Digital power IC combines power conversion and management

By Margery Conner, Technical Editor -- 10/11/2005

Going head-to-head with offerings from Texas Instruments and Silicon Labs, new-kid-on-the-block Zilker Labs has introduced the ZL2005, a digital-power-control IC that combines power-conversion functions with power-management capabilities.

Power-conversion functions generally consist of taking a higher voltage to a lower voltage, while power management comprises such decisions as how fast power supplies turn on and in what sequence, as well as housekeeping chores such as what happens when a supply gets too hot.

Jim Templeton, Zilker Labs founder and vice president of marketing, contrasted Zilker's approach with competing products: "The industry treats conversion and management as two separate issues, because there's this mindset that power conversion needs to be an analog function, and power management is better as a digital function." (For more information on digital power, see A bit-o'-power: digitally controlled power conversion.)

Zilker's approach attempts to unify power conversion and management, according to Chris Ambarian, senior analyst for power-management semiconductors with iSuppli. "[Zilker] put them on the same chip with no—or very little—mixed signal," he said. "They're just using some really tricky techniques to use the same chip technology [for both functions]."

The chip is based on what Templeton referred to as a "plain vanilla" digital-CMOS process. "We were able to overcome the [poor analog process] by using state-machine-based digital processing math and calibration schemes to bring back a much higher level of analog performance," he said.

Templeton claims that whereas other chips run at 1W or higher, the ZL2005 runs at under 200 mW. "We don't use a high-speed, high-resolution ADC [analog-to-digital converter], and rather than a programmable processor or DSP, the ZL2005 uses a hardwired digital filter in there," he said. "So the chip runs at a much lower current and therefore uses much lower power." The chip's power thriftiness allowed Zilker to incorporate the switching components' drivers.

The chip requires only a single voltage, which can be derived from the intermediate bus voltage, and can range from 3 to 14V with the output ranging from 0.6 to 5V.Because there's no processor or DSP, the device requires no programming on the part of the user. An engineer can configure the ZL2005 via pin-strap connections, resistor selection, or through the device's on-board serial port using the industry standard PMBus command set, although the chip can also operate stand-alone from the new power-control bus.

Zilker realized that difficulty of use was going to be a major impediment to the widespread adoption of digital power, Templeton said. " If you're asking the analog power designer to learn how to do digital software development, you're adding a tremendous amount of cycle time in the learning curve," he said. "With this IC, users take a resistor divider, do the compensation [to select the input and output voltages], and they've got a power supply. They don't need a GUI and they don't need to write code."

iSuppli's Ambarian concurs: "Zilker has had the insight to take software more out of the question. One of the things that really daunts designers in looking at digitalized power is that [most are not software engineers]. That's a legitimate concern, because even software engineers mess up software. [Zilker] is just taking care of them."

The ZL2005 comes in a 6×6-mm, 36-lead MLF (micro lead frame) package. Pricing starts at US$4.25 (1000). The company also offers an evaluation kit, the ZL2005EV-1.

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