LTC3882-1
99
Rev A
Figure 51 shows an example of the Write Word format used to set an
ALERT
mask, in this case without PEC. The bits
in the mask byte align with bits in the specified status register. For example, if the STATUS_TEMPERATURE command
code is sent in the first data byte, and the mask byte contains 0x40, then a subsequent External Overtemperature Warn-
ing would still set bit 6 of STATUS_TEMPERATURE but not assert
ALERT
. All other supported STATUS_TEMPERATURE
bits would continue to assert
ALERT
if set.
PMBus COMMAND DETAILS
(Fault Response and Communication)
Figure 52. Example of Reading SMBALERT_MASK
Figure 51. Example of Setting SMBALERT_MASK
SMBALERT_MASK cannot be applied to STATUS_BYTE, STATUS_WORD, MFR_COMMON or MFR_PADS_LTC3882-1.
Factory default masking for applicable status registers is shown below. Providing an unsupported command code to
SMBALERT_MASK will generate a CML for Invalid/Unsupported Data.
SMBALERT_MASK Default Setting: (Refer Also to Figure 2)
STATUS RESISTER
ALERT Mask Value MASKED BITS
STATUS_VOUT
0x00
None
STATUS_IOUT
0x00
None
STATUS_TEMPERATURE
0x00
None
STATUS_CML
0x00
None
STATUS_INPUT
0x00
None
STATUS_MFR_SPECIFIC
0x11
Bit 4 (internal PLL unlocked), bit 0 (
FAULT
low)
MFR_FAULT_PROPAGATE_LTC3882-1
The MFR_FAULT_PROPAGATE_LTC3882-1 command determines events that cause
FAULT
to be asserted. Setting a
bit in this register to a one allows the specified condition to assert the
FAULT
output for that channel.
FAULT
is not as-
serted by a fault, even if set to propagate, if that FAULT_RESPONSE is set to Ignore. The state of SMBLALERT_MASK
does not affect
FAULT
propagation.
of any supported status register, again without PEC.
P
1
SLAVE
ADDRESS
SMBALERT_MASK
COMMAND CODE
STATUS_x
COMMAND CODE
W A
A
S
7
8
8
1
8
1
1 1
1
1
A
A
MASK BYTE
38821 F51
SLAVE
ADDRESS
SMBALERT_MASK
COMMAND CODE
BLOCK COUNT
(= 1)
W A
A
S
7
8
8
1
STATUS_x
COMMAND CODE
8
1
1 1
1
1
A
A
…
Sr
1
BLOCK COUNT
(= 1)
A
NA P
38821 F52
A
8
8
1
1 1
1
MASK BYTE
SLAVE
ADDRESS
7
R
1