ISO121BG - ±10V Precision Isolation Amplifier 3500Vrms | Texas Instruments
料号： ISO121BG ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $28.5 | $28.50 |
| 10 | $26.1 | $261.00 |
| 100 | $23.4 | $2,340.00 |
| 500 | $21.05 | $10,525.00 |
| 1,000 | $19.2 | $19,200.00 |
ISO121BG 概述
An isolation amplifier is a specialized differential amplifier that provides galvanic isolation between its input and output stages, breaking ground loops and protecting downstream circuitry from high-voltage transients. Within the broader signal-chain hierarchy, isolation amplifiers sit between instrumentation amplifiers (which amplify small differential signals) and digital isolators (which only pass logic levels). They combine precision analog front-end conditioning with reinforced isolation, making them essential in systems where analog signals must cross a safety barrier.
Key features of the ISO121BG include user control of the carrier frequency for synchronization, 100% partial discharge testing, high common-mode rejection (IMR) at 60Hz, and bipolar operation across its ±10V input range. The part is rated for -55C to +125C operation and is specified for the 16-pin side-brazed ceramic DIP (CDIP_SB) package designed for high-voltage isolation applications.
The device uses duty-cycle modulation to encode the analog input as a digital pulse train that crosses a 2pF capacitive isolation barrier; the output side demodulates this pulse train back to an analog voltage. Because modulation is digital, the barrier's analog imperfections (nonlinearity, drift, aging) do not corrupt signal integrity, yielding 0.01% max nonlinearity and stable gain over time.
Typical applications include precision voltage sensing in motor drives, shunt-based current sensing in high-voltage systems, isolated process-control signal acquisition, medical patient monitoring with reinforced isolation, and ground-loop elimination in industrial 4-20mA loops. Designers choose the ISO121BG when the application demands 3500Vrms isolation (vs. the 1500Vrms ISO120) and excellent DC accuracy at industrial temperatures.
When designing with the ISO121BG, pay attention to PCB layout: keep input and output grounds physically separated by the package isolation barrier, use star-grounding at the power supplies, and place the external oscillator capacitor as close to the OSC pin as possible to minimize carrier-frequency drift and IMR degradation.
This page synthesizes distributor stock levels, drop-in ISO12x family alternatives, and practical PCB layout guidance not found in the manufacturer datasheet alone.
直接替换替代料： ISO121BG ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： ISO121BG （相同外形与封装尺寸） ——差异在于 Package, Carrier Frequency, Product Type, Nonlinearity, Isolation Voltage Rating.
快速对比工具——选择替代料号进行并排对比：
ISO121G
✅ 直接替换✓ 有现货
$160.4014 / 个
查看数据手册 →ISO120BG
✅ 直接替换✓ 有现货
联系询价
查看数据手册 →ISO120G
✅ 直接替换✓ 有现货
$184.6906 / 个
查看数据手册 →ISO120SG
✅ 直接替换✓ 有现货
$471.7929 / 个
查看数据手册 →ISO121BG 最大额定值与电气特性
| Product Type | Isolation Amplifier |
| Number of Channels | 1 |
| 输入电压范围 | ±10 V |
| Isolation Voltage Rating | 3500 Vrms |
| Nonlinearity (max) | ±0.01 % |
| Supply Voltage Range | ±4.5 V to ±18 V |
| Common-Mode Rejection (IMR) at 60 Hz | High (per datasheet) |
| Modulation Technique | Duty-cycle modulation/demodulation |
| Isolation Barrier | 2 pF differential capacitive |
| Carrier Frequency | User-controlled (external capacitor) |
| Partial Discharge Tested | 100% tested |
| 工作温度范围 | -55 C to +125 C |
| 封装 | 16-pin CDIP_SB (JVD) side-brazed ceramic DIP |
| 安装类型 | Through-Hole |
ISO121BG 引脚配置
| 引脚 1 | V+ — Positive analog supply (input side) |
| 引脚 2 | VIN — Analog input (bipolar ±10V) |
| 引脚 3 | VREF — Input-side reference (ground sense) |
| 引脚 4 | GND1 — Input-side ground |
| 引脚 5 | COSC — External carrier-frequency capacitor |
| 引脚 6 | NC — Not connected (per datasheet) |
