LM5056 datasheet(40/49 Pages) TI2

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Alert Mask D8h

From PMBus

From other

fault inputs

ARA Auto Mask

Set

Clear

Fault Condition

ARA Operation Flag Succeeded

Clear_Fault Command Received

SMBA

LM5056, LM5056A

SNVS827A – OCTOBER 2012 – REVISED APRIL 2013

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SMBA Response

The SMBA effectively has two masks:

1. The Alert Mask Register at D8h, and

2. The ARA Automatic Mask.

The ARA Automatic Mask is a mask that is set in response to a successful ARA read. An ARA read operation

returns the PMBus address of the lowest addressed part on the bus that has its SMBA asserted. A successful

ARA read means that THIS part was the one that returned its address. When a part responds to the ARA read, it

releases the SMBA signal. When the last part on the bus that has an SMBA set has successfully reported its

address, the SMBA signal de-asserts.

The way that the LM5056/LM5056A releases the SMBA signal is by setting the ARA Automatic mask bit for all

fault conditions present at the time of the ARA read. All status registers still show the fault condition, but it is not

generated and SMBA on that fault again until the ARA Automatic mask is cleared by the host issuing a

CLEAR_FAULTS command to this part. This should be done as a routine part of servicing an SMBA condition on

a part, even if the ARA read is not done. Figure 20 depicts a schematic version of this flow.

Figure 20. Typical Flow Schematic for SMBA Fault

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LM5056 Datasheet(PDF) 40 Page - Texas Instruments