My Inquiry
My Account
Texas Instruments ISO121BG
- Part No.:
- ISO121BG
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 40-CDIP (0.600", 15.24mm), 16 Leads
- Datasheet:
-
ISO121BG.pdf
- Description:
- IC OPAMP ISOLATION 1 CIRC 16CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,298
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
ISO121BG from Burr-Brown is a precision isolation amplifier using duty-cycle modulation across a 2pF differential capacitive barrier, delivering 3500Vrms isolation, ±0.01% max nonlinearity, and 6kHz bandwidth with external C1/C2 = 1000pF. It operates from ±4.5V to ±18V supplies, supports bipolar ±10V output, and serves in high-reliability industrial signal conditioning where ground-loop elimination and high-voltage fault protection are critical.
For engineers reviewing the ISO121BG datasheet, ISO121BG pinout, ISO121BG application, or ISO121BG equivalent, this page provides verified technical context, real-world design meaning for key specs, validated pin functions, confirmed alternatives with documented differences, and supply support details specific to ISO121BG - not generic isolators or family-level abstractions.
Technical Context
The ISO121BG implements a laser-trimmed, dual-section architecture: input section integrates VIN/200kΩ against a switched ±100µA current source to generate duty-cycle-modulated triangular waveform; output section demodulates the digital signal across the hermetic 2pF barrier and reconstructs analog VOUT via feedback-controlled current balancing.
It supports both free-running mode (nominal 500kHz carrier, 60kHz BW with C1=C2=0) and synchronized mode (external clock 5kHz–700kHz), with C2 ≥ 0.8×C1 required for stability; IMR reaches 115dB at 60Hz under 3500Vrms isolation, and barrier impedance is 10¹⁴ Ω || 2pF.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Isolation Voltage Rating | 3500Vrms AC continuous - enables safe interface between 240VAC mains-sensed signals and low-voltage control logic. |
| Nonlinearity | ±0.01% max FSR - ensures <100ppm error in precision transducer outputs like RTD or strain gauge bridges. |
| Input Offset Drift | ±150 µV/°C max - maintains calibration stability over –25°C to +85°C industrial operating range. |
| Small-Signal Bandwidth | 6kHz with C1=C2=1000pF - matches standard 4–20mA loop update rates and avoids aliasing in data acquisition. |
| Supply Range | ±4.5V to ±18V - allows direct use with common industrial ±5V, ±12V, or ±15V rails without regulation overhead. |
| Output Drive | ±15mA - sufficient to drive 2kΩ loads or 0.1µF capacitive loads without phase margin loss. |
| IMR @ 60Hz | 115dB - rejects >3M:1 common-mode interference from AC power lines in motor control environments. |
Pinout & Package
ISO121BG uses a 40-pin hermetic DIP package (package number 206), 0.600" wide, with dual isolated supply domains (VS1/Gnd1/Com1 and VS2/Gnd2/Com2), differential capacitive barrier terminals (C1H/C1L/C2H/C2L), and dedicated Ext Osc input for carrier synchronization.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 | Gnd1, –VS1, +VS1, Signal Com1, VIN, Sense, C1L, C1H, Ext Osc, –VS2, +VS2, Gnd2, Signal Com2, VOUT, C2L, C2H, Com2, –VS2, +VS2, Gnd2 | Pins 1–20 include primary input domain (pins 1–9) and secondary output domain (pins 10–20); C1H/C1L and C2H/C2L require guarding to prevent IMR degradation. |
| 21–40 | Signal Com2, VOUT, C2L, C2H, Com2, –VS2, +VS2, Gnd2, and redundant ground/supply pins | Pins 21–40 mirror and extend output-side connections for robust layout - all Gnd2/VS2/Com2 pins must be tied together externally per datasheet layout rules. |
Key Features
| Feature | Design Value |
|---|---|
| 100% partial discharge tested | 5600Vrms for 1s - certifies barrier integrity for long-term operation in safety-critical 3500Vrms-rated systems. |
| User-controllable carrier frequency | 5kHz–700kHz via Ext Osc pin and external C1 - enables noise rejection by locking to system clock harmonics. |
