powerZONE Products for the week of June 2, 2003
Summit Microelectronics Says . . .
Summit Microelectronics Six-Channel Controller Delivers
Highly Accurate Intelligent Power Management
Margining And Sequencing Supplement The Device's Closed-Loop
Active Control Capability
Summit Microelectronics has raised the bar in intelligent power management devices with the introduction of the SMM665, a six-channel active controller that includes sequencing and margining functions. Ideal applications for the device include networking and communications equipment where carrier-class availability (ie 99.999% up-time) is essential.
The SMM665 utilizes a new engineering concept created by Summit called Active DC Output Control (ADOC). The ADOC function intelligently maintains the output voltage of up to six DC/DC converters on the user's board, dramatically improving voltage accuracy in normal system use -- down as low as 0.2% of voltage output.
In addition, the SMM665 is highly useful in initial turn-on of the board during production to perform "margining." This is the temporary adjusting of each of the six DC/DC converter supply voltages up to +/-10% in any combination -- so that sensitivity of the system to power supply changes can be determined. Margining can be performed either just on prototype boards before production launch, or can be done board-by-board in production to test for manufacturing variations.
Finally, the SMM665 can be configured to sequence up to six voltage supplies in any order during both power-up and power-down transitions. This sequencing can be set by the user to cascade each supply as the prior supply completes its transition, therefore relieving the user of the need to calculate the slew rate of each supply voltage depending on its loading, and specifying a safe delay time before the next supply can be actuated. This guarantees that unwanted crossover will not occur.
The SMM665 can be accessed by the popular I²C bus to exercise complete control of the board's power characteristics. This can be done during production, or each time that the board is booted up, or during normal operation "on the fly."
Design Software And Programmer For Prototype Development
To speed user product development using the SMM665 and Summit's other programmable products, Summit offers customers the SMX3200 programming system. This is a complete development tool that lets designers easily manipulate the characteristics of their system. The SMX3200 design kit includes menu-driven Microsoft Windows graphic user interface (GUI) software to automate programming tasks and also includes all necessary hardware to interface to the parallel port of a laptop or PC.
Once a user completes design and prototyping, SMX3200 automatically generates
a HEX data file that can be transmitted to Summit for review and approval.
Summit than assigns a unique customer identification code to the HEX file
and programs the customer's production devices prior to final electrical
test operations. This ensures that device will operate properly in the end
application.
analogZONE Says...
One of the definitions of an analog engineer must be an built-in fascination with all things accurate. Seeing a three-digit digital voltmeter lock its reading on a voltage rail with stunning accuracy is way up there on an E-ride classification - and that's what Summit is achieving with this highly-innovative part. Absolute accuracy depends on the reference used but an external 0.1% reference can yield ±0.2% while the internal reference can give ±0.4%.
The system works by feeding the outputs of up to six dc-dc converters back to an on-chip 10-bit ADC where the conversion is compared with what has been programmed for each channel. Any error results in the active dc control stages changing the trim voltage to the converter blocks. Voltages anywhere from 0.3 V to 5.5 V can be set using a 1.25-V reference.
Beyond accuracy, sequencing of supplies is becoming more and more critical in multi-voltage processors/DSPs and combination products. The sequence of power-up of the supplies can be set in the SMM665 in any order, with the power-down either in exactly the same order, or in the reverse order. Power-on can be initiated through a dedicated pin or through the I2C control. That control monitors all the voltages, including the rail(s), and can also monitor the ADC conversion results.
As end products become more and more competitive manufacturers are looking for ways to margin the supply rails so that the product works - maybe just works - with the minimum amount of power being used. Here each supply can be margined by up to ±10% of the converters' nominal outputs. Apart from margining for minimum power it also means that a dc-dc converter "near" the voltage you want can be used, potentially easing supply line problems.
There is also an on-chip temperature sensor, which can be replaced by an external sensor, used as an additional ADC input and a second general-purpose ADC input is also available. A 12-V input point (with internal voltage regulators) is provided for industrial use, but a separate drain supply pin allows operation from 2.7 V to 5.5 V, depending on the dc-dc conversion requirements. Programmable RESET, HEALTHY, and FAULT functions are also provided. There is 4-kbit of general-purpose non-volatile memory also on chip.
In many ways this is an engineer's part but there is absolutely no doubt that there are a myriad of applications out there and Summit needs to get the message out that it is available. The pre-programming service that the company is offering will migrate a lot of users who might otherwise be a little leery of margining fully in their applications. I think it will do extremely well and is a cost-effective way of designing highly-accurate multiple rail solutions without resorting to ASICs. The question of whether six-rail control is enough will be heard by Summit quite early on, and we may see a larger number of channels in the future. With I2C control it should also be possible to fairly simply multiplex additional devices to provide more voltage rails.
The SMM665 is in production in a TWFP-48 and is priced at $9.00 in 10-k piece lots. An evaluation card with the controller and six dc-dc converters is available with a "plug and play" programming port.
Data Sheet available on request. from the manufacturer.