LTC3300-2_15 Datasheet, PDF (35/42 Pages) Linear Technology – Addressable High Efficiency Bidirectional Multicell Battery Balancer

LTC3300-2
APPLICATIONS INFORMATION
“Ø”
“Ø”
D6B
D5B
D3B
D1B
D2A
D5A
D3A
D1A
D4B
CRC [3]
CRC [3]
CRC [2]
CRC [2]
D2B
CRC [1]
CRC [1]
D4A
D6A
“Ø”
“Ø”
CRC [0]
CRC [0]
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Figure 14. Combinational Logic Circuit Implementation of the CRC Calculator
Serial Communication Using the LTC6803 and LTC6804
The LTC3300-2 is compatible with and convenient to
use with all LTC monitor chips, such as the LTC6803 and
LTC6804. Figure 17 in the Typical Applications section
shows the serial communications connections for a joint
LTC3300-2/LTC6803-2 BMS using a common micropro-
cessor SPI port. The SCKI, SDI, and SDO lines of the low-
ermost LTC3300-2 and LTC6803-2 are tied together. The
CSBI lines, however, must be separated to prevent talking
to both ICs at the same time. This is easily accomplished
by using one of the GPIO outputs from the LTC6803-2
to gate and invert the CSBI line to the LTC3300-2. In this
setup, communicating to the LTC6803-2 is no different
than without the LTC3300-2, as the GPIO1 output bit is
normally high. To talk to the LTC3300-2, written commands
must be “bookended” with a GPIO1 negation write to the
LTC6803-2 prior to talking to the LTC3300-2 and with
a GPIO1 assertion write after talking to the LTC3300-2.
Communication to all non-ground referred LTC3300-2 and
LTC6803-2 ICs is done through digital isolators.
The Typical Application shown on the back page of this
data sheet shows the serial communication connections
for a joint LTC3300-2/LTC6804-2 BMS. Each stacked
12-cell module contains two LTC3300-2 ICs and a single
LTC6804‑2 monitor IC. . The LTC6804-2 in the module
is configured to provide an effective SPI port output at its
GPIO3, GPIO4, and GPIO5 pins which connect directly to
the low side communication pins (CSBI, SDI=SDO, SCKI)
of the lower LTC3300-2. The upper LTC3300-2 in each
module receives its serial communication via a digital
isolator from the lower LTC3300-2. Communication to
the lowermost LTC6804-2 and between monitor chips is
done via the LTC6820 and the isoSPI™ interface. In this
application, unused battery cells can be shorted from
the bottom of any module (i.e., outside the module, not
on the module board) as shown without any decrease in
monitor accuracy.
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For more information www.linear.com/LTC3300-2
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