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Get out of that low-voltage design land

Every day we read about the latest in low-power, low-voltage design. From 5 volts to 3 volts to 1 volt, there's a lot of need to save power by reducing those supply rails. For many applications, lower voltage yields longer battery life and also reduced thermal dissipation, both of which are critical.

But there's a large and diverse world where low voltage in incompatible with the realities of the source or load power needs. These higher voltages aren't necessarily in the potentially lethal hundred- or thousand-volt range. Many of these are in the low double-digit voltage zone. The need for this higher voltage falls into three broad categories: interfacing with sensors and transducers which inherently need higher voltages; increasing voltage to improve SNR and dynamic range; and situations where real power (volts x current and the electromechanical equivalent) must be transferred, delivered, or controlled.

Despite the outpouring of low-voltage components from the IC and passive vendors, I see a large number of the higher-voltage devices as well. These include supply-related ICs, amplifiers, MOSFETs, protection devices, LED drivers, sensor and transducer interfaces, to name a few.

But it's not just component ratings which distinguish these applications. Often, they have special requirements and needs which demand that the design engineer provide clever or unique circuit topologies as well, and not just drop the component into an established, cookie-cutter circuit. These circuits often have relatively few components, or a large fraction of passives and single-function ICs, compared to the more complex ICs that dominate so much of today's designs. They also offer a lot of really creative engineering opportunity, because the designer has so much control over the circuit specifics and architecture.

In contrast, where there is a large IC dominating the design, the engineer has to live with what is, in effect, a “black box” with few hooks or opportunities to affect topology, only operating parameters. Dealing with higher-voltage applications can open you to a new world of components, certainly, but also to a very interesting world of design issues and circuit possibilities!

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