The internal LDO input voltage and external unregulated supply pin. The maximum current

deliverable through this pin depends on the following two conditions: LDO load and battery

status. However, if none of the above loads sink current, the maximum SYS current budget

is 450 mA, provided that the input voltage source can deliver that amount of current.

SYS voltage source can be either IN or BAT, depending on the operating conditions (refer

to the following table). A ceramic bypass capacitor of 1 µF must be connected to GND.

Table 7: SYS voltage source

VIN

VBAT

SYS status

LDO status

< VUVLO

< VODC(1)

Not powered

Off

< VUVLO

> VODC

VBAT(2)

> < VUVLO and < VINOVP

X (don’t care)(3)

VIN

> VINOVP

< VODC

Not powered

Off

> VINOVP

> VODC

VBAT(2)

Notes:

(1)VODCR if the shutdown mode or the over-discharge protection has been previously activated.

(2)Voltage drop over internal MOSFET is not included.

(3)Battery disconnected (0 V) or fully discharged. Resistive short-circuit is not supported for safety reasons.

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