Overview

This DC-DC power module provides galvanically isolated (electrically isolated) and regulated 5 V or 3.3 V power at up to 200 mA. Unlike non-isolated regulators, the output ground (GND2) is effectively independent of the input side, which can be useful for preventing ground loops and avoiding ground currents that can cause unpredictable system behavior or even lead to destruction. This module is based on the MPS MIE1W0505BGLVH, which has a 2.5 kV_RMS isolation rating; the PCB is designed with the same 3.5 mm minimum clearance and creepage between the isolated sides as the IC, but please note that the module itself is not certified to any standard. See the MIE1W0505BGLVH datasheet (624k pdf) for more information.

Here are some of the module’s key features:

• Galvanic isolation between input and output
• 3 V to 5.5 V input voltage range
• Selectable 5 V or 3.3 V regulated output (5 V default)
  • up to 180 mA out continuous (200 mA peak) at 5 V in
  • up to 75 mA out continuous at 3 V in
• Over-temperature and short-circuit protection
• Compact 0.3″ × 0.6″ size with breadboard-compatible, 0.1″-pitch through holes

Using the module

Input power is supplied across VIN and GND1 and output power is delivered across VOUT and GND2. The two sides are galvanically isolated (GND1 is NOT connected to GND2). Note that the efficiency of this regulator is less than 50%, so the input power will need to be at least twice the output power.

The enable input, EN, is pulled up to VIN through a 100 kΩ resistor, which enables the regulator by default. This pin can be driven low to put the device into a low-power state where the shutdown current draw is typically dominated by the current through the pull-up resistor (10 µA per volt on VIN).

The output voltage selection input, VSEL, is floating, which sets the output voltage to 5 V by default. To select 3.3 V for the output voltage, connect VSEL to GND2. This can be done using the board’s through holes or by adding an SMT jumper to the pads circled in the picture below. Note: Do not change VSEL while the regulator is powered.

An SMT jumper can be added here to connect VSEL to GND2, which sets VOUT to 3.3V.

We manufacture these boards in-house at our Las Vegas facility, so we can make these regulators with the jumper installed for 3.3 V output. Please contact us if you are interested in this customization.

Schematic