AN2390 datasheet(28/42 Pages) STMICROELECTRONICS

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How to use the evaluation board

AN2390

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The role of each jumper is as follows:

J2: Used to connect NiMH Battery Charger Slot

J3: Used to connect NiMH Battery Charger Slot

RT1: RT1 is used to connect external NTC. This NTC is put close to the NiMH charger slot

to correctly monitor the NiMH battery temperature.

3.1.2

Powering and running the evaluation board

After all the jumpers are connected as described in Section 3.1.1, you can connect the

power supply. To connect the power supply there is a power jack X1 (5V, Gnd) available on

the evaluation board. You need to connect a DC power supply of (5V, 2A) to this connector.

After connecting the power supply, you need to press the Reset button on the evaluation

board for correct operation.

Now the evaluation board is in running mode and you can monitor the charging status

through LED D5 status as mentioned in Table 3.

Note:

It is necessary to press the Reset button once after connecting the power supply as the LVD

feature is not used in this evaluation board. However the LVD can be implemented in a real

application

3.2

Warnings/ Limitations

The user should be aware of the following warnings/limitations when using this evaluation

board.

Only one type of battery can be charged at a time and there is no protection to prevent

shorting the batteries if they are connected simultaneously in both slots. So the user

has to make sure to connect only one battery at a time.

There is no protection for reverse battery polarity connection but it can be provided on

customer request.

To minimize noise spikes at the input power supply, please connect a capacitor of 100 -

220 uF between the input power supply and Gnd.

3.3

Example test results with evaluation board

3.3.1

Test environment

In this implementation of the buck-boost converter, the following values are taken into

account.

Transistor drop |VCE| (SAT) = 0.2V, Diode drop |Vd| = 0.55 V, L = 75 mH, C = 470 uF, Max

Vsense = 0.5V, Fcpu = 8 MHz, Fpwm = 16 kHz and Ambient Temperature = 24 deg C. Also the

timer is updated at 500 Hz.

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