| 引脚 7 | NC — Not connected (per datasheet) |
| 引脚 8 | NC — Not connected (per datasheet) |
| 引脚 9 | GND2 — Output-side ground (isolated from pin 4) |
| 引脚 10 | VOUT — Isolated analog output |
| 引脚 11 | NC — Not connected (per datasheet) |
| 引脚 12 | NC — Not connected (per datasheet) |
| 引脚 13 | VISO+ — Output-side positive supply |
| 引脚 14 | NC — Not connected (per datasheet) |
| 引脚 15 | NC — Not connected (per datasheet) |
| 引脚 16 | VISO- — Output-side negative supply |
典型应用
ISO121BG 适用于 6 应用s: Isolated Motor Drive Current Sensing, Medical Patient Monitoring with Reinforced Isolation, Isolated Process-Control Signal Acquisition (4-20mA), High-Voltage Battery-Stack Monitoring, Shunt-Based DC Bus Monitoring in Solar Inverters, Industrial PLC Isolated Analog Input Module.
Isolated Motor Drive Current Sensing
The ISO121BG's 3500Vrms isolation and ±10V input make it a strong fit for high-voltage motor-drive current sensing. It accepts the differential voltage from a shunt resistor in the inverter leg, transmits the signal across the 2pF capacitive barrier, and outputs an isolated analog voltage proportional to phase current. The 0.01% nonlinearity preserves control-loop accuracy at low currents, while the -55C to +125C range covers under-hood automotive and industrial-cabinet environments. Designers place the part on the low-voltage side of the isolation barrier so the MCU's ADC sees a safe, low-voltage analog signal.
推荐
Medical Patient Monitoring with Reinforced Isolation
The ISO121BG is suited to medical patient-monitoring front ends where reinforced 3500Vrms isolation is required between the patient-connected electrodes and the host monitoring system. It amplifies small biopotential signals (ECG, EMG) with 0.01% max linearity, then crosses the 2pF capacitive barrier so the host computer is fully isolated from any fault current. The wide bipolar input range accommodates electrode offset voltages that drift over time. The CDIP_SB package provides the creepage and clearance distances required by IEC 60601-1 reinforced-isolation rules.
推荐
Isolated Process-Control Signal Acquisition (4-20mA)
The ISO121BG works well as the front-end isolator for 4-20mA loop-powered process signals, particularly where hazardous-area intrinsic safety demands reinforced isolation. The ±10V input covers a 1-5V loop sense resistor voltage directly; the 3500Vrms isolation barrier breaks ground loops between field sensors and the control-room PLC. The duty-cycle modulation topology gives stable gain over time, eliminating recalibration cycles typical of older optocoupler-based isolators. Mount the input ground locally to the field cable shield to maximize IMR at 60Hz.
推荐
High-Voltage Battery-Stack Monitoring
The ISO121BG is well matched to high-voltage lithium battery-stack monitoring in EVs and grid storage, where each cell module sits at a different potential. The 3500Vrms isolation allows direct shunt-based current measurement on the high-voltage stack, while the isolated output feeds a low-voltage MCU ADC. The 0.01% nonlinearity preserves state-of-charge calculation accuracy over the full 0-1C discharge profile, and the -55C to +125C range covers under-bonnet automotive and outdoor cabinet deployments.
推荐
Shunt-Based DC Bus Monitoring in Solar Inverters
The ISO121BG is widely used in solar-inverter DC-bus current and voltage monitoring where 1000-1500V DC strings must be measured safely. The 3500Vrms isolation handles string-to-ground transients during inverter switching, and the ±10V bipolar input directly accepts a divided-down DC-bus voltage without additional signal conditioning. Combined with 0.01% nonlinearity, the ISO121BG keeps MPPT accuracy high over the full operating range. Its user-controlled carrier frequency lets designers avoid interference with the inverter's PWM fundamental.
推荐
Industrial PLC Isolated Analog Input Module
The ISO121BG is a natural fit for industrial PLC analog-input modules requiring 8-16 channels of isolated measurement. Each channel uses one ISO121BG to convert a high-side analog signal into an isolated analog voltage, which is then multiplexed into a single ADC. The 3500Vrms isolation satisfies IEC 61131-2 and most factory-floor surge-withstand requirements. The CDIP_SB package's wide pin pitch simplifies PCB creepage design and helps the module pass 8kV ESD and 4kV burst tests. Use a star-ground layout at the field-side ground to maximize IMR.
推荐
推荐产品汇总
工程参考数据： ISO121BG ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | ISO121G | ISO120BG | ISO120G | ISO120SG |
|---|---|---|---|---|---|
| Package | 16-pin CDIP_SB (JVD) | 16-pin SBCDIP (tube) | 16-pin CDIP_SB (JVD) - same | 16-pin CDIP_SB / SBCDIP | 16-pin CDIP_SB (JVD) - same |
| Brand | Texas Instruments (Burr-Brown) | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Isolation Voltage | 3500 Vrms | 3500 Vrms (same) | 1500 Vrms | 1500 Vrms | 1500 Vrms |
| Input Voltage Range | ±10 V | ±10 V (same) | ±10 V | ±10 V | ±10 V |
| Nonlinearity (max) | ±0.01 % | ±0.01 % (same) | ±0.01 % | ±0.01 % | ±0.01 % |
| Supply Voltage Range | ±4.5 V to ±18 V | ±4.5 V to ±18 V (same) | ±4.5 V to ±18 V | ±4.5 V to ±18 V | ±4.5 V to ±18 V |
| Operating Temperature | -55 C to +125 C | -55 C to +125 C (same) | -55 C to +125 C | -55 C to +125 C | -55 C to +125 C |
| Modulation Topology | Duty-cycle, 2pF cap barrier | Duty-cycle, 2pF cap barrier (same) | Duty-cycle, 2pF cap barrier | Duty-cycle, 2pF cap barrier | Duty-cycle, 2pF cap barrier |
关键差异点
- Higher isolation voltage rating (3500 Vrms) （对比 ISO120BG)
- Same die, easier procurement alternative （对比 ISO121G)
- Mature through-hole CDIP_SB package （对比 ISO120SG)
设计说明
Keep input-side ground (GND1, pin 4) and output-side ground (GND2, pin 9) physically separated on the PCB by at least the package's creepage distance. The 16-pin CDIP_SB has a clear isolation slot between pins 1-8 and 9-16; route all input signals to one side and all output signals to the other. Use a star-ground configuration at the power supplies and avoid stitching capacitors or traces that bridge the barrier. This layout is the single biggest determinant of achieved IMR at 60 Hz.
Do not place the external carrier-frequency capacitor (COSC, pin 5) more than 5 mm from the package. Long traces add parasitic capacitance that drifts the carrier frequency and degrades IMR. Use an NPO/C0G dielectric capacitor for stability over temperature, and choose the value per the datasheet's carrier-frequency selection table - typically 1000 pF to 10 nF sets the carrier in the 100 kHz to 1 MHz range. Synchronize the carrier to a system clock by feeding it into a PLL when multiple ISO121BG parts are used in a single design.
Use independent low-noise LDO regulators for the V+/V- and VISO+/VISO- supplies, with pi-filter LC networks at each supply pin to prevent switching noise from coupling across the isolation barrier. The ISO121BG draws a few milliamps on each side; a 10 uF ceramic + 100 nF ceramic + ferrite bead combination on each rail is a robust default. Sharing the same physical +15 V rail between input and output sides will defeat the purpose of isolation by reintroducing ground loops.
合规信息
RoHS, lead-free, and halogen-free status not explicitly stated in the verified web data for ISO121BG; confirm directly with supplier. The 16-pin CDIP_SB is a hermetic ceramic package traditionally used in military and aerospace, and many through-hole isolation amplifiers ship as non-RoHS tin-lead parts.
