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REVIEW: PMBus point-of-load DC-to-DC chip has 500-mV to 8-V output ranges

Primarion Offers Industry's First Dual-Output Digital Synchronous DC/DC Controller

PX7522 Delivers Power Conversion, Power Management and PMBus Support for Two Rails

TORRANCE, Calif.—Primarion, a mixed-signal semiconductor company that designs, manufactures and markets digital power ICs, announces the addition of the dual-output, dual-phase PX7522 to the Primarion Di-POL product family of fully programmable digital power conversion and power management ICs.

The PX7522 is a power conversion and power management IC for synchronous DC/DC converters in the telecom, datacom, computing and storage markets. The PX7522 is configured to regulate two independent outputs, or two phases in a single output mode. It supports both DCR and RDSon current sense topologies and a wide output range of 0.5V to 8V. This highly configurable control IC utilizes PMBus and on-chip non-volatile memory (NVM) for extensive user-friendly control and real-time system monitoring.

“With the introduction of PX7522, Primarion has taken another major step forward towards increasing system-level integration,” said Mohan Mankikar, president of Micro-Tech Consultants, a research and consulting firm specializing in the power electronics market. “The PX7522's higher level of flexibility, with its dual-output feature and PMBus compatibility for system communication, will enable OEMs to use this IC in a very cost-effective manner. This is precisely the type of product progression that will accelerate market adoption of digital ICs.”

The PX7522's control functions utilize digital technology, providing the ultimate in adaptable, stable and flexible solutions at an increased output load. By incorporating an industry standard I2C PMBus serial interface for control and monitoring, Primarion enables the power supply designer to quickly optimize designs and monitor real-time system performance.

“The PX7522 and the Di-POL product family address two aspects that are becoming increasingly important to OEMs; the first is time to market and the second is simple system-level communications,” said Deepak Savadatti, vice president of marketing for Primarion. “A complete system can quickly and easily be built around the PX7522 and other members of the Di-POL product family with a simple graphical user interface (GUI). The GUI enables designers to perform design, analysis and optimization without having to devote time to software programming. We are excited to be able to bring such a complete solution to the market.”

Configurations for the PX7522 are easily loaded, edited and saved to NVM over the device's I2C serial interface using Primarion's GUI. With configurations stored on the IC, the controller can perform real-time adjustments to the designer's previously configured settings and thereby optimize performance accuracy, without the delay of accessing outside memory storage.

With other technologies, many of these configurable functions would typically require an external microcontroller. The extensive flexibility offered by the fully digital control, PMBus interface and user-friendly GUI allows optimization of the PX7522's power management performance within an already existing system.

The PX7522 operates on a single +5V supply and has a switching frequency range of 150KHz to 1MHz. Accurate sharing between phases (in a single mode operation) enables the flexibility to support multi-phase operation for increased power requirements. The PX7522 provides superior accuracy through internal calibration that measures and corrects system-level current sense error sources upon startup. The programmable current sense temperature compensation allows the designer to tailor the response for the best accuracy over temperature.

With innovative easy-to-use solutions, offering cost savings and improved system-level performance, Primarion continues to drive the future of digital power management and is proving to be the IC vendor of choice for manufactures in the telecom, datacom, computing, storage and graphics markets.

Summary of Features:

o “Dual-loop” operation: supports two independent outputs at different voltage levels with single-phase control for each output

o “Single-loop” operation: supports a single output with one or two phases. Capable of current sharing and frequency sync with other controllers in the family

o Wide output range: 0.5V to 8V

o Supports both DCR and RDSon current sense topologies with digital temperature compensations

o Compatible with both tri-state and non-tri-state FET drivers

o Real-time current, temperature and input voltage sense telemetry

o Extensive fault protection and reporting with user-configurable fault behavior

o Digital control loop and active voltage positioning (AVP)

o Sequencing, margining and tracking of the output voltage over the serial interface

o Configurable PWM generator

o Start-up into pre-biased load

o PMBus-compatible serial interface (library of 60 core PMBus commands)

o Internal voltage and temperature referencing

o Internal oscillator (no external reference required)

Availability

Already sampling with top-tier customers, Primarion's PX7522 is available for general sampling this quarter. The PX7522 is available in a RoHS-compliant, 6mm-x-6mm 40-lead QFN package.

More information about PX7522 is available by contacting Primarion at (866) 321-7746 or by visiting the company's Web site at http://www.primarion.com.

As you can determine from the comprehensive press statement (on the left), fabless mixed-signal IC company Primarion 's latest Di-POL (D igital i ntegrated Point-of-Load ) PX7522 power conversion IC—for synchronous DC-to-DC converter POL applications—is overflowing with features.

It's also apparent that Primarion is addressing inflection points in the industry, with respect to power conversion and power management, especially system-communicative devices.

