LTC4306

4306f

6

ALERT (Pin 3/Pin 1): Fault Alert Output. An open-drain

output that is pulled low when a fault occurs to alert the

host controller. The LTC4306 pulls ALERT low when any

of the ALERT1-ALERT4 pins is low, when the 2-wire bus

is stuck low, or when the Connection Requirement bit of

Register 2 is low and a master tries to connect to a

downstream channel that is low. See Operation section for

the details of how ALERT is set and cleared. The LTC4306

is compatible with the SMBus Alert Response Address

protocol. Connect a 10k resistor to a power supply voltage

to provide the pull-up. Tie to ground if unused.

SDAIN (Pin 4/Pin 2): Serial Bus Data Input and Output.

Connect this pin to the SDA line on the master side. An

external pull-up resistor or current source is required.

GND (Pin 5/Pin 3): Device Ground.

SCLIN (Pin 6/Pin 4): Serial Bus Clock Input. Connect this

pin to the SCL line on the master side. An external pull-up

resistor or current source is required.

ENABLE (Pin 7/Pin 5): Digital Interface Enable and Regis-

communication to the LTC4306 and resets the registers to

their default state as shown in the Operation section.

When ENABLE returns high, masters can read and write

bypass capacitor of at least 0.01

and GND for best results.

GPIO1-GPIO2 (Pins 10, 11/Pins 8, 9): General Purpose

Input/Output. These two pins can be used as logic inputs,

open-drain outputs or push-pull outputs. The N-channel

MOSFET pull-down devices are capable of driving LEDs.

When used in input or open-drain output mode, the GPIOs

can be pulled up to a supply voltage ranging from 1.5V to

high impedance open-drain output mode. There are GPIO

configuration and status bits in Register 1 and Register 2.

Float if unused.

ADR0-ADR2 (Pins 12, 13, 14/Pins 10, 11, 12): Three-

State Serial Bus Address Inputs. Each pin may be floated,

possible addresses. See Table 1 in applications informa-

tion. When the pins are floated, they can tolerate

±5µA of

leakage current and still convert the address correctly.

READY (Pin 15/Pin 13): Connection Ready Digital Output.

An N-channel MOSFET open-drain output transistor that

pulls down when none of the downstream channels is

connected to the upstream bus and turns off when one or

more downstream channels is connected to the upstream

bus. Connect a 10k resistor to a power supply voltage to

provide the pull-up. Tie to ground if unused.

SCL1-SCL4 (Pins 18, 23, 1, 17/Pins 16, 21, 23, 15):

Serial Bus Clock Outputs Channels 1-4. Connect pins

SCL1-SCL4 to the SCL lines on the downstream

channels 1-4, respectively. It is acceptable to float any pin

that will never be connected to the upstream bus. Other-

wise, an external pull-up resistor or current source is

required on each pin.

SDA1-SDA4 (Pins 19, 22, 2, 16/Pins 17, 20, 24, 14):

Serial Bus Data Output Channels 1-4. Connect pins

SDA1-SDA4 to the SDA lines on downstream channels

1-4, respectively. It is acceptable to float any pin that will

never be connected to the upstream bus. Otherwise, an

external pull-up resistor or current source is required on

each pin.

ALERT1-ALERT4 (Pins 20, 24, 21, 9/Pins 18, 22,

19, 7): Fault Alert Inputs, Channels 1-4. Devices on each

of the four output channels can pull their respective pin

low to indicate that a fault has occurred. The LTC4306 then

pulls the ALERT low to pass the fault indication on to the

host. See Operation section below for the details of how

ALERT is set and cleared. Connect unused fault alert

Exposed Pad (Pin 25, UFD Package Only): Power Ground.

Exposed Pad may be left open or connected to device

ground.