Precision control for power subsystems

A new solution improves the performance and reliability of enterprise server, datacommunications and telecommunications equipment through precision power subsystem control.

Summit Microelectronics has a new way to improve the performance and reliability of enterprise server, datacommunications and telecommunications equipment through precision power subsystem control.

The SMM150 is a digital power supply marginer that can easily be designed to work with either point-of-load (POL) DC/DC power modules or monolithic embedded DC/DC convertors.

The device performs two essential functions: trimming the output voltage of the power supply to +/-0.5% accuracy, and margining the output voltage above or below the nominal setpoint from +300mV to VDD.

Designed for applications where product quality is paramount to avoid costly downtime, the SMM150 is ideal for servers, switches, routers and basestations.

The SMM150 uses a precise onboard reference, a 10bit ADC and control loop to measure and control the output voltage of the DC/DC convertor.

When a margin/trim request is received, the SMM150 will adjust the trim pin or feedback pin of the convertor, to provide the correct margined output voltage from +300mV to VDD.

During this period the SMM150 controls the output voltage very accurately to +/-0.5% using Summit's Active DC Output Control (ADOC) technology.

The SMM150 can margin by either a remote I2C command or by driving the margin up/down pins.

Additionally the SMM150 provides status flags- 'Ready' provides an indication if the margined voltage has been reached, and 'Fault' provides an error flag.

Accurate power regulation and control in advanced digital systems is more critical than ever because the signal integrity of high-performance digital semiconductors is increasingly dependent on the quality of associated power supplies.

Unfortunately, most off-the-shelf power supplies cannot provide this level of performance on their own.

High-accuracy voltage trimming and margining is needed to extract the most performance and reliability from these digital systems.

Accuracy in margining is especially critical - for example if a DC/DC convertor is 2% below its nominal set point due in inherent error and then it is margined to -5%, then the test will be conducted at -7% instead of the -5% as specified.

Additionally, as the number of voltage rails for these systems continue to increase, the difficulty in testing for worst-case combinations of power supply tolerances is dramatically compounded.

Finding components and/or subsystems that do not meet these worst-case conditions in development or production is becoming vital to ensure product quality, and reduce field failure return rates.

The SMM150 is programmed via the I2C bus to set margin high and low voltages, these values are held in a nonvolatile store on the device and are absolute values.

By storing absolute values and having a digital control loop, the engineer can guarantee the board is tested to the correct voltage unlike other passive solutions on the market.

The 10bit ADC can be used to monitor the absolute value of the DC/DC output via the I2C bus for system diagnosis purposes.

The I2C bus is also used to access the electrically erasable memory integrated into the SMM150.

Summit provides an evaluation system SMM150EV which comprises of an evaluation board, a programming cable, and graphical user interface software, which is also downloadable from the website.

The SMB150 operates directly from +2.7 to +5.5V and the operating temperature range is 0 to +70C.

It is available in a 5 x 5mm QFN-28 or a 2.7 x 3.6mm CSP package that are lead-free and RoHS-standard compliant.

Available now in production quantities, the device is priced at $2.60 for QFN-28 packaged units in quantities of 1000 units (CSP package pricing available from factory).

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