Datasheet LTC4312 (Analog Devices) - 6

LTC4312
PIN FUNCTIONS ACC:
Three-State Acceleration and Buffer Mode Selector.
SCLIN:
Upstream Serial Bus Clock Input/Output. Connect This pin controls the turn on voltage of the rise time ac- this pin to the SCL line on the upstream bus. Connect an celerators and their current strength on both the input and external pull-up resistor or current source between this output sides. It also controls the turn-off voltage of the pin and the bus supply. Do not leave open. buffers. See Table 1 in the Applications Information section.
SCLOUT1-SCLOUT2:
Downstream Serial Bus Clock Input/
DISCEN:
Disconnect Stuck Bus Enable Input. When this Output Channels 1-2. Connect pins SCLOUT1-SCLOUT2 pin is high, stuck busses are automatically disconnected to the SCL lines on the downstream channels 1-2, respec- and FAULT is pulled low after a timeout period of 45ms. tively. When in use, an external pull-up resistor or current Up to sixteen clock pulses are subsequently applied to the source is required between the pin and the corresponding stuck output channels. When DISCEN pin is low, stuck bus supply. Leave open or tie to GND and connect the busses are neither disconnected nor clocked but FAULT corresponding ENABLE pin to GND, if unused. is pulled low. Connect to GND if unused.
SDAIN:
Upstream Serial Bus Data Input/Output. Connect
ENABLE1-ENABLE2:
Connection Enable Inputs. These this pin to the SDA line on the upstream bus. Connect an input pins enable or disable the corresponding output external pull-up resistor or current source between this channel. Driving an ENABLE pin low isolates SDAIN and pin and the bus supply. Do not leave open. SCLIN from the corresponding SDAOUT and SCLOUT.
SDAOUT1-SDAOUT2:
Downstream Serial Bus Data Input/ Only enable and disable a channel when all busses are Output Channels 1-2. Connect pins SDAOUT1-SDAOUT2 to idle. During a bus stuck low fault condition, a falling edge the SDA lines on downstream channels 1-2, respectively. on all ENABLE pins followed by a rising edge on one or When in use, an external pull-up resistor or current source more ENABLE pins forces a connection from SDAIN to is required between the pin and the corresponding bus the selected SDAOUT and SCLIN to the selected SCLOUT. supply. Leave open or tie to GND and connect the cor- Connect to GND if unused. responding ENABLE pin to GND, if unused.
Exposed Pad (DFN Package Only):
Exposed pad may be
V
left open or connected to device ground.
CC:
Power Supply Voltage. Power this pin from a sup- ply between 2.9V and 5.5V. Bypass with at least 0.01μF
FAULT:
Stuck Bus Fault Output. This open drain N-channel to GND. MOSFET output pulls low if a simultaneous high on the
V
enabled SCLOUT and SDAOUT channels does not occur in
CC2:
Output Side Rise Time Accelerator (RTA) Power Supply Voltage. When powering V 45ms. In normal operation FAULT is high. Connect a pull CC2, use a supply volt- age ranging from 2.25V to 5.5V and bypass with at least up resistor, typically 10k, from this pin to the bus pull-up 0.01μF to GND. If the downstream busses are powered supply. Leave open or tie to GND if unused. from multiple supply voltages, power VCC2 from the low-
GND:
Device Ground. est supply voltage. Output side RTAs are active if VCC2 ≥ 2.25V and ACC is low or open. Grounding VCC2 disables output side RTAs. 4312f 6