Small and Efficient Fractional Charge Pump from Catalyst Semi

7th February 2007

ES Admin

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Catalyst Semiconductor, Inc. has introduced its CAT3643 three-channel and CAT3644 four-channel Quad-Mode charge pumps. The CAT3643 Quad-Mode charge pump is said to be the world’s smallest, highest efficiency charge pump, delivering 10 percent higher efficiency compared to three-mode charge pumps, in a 2.5mm x 2.5mm XQFN package with a 0.4mm profile. The CAT3643 drives up to three LEDs and comes just two months after Catalyst’s launch of its groundbreaking Quad-Mode technology with the CAT3636 six-LED driver.

With the Quad-Mode switching architecture, the new CAT3643 and CAT3644 deliver efficiency levels as high as 92 percent, yet save significant board space and costs. The CAT3643 is the only charge pump available in an eXtra-thin 2.5mm x 2.5mm 12-lead XQFN package, with a 0.4mm profile, versus the traditional 3mm x 3mm 16-lead TQFN package and 0.8mm profile of most three-mode LED drivers.

The innovative, patent-pending Quad-Mode charge pump architecture delivers the high efficiency levels of inductor-based LED drivers, while eliminating the associated high-profile inductors, and unwanted EMI. Most charge pump LED drivers today offer three modes of operation corresponding to the ratio of the output voltage to the input voltage: 1x, 1.5x and 2x. The Quad-Mode architecture adds a fourth mode of operation, 1.33x, without the need for the additional capacitor and associated extra two pins required by all existing four-mode charge pumps, which enables the dramatically smaller, lower pin count XQFN package.

The 1.33x fractional operating mode also reduces the input switching currents seen at the battery, minimizing the overall supply noise – a critical parameter in portable devices such as cell phones. Additionally, by utilizing the 1.33x mode of operation, the excess boosted voltage is kept to a minimum, which reduces wasted power and subsequent device heat losses.

The XQFN package, reduced number of leads and high efficiency of the CAT3643 make it the world’s lowest profile (0.4mm) and smallest size (65 percent smaller) fractional charge pump available.

According to Scott Brown, Vice President of Marketing for Catalyst Semiconductor, “The performance and space saving benefits of the CAT3643, combined with its eXtra-thin, low profile XQFN package provide an unprecedented performance alternative for designers of today’s emerging, ultra-thin portable products. This device also addresses the ‘sweet spot’ of the portables market where 3-LEDs are becoming norm. Catalyst is proud to be in the unique position of giving designers a totally new LED driver alternative with the world’s smallest profile and highest efficiency charge pump.”

The CAT3643 includes fully featured LED programming and dimming control via Catalyst’s flexible 1-wire EZDim™ programming interface. Six different current ratios are available via the EZDim interface.

Together with the CAT3643, Catalyst is also introducing the CAT3644 four-channel Quad-Mode device, which drives up to four LEDs, with efficiency levels as high as 92 percent.

Pricing for the CAT3643 in 10,000 piece quantities starts at $0.64 each. Pricing for 10,000 piece quantities of the CAT3644 is $0.68 each. Samples and evaluation kits are now available. Projected lead-times for production quantities are currently 6 to 8 weeks ARO.