Datasheet

LTC3300-1
26
33001fb
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CSBI
SCKI
SDI
MSB (CMD) LSB (CMD)
33001 F08
CSBI
SCKI
SDI
MSB (CMD) LSB (CMD)
LSB (DATA)
MSB (DATA)
Transmission Format (Write)
Transmission Format (Read)
LSB (DATA)
MSB (DATA)SDO
Figure 8
OPERATION
Figure 9. Current Mode Interface
+
–
WRITE
READ 1
V
SENSE
(WRITE)
+
–
V
SENSE
(READ)
33001 F09
HIGH SIDE PORT
ON LOWER DEVICE
LOW SIDE PORT
ON HIGHER DEVICE
See Figure 9. Since CSBO, SCKO and SDOI voltages are
close to the V
–
of the high side device, the V
–
of the high
side device must be at least 5V higher than that of the low
side device to guarantee current flows of the current mode
interface. It is recommended that high voltage diodes be
placed in series with the SPI daisy-chain signals as shown
if Figure 13. These diodes prevent reverse voltage stress
on the IC if a battery group bus bar is removed. See Bat
-
tery Interconnection Integrity for additional information.
Standby current consumed in the current mode serial
inter
face is minimized when CSBI is logic high.
The voltage mode pin (V
MODE
) determines whether the low
side serial port is configured as voltage mode or current
mode. For the bottom device in a daisy-chain stack, this