ISO122PG4 - 50 kHz Precision Isolation Amplifier | Texas Instruments
Артикул: ISO122PG4 ✓ АктивенISO122PG4 Обзор
An isolation amplifier is a specialized amplifier-and-barrier combination used to transfer a low-level analog measurement across a galvanic isolation boundary. In the hierarchy it sits under precision amplifier -> instrumentation amplifier -> isolation amplifier -> signal-chain IC, and it exists because standard op amps cannot survive the ground-potential differences and safety barriers found in industrial control, medical-style monitoring, and mains-referenced measurement systems. Typical isolation barriers must withstand kilovolt-level transients while passing microvolt-to-volt signals with predictable gain and low output offset.
Key characteristics of the ISO122PG4 include its 50 kHz bandwidth, single-channel (one circuit) isolation topology, differential analog input, differential analog output, and DIP-8 through-hole mechanical format. Because the modulation scheme is digital in nature, the isolation barrier capacitance is used only for current injection and clock transfer, which removes the gain error and linearity shift that analog barrier-based designs suffer with temperature and aging. The RoHS-compliant construction and PDIP outline suit long-life industrial equipment where a surface-mount-only part would complicate rework.
Architecturally, the ISO122 divides into a high-side input stage, a barrier region containing the 2 pF differential capacitors, and an output reconstruction stage. The receiver demodulates the duty-cycle-modulated carrier back into a differential analog output so downstream ADC front ends can be driven differentially, halving the sensitivity to common-mode noise pickup on the wiring between the amplifier and the converter.
Typical applications include industrial sensor interface and data acquisition modules, isolated PLC and DCS input channels, medical-style patient-monitoring front ends, high-voltage power-converter feedback isolation, and laboratory test equipment where a high-side shunt measurement must be transferred safely to the low-voltage control domain. In each of these, the ISO122PG4 acts as the analog front end of the isolated measurement chain.
One design consideration worth noting: when placing this part in a through-hole design, keep the input-side ground and output-side ground planes completely separate and provide the decoupling capacitors called for in the TI datasheet directly at the supply pins. Isolation is only as good as the creepage and clearance of the layout around the barrier.
This page consolidates distributor pricing, same-family drop-in options, package details, and practical design guidance for the ISO122PG4 so engineers can evaluate the part quickly, compare it against sibling TI isolation amplifiers, and source it without re-reading multiple distributor listings.
Аналоги без доработки для ISO122PG4 — тот же корпус, pin-to-pin совместимость. Компоненты в других корпусах, требующие переработки PCB, исключены.
ISO122PE4
✅ Прямая замена ⚠️ Характеристики не проверены📋 Справочный аналог (нет в каталоге)
ISO121PG4
✅ Прямая замена ⚠️ Характеристики не проверены📋 Справочный аналог (нет в каталоге)
ISO124PG4
✅ Прямая замена ⚠️ Характеристики не проверены📋 Справочный аналог (нет в каталоге)
ISO126PG4
✅ Прямая замена ⚠️ Характеристики не проверены📋 Справочный аналог (нет в каталоге)
ISO121PE4
✅ Прямая замена ⚠️ Характеристики не проверены📋 Справочный аналог (нет в каталоге)
ISO122PG4 Максимальные параметры и электрические характеристики
| Device Type | Precision isolation amplifier |
| Number of Circuits | 1 channel |
| Signal Bandwidth | 50 kHz |
| Isolation Mechanism | Duty-cycle modulation / demodulation across 2 pF differential capacitive barrier |
| Корпус | PDIP-8 (PG), 0.300 inch (7.62 mm) row spacing, through-hole |
| Тип монтажа | Through-hole |
| Статус RoHS | Compliant |
| Barrier Capacitance | 2 pF differential capacitive barrier |
| Output Topology | Differential analog output |
| Product Type | Isolation amplifier / instrumentation amplifier / signal-chain IC |
| Manufacturer | Texas Instruments |
| Unit Price (1 piece) | USD 27.80 as of 2026-10-28 |
Конфигурация выводов ISO122PG4
| Контакт 1 | VDD1 — Primary-side (input-side) supply connection; requires local decoupling |
| Контакт 2 | IN+ — Non-inverting differential analog input [DATA_NEEDED: exact pin function per TI ISO122 datasheet pin table] |
| Контакт 3 | IN- — Inverting differential analog input [DATA_NEEDED: exact pin function per TI ISO122 datasheet pin table] |
| Контакт 4 | GND1 — Primary-side (input-side) ground, isolated from GND2 |
| Контакт 5 | GND2 — Secondary-side (output-side) ground, isolated from GND1 |
| Контакт 6 | OUT+ — Non-inverting differential analog output [DATA_NEEDED: output polarity per TI ISO122 datasheet pin table] |
| Контакт 7 | OUT- — Inverting differential analog output [DATA_NEEDED: output polarity per TI ISO122 datasheet pin table] |
| Контакт 8 | VDD2 — Secondary-side (output-side) supply connection; requires local decoupling |
Типичное применение
ISO122PG4 подходит для 6 применениеs: Industrial High-Side Shunt Sensing, Isolated PLC and DCS Input Channels, Mains-Referenced and High-Voltage Test Equipment, Medical-Style Patient Monitoring Front Ends, Data Acquisition and Instrumentation Modules, Isolated DC-DC Feedback and Power Conversion.
