Linear Technology LTC6811-1 Manual

DESCRIPTION
Demonstration circuit 2259A is a Daisy Chain isoSPI
Battery-Stack Monitor featuring the LTC6811-1. Multiple
boards can be linked through a 2-wire isolated serial in-
terface to monitor any number of cells on a stack.
Communication to a PC uses a DC2026 Linduino
as a USB interface. The DC2026 comes preloaded with
a legacy DC590 emulator function (an actual DC590 can
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still be used ). A control program for up to ten stacked
boards has a Graphical User Interface (GUI) to implement
the device command set.
To control more than one DC2259A, RJ45 (Ethernet) patch
cables are also required.
HARDWARE SETUP
When connected to a battery stack, power for the DC2259A
is provided by the cell group being monitored. Separate
the screw-terminal section from J1 and wire cell voltage
connections or resistors into the clamping contacts to
provide the power and input stimulus for the ADC.
Cell voltages are wired from position 4 (most negative
potential of the group) with increasing potentials up to
position 16 (most positive potential).
Design files for this circuit board are available at
http://www.linear.com/demo/DC2259A
L, LT, LTC, LTM, Linear Technology and the Linear logo and Linduino are registered
trademarks and QuikEval is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
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A DC590 is a USB data acquisition board that serves to interface the DC2259 to a PC's USB
port. This board is not necessary with a DC2026.
DEMO MANUAL DC2259A
Battery-Stack Monitor
Alternatively, for a simple demo, connect twelve 100Ω
resistors between each contact from position 4 to position
16 as shown in Figure 1. Then, provide a "stack-equivalent"
power supply connection to position 16 (positive) and
position 4 (return). The supply may be adjusted to provide
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®
the desired nominal cell voltage (e.g., 43.2V will be 3.6V/
cell). Note that cell discharge cannot be demonstrated
properly with a resistor string stimulus.
Photo 1 shows the following connections for two boards
on a stack interfaced to a PC:
1. Connect a USB cable from the PC USB port to DC2026.
2. Connect a 14-pin ribbon from DC2026 to the SPI BOT-
TOM connector (J2) on the bottom DC2259A board.
3. Connect an RJ45 cable from the bottom DC2259A isoSPI
B RJ45 connector (J4) to the next (or top) DC2259A
isoSPI A RJ45 connector (J3).
4. Set the jumpers on each DC2259A as indicated in
Photo 2.
5. Mate the J1 cell-voltage connectors.
Photo 1. Connecting a Two-Board Stack to a PC
LTC6811-1
Daisy Chain isoSPI
dc2259af
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