Summit Microelectronics Device Minimizes Power-Supply Differential of Four Channels

9/9/2002 - Summit Microelectronics announced that it has introduced the second member of its innovative TrakkerTM power supply controller family. The new SMT4214 four-channel tracking power-supply controller complements the Summit SMT4004 power supply controller, which has seen widespread use in high-end communications and networking systems since its introduction in 2001. The SMT4214 is targeted specifically at broadband access applications such as DSLAMs, mini-DSLAMs and access routers which require differential supply tracking, expandability and low cost.

"Our broadband access customers have demanding and varied requirements in terms of port densities, power levels, and protocols supported," said Art Swift, vice president of marketing at Summit. "We expect that the flexibility of a programmable tracking device such as the SMT4214 will prove invaluable to these customers in shortening their design cycles as they bring their new designs, based on the most advanced DSL chipsets, to market."

The SMT4214 is ideally suited for controlling and monitoring the multiple core and I/O voltages required by the advanced DSP chipsets used in broadband access systems. For example, advanced ADSL chipsets typically require multiple supply voltages (e.g. 1.5V for the DSP core, 3.3 Volts for I/Os, and 5V for the AFE). Manufacturers of such advanced devices often specify power-on and power-off sequence requirements for the core and I/O voltages in order to prevent fault conditions or inadvertent damage to the chipsets. In many cases, the chipset manufacturer will also specify the maximum differential voltages allowed between the various supplies required by the chipset.

Using the Summit SMT4214, access system designers can minimize power supply differential during power-on and power-off, and directly control on-off order and under-voltage thresholds of as many as four system power supply channels. In addition, the SMT4214 includes a simple 4-wire master/slave interface which allows multiple SMT4214 devices to be used together to track and monitor up to 32 power supplies. In this configuration, the slave devices use the VRLINK output from the master as their ramp reference to enable tracking between all the power supplies in the system.

In the typical DSLAM line card, the card side voltages (5V, 3.3V, 2.5V, 1.8V, etc.) are derived from the higher bus side voltage using low-cost DC:DC converters or LDO regulators. The SMT4214 is designed to monitor the voltages on both the bus side and card side to ensure that there are no under-voltage fault conditions present. The under-voltage thresholds are programmable in 20mV increments from 0.9V to 6.0V.

If a card side device moves into an under-voltage condition, the SMT4214 can be programmed to signal a fault condition or an interrupt request. The trigger sources include both the under-voltage monitors and programmable reset timers. In addition, the SMT4214 can be programmed to immediately initiate forced shutdown if a fault is detected. In normal operation, the SMT4214 can also be programmed to track down the supplies in the same fashion as during the power-on sequence.

The SMT4214 provides high-side drive outputs to directly drive the MOSFETs which in turn gate the voltages applied to the card-side chipset and logic. The SMT4214 can be configured to "softstart" each voltage channel with a controlled MOSFET gate slew rate of 500V/s, or alternately, the channels can be configured to "track" each other during power-on to minimize the differential voltage between the supply rails. A typical DSLAM line-card design might use the softstart function to turn on a DC:DC converter or group of LDOs, and use the tracking function to control the voltages that are applied to the card-side chipset and logic.

Programming is performed over an industry-standard I2C-bus, 2-wire serial data interface. It allows configuration of the device, real-time control of the power-on/power-off processes and instant access to the power supply status of the application circuit. The bus also interfaces the host to the device's nonvolatile memory block and the programmable configuration registers.

Design Kit for Automated Prototype Development
To speed design and product development using the SMT4214, Summit offers customers the SMX3200 programming system. As with all Summit design kits, the SMX3200 kit is a complete development tool that lets designers easily manipulate analog 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 company completes the design prototyping phase, the kit software automatically generates a HEX data file that can be transmitted to Summit for review and approval. Summit then 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. The design kit software can be downloaded today from Summit's website.

Packaging, Price and Availability
Summit's highly-integrated, programmable analog technology allows the company to offer the SMT4214 in a space-saving 28-lead SSOP package. Sample quantities are available now, and production is planned for September. The SMT4214 is priced at $7.15 each in quantities of 10,000 devices.

About Summit (
Summit Microelectronics supplies semiconductors that manage the power functions in communications, networking, storage and server systems. Using Summit's programmable analog technology, customers can achieve carrier-class availability, the highest standard of reliability available today for telecommunications, data communications and Internet applications. Founded in 1997, Summit is headquartered in Campbell, California. The Company is ISO 9001 certified.

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