Silica Speaks Every Voltage
Voltage Translators, also known as level shifter, are electronic components designed to be used as an adapter or ´translator’ of the voltage level at which a data signal transitions. Level shifters commonly receive signals transitioning at a low voltage level and output a signal transitioning within a wider voltage range. However, many of them are also designed to translate from a higher transitioning voltage level to a lower voltage level.
The need for voltage level translation is prevalent on most electronic systems today. For example, the GPIOs from an ASIC might be operating with suply-voltage VCCA, while a peripheral device, which needs to be connected to these GPIOs, operates with supply-voltage VCCB.
Key Features
How do they work?: When a signal is transmitted, the driver´s output thresholds must be compatible with the receiver Input thresholds (i.e. Driver Output > Receiver Sensitivity. Fig 2) These thresholds vary, depending on the device technology and supply voltage used. Fig.3 shows the thresholds levels for different supply voltages and device technologies.
For two devices to have switching compatibility the following requirements must be met.
- VOH of Driver must be greater than VIH of Receiver
- VOL of Driver must be lower than VIL of Receiver
- The output voltage from the driver must not exceed the I/O tolerance of the receiver
Def:
- VOH = Driver Output Voltage High
- VOL = Driver Output Voltage Low
- VIL = Receiver Input Voltage Low
- VIH = Receiver Input Voltage High
