lm25066apsqx National Semiconductor Corporation, lm25066apsqx Datasheet - Page 46

• Manufacturer Part Number: lm25066apsqx
• Description: Lm25066a System Power Management And Protection Ic With Pmbus
• Manufacturer: National Semiconductor Corporation

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SMBALERT Response
The SMBALERT 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 SMBALERT 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 SM-
BALERT signal. When the last part on the bus that has an
FIGURE 20. Typical Flow Schematic for SMBALERT Fault
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SMBALERT set has successfully reported its address, the
SMBALERT signal will de-assert.
The way that the LM25066A releases the SMBALERT signal
is by setting the ARA Automatic mask bit for all fault conditions
present at the time of the ARA read. All status registers will
still show the fault condition, but it will not generate and SM-
BALERT on that fault again until the ARA Automatic mask is
cleared by the host issuing a Clear Fault command to this part.
This should be done as a routine part of servicing an SM-
BALERT condition on a part, even if the ARA read is not done.
Figure 20
depicts a schematic version of this flow.
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