SLVSDF3F MARCH 2017 – JANUARY 2019 TPSM846C23
The PMBus interface implemented in the TPSM846C23 device consists of four signal lines: CLK, DATA, ALERT, and CNTL. The electrical specifications for the hardware interface follow the specifications given in System Management Bus (SMBus) specification V2.0. The module supports both the 100-kHz and 400-kHz bus speeds. For 400-kHz operation, observe the high-power DC specifications found in section 3.1.3 of the SMBus specification.
Communication over the PMBus using packet error checking (PEC) is supported but is optional. If the master supplies CLK pulses for the PEC byte, the PEC is used. If CLK pulses are not present before a STOP, the PEC is not used. When data is transmitted over the bus, the lowest order byte is sent first, and the highest order byte is sent last. Within any byte, the most significant bit (MSB) is sent first, and the least significant bit (LSB) is sent last.
The TPSM846C23 supports the SMBALERT response protocol. This protocol is a mechanism by which a slave (the TPSM846C23) can alert the bus master, via the ALERT pin, that it must communicate. 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 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 protocol, see the SMBus specification.
The CNTL signal is an input signal on the PMBus. It can be used to turn the power-conversion function of the module on and off in conjunction with commands received over the bus. It can be configured as an active high or active low signal through the ON_OFF_CONFIG command. The CNTL signal is programmed at the factory to be an active high signal; that is, the CNTL pin must be pulled high for power conversion to occur. The customer can change this configuration if desired.
For more information, see the PMBus Interface section of the Programmable Characteristics table.