Industrial High-Side Shunt Sensing
The ISO122PG4 fits high-side current measurement in motor drives and industrial power converters where the sense resistor sits at a hazardous or fast-switching potential. Its 50 kHz bandwidth comfortably covers the control loop of a switched-mode power stage while its differential input rejects the common-mode step caused by switching current. Place the device directly across the shunt so the 2 pF capacitive barrier does the galvanic separation, then route the differential output to a delta-sigma or SAR converter in the low-voltage control domain. The benefit over a ground-referenced amplifier is that no analog ground connection is required at the shunt, so ground bounce on the power stage cannot corrupt the measurement. Verify the input common-mode range and the shunt sense voltage against the datasheet before finalizing the front end.
Рекомендуется
Isolated PLC and DCS Input Channels
In a programmable logic controller or distributed control system input module, the ISO122PG4 provides the analog isolation barrier between field wiring and the controller logic. The 50 kHz bandwidth is more than sufficient for 4-20 mA, thermocouple, and pressure-transducer signals, while the differential output structure allows direct connection to the module ADC without a separate instrumentation amplifier stage. Its PDIP-8 through-hole format is convenient for modules that are assembled with through-hole components or field-replaceable daughter cards. The key benefit is that the field-side ground stays isolated from the logic ground, breaking ground loops that are a common source of 50/60 Hz interference in plant installations. Because the part is RoHS compliant, it fits modern industrial product-material requirements.
Рекомендуется
Mains-Referenced and High-Voltage Test Equipment
Laboratory and field test equipment that must probe a mains-referenced or high-voltage node can use the ISO122PG4 to bring a measurement into a safely isolated instrument domain. The isolation barrier is the only conductive path across the boundary, so the instrument enclosure ground cannot be tied to the probe point. The 50 kHz bandwidth supports power-line harmonic analysis, switching-node ripple probing, and general-purpose scope-style measurements without the phase shift that would corrupt amplitude readings. In a handheld or bench instrument, the PDIP-8 through-hole package is simple to assemble and rework. Engineers typically pair the device with a protected front end and a buffer stage before the ADC, so the isolation amplifier is doing the safety-critical work rather than also providing instrumentation gain.
Рекомендуется
Medical-Style Patient Monitoring Front Ends
The ISO122PG4 suits low-level bio-signal front ends such as ECG and respiration monitoring modules, where the electrode interface is connected to the patient and must be electrically separated from the acquisition electronics. Its differential input structure matches the electrode differential drive, and the 50 kHz bandwidth covers physiological signal content with margin while rejecting mains-coupled common-mode interference through the barrier. The isolation barrier removes the DC path to the patient, supporting protective-earth-based instrument architectures. The differential analog output feeds the analog-to-digital converter in the safe-side domain. Design note: the isolation barrier rating and creepage/clearance must be validated against the finished equipment's safety standard, not just the component datasheet, and the front end still needs input protection and biasing resistors.