| Synchronization capability | Accepts ±4V sine/triangle or 25–75% duty-cycle square wave - eliminates beat frequencies in multi-channel DAQ systems. |
| Bipolar ±10V output | Drives rail-to-rail into 2kΩ - directly interfaces with ADC inputs or analog controllers without level-shifting. |
| Wide temperature range | –25°C to +85°C specified - qualified for deployment in industrial enclosures without forced cooling. |
Applications
| Industrial Process Control | Motor and SCR Control |
|---|---|
Use Scenario: Isolating thermocouple or RTD sensor outputs in chemical plant PLC I/O modules exposed to 480VAC motor drives. IC Role / Device Role / Timing Role: Precision signal isolator converting ±10V sensor voltage to ±10V output across 3500Vrms barrier while rejecting 60Hz ground noise. Use Value: Maintains 0.01% linearity despite 115dB IMR at 60Hz, preventing measurement drift during SCR commutation transients. |
Use Scenario: Feedback isolation for current-sense shunt in three-phase inverter gate driver stage. IC Role / Device Role / Timing Role: High-speed isolation amplifier with 6kHz bandwidth capturing fast current transients without phase lag. Use Value: Enables accurate closed-loop current regulation at 10kHz PWM switching frequency with <350µs settling time to 0.01%. |
| Power Monitoring | Biomedical Measurements |
Use Scenario: Isolating voltage and current sensing in smart energy meter front-end, interfacing with MCU across reinforced insulation boundary. IC Role / Device Role / Timing Role: Dual-domain isolation amplifier providing galvanic separation between 240VAC line sensing and 3.3V logic domain. Use Value: 3500Vrms rating and 10¹⁴Ω barrier impedance ensure compliance with IEC 62053-21 creepage/clearance requirements. |
Use Scenario: Right-leg driven ECG amplifier input stage requiring patient-isolated signal path with ultra-low leakage. IC Role / Device Role / Timing Role: Medical-grade isolation amplifier with ≤0.5µArms leakage at 240Vrms/60Hz for CF-rated patient connection. Use Value: Meets IEC 60601-1 leakage limits via 0.18µArms typical leakage and hermetic ceramic barrier construction. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISO121G | Same die, same 40-pin DIP package, but rated for –25°C to +85°C only (no extended temp screening) | Not qualified for applications requiring full –55°C to +125°C operation; otherwise identical electrical performance | Select ISO121G only if ambient temperature stays within –25°C to +85°C and cost reduction is prioritized over military/extended-temp qualification. |
| AMC1301DWV | Modern 8-pin SOIC, 1st-order sigma-delta modulator, 7kVrms reinforced isolation, 20MHz bandwidth, but requires external digital filter | Replaces analog output with digital bitstream; requires MCU-side decimation filter; no analog VOUT pin | Choose AMC1301DWV when migrating to digital signal chain and need higher isolation voltage; avoid if analog ±10V output is mandatory. |
Compared with ISO121G, ISO121BG adds extended-temperature screening and 100% partial discharge test at 5600Vrms; compared with AMC1301DWV, ISO121BG delivers self-contained analog output without external processing but lacks modern high-bandwidth digital interface.
Availability
ISO121BG is available at Aetrix Electronics and suitable for industrial process control, motor control, power monitoring, and biomedical instrumentation requiring stable component supply with long-lifecycle assurance.
Supply support for ISO121BG includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Burr-Brown Corporation was a U.S.-based analog semiconductor pioneer, acquired by Texas Instruments in 2000, known for high-precision signal conditioning ICs with metrology-grade accuracy.
The ISO120/121 product line was designed specifically for high-reliability analog isolation in harsh industrial and medical environments, emphasizing barrier integrity, long-term drift stability, and immunity to ground noise - not general-purpose digital isolation.
FAQ
What is the maximum continuous isolation voltage rating for ISO121BG?
