A logic-level shifter converts one voltage or logic level to another in an electronic circuit. Because of logic shifters, compatibility is developed between ICs that have dissimilar voltage requirements like CMOS and TTL. Nowadays, systems incorporate logic-level shifters to form compatibility between processors that run on low voltages, such as 1.8V and sensors and other analog devices that run at relatively higher voltages, as 5 or 3.3V.
Types Of Logic Shifters
These are the kinds of logic shifters that are commonly used in digital electronics:
Uni-Directional Shifters
These shifters have two different voltage domains for their input and output pins.
Bi-Directional Shifters
These come with dedicated ports and have output and input pins for each domain of voltage. However, the direction of data of a particular pin remains same.
Bi-Directional Shifters With Direction Indicators
These shifters come with external direction indicators and change the outputs to inputs and vice versa whenever there’s a change in the external signal.
Bi-Directional Shifters With Auto-Sensing
These have two I/O traversing voltage domains acting as either outputs or inputs depending on an external stimulus. Auto-sensing shifters eliminate the need for a direction control pin.
Importance Of Logic Shifters In Electronic Circuits
Several years ago, 5V was the standard voltage for logic devices. Technological advancements resulted in devices that were not only smaller in size but more power efficient. Such devices are now developed that work on 3.3V and show decreased power consumption and waste.
These devices can’t be used with higher voltages as they can damage the processor and other devices used in the circuit.
Therefore, in order to prevent costly damages to the circuit, a logic level is required to interface devices with different voltage levels.
Hardware Implementation Of Logic-Level Shifters
Logic shifters are available in these hardware implementations:
Fixed Function Logic Shifter ICs
These level shifters offer various kinds of level shifts in devices that are fixed in function. These come in 2-bit, 4-bit and 8-bit configurations and are offered with several VDD2 and VDD ranges. Using fixed function logic shifter ICs eliminate the requirement of an additional timing adjustment or integrated logic in the circuit.
CMICs
CMICs or Configurable Mixed-Signal Integrated Circuits are also used for implementing logic shifting. Because CMICs allow no-code programming, designers can easily implement these shifters and can integrate various timing adjustments and configurable logic in the device.
If you’re looking for logic shifters for your next electronic project, get in touch with ADSANTEC.
Our range of products includes error detectors, active power dividers, clock distributors, fanout buffers, etc. You can contact us for further information.