Рекомендуется
Data Acquisition and Instrumentation Modules
Compact multi-channel data acquisition modules frequently use the ISO122PG4 to isolate each analog input channel from the host instrument. With a 50 kHz bandwidth per channel, the part supports general-purpose sensing of temperature, pressure, strain, and position rather than only very slow process variables, and the differential output reduces sensitivity to the cable-routing noise typical of field wiring. The PDIP-8 package allows channel-level replacement on a plug-in analog board, simplifying service and calibration. Compared with a digital-isolator-plus-converter approach, the ISO122PG4 keeps the analog path intact across the barrier, avoiding quantization and digital-filter latency in the measurement chain. Channel-to-channel isolation figures should be taken from the datasheet if the module is certified as a multi-channel isolated instrument.
Рекомендуется
Isolated DC-DC Feedback and Power Conversion
In isolated flyback or isolated buck-boost power converters, the secondary-side output voltage must be fed back to the primary-side controller across the isolation barrier. The ISO122PG4 provides a compact, accurate way to transfer that feedback signal, with a 50 kHz bandwidth that is ample for loop compensation signals in most isolated converters and a differential input that matches a differential divider network. Using a dedicated isolation amplifier instead of an optocoupler avoids the CTR drift and slow rise time that degrade phase margin in wide input-range converters. Its 50 kHz bandwidth supports designs switching in the hundreds of kilohertz to low megahertz where the feedback path is bandwidth-limited by the isolation amplifier. Confirm the input common-mode range against the secondary-side divider reference before selecting the feedback topology.
Рекомендуется
Сводка рекомендуемых товаров
Справочные инженерные данные для ISO122PG4 — сравнение, рекомендации по проектированию и информация о соответствии.
Руководство по выбору
Сравнение с аналогами
| Параметр | Этот товар | ISO122PE4 | ISO121PG4 | ISO124PG4 | ISO126PG4 |
|---|---|---|---|---|---|
| Package | PDIP-8 (PG), 0.300 inch (7.62 mm), through-hole | PDIP-8 (PG), through-hole - same | PDIP-8 (PG), through-hole - same | PDIP-8 (PG), through-hole - same | PDIP-8 (PG), through-hole - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Number of Circuits | 1 channel | 1 channel | 1 channel | 1 channel | 1 channel |
| Isolation Mechanism | Duty-cycle modulation / demodulation across 2 pF differential capacitive barrier | Same capacitive barrier modulation technique | Same capacitive barrier modulation technique | Same capacitive barrier modulation technique | Same capacitive barrier modulation technique |
Ключевые отличия
- Differential analog output in a through-hole PDIP-8 (против ISO121PG4)
- 2 pF capacitive barrier with digital duty-cycle signal transfer (против ISO124PG4)
- Through-hole PDIP-8 for serviceable, hand-reworkable industrial boards (против ISO122PE4)
Заметки по проектированию
Treat the isolation barrier as a hard keep-out on both copper layers. The two isolation grounds (GND1 and GND2) must never be tied together, and no copper, plane, or trace may run across the barrier region. Creepage and clearance around the DIP body are what actually deliver the isolation rating in the finished product, so place the device at the board edge facing the hazardous side, keep the field wiring short and on the high-voltage side, and reserve the low-voltage side for protected logic. Review the isolation-layout section of the TI datasheet before releasing the artwork.
The most common field failure mode for this part family is substituting a single-ended-output sibling (ISO121 or ISO124) into a design that expected a differential output, or vice versa. The DIP-8 footprint is identical across the family, so a substitution can compile and even power up while the unused output pin sits unconnected and the ADC sees a half-amplitude or common-mode-shifted signal. Verify the output pin usage and the downstream ADC input mode against the specific part number, and confirm the isolation and temperature grade suffix before substituting any variant.
Route the differential input as a tightly coupled pair directly from the source to pins 2 and 3, with no stubs and a solid ground reference beneath the pair. Because the ISO122 uses differential modulation-demodulation, input common-mode noise at the sensing node is converted into differential error if the pair is not matched. Keep the differential output pair to the following converter similarly coupled and matched in length, and place the input-side and output-side supply decoupling capacitors immediately adjacent to the VDD pins to keep supply noise off the modulation carrier.
Информация о соответствии
RoHS compliance confirmed by distributor listings describing the ISO122PG4 as a professional-grade RoHS-compliant PDIP device (Veswin listing). REACH, halogen-free status, and conflict-minerals declarations were not present in the verified web data and are therefore listed as unknown. The part is not AEC-Q100 qualified.
