UM0442 datasheet(7/33 Pages) STMICROELECTRONICS

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UM0442

Hardware configuration and functionality

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When another power source (USB, 9 Vdc) is selected, it is possible to recharge the battery

pack. The L6924D battery charger system performs this task.

4.2.1

How to charge the battery pack

It is possible to charge a battery pack connected to the STR750-MAP while the board is

powered through the power supply or the USB connector. Although the first method is

outlined, the procedure to implement the charge phase is the same for both ways.

First of all, the STR750-MAP needs to be supplied. For example, plug in the 9÷12 Vdc

power supply connector (closing the appropriate jumper).

As a second step, connect the battery pack to the connector, without closing the

correspondent jumper in the power source selector.

To set up the recharging process, follow these steps:

Close the selector S7 in the position 1-2: this is to connect the battery to the recharging

circuit.

Close the selector S8 in the position 2-3: this is in order to select 5 V standard power

source.

Close the selector S9 in the position 1-2: by doing this, the L6920 and its circuitry is

switched off in order to save power.

Figure 5.

Selectors configuration to recharge the battery pack

4.3

External 5 V power sourcer

It is possible to plug in an external 5 V power source by closing the jumper EXT in the power

source selector.

This feature makes the STR750-MAP highly versatile. Since this power source has no

specific connectors, the only way to furnish 5 V to the STR750-MAP, comes directly from the

STR750FV2 pin-out placed around the microcontroller itself.

In this way, the user can make his own interface board or connect it directly to the

microcontroller's pins.

Take care to follow these simple steps: the external 5 V can operate only if the EXT (see

Figure 3) jumper is closed. After this, the 26th pin of the connectors J1, J2, J3 and J4 placed

around the microcontroller (see the following Figure 6), is available to receive the external

supply. Pay attention when connecting boards outputting 600 mA as maximum current in

order to preserve the STR750-MAP functionalities from damage.

UM0442 Datasheet(PDF) 7 Page - STMicroelectronics