LJTick-LVDigitalIO Datasheet
The LJTick-LVDigitalIO (LJT-LVDIO) A bidirectional logic shifting board for converting 3.3V logic down to 2.5V or 1.8V. There is also a VOUT terminal which can source power at the selected voltage. Useful for users who have external boards that run on lower logic thresholds, or simply want a 3.3V, 2.5V, or 1.8V supply.
Supports bi-directional communication
Up to 800kHz
3.3V, 2.5V, or 1.8V
VOUT terminal can source up to 200mA
Note: Advanced users may convert the 1.8V option to 5V by installing a jumper on R5, and removing or destroying the voltage regulator marked U3. Instructions for doing this can be found on the modifying the LJTick-LVDigitalIO page.
Subsections
Common Applications
Communicating with SPI, I2C, UART, 1-Wire, and other Digital IO sensors that require a supply voltage that is the same voltage as the logic level.
Figure 1: LJTick-LVDigitalIO
Figure 2: LJTick-LVDigitalIO With U3
Screw Terminal Descriptions
Vout: This voltage can be selected to be either 3.3V, 2.5V, or 1.8V with the slide switch.
GND: Same as LabJack ground (GND).
DIOA/DIOB: These logic input and output lines can be configured to communicate with 3.3V, 2.5V, or 1.8V circuitry.
LJTick-LVDigitalIO Hardware Block Diagram
Figure 3: LJTick-LVDigitalIO Hardware Block Diagram
LJTick-LVDigitalIO Schematic
Figure 4: LJTick-LVDigitalIO Schematic
Specifications
Parameter | Conditions | Min | Typical | Max | Units |
Supply Voltage |
| 3.6 |
| 5.25 | V |
Supply Current | No Load |
| 0.2 |
| mA |
Operating Temperature |
| -40 |
| 80 | °C |
Output Drive Current |
|
| 100 |
| mA |
|
|
|
|
|
|
1.8V Logic Voltage |
|
|
|
|
|
Vout Output Voltage |
|
| 1.8 |
| V |
Vout Current |
|
| 300 |
| mA |
Rise time |
|
| 180 |
| ns |
Fall time |
|
| 580 |
| ns |
Max Recommended Frequency | No load, 50% duty cycle |
| 1 |
| MHz |
Logic High |
|
| 1.78 |
| V |
|
|
|
|
|
|
2.5V Logic Voltage |
|
|
|
|
|
Vout Output Voltage |
|
| 2.5 |
| V |
Vout Current |
|
| 300 |
| mA |
Rise time |
|
| 560 |
| na |
Fall time |
|
| 640 |
| na |
Max Recommended Frequency | No load, 50% duty cycle |
| 1 |
| MHz |
Logic High |
|
| 2.46 |
| V |
|
|
|
|
|
|
3.3V Logic Voltage |
|
|
|
|
|
Vout Output Voltage |
|
| 3.3 |
| V |
Vout Current |
|
| 300 |
| mA |
Rise time |
|
| 2 |
| ns |
Fall time |
|
| 800 |
| ns |
Max Recommended Frequency (1) | No load, 50% duty cycle |
| 1 |
| MHz |
Logic High |
|
| 3.26 |
| V |
Logic High (Vmax) at max frequency | 1MHz, no load, 50% duty cycle |
| 3.1 |
| V |
(1) Frequencies higher than 350kHz will not produce the full logic high voltage.
For more specifications about the MOSFETs and voltage regulators used in the LJTick-LVDigitalIO look at the following datasheets:
ON Semiconductor (Logic Level Shifters) NTR4003N datasheet.
Diodes Incorporated (3.3V Regulator) AP2127K-3.3TRG1 datasheet
Richtek (2.5V Regulator) RT9193 datasheet
Diodes Incorporated (1.8V Regulator) AP2127K-1.8TRG1 datasheet
Files
ON-Semiconductor-NTR4003N-Datasheet.PDF