Do you need to monitor system operation or collect data about the power supply? If the answer is yes, then PMBus is for you.
PMBus is an industry-standard protocol that facilitates 2-wire digital communication with power converters and other devices in a power system. Using PMBus in your system increases power density and reliability of the power supply, as well as optimizing component performance and efficiency with reduced design time, risk and cost. PMBus enables you to monitor current, voltage, and temperature as well as report and log faults. Through PMBus, the designer is able to configure the IC on the fly by storing new default parameters in the nonvolatile memory, thus allowing new designs to be generated and validated in a shorter period of time.
TI supports a broad range of PMBus based DC/DC converters, point-of-load (POL) single-/multi-output and single-/multi-phase pulse-width modulation (PWM) controllers, hot swap ICs, sequencers/managers and isolated PWM controllers. With multiple options, it can be challenging to select the correct device for your application.
Figure 1. TI’s PMBus power chain diagram.
TI’s PMBus controllers and converters are offered in two different control mode topologies: an analog control loop, which is often the fastest, and a digital control loop, which can add delays to the system due to its clock and proportional-integral-derivative (PID) circuitry. Many of TI’s PMBus D-CAP™, D-CAP2™ and D-CAP3™ based controllers and iFETs feature an analog control loop, which allows for faster load transient response and no loop compensation.
Integrating the driver onto the chip does not always provide the optimal power partitioning because it limits the switching frequency (Fsw) and increases power dissipation in the PWM controller. TI has many devices that support a driverless architecture, which was first implemented in TI’s multiphase PWM controllers in 2013. This architecture enabled an impressive power density increase and board area reduction (up to 3x area reduction) due to the increased switching frequency capability. It also allowed the manufacturer to heat sink the large bottom pad of the complementary power stage directly into the PCB internal ground layers for easier layout.
PMBus examples for the different architectures:
Multiphase PWM controllers (driverless):
Multiphase PWM controllers (with gate drivers):
TPS40422 dual phase, dual output multiphase PWM controller features voltage mode control with feed forward.
iFET converters (with integrated MOSFETs):
Table 1. TI’s PMBus SWIFT DC/DC converter solutions.
Table 2. TI’s PMBus PWM controller solutions
I hope this helps you understand the various PMBus based products that TI offers while helping you to select the correct device for your application.
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