5392-POLOLU, Pololu I²C Isolator with Isolated Power, ISO1640, MIE1W0505BGLVH, 5V/3.3V, 200mA
This module enables galvanically isolated, bidirectional communication between two I²C devices, while also providing isolated and regulated 5 V or 3.3 V power at up to 200 mA. The signal isolation, achieved via the TI ISO1640B, prevents electrical faults or incorrect connections on one side from affecting the other. It supports bidirectional I²C communication with clock stretching up to 1.7 MHz.
Note: This version does not include connectors.
Key features:
- Galvanic isolation between two I²C devices
- Bidirectional SDA and SCL lines with clock stretching support
- Input voltage range: 3 V to 5.5 V
- Selectable regulated output voltage: 5 V (default) or 3.3 V
- 180 mA continuous (200 mA peak) output at 5 V input
- 75 mA continuous output at 3 V input
- Over-temperature and short-circuit protection
- Compact 0.5″ × 0.6″ board with 0.1″-pitch breadboard-compatible through-holes
Using the module:
Input power is applied to VCCIN and GND1, while the isolated output is available at VCCOUT and GND2. Note: GND1 is not connected to GND2, maintaining full isolation. Efficiency is under 50%, so input power must be at least double the required output power.
| VCCIN Range | VSEL | VCCOUT | Output Current |
|---|---|---|---|
| 4.5 V to 5.5 V | NC (default) | 5 V | 180 mA continuous 200 mA peak |
| GND2 | 3.3 V | ||
| 3 V to 3.6 V | GND2 | 3.3 V | 75 mA continuous |
I²C connections:
- SDA1/SCL1: connect to one I²C device
- SDA2/SCL2: connect to the other I²C device
Each pair has 10k pull-up resistors to its respective VCC. For high-speed use, add stronger pull-ups as needed.
The EN pin is pulled up to VCCIN by a 100 kΩ resistor, enabling the module by default. Drive this pin low to disable the output and enter low-power mode (input side of ISO1640 remains powered).
VSEL selects the output voltage:
- Floating (default): 5 V output
- Connected to GND2: 3.3 V output
Important: Do not change VSEL while the regulator is powered.
Schematic:
Isolation and Clearance:
The ISO1640 IC is rated for 3 kVRMS isolation, and the MIE1W0505BGLVH provides up to 2.5 kVRMS. However, the physical board spacing is limited (minimum 2 mm), which is smaller than the IC packages’ ratings (ISO1640 = 4 mm, MIE1W0505BGLVH = 3.5 mm). These constraints limit the maximum safe isolation voltage.
