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Non-Inverting Level Shifter Requires Only One Op Amp, One Supply Voltage – Sustainability Analysis

Sustainability is defined as a condition in which natural systems and social systems survive and thrive together indefinitely [1]. This definition provides a goal for every person on the planet to strive toward if we want our planet to continue to provide us with a place to live for generations to come. As human society stands, we consume more of the earth’s natural recourses than we or the earth can replenish [1]. This fact means that humans will inevitably contribute to the destruction of earth and the entire race if this trend continues.

One of the big contributors to the detriment of a sustainable world is the Electronics Industry. Everything people do on a day to day basis includes some interaction with electronics. All of these devices have to go somewhere when they break or when technology advancements forces their replacement. According to the Government Accountability Office, over 100 million computers, TVs and monitors are discarded each year and even though e-recycling programs are becoming more prevalent, their methods are extremely labor intensive and only pay if working components can be salvaged [2]. Due to the fact that most electronics have something to do with interacting with the human senses (i.e. audio and video), it is extremely important that A/V support circuitry, such as level shifters, are as sustainable as possible. The following analysis will discuss a single supply, non-inverting, single op-amp level shifter and how it impacts the four “E”s of sustainability along with how it embodies green engineering principles.

Energy
The design of this level shifter circuit definitely takes energy conservation into account with all of its components. First, the design uses a MAX4380 single supply op-amp which has a typical quiescent current of 5.5mA [4]. If a single 5V supply is used (typical for A/D applications) only 27.5mW of power is consumed by the op-amp. The MAX4380 also has a built-in “disable” feature that puts the output of the op-amp in high-z and requires only .45mA of quiescent current translating to only 2.25mW of dissipated power from a 5V supply [4]. This disable state can be controlled digitally by a processor or microcontroller in order to minimize power consumption by the circuit. These perks, along with the use of only one op amp, make for a very energy efficient design. The only downside to this circuit is the use of small resistors which minimize voltage noise but also induce more feedback current. Larger resistors can be used in order to minimize power consumption without changing the operation of the circuit.

Environment
The premise of designing a single supply level shifter is so that it can be used in portable applications which use batteries as a power source. Therefore, the power for this circuit comes from batteries which are an extremely wasteful power source. Americans throw out more than 179,000 tons of batteries per year into landfills. Batteries, especially rechargeable batteries contain significant amounts of heavy metals and other toxic substances such as mercury, cadmium and lead [5]. These chemicals have proved detrimental to the environment when mixed with other materials in a landfill.

Economics
The motivation behind this design is heavily economical because it emphasizes saving cost and space. As devices get smaller and smaller, PC board real estate becomes more precious. This means board space must be used efficiently and cost effectively. This level shifter design accomplishes this task by the use of its MAX4380 ultra small, low cost op amp. The MAX4380 op amp costs 74 cents apiece and takes up about 3mm2 of room on a PCB [4]. The total cost of the circuit with 10 cent resistors and a 50 cent capacitor costs only $1.94. The space and capabilities of this design allow people to take their electronics with them, allowing them to accomplish more and make more money.

Equity
The application of this design impacts all electronic consumers. Most consumer electronics have something to do with audio and video combined with portability. People from businessmen to college students use portable devices to help them communicate with others that are important to them. Direct stakeholders include Maxim who makes the op-amp along with the electronics companies that would implement this product in their design such as Motorola or Sony. Indirect stakeholders include the consumers who use the device. The direct stakeholders benefit from this design financially, while the consumers benefit from the product emotionally by improving their quality of life.

Citations

[1] D. Braun and Cal Poly Electrical and Computer Engineering Students, “Cal Poly’s wiki for Sustainability in Integrated Circuits,” Available: []. [Accessed April 24, 2011].

[2] Jeff Johnson, "A Tsunami of Electronic Waste," //Chemical & Engineering News //, vol. 86 no. 21, 2008, pp. 32-33, Available: [] [Accessed April 24, 2011].

[3] Erik Matlin, "Non-Inverting Level Shifter Requires Only One Op Amp, One Supply Voltage", Electronic Design, 5/5/2010, Available: [] [Accessed April 24, 2011].

[4] Unknown Author, MAX4380 Datasheet, “ Ultra-Small, Low-Cost, 210MHz, Single-Supply Op Amps with Rail-to-Rail Outputs and Disable”, Rev 2, 4/2003, Maxim Integrated Products, Available: []

[5] Unknown Author, “ Community Waste Prevention Toolkit: Battery Fact Sheet”, INFORM, Available: [] [Accessed April 24, 2011].