ATmega16HVB datasheet(119/273 Pages) ATMEL

119 / 273 page

119

8042A–AVR–07/09

ATmega16HVB/32HVB

20.3.2

Cell inputs

The V-ADC features one input channel for each battery cell to be able to measure each cell indi-

vidually and to measure the total battery voltage through the input pins NV, PV1, PV2, PV3 and

PV4. Note that the internal Cell Balancing uses the same pins to bypass balancing current (See

”Cell Balancing” on page 154.) for details for balancing the battery cells. When balancing a cell

the V-ADC should not do conversion on the selected channel, as the internal Cell balancing will

affect the conversion result.

The V-ADC is designed to operate on PV1 pin voltages above 2V. If the battery cell voltage on

PV1 input falls below 2V the upper cell voltage appears to be lower than the its actual value. To

avoid that cells get potentially overcharged software should keep the cells in balance using the

internal Cell Balancing. See ”Cell Balancing” on page 154. for details.

When not using all the cell inputs, the unused cells should be connected to the cell below. An

example external coupling in 3-cell mode is shown in Figure 20-3 on page 119. Note that even if

the input is not used, it is recommended to connect the input through an external resistance to

limit inverse coupling current. This is to be able to protect the battery if cells are reversed cou-

pled during production.

Figure 20-3. 1 3-cell mode connection

ATmega16HVB/32HVB

PV4

PV3

PV2

PV1

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