Functional description

STC3115

18/31

DocID023755 Rev 4

6.5

Improving accuracy of the initial OCV measurement with the

advanced functions of BATD/CD and RSTIO/BATD pins

The advanced functions of the BATD/CD and RSTIO/BATD pins provide a way to ensure

that the OCV measurement at power-up is not affected by the application startup or by the

charger operation. This occurs as follows:

•

(assuming that the BATD/CD signal is connected to disable input of the charger circuit).

•

The RSTIO/BATD pin senses the system reset state and if the system reset is active

(that is RSTIO/BATD is low), the RSTIO/BATD is kept low until the end of the OCV

measurement.

Figure 10 describes the BATD/CD and RSTIO/BATD operation at power-up. Please refer to

the block diagram of Figure 11 for the RSTI, RSTO, BATD_comp_out, and

BATD_drive_high signals.

At the end of the OCV measurement, the BATD/CD and RSTIO/BATD pin are released

(high impedance), the application can start and the charger is enabled.

Figure 10. BATD and RSTIO timing diagram at power-up

6.5.1

BATD and RSTIO pins

The STC3115 provides platform synchronization signals to provide reliable SOC information

in different cases.

The BATD/CD pin senses the presence of the battery independently of the battery voltage

and it controls the battery charger to inhibit the charge during the initial OCV measurement.

The RSTIO/BATD pin can be used to delay the platform startup during the first OCV

measurement at battery insertion.

VCC

UVLO

BATD_comp_out

RSTI

POR

Voltage

measurement

1.61V

delay

RST0

Voltage

register

SOC register

BATD_drive_high

OCV

meas.

Application can start,

charge is enabled

SOC

calc.