Smaller Power Supplies for WiFi Devices

Smaller Power Supplies for WiFi Devices

Early Monday morning, while waiting for my coffee, I used Google over the WiFi at Starbucks to browse the day’s news on my iPad. Later that afternoon, I met a few friends at Specialty’s Café in Santa Clara to discuss new business ideas, and used Microsoft 360 over WiFi to create a shared OneNote notebook. After ordering pet food for Tiger over WiFi using an Amazon Dash Button at home, my wife, kids, and I caught a simple dinner at Dish Dash in Silicon Valley. With my wife driving, our boys and I played DreamLeague soccer over WiFi—it was amazing to note the number of WiFi networks you can connect to over open WiFi routers in the neighborhood. This accessibility of WiFi networks has led to an explosion of numerous WiFi-connected devices in the last few years—hundreds of thousands are appearing every day.

Figure 1: WiFi access at places like coffee houses enables us to connect with friends, catch up on work, or read the latest news.

I'm talking not about a lunchbox-sized WLAN router, but e-commerce gadgets like the Dash Button and numerous smart-home devices like plugs, garage door openers, door locks, lighting dimmers, connected coffee machines, pet-food dispensers, and more that have come up. While many of these gadgets are plugged in, there are several that even operate on coin-cell batteries. All of them deal with tiny form-factors and weird shapes like rings, tubes, and circles—in other words, miniaturized electronics that need to be mounted on highly space-constrained boards. WiFi 802.11x technologies require 200mA of typical current for connectivity and protocol processing. In the past, for these types of devices, the voltage drop was small and with low currents, power dissipation was a non-issue: an LDO (linear regulator) did the job handsomely. But with increased intelligence and increased power draw housed in a small casing, new tricks are needed to address power dissipation.

Clearly, switch-mode power supplies can dramatically improve power conversion efficiency and reduce heat dissipation. But what to do with solution size? For all of the benefits switching regulators provide, they occupy much larger PCB area than a linear regulator as the ICs need MOSFETs for switching, inductors for storing energy, and resistors and capacitors for control-loop stability compensation. Vendors have developed power modules that integrate these additional components along with an IC in a single package. But, they are still big, offering a typical size of 47mm2. It is here that Maxim's new Himalaya uSLIC modules come in. MAXM15462 is a 4.5-42V wide-input power module that supports up to 300mA load current, giving system designers margin for their WLAN systems in a footprint of 2.6mm x 3mm. When coupled with supporting devices such as a resistor divider, the net solution component area is 14.3mm2. Read our whitepaper, "Meeting the Efficiency and Power Dissipation Needs of Space-Constrained Applications," for more information on using MAXM15462 and MAXM17532 (4-42Vin, 100mA load current).

Figure 2: Himalaya uSLIC power modules accept a wide input voltage from 4.0V to 42V in a tiny package.

With the explosion of WiFi usage in numerous intelligent and networked consumer devices that can run at multiple popular nominal voltage rails, system designers can get a leg up on their competition by using the smallest power solution that meets CISPR 22 (EN 55022) EMI standards for conducted and radiated emissions as well as JEDEC22 vibration/drop standards. Looking forward to simplifying my life at home, work, and everywhere else with more WiFi devices.