Example of USB NiMH charger implementation using the STEVAL-ISB003V1

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Example of USB NiMH charger implementation using

the STEVAL-ISB003V1

3.1

Introduction to the STEVAL-ISB003V1

This board consists of a low-speed USB controller based on the ST72F60E2M1 and a

battery charger based on the ST7FLIT15BY0.

The board includes a power selector circuit to select the appropriate power supply source

and a step-up converter circuit based on a synchronous step-up converter (L6920) device to

provide a fixed O/P voltage to the USB controller. The power supply for the battery charger

controller is generated from an adjustable voltage reference (TL1431) keeping in mind the

accuracy requirement for charging. An additional current limiter is also located in series with

the USB power supply to show any incorrect behavior through a status LED.

Any external low-speed USB controller can be used with this demonstration board to control

the charger operation.

The charger used in the present demonstration board uses a modified form of non-inverting

buck-boost converter to support the charging voltage requirement for single-cell Li-Ion

batteries. In-circuit programming (ICP) connectors are also available with the demonstration

board to program the USB controller and charger system if necessary.

3.2

Customizing the STEVAL-ISB003V1 for NiMH charger

The STEVAL-ISB003V1 is a platform used to implement the USB-based Li-Ion battery

charger application. Refer to UM0497 for more information on the STEVAL-ISB003V1

demonstration board.

Figure 5.

USB-based battery charger demonstration board (STEVAL-ISB003V1)

AM01044v1