LTC3300-1 Datasheet, PDF (38/44 Pages) Linear Technology – High Effciency Bidirectional Multicell Battery Balancer

LTC3300-1
APPLICATIONS INFORMATION
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Figure 17. Combinational Logic Circuit Implementation of The CRC Calculator
CRC [3]
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CRC [0]
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Serial Communication Using the LTC6803 and LTC6804
The LTC3300-1 is compatible with and convenient to
use with all LTC monitor chips, such as the LTC6803 and
LTC6804. Figure 20 in the Typical Applications section
shows the serial communications connections for a joint
LTC3300-1/LTC6803-1 BMS using a common micropro-
cessor SPI port. The SCKI, SDI, and SDO lines of the
lowermost LTC3300-1 and LTC6803-1 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 LTC6803-1
to gate and invert the CSBI line to the LTC3300-1. In this
setup, communicating to the LTC6803-1 is no different
than without the LTC3300-1, as the GPIO1 output bit is
normally high. To talk to the LTC3300-1, written commands
must be “bookended” with a GPIO1 negation write to the
LTC6803-1 prior to talking to the LTC3300-1 and with
a GPIO1 assertion write after talking to the LTC3300-1.
Communication “up the stack” passes between LTC3300-1
ICs and between LTC6803-1 ICs as shown.
The Typical Application shown on the back page of this
data sheet shows the serial communication connections for
a joint LTC3300-1/LTC6804-1 BMS. Each stacked 12-cell
module contains two LTC3300-1 ICs and a single LTC6804‑1
monitor IC. The upper LTC3300-1 in each module is con-
figured with V_MODE = 0, TOS = 1, and receives its serial
communication from the lower LTC3300-1 in the same
module, which itself is configured with V_MODE = 1, TOS
= 0. The LTC6804-1 in the same 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
LTC3300-1. Communication to the lowermost LTC6804-1
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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