Software configuration

UM1836

6/16

DocID027146 Rev 1

2.2

Application parameters configuration

An extract of the stc3115_Battery.h file where the application parameters are defined is

shown below. A detailed explanation of the parameters used in this code (VMODE,

ALM_EN, ALM_SOC, ALM_VBAT, RSENSE, APP_EOC_CURRENT, and

APP_CUTOFF_VOLTAGE) is also available below.

/*Application parameters define ------------------------------------*/

#define VMODE MIXED_MODE/* running mode constant, VM_MODE or

MIXED_MODE*/

#define ALM_EN 0

/* Alarm enable constant, set at 1 to enable

*/

#define ALM_SOC 10

/* SOC alarm in %

*/

#define ALM_VBAT 3600 /* Voltage alarm in mV

*/

#define RSENSE 10

/* sense resistor in mOhms

*/

#define APP_EOC_CURRENT 75

/* end charge current in mA

*/

#define APP_CUTOFF_VOLTAGE 3000 /* application cut-off voltage in mV*/

The VMODE parameter describes the VMODE bit in the REG_MODE register

(see STC3115 datasheet). This parameter has to be set up as the default operating mode

of the application. It can be initialized with MIXED_MODE or VM_MODE. If mixed mode is

selected, an external sense resistor is mandatory to measure the battery current that is

flowing. Also, if mixed mode is selected, it is possible to switch to voltage mode after

STC3115 initialization (see Section 3: API overview)

The ALM_EN parameter is dedicated to the alarm. If the value of ALM_EN is set to 0, the

alarm is not enabled by default. Consequently, dedicated API alarm functions have to be

used to enable and configure the alarm. If the value of ALM_EN is set to 1, the alarm is

enabled by default and alarm thresholds such as ALM_SOC and ALM_VBAT (see below)

can be initialized.

The ALM_SOC parameter is an alarm threshold in % which is based on the state-of-charge

(SOC) value. If the alarm is enabled and the REG_SOC register is below the ALM_SOC

parameter, the alarm pin is driven low (active) automatically.

The ALM_VBAT parameter is an alarm threshold in mV which is based on the voltage

value. If the alarm is enabled and the REG_VOLTAGE register is below the ALM_VBAT

parameter, the alarm pin is driven low (active) automatically.

The RSENSE parameter is the sense resistor value in milliohms. This parameter can be a

value between 5 and 50 milliohms. If there is no sense resistor, RSENSE can be set to 0

but, in this case, VMODE must be set to 1 (VM_MODE).

The APP_EOC_CURRENT parameter has to be configured with a targeted end-of charge

(EOC) current in mA. Typically, the EOC current is equal to the battery capacity divided by

20. However, this value has to be set according to application charger behavior and can be

different to the standard value.

The APP_CUTOFF_VOTLAGE parameter has to be configured with the application

minimum voltage in mV. This value is the minimum voltage which cuts off the application.

Below this voltage, the STSW-BAT001 driver reports an SOC of 0 %, the application cuts

off and is thereby secured.