Datasheet

LTC4300-1/LTC4300-2
5
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pin FuncTions
ENABLE/V
CC2
(Pin 1): Chip Enable Pin/Card Supply Volt-
age. For
the LTC4300-1, this is a digital CMOS threshold
input pin. Grounding this pin puts the part in a low current
(<1µA) mode. It also disables the rise time accelerators,
disables the bus precharge circuitry, drives READY low,
isolates SDAIN from SDAOUT and isolates SCLIN from
SCLOUT. Drive ENABLE all the way to V
CC
for normal
operation. Connect ENABLE to V
CC
if this feature is not
being used. For the LTC4300-2, this is the supply voltage
for the devices on the card I
2
C busses. Connect pull-up
resistors from SDAOUT and SCLOUT to this pin. Place a
bypass capacitor of at least 0.01µF close to this pin for
best results.
SCLOUT (Pin 2): Serial Clock Output. Connect this pin
to the SCL bus on the card. See Figures 3 and 4 for bus
pull-up resistance and capacitance requirements.
SCLIN (Pin 3): Serial Clock Input. Connect this pin to the
SCL bus on the backplane. See Figures 3 and 4 for bus
pull-up resistance and capacitance requirements.
GND (Pin 4): Ground. Connect this pin to a ground plane
for best results.
READY/ACC (Pin 5): Connection Flag/Rise
time Accel-
erator Control
. For the LTC4300-1, this is an open-drain
NMOS output which pulls LOW when either ENABLE is
LOW or the start-up sequence described in the Operation
section has not been completed. READY goes HIGH when
ENABLE is
HIGH and start-up is complete. Connect a 10k
resistor from this pin to V
CC
to provide the pull up. For
the LTC4300-2, this is a CMOS threshold digital input pin
that enables and disables the rise time accelerators on all
four SDA and SCL pins. Drive ACC all the way to the V
CC2
supply voltage to enable all four accelerators; drive ACC
to ground to turn them off.
SDAIN (Pin 6): Serial Data Input. Connect this pin to the
SDA bus on the backplane. See Figures 3 and 4 for bus
pull-up resistance and capacitance requirements.
SDAOUT (Pin 7): Serial Data Output. Connect this pin
to the SDA bus on the card. See Figures 3 and 4 for bus
pull-up resistance and capacitance requirements.
V
CC
(Pin 8): Main Input Power Supply From Backplane.
This is the supply voltage for the devices on the backplane
I
2
C busses. Connect pull-up resistors from SDAIN and
SCLIN to this pin
. Place a bypass capacitor of at least
0.01µF close to this pin for best results.