Since EDN's cover story on digital power controllers in May, two more digital power controller ICs have appeared (and at least one more is rumored to debut shortly). Primarion's PX7520, a new member of its existing Di-POL family, does both power control and management digitally, while Maxim's MAX8688 is a hybrid approach in that the PWM control loop is still analog but the power management and communication are digital. When added to the existing digital control and management parts from Texas Instruments, Zilker Labs, and Silicon Labs, this influx of parts continues to serve as a good a good indicator that the serious players in the analog world see digital power as being worth their serious attention.

Like the previous member of Primarion's Di-POL family of digital power controllers, the PX7510, the PX7520 is PID-control-loop based, putting Primarion firmly in the camp of those who see full digital power as necessary and inevitable for the new generation of power subsystems for telecom and datacom apps, which rely on huge banks of power-hungry servers. The news about the 7520 is that it offers dual-phase control capability at a switching frequency of 150KHz to 2MHz in addition to the existing Di-POL family features such as a PMBus/I2C serial interface, including a library of 60 core PMBus commands, internal voltage and temperature referencing, and an internal oscillator. Primarion hasn't officially announced the price yet.

The MAX8688 from Maxim serves designers seeking to add digital power communication and management capability to legacy analog power supplies. It's really a toe-in-the-water approach for Maxim which sees the digital power market in much less rosy terms than companies like Primarion, going so far as to say in the product announcement that, "Although some argue that digital PWMs provide higher efficiency, faster transient response, and lower EMI, no factual data support this." The chip interfaces with the system controller through the PMBus, sending and receiving system-level control queries and commands such as peak temperature, output current, and output voltage data for all power subsystem modules under its control, allowing the system controller to poll each module at fixed intervals and log the information for field failure analysis. The chip can tap into the enable node, the feedback node, and/or the reference input of the power supply's analog control circuitry to provide voltage tracking and sequencing, as well as setting the output voltage at within ±0.2% accuracy over the industrial temperature range. Prices start at $1.95