TPS546C23 Datasheet, PDF (40/97 Pages) Texas Instruments – 4.5-V to 18-V, 35-A Stackable Synchronous Buck Converters With PMBus

TPS546C23
SLUSCC7A – JULY 2016 – REVISED AUGUST 2016
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NOTE
The command uses the SMBus Write Word command protocol to overlay a “mask byte”
with an associated/designated status register. It uses the SMBus Block Write/Block Read
protocol – with a block size = 1, to read the mask settings for any given status register. If
the host in the Block_Count field of the Block Write portion sends a block size unequal to
1 the device returns a NACK. The device always returns a Block Count of 1 upon reads of
SMBALERT_MASK.
The bits in the mask byte align with the bits in the corresponding status register. For example, if the
STATUS_TEMPERATURE command were sent with the mask byte 01000000b, then an Overtemperature
Warning condition would be blocked from asserting SMBALERT. Please refer to the PMBus v1.3 specification -
section 15.38 (SMBALERT_MASK Command) and the SMBus specification Block Write/Block Read protocol for
further details.
There are 19 maskable SMBALERT sources in the TPS546C23. Each of these 19 status conditions has an
associated EEPROM backed mask bit. These sources are represnted and identified in the status register
command descriptions by a particular status bit denoted as having EEPROM backup (for example a bit access of
r/w^E). Writes and reads to SMBALERT_MASK command code accepts only the following as valid STATUS_x
command codes:
• STATUS_WORD
• STATUS_VOUT
• STATUS_IOUT
• STATUS_INPUT
• STATUS_TEMPERATURE
• STATUS_CML
• STATUS_MFR_SPECIFIC
Attempting to write a mask byte for any STATUS_X command code other than this list causes the device to set
the cml bit in the STATUS_BYTE and the ivd bit in the STATUS_CML registers, and triggers SMBALERT.
Attempting to read a mask byte for any STATUS_x command code other than this list returns 00h for the mask
byte. Refer to these individual command descriptions for further details on their specific SMBALERT masking
capabilities.
There is 1 unique status bit in the TPS546C23 that warrants special clarification: PGOOD_Z
(STATUS_WORD[10]) is maskable as an SMBALERT source through SMBALERT_MASK commands to
STATUS_WORD. If the user wants to write, or read, the mask bit for PGOOD_Z, the user must put 79h in the
STATUS_x COMMAND_CODE field of the SMBALERT_MASK command. PGOOD_Z SMBALERT_MASK bit
default to 1.
7.6.11 VOUT_MODE (20h)
The PMBus specification dictates that the data word for the VOUT_MODE command is one byte that consists of
a 3-bit mode and 5-bit exponent parameter, as shown below. The 3-bit mode sets whether the device uses the
Linear or Direct modes for output voltage related commands. The 5-bit parameter sets the exponent value for the
linear data mode. The mode and exponent parameters are fixed and do not permit the user to change the
values.
For loop slave device, this command cannot be accessed. Any writes to this command will be ignored. An
attempt to read or write this command will result in a NACK’d command, the reporting of an IVC fault, and
triggering of SMB_ALERT.
COMMAND
Bit Position
Access
Function
Default Value
VOUT_MODE
7
6
5
4
3
2
1
0
r
r
r
r
r
r
r
r
Mode
Exponent
0
0
0
1
0
1
1
1
40
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