AN2946 datasheet(8/38 Pages) STMICROELECTRONICS

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General description

AN2946

8/38

Doc ID 15473 Rev 2

The MCU implements the sophisticated peripherals as listed in Table 1.

2.4

Main functions of the controller

2.4.1

Battery charging management

During the daytime, the battery is charged by PV electricity according to the typical pattern.

An MPPT (maximum power point tracing) algorithm is applied to enable the PV module to

output as much electricity power as it can. Refer to Section 4.2 for more information

concerning MPPT. The pattern for the 12 V battery system is shown in Figure 4. The pattern

differentiates the entire charging process into 3 stages. During stage 1 and stage 2, the

battery is charged with the solar module maximum power. In stage 3, the battery is charged

in constant voltage algorithm.

Figure 4.

Battery charging pattern

●

Stage 1 (trickle charging): UBAT < 11 V. The battery is charged with the maximum

power of the PV module. This stage is designed for a battery which is deeply

Table 1.

MCU peripheral allocation

Peripheral

Number

Description

ADC

USC+, USC-, UBAT, ULED, ISC, IBAT, ILED, TCHG, TBAT, TDRV, TLED

GPIO

Inputs

DIP1~4 (up to 16 modes) JTAG

Status indication

Charger_EN for anti-backflow charge

Mains_EN for switching to mains supply

Battery LED1-2 for indicating battery status

Debug LED1-4 for diagnosis (up to 16 messages)

PWM

PWMCHG, PWMDRV (100 kHz)

EXT1

LED fault

AN2946 Datasheet(PDF) 8 Page - STMicroelectronics