LS1 Bi-Directional Level Shifter

Connecting a 3.3V device to a 5V system or a 5V device to a 12V system can be a challenge. The LS1 level shifter converter is a small circuit device that safely steps down 5V signals to 3.3V and steps up 3.3V to 5V. This level converter also works with 12V, 2.8V and 1.8V devices. Each LS1 converter has the capability of converting up to 8 signals from high to low or low to high. They don’t have to be all in the same direction. It can convert a few from low to high, and others from high to low, up to the total of 8 signals. Each pair of pins can work in either direction, low to high or high to low. It can be used to convert I2C Clock and Data lines for up to four I²C buses. Bread board friendly! The LS1 has pins on a 0.1″ pitch and the rows are 0.6″ apart, just like wide DIP IC’s. Each LS1 has 20 pins. It can be used with normal serial, I²C, SPI, and any other digital signal. The LS1 is designed for converting logic level and does not work with analog signals. The level shifter is very easy to use. The board must be powered from the two voltage sources (high voltage and low voltage) that your system is using. High voltage (5V for example) to the ‘VHi’ pin, low voltage (3.3V for example) to ‘VLo’, and ground from the system to the ‘GND’ pin. Pins are labeled as Lo0..Lo7 and Hi0..Hi7. A digital one going to the Lo1 pin on the Vlo (3.3V) side will show up on the Hi1 pin on the VHi (5V) side as 5V. A digital one going into the Hi2 pin on the 5V side will show up on the Lo2 pin on the Vlo side as 3.3V. There is no need for direction control. Unused pins will be pulled high. As an added advantage the LS1 contains two 100nF capacitors to decouple the Vlo and Vhi power supplies. To prevent breakage and to save on shipping costs the pins will not be soldered to the PCB.

The LS1 is an all surface mount design and is assembled on a pick and place machine and soldered in a reflow oven.  The process and components used are lead-free.  By default the supplied pins are gold-plated, round, machine pins that can be plugged into an IC-socket, solderless breadboard or soldered into a PCB.  By request square header pins can be supplied.

Waveforms

The yellow trace at the top is the 3.3V input and the blue trace at the bottom is the 5V output signal.

The following two waveforms are expanded views of the rising and falling edges.

The falling edge: