Isolation Amplifiers Integrated Circuit
An isolation amplifier acts as a “safety firewall” for circuits. It provides galvanic isolation between input and output while accurately transmitting and amplifying analog signals. This prevents high-voltage surges from destroying low-voltage controllers.
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(from leading manufacturers)
Top Global Isolation Amplifiers IC Manufacturers and Representative Models
1. Texas Instruments (TI)
Industry leader specializing in Capacitive Isolation (SiO2). It is the top choice for industrial control and automotive applications.
| Application | Representative Models | Notes |
| Current Sensing (Low Input Impedance) | AMC1301, AMC1300 | Fully differential analog output; high precision. |
| Voltage Sensing (High Input Impedance) | AMC1311, AMC1350 | Designed for high-voltage bus monitoring. |
| Digital Bitstream Output (Σ-Δ) | AMC1306, AMC1303 | Pairs with internal MCU digital filters (Sinc). |
| Classic Legacy Models | ISO124, ISO121 | Analog isolation; long lifecycle despite age. |
2. Analog Devices (ADI)
Dominates the high-speed and high-reliability markets with iCoupler® Magnetic Isolation technology.
| Application | Representative Models | Notes |
| High-Frequency Σ-Δ Modulators | AD7403, AD7405 | The benchmark for industrial motor control. |
| Linear/Error Amplifiers | ADuM3190, ADuM4190 | Replaces optocouplers in power system voltage feedback. |
| High-Bandwidth Isolation | AD8410 (Isolated Version) | Optimized for high-speed current sampling. |
3. Broadcom (Formerly Avago)
A pioneer in Optical Isolation. Known for excellent creepage distance and a strong base in power electronics.
| Application | Representative Models | Notes |
| High-Precision Current Sampling | ACPL-C79A, ACPL-C790 | Used in inverters and servo drives. |
| General-Purpose Isolation Amps | HCPL-7840, HCPL-7800 | Classic industrial-grade models with high volume. |
| Voltage Sensors | ACPL-C87A, ACPL-C870 | Wide input range for voltage detection. |
4. Skyworks (Formerly Silicon Labs)
Uses robust Capacitive Isolation with superior CMTI (Common-Mode Transient Immunity) and compact packaging.
| Application | Representative Models | Notes |
| General Current Sensing | Si8920, Si8921 | Compact and highly reliable. |
| Voltage Sensing | Si8931, Si8932 | Optimized for high-voltage DC bus monitoring. |
Top Chinese Manufacturers and Typical Models
1. Novosense
The leader in domestic digital isolation. Highly recognized in automotive and high-voltage industrial sectors.
- NSI1300/NSI1200 Series: Optimized for current sensing.
- NSI1311 Series: Designed for voltage sensing with high input impedance.
- NSI1306/NSI1303: Σ-Δ modulators, equivalent to TI’s AMC1306.
- Technology: Proprietary capacitive isolation with CMTI over 150kV/µs.
2. Chipanalog
Offers a complete lineup of isolation products, directly targeting the TI portfolio.
- CA-IS1200G/U: Precision analog output; pin-compatible with TI’s AMC1301.
- CA-IS1305 Series: Modulators for high-performance motor control.
- Technology: SiO2 capacitive isolation with low bias current and low drift.
3. 3PEAK
A top domestic analog IC player focusing on high-performance industrial and automotive needs.
- TPA8000 Series: Core isolated sampling product.
- TPA8000-SM1R: Analog output isolation amp matching international standards.
4. RPsemi
Uses proprietary iDivider® technology for advantages in power consumption and speed.
- Pai1300/Pai1311 Series: Current and voltage sampling isolation amplifiers.
China vs. International Models Cross-Reference
| Function | International Benchmark | Recommended Domestic Alternative |
| General Current Sensing | AMC1301 / ACPL-C79A | NSI1300 / CA-IS1200 / TPA8000 |
| High-Voltage Monitoring | AMC1311 / ACPL-C870 | NSI1311 / CA-IS1311 |
| Σ-Δ Modulators | AMC1306 / AD7403 | NSI1306 / CA-IS1305 |
| Classic Analog Isolation | ISO124 | HJISO124 (Saiteron or others) |
What is an Isolation Amplifier?
Isolation amplifiers transmit signals across an isolation barrier without direct electrical contact using optical, capacitive, or magnetic coupling.
- Signal Transmission: Accurately passes weak voltages (like millivolts from a shunt resistor) to the output.
- Electrical Protection: Blocks high common-mode voltages, eliminates ground loops, and protects controllers from shocks.
Typical Application Scenarios
- Industrial Motor Drives (VFD/Inverters): Monitors phase currents and bus voltages while isolating controllers from high-power electricity.
- Electric Vehicles (EV/HEV): Monitors battery pack voltage (400V-800V) in BMS and ensures safety in On-Board Chargers (OBC).
- Solar & Energy Storage: Precise current monitoring for MPPT and leakage prevention in solar inverters.
- Medical Equipment: Ensures high-voltage current never reaches patients during ECG or EEG monitoring.
- Rail & Grid Monitoring: Protects data acquisition from EMI in high-power electricity systems.
Why They Are Indispensable
| Problem Solved | Standard Op-Amp | Isolation Amplifier (Iso-Amp) |
| Common-Mode Rejection | Limited by supply voltage | Extremely High (withstands kV surges) |
| Ground Loops | Prone to noise/interference | Physical Cut eliminates loop noise |
| Safety | No protection; high voltage kills | Mandatory Isolation for safety |
Core Classification Dimensions
1. By Output Signal
- Analog Output: Continuous voltage for traditional ADCs (e.g., AMC1301, ISO124).
- Digital Output: High-frequency Σ-Δ bitstream for digital filters (e.g., AMC1306, AD7403).
2. By Measurement Target
- Current Sensing: Low input impedance (±50mV or ±250mV) for shunt resistors (e.g., AMC1301, Si8920).
- Voltage Sensing: High input impedance (GΩ range) to prevent measurement errors (e.g., AMC1311, ACPL-C870).
3. By Isolation Technology
- Capacitive: SiO2 capacitors; long life and wide bandwidth (e.g., AMC1300, Si8921).
- Magnetic: Micro-transformer coupling; low latency and high efficiency (e.g., ADuM4190).
- Optical: LED + Photodiode; superior EMI resistance (e.g., ACPL-C79B).