LTC4331

21

Rev 0

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APPLICATIONS INFORMATION

PCB Layout

A ground plane layout is recommended. A 4.7F bypass

capacitor should be placed no more than 7mm away from

the VCC pin. The PC board traces connected to signals A

and B should be symmetrical and as short as possible to

maintain good differential signal integrity. Route the dif-

ferential signals A and B as an edge coupled microstrip

with a differential impedance approximately matching the

cable impedance.

Link Termination and Biasing

To minimize the transmission line reflections over the

link, a termination resistor should be connected between

pins A and B at each node. Each resistor’s value should

closely match the characteristic impedance of the differ-

ential cable to reduce reflections.

A bias resistor network should also be inserted at each

node to maintain the idle state during link turnaround

when all drivers are momentarily disabled. See Figure 20.

For DC-coupled (non-isolated) link applications, select RB

and RT2 such that 200 ≤ RB ≤ 620 and 100 ≤ RT2

≤ 110.

Isolation

Galvanically isolating the link is supported with the

LTC4331 allowing applications with safety requirements

or applications with independent ground potentials. A bias

network along with termination resistors must be used

EVENT (W0C): Events Are Set by the System and Cleared by the User

FIELD

DESCRIPTION

LINK_GOOD

The local and remote I2C networks are connected.

LINK_LOST

The local and remote I2C networks have lost link communication.

FAULT

Set if any field in the FAULT register is set by the system. Clearing this bit clears all bits in the FAULT register.

ALERT_EN (RW): Asserts ALERT if Corresponding EVENT Bit Is Set

FAULT (RO): If the FAULT EVENT Bit Is Set, at Least One of the Following Bits Is Set.

To Clear, Clear the FAULT Event Bit

FIELD

DESCRIPTION

I2C_WRITE_FAULT

An incomplete write transaction after the internal address byte or PEC error detected.

LINK_FAULT

Link communication corruption detected.

EXT_I2C_FAULT

A fault, or stuck bus recovery occurred on the remote I2C bus.

TX_BUF_OVERFLOW The transmit buffer overflowed, I2C events lost.

SCRATCH (RW)

FIELD

DESCRIPTION

SCRATCH

Used to test read/write access to the control interface.

ADDR_TRANS (RW)

FIELD

DESCRIPTION

I2C_TRANS

Incoming 7-bit I2C addresses are translated to the remote network by: AddressOUT = I2C_TRANS XOR AddressIN

CTRL (RW)

FIELD

DESCRIPTION

SW_CTRL

Sets the output value of the remote CTRL pin when CTRL_SEL is high.