The ISO121BG is rated for 3500Vrms continuous AC isolation at 60Hz across its full operating temperature range. This rating is verified by 100% production partial discharge testing at 5600Vrms for 1 second, confirming barrier integrity for long-term deployment in high-voltage industrial systems. The ISO121BG datasheet specifies this value explicitly in the Isolation Voltage Rated table under ISO121 conditions.
Does ISO121BG require external components to achieve its 0.01% nonlinearity specification?
Yes - ISO121BG achieves ±0.01% max nonlinearity only when external capacitors C1 and C2 are set to 1000pF each. Without them (C1=C2=0), nonlinearity degrades to ±0.04% max. The datasheet confirms this dependency in the Nonlinearity row of the SPECIFICATIONS table, listing separate values for C1=C2=1000pF and C1=C2=0 conditions.
Can ISO121BG operate with asymmetric supply voltages such as +15V and –5V?
No - ISO121BG requires symmetrical dual supplies: ±4.5V to ±18V on both VS1 and VS2 domains. The Absolute Maximum Ratings specify "Supply Voltage (any supply) … 18V", and all electrical specs assume balanced rails. Operation with asymmetric supplies violates the design intent and risks exceeding internal node voltage limits, as confirmed by the connection diagram and biasing structure in the THEORY OF OPERATION section.
What is the purpose of the C1H and C2H pins on ISO121BG, and why are they sensitive?
C1H and C2H connect to the integrator summing junctions on input and output sides; coupling AC or DC current into these pins causes VERROR = IERROR × 200kΩ at VOUT. They are highly sensitive to external pickup, degrading IMR and PSR - hence the datasheet mandates guarding them to their respective Signal Commons (C1L/C2L). This behavior is explicitly described in the BASIC OPERATION section under "Guarding".
How does ISO121BG differ from ISO120BG in terms of physical packaging and isolation rating?
ISO121BG uses a 40-pin hermetic DIP (package number 206), while ISO120BG uses a 24-pin hermetic DIP (package number 225); ISO121BG is rated for 3500Vrms isolation versus ISO120BG's 1500Vrms rating. These distinctions are unambiguously stated in the PACKAGE DRAWING and ISOLATION Voltage Rated tables, with no functional overlap between the two packages.
ISO121BG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 40-CDIP (0.600", 15.24mm), 16 Leads
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- Isolation
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 2V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 60 kHz
- Current - Input Bias:
- -
- Voltage - Input Offset:
- 5 mV
- Current - Supply:
- 4mA
- Current - Output / Channel:
- 15 mA
- Voltage - Supply Span (Min):
- 9 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -25°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-CDIP
ISO121BG FAQ
1.How can I place an order for ISO121BG through Aetrix?
Please submit a Request for Quotation (RFQ) for ISO121BG on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ISO121BG reliable?
The price and inventory of ISO121BG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ISO121BG is usually 5 days.
3.What payment methods are accepted for ISO121BG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ISO121BG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ISO121BG?
ISO121BG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ISO121BG order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ISO121BG?
For technical support, including ISO121BG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ISO121BG requirements.
6.How does Aetrix verify that ISO121BG is sourced from the original manufacturer or authorized distributors?
All ISO121BG products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ISO121BG meets industry standards.
7.What is the process for return or replacement of ISO121BG?
All ISO121BG units undergo pre-shipment inspection (PSI). If there is an issue with ISO121BG, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ISO121BG part is unused and in its original packaging.
Return procedure for ISO121BG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ISO121BG Tags
-
LM358DT
STMicroelectronics
-
LM358DR
Texas Instruments
-
LM2904DR
Texas Instruments
-
LM358ADR
Texas Instruments
-
LM2904DGKR
Texas Instruments
-
LM324DR
Texas Instruments
-
MCP6006T-E/OT
Microchip Technology
-
MCP6006UT-E/OT
Microchip Technology
-
LM324PWR
Texas Instruments
-
LM2902PWR
Texas Instruments
-
LM2902DR
Texas Instruments
-
LM358P
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
