ADT7467ARQZ-R7 datasheet(14/77 Pages) ONSEMI

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ADT7467

Rev. 3 | Page 14 of 77 | www.onsemi.com

Alert Response Address

Alert response address (ARA) is a feature of SMBus devices that

allows an interrupting device to identify itself to the host when

multiple devices exist on the same bus.

The SMBALERT output can be used as either an interrupt

output or an SMBALERT. One or more outputs can be

connected to a common SMBALERT line connected to the

master. If a device’s SMBALERT line goes low, the following

procedure occurs:

SMBALERT is pulled low.

The master initiates a read operation and sends the alert

response address (ARA = 0001 100). This is a general call

address that must not be used as a specific device address.

The device whose SMBALERT output is low responds to

the alert response address, and the master reads its device

address. The address of the device is now known and can

be interrogated in the usual way.

If more than one device’s SMBALERT output is low, the

one with the lowest device address has priority in accor-

dance with normal SMBus arbitration.

Once the ADT7467 has responded to the alert response

address, the master must read the status registers. The

SMBALERT is cleared only if the error condition is absent.

SMBus TIMEOUT

The ADT7467 includes an SMBus timeout feature. If there is no

SMBus activity for 35 ms, the ADT7467 assumes that the bus is

locked and releases the bus. This prevents the device from

locking or holding the SMBus in anticipation of receiving data.

Some SMBus controllers cannot handle the SMBus timeout

feature, so it can be disabled.

Configuration Register 1 (0x40)

<6> TODIS = 0, SMBus timeout enabled (default)

<6> TODIS = 1, SMBus timeout disabled

ADT7467ARQZ-R7 Datasheet(PDF) 14 Page - ON Semiconductor