Electronics

One of the by-products of our ever increasing need for processing speed is the steady reduction in the size of the transistors used to build microcontrollers. Up-integration at cheaper cost also drives the need for smaller geometries. With reduced size comes a reduction in the transistor breakdown voltage, and ultimately, a reduction in the supply voltage when the breakdown voltage falls below the supply voltage. So, as speeds increase and complexity mounts, it is an inevitable consequence that the supply voltages would drop from 5V to 3.3V, or even 1.8V for high density devices.

Microchip microcontrollers have reached a sufficient level of speed and complexity that they too are making the transition to sub-5V supply voltages. The challenge is that most of the interface circuitry is still designed for 5V supplies. This means that, as designers, we now face the task of interfacing 3.3V and 5V systems. Further, the task includes not only logic level translation, but also powering the 3.3V systems and translating analog signals across the 3.3V/5V barrier.

This Tips ‘n Tricks book addresses these challenges with a collection of power supply building blocks, digital level translation blocks and even analog translation blocks. Throughout the book, multiple options are presented for each of the transitions, spanning the range from all-in-one
interface devices, to low-cost discrete solutions. In short, all the blocks a designer is likely to need for handling the 3.3V challenge, whether the driving force is complexity, cost or size.

Note: The tips ‘n tricks presented here assume a 3.3V supply. However, the techniques work equally well for other supply voltages with the appropriate modifications.

TIP #01: Powering 3.3V Systems From 5V Using an LDO Regulator
TIP #02: Low-Cost Alternative Power System Using a Zener Diode
TIP #03: Lower Cost Alternative Power System Using 3 Rectifier Diodes
TIP #04: Powering 3.3V Systems From 5V Using Switching Regulators
TIP #05: 3.3V – 5V Direct Connect
TIP #06: 3.3V – 5V Using a MOSFET Translator
TIP #07: 3.3V – 5V Using A Diode Offset
TIP #08: 3.3V – 5V Using A Voltage Comparator
TIP #09: 5V – 3.3V Direct Connect
TIP #10: 5V – 3.3V With Diode Clamp
TIP #11: 5V – 3.3V Active Clamp
TIP #12: 5V – 3.3V Resistor Divider
TIP #13: 3.3V – 5V Level Translators
TIP #14: 3.3V – 5V Analog Gain Block
TIP #15: 3.3V – 5V Analog Offset Block
TIP #16: 5V – 3.3V Active Analog Attenuator
TIP #17: 5V – 3V Analog Limiter
TIP #18: Driving Bipolar Transistors
TIP #19: Driving N-Channel MOSFET Transistors

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