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dc2260af
DEMO MANUAL DC2260A
measurements are displayed in groups of 3 when each
command button inside the READ CELLS box is clicked.
NOTE:
The READ DISPLAY box has options to display
Cell Voltages in VOLTS or HEX. First select VOLTS or
HEX then click on one of the command buttons inside
READ CELLS box. Every time a command button
inside the READ CELLS box is clicked; new data is
downloaded from the board and displayed as selected
in VOLTS or HEX.
6: Discharge Cells
OPERATING THE CONTROL SCREEN
The LTC6811 offers the option of keeping the discharge
transistors on while measuring the cell voltages. This is
done using the STARTCELL DCC command button. The
command button is illuminated blue when this command
has been executed. This lower voltage reading also includes
I•R errors introduced by cabling and connectors.
7. Other Control Features
Additional command buttons are provided on the control
screen. The POLL ADC command button is used to test
if the ADC is busy making conversions of any LTC6811
devices in a system. The result of this command can be
observed by monitoring the serial data output line of the
SPI interface to the Bottom Port, J2. There is no indication
provided on the control screen.
The START OPEN (WIRE) command button connects
the built in open wire detection circuitry to all cells. This
command must be followed by any command buttons
inside the READ CELLS box click to see the result. The
OPEN WIRE TEST CURRENT box provides options to use
either PULLUP or PULLDOWN Open Wire Test Currents.
An open wire connection to any cell will be indicated by an
abnormally high voltage measurement for the cell above
the open wire and a near zero measurement for the cell
with the open wire in the PULLDOWN case.
8. Continuous Operation
The LTC6811 includes the ability to remove charge from
individual cells to help equalize cell charges within a stack
of batteries. DC2260A contains a P-channel MOSFET in
series with a 33Ω resistor across each cell connection.
When enabled, a cell is loaded and charge is pulled from
the cell with energy dissipated in the switch and resistor.
A check box is provided for each cell to be discharged.
Checking this box (Cell 2 in the above example screen
shot) and then writing the new configuration with a WRITE
CONFIG button push will load the cell.
The discharge transistors are automatically turned off
momentarily while the A/D converter is measuring the
cell voltage using the normal STARTCELL command. This
prevents any voltage drop errors caused by the discharge
current flowing through the cell inter-connection wiring. An
accurate indication of the true cell voltage is then obtained.
