What Are Isolators?
Isolators provide galvanic isolation between two circuit sections, preventing dangerous voltages or noise from crossing between them while still allowing signal or power transfer. Types include digital isolators (capacitive or magnetic coupling), analog isolators, isolated gate drivers (for MOSFETs/IGBTs), isolated power modules, and optocoupler-based isolators. LCSC stocks 5,000+ isolator SKUs from 100+ manufacturers.
Isolators — Definition and Sub-Categories
An isolator is a component that transfers signals or power across an insulation barrier, maintaining electrical separation between input and output. Isolation is measured in voltage (typically 2.5–5 kV RMS) and is required for safety in mains-connected equipment, medical devices, and industrial systems.
|
Sub-Category |
Function |
Key Parameters |
|
Digital Isolators |
Isolated digital signal transfer (SPI, I2C, GPIO) |
Channels, data rate, isolation voltage, propagation delay |
|
Analog Isolators |
Isolated analog signal transfer |
Bandwidth, accuracy, isolation voltage, linearity |
|
Isolated Gate Drivers |
Drive MOSFET/IGBT gates with isolation |
Peak current, CMTI (dv/dt), isolation, dead time |
|
Isolated DC-DC |
Provide isolated power across barrier |
Power (mW–W), isolation voltage, efficiency |
How to Choose: Isolators Selection Guide
Choose isolator type based on what you need to transfer across the barrier. For digital signals, capacitive-coupled digital isolators (like those from Silicon Labs or TI) offer higher speed and lower power than optocouplers. For MOSFET/IGBT gate drive in power converters, use isolated gate drivers with high CMTI (common-mode transient immunity). For power transfer across the barrier, use isolated DC-DC modules sized for your load.
Isolators Comparison
|
Isolator Type |
Speed |
Isolation |
Power Consumption |
vs. Optocoupler |
|
Capacitive Digital |
Up to 150 Mbps |
2.5–5 kV RMS |
Low (5–15 mA) |
10–100x faster, lower power |
|
Magnetic Digital |
Up to 100 Mbps |
2.5–5 kV RMS |
Low (5–15 mA) |
High CMTI, robust |
|
Optocoupler (for comparison) |
Up to 25 Mbps |
2.5–5 kV |
Higher (10–30 mA) |
Simpler, legacy standard |
|
Isolated Gate Driver |
N/A (gate drive) |
Up to 5 kV |
Varies |
Essential for power FETs |
Why Source Isolators from LCSC Electronics
LCSC stocks 5,000+ isolator SKUs from 100+ manufacturers including Silicon Labs, TI, Analog Devices, and Asian alternatives from Novosense, 2Pai Semi, and CoolReap. Engineers can source both the isolators and the power components they protect in a single order.
Frequently Asked Questions
Q: What is the difference between an optocoupler and a digital isolator?
Optocouplers use an LED and photodetector for isolation — they’re simple and cheap but slower and consume more power. Digital isolators use capacitive or magnetic coupling for much higher speed (up to 150 Mbps vs. 25 Mbps), lower power, and better timing consistency. For new designs, digital isolators are generally preferred; optocouplers remain common in legacy designs and simple on/off isolation.
Q: When do I need galvanic isolation?
You need isolation when: (1) your circuit connects to AC mains voltage (safety requirement), (2) you’re measuring high voltages relative to your MCU’s ground, (3) you need to break ground loops in multi-board systems, or (4) safety standards require it (medical, industrial, automotive).
Q: What is CMTI and why does it matter?
CMTI (Common-Mode Transient Immunity) measures how well an isolator rejects fast voltage transients across its barrier, specified in kV/µs. High CMTI is critical for isolated gate drivers in power converters where switching events create rapid voltage changes. Low CMTI can cause false triggering.
Q: Does LCSC stock isolated gate drivers for GaN and SiC?
Yes. LCSC carries isolated gate drivers suitable for wide-bandgap (WBG) power devices including GaN FETs and SiC MOSFETs. These drivers offer the high CMTI, fast rise times, and appropriate gate voltage ranges needed for WBG switching.