Datasheet LTC4306 (Analog Devices) - 6

LTC4306
U U U PI FU CTIO S (GN24 Package/UFD24 Package) ALERT (Pin 3/Pin 1):
Fault Alert Output. An open-drain
ADR0-ADR2 (Pins 12, 13, 14/Pins 10, 11, 12):
Three- output that is pulled low when a fault occurs to alert the State Serial Bus Address Inputs. Each pin may be floated, host controller. The LTC4306 pulls ALERT low when any tied to ground or tied to VCC. There are therefore 27 of the ALERT1-ALERT4 pins is low, when the 2-wire bus possible addresses. See Table 1 in applications informa- is stuck low, or when the Connection Requirement bit of tion. When the pins are floated, they can tolerate ±5µA of Register 2 is low and a master tries to connect to a leakage current and still convert the address correctly. downstream channel that is low. See Operation section for
READY (Pin 15/Pin 13):
Connection Ready Digital Output. the details of how ALERT is set and cleared. The LTC4306 An N-channel MOSFET open-drain output transistor that is compatible with the SMBus Alert Response Address pulls down when none of the downstream channels is protocol. Connect a 10k resistor to a power supply voltage connected to the upstream bus and turns off when one or to provide the pull-up. Tie to ground if unused. more downstream channels is connected to the upstream
SDAIN (Pin 4/Pin 2):
Serial Bus Data Input and Output. bus. Connect a 10k resistor to a power supply voltage to Connect this pin to the SDA line on the master side. An provide the pull-up. Tie to ground if unused. external pull-up resistor or current source is required.
SCL1-SCL4 (Pins 18, 23, 1, 17/Pins 16, 21, 23, 15): GND (Pin 5/Pin 3):
Device Ground. Serial Bus Clock Outputs Channels 1-4. Connect pins
SCLIN (Pin 6/Pin 4):
Serial Bus Clock Input. Connect this SCL1-SCL4 to the SCL lines on the downstream pin to the SCL line on the master side. An external pull-up channels 1-4, respectively. It is acceptable to float any pin resistor or current source is required. that will never be connected to the upstream bus. Other- wise, an external pull-up resistor or current source is
ENABLE (Pin 7/Pin 5):
Digital Interface Enable and Regis- required on each pin. ter Reset. Driving ENABLE high enables I2C communica- tion to the LTC4306. Driving this pin low disables I2C
SDA1-SDA4 (Pins 19, 22, 2, 16/Pins 17, 20, 24, 14):
communication to the LTC4306 and resets the registers to Serial Bus Data Output Channels 1-4. Connect pins their default state as shown in the Operation section. SDA1-SDA4 to the SDA lines on downstream channels When ENABLE returns high, masters can read and write 1-4, respectively. It is acceptable to float any pin that will the LTC4306 again. If unused, tie ENABLE to V never be connected to the upstream bus. Otherwise, an CC. external pull-up resistor or current source is required on
VCC (Pin 8/Pin 6):
Power Supply Voltage. Connect a each pin. bypass capacitor of at least 0.01µF directly between VCC and GND for best results.
ALERT1-ALERT4 (Pins 20, 24, 21, 9/Pins 18, 22, 19, 7):
Fault Alert Inputs, Channels 1-4. Devices on each
GPIO1-GPIO2 (Pins 10, 11/Pins 8, 9):
General Purpose of the four output channels can pull their respective pin Input/Output. These two pins can be used as logic inputs, low to indicate that a fault has occurred. The LTC4306 then open-drain outputs or push-pull outputs. The N-channel pulls the ALERT low to pass the fault indication on to the MOSFET pull-down devices are capable of driving LEDs. host. See Operation section below for the details of how When used in input or open-drain output mode, the GPIOs ALERT is set and cleared. Connect unused fault alert can be pulled up to a supply voltage ranging from 1.5V to inputs to VCC. 5.5V independent of the VCC voltage. GPIOs default to a high impedance open-drain output mode. There are GPIO
Exposed Pad (Pin 25, UFD Package Only):
Power Ground. configuration and status bits in Register 1 and Register 2. Exposed Pad may be left open or connected to device Float if unused. ground. 4306f 6