Paper Tiger?

Unfortunately, the company is tight-lipped about detailed specs for this new IC, and will apparently only release an engineering datasheet to pre-qualified customers. The rest of us get an “advanced product brief,” which presumably means the chip isn't fully characterized.

There's also no mention of pricing.

In any case, Primarion's PX7522 IC, in sampling (but only to top-tier prospects), is configurable with two loops and two totally independent PWM (pulse width modulation) outputs. Prior to this device, a typical approach to a 2-rail system would usually demand a microcontroller (for monitoring), a sequencer chip, a pair of analog PWM controllers, and two power stages.

Current-Sense Options

The PX7522 can be used in high-current buck converters, and as the press statement notes, with either resistive or FET (field effect transistor) RDS on current-sensing. For DCR current sensing, the IC's output range spans 500-mV to 3.6-V. If you use it in an RDS on sense circuit, the output range extends to 8-V.

The output voltage can also be fine trimmed with 1.6-mV resolution, and coarse set with 12.5-mV resolution.

This diagram shows a typical application, using the company's PX3511 FET driver chips.


Click to view

In its dual-loop mode, the PX7522 supports two independent outputs with single phase control for each. In single-loop mode, the PX7522 can provide a single output rail with one or two phases. Notably, up to four phases can be interleaved for multi-phase operation.

Uses Power Management Bus

The PX7522's PMBus (Power Management Bus) POL power regulation supports current sharing to balance power supply currents. For those of you not familiar with it, the PMBus is an open royalty-free standard power-management protocol with a fully defined command language that facilitates communication with power converters and other devices in a power system.

The PMBus protocol is implemented using the industry-standard SMBus (System Management Bus) serial interface. This interface supports programming, control, and realtime monitoring of power conversion devices. What's more, the standard supports communication between devices based on both analog and digital technologies.

Significantly, PMBus devices can start up safely without bus communication, and can be used with or without a system manager/controller. Moreover, PMBus devices can be programmed once at time-of-manufacture, and then operate without any further bus communication.

In the PX7522, digital circuitry is used to implement control functions, with the PMBus serial hooks supporting realtime system control. Through the serial interface, you can optimize your design, while monitoring system performance—without having to make any hardware adjustments or ECO s.

The PMBus interface lets you set voltage and make adjustments, and handle tracking, sequencing, and margining. PMBus also lets you query voltage, current, and temperature faults, and implements fault handling.

Fault Detection Protection, Reporting

Fault detection and protection, and fault reporting, is implemented with two user-configurable output pins per loop. These pins let you monitor input under-voltage and input over-voltage, as well as output under-voltage and output over-voltage. The fault detection can also detect a high-side short, and implements peak, average, and constant-current limit protection.

The PX7522 chip's protection circuitry also signals internal and external temperature alert and shut-down limits, time-outs, and the IC's calibration range. The fault protection circuits also check for phase sync reference detect/lock, and even ride herd on any PMBus protocol violations.

Internal Calibration

The PX7522 ensures accuracy through internal calibration that measures and corrects current-sense error sources on start-up. Moreover, the PX7522 has programmable current-sense temperature compensation. It permits you to tailor the IC's response for best accuracy over temperature.

The IC's digital control loop, and what Primarion calls AVP (active voltage positioning) implements a digital control loop with familiar PID (proportional, integral, derivative) compensation. Other features include soft-starting (into a pre-biased load), and non-volatile memory that can store custom configurations, ATE trim values, and the like.

Briefly mentioned in Primarion's press release is the company's GUI -based (graphical user interface) development software. It lets you input system parameters such as output voltage, scale factors, the number of phases, and bus addresses, by rail. You can also input time delays, set system faults and behaviors, and generate graphs, to name just a few functions within this software package.

Predecessor Silicon

Note that Primarion also offers two predecessor Di-POL devices to the PX7522. Both of these are claimed to be in volume production.

The company's PX7510 chip is a configurable POL controller, but for single-phase buck converter circuits operating at switching frequencies from 150-kHz to 1.5-MHz. Using it, up to four Di-POL family controllers can be synchronized for multi-phase operation. The PX7510 also uses PMBus-compliant regulation, and supports current sharing of multiple chips to balance power supply currents. The PX7510's output voltage range extends from 700-mV VCC (minus 0.9-V).

Primarion's PX7520 IC has two PWM outputs. It's also for current buck converter topologies. Like the PX7510, up to four controllers can be synced.

For more details contact Vice President of Marketing Deepak Savadatti at Primarion, 2780 Skypark Drive, Suite 100, Torrance, Calif. 90505. Phone: 310-602-5500. Fax: 310-602-5559. E-mail:sales@primarion.com or deepak.savadatti@primarion.com

Primarion , 310-602-5500, www.primarion.com

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