SLUSBO6C JANUARY 2014 – October 2018 TPS40425
PRODUCTION DATA.
Timing and electrical characteristics of the PMBus can be found in the PMB Power Management Protocol Specification, Part 1, revision 1.1 available at http://PMBus.org. The TPS40425 device supports both the 100-kHz and 400-kHz bus timing requirements. The TPS40425 device does not stretch pulses on the PMBus when communicating with the master device.
Communication over the TPS40425 device device PMBus interface can support the packet error checking (PEC) scheme if desired. If the master supplies CLK pulses for the PEC byte, PEC is used. If the CLK pulses are not present before a STOP, the PEC is not used.
The TPS40425 device supports a subset of the commands in the PMBus 1.1 specification. Most of the controller parameters can be programmed using the PMBus and stored as defaults for later use. All commands that require data input or output use the literal format. The exponent of the data words is fixed at a reasonable value for the command and altering the exponent is not supported. Direct format data input or output is not supported by the TPS40425 device. See the Supported PMBus Commands section for specific details.
The TPS40425 device also supports the SMBALERT response protocol. The SMBALERT response protocol is a mechanism by which a slave (the TPS40425 device) can alert the bus master that it wants to talk. The master processes this event and simultaneously accesses all slaves on the bus (that support the protocol) through the alert response address. Only the slave that caused the alert acknowledges this request. The host performs a modified receive byte operation to get the slave’s address. At this point, the master can use the PMBus status commands to query the slave that caused the alert. For more information on the SMBus alert response protocol, see the System Management Bus (SMBus) specification.
The TPS40425 device contains non-volatile memory that is used to store configuration settings and scale factors. The settings programmed into the device are not automatically saved into this non-volatile memory though. The STORE_USER_ALL command must be used to commit the current settings to non-volatile memory as device defaults. The settings that are capable of being stored in non-volatile memory are noted in their detailed descriptions.