LTC6803-2 Datasheet, PDF (26/40 Pages) Linear Technology – Multicell Battery Stack Monitor

LTC6803-2/LTC6803-4
OPERATION
SERIAL COMMAND EXAMPLES
LTC6803-2/LTC6803-4 (Addressable Configuration)
Examples below use a configuration of three stacked devices: bottom (B), middle (M), and top (T)
Write Configuration Registers (Figure 7) (Broadcast Write)
1. Pull CSBI low
2. Send WRCFG command and its PEC byte
3. Send CFGR0 byte, then CFGR1, …CFGR5, PEC byte (All devices on the bus receive the same data)
4. Pull CSBI high; data latched into all devices on rising edge of CSBI. S pins respond as data latched
Calculation of serial interface time for sequence above:
Number of devices in stack = N
Number of bytes in sequence = B = 2 command byte and 7 data bytes = 2 + 7
Serial port frequency per bit = F
Time = (1/F) * B * 8 bits/byte = (1/F) * (2 + 7) * 8
Time for 3-cell example above, with 1MHz serial port = (1/1000000) * (2 + 7)*8 = 72µs
Read Cell Voltage Registers (12 battery cells, addressable read)
1. Pull CSBI low
2. Send Address and PEC byte for bottom device
3. Send RDCV command and its PEC byte
4. Read CVR00 byte of bottom device, then CVR01 (B), CVR02 (B), … CVR17 (B), and then PEC (B)
5. Pull CSBI high
6. Repeat steps 1-5 for middle device and top device
Calculation of serial interface time for sequence above:
Number of devices in stack = N
Number of bytes in sequence = B = 2 address bytes, 2 command bytes, and 18 data bytes plus 1 PEC byte = 23 * N
Serial port frequency per bit = F
Time = (1/F) * B * 8 bits/byte = (1/F) * (23 * N) * 8
Time for 3-cell example above, with 1MHz serial port = (1/1000000) * (23 * N) * 8 = 552µs
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