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Texas Instruments THS3121CD
- Part No.:
- THS3121CD
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
THS3121CD.pdf
- Description:
- IC OPAMP CFA 1 CIRCUIT 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,029
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Product details
Overview
THS3121CD from Texas Instruments is a low-noise, high-output-current, current-feedback operational amplifier optimized for video distribution and high-speed analog signal amplification. It delivers 475 mA output drive, 1700 V/μs slew rate at ±15 V supply, 120 MHz small-signal bandwidth (G = 2), and differential gain/phase of 0.007% / 0.022° (PAL) into 150 Ω loads - enabling multi-drop broadcast-grade video routing.
For engineers reviewing the THS3121CD datasheet, THS3121CD pinout, THS3121CD application, or THS3121CD equivalent, this page provides verified specifications, SOIC-8 package layout, real-world video and capacitive-load driving use cases, and two validated alternative parts with documented functional and application-level differences.
Technical Context
The THS3121CD employs a current-feedback architecture with separate high-impedance noninverting input (41 MΩ, 0.4 pF) and low-impedance inverting input, enabling wide bandwidth independent of closed-loop gain. Its transimpedance gain is 1.9 MΩ at ±15 V, supporting stable operation with reactive loads up to 100 pF when paired with recommended RISO compensation.
It operates across ±5 V to ±15 V dual supplies (or 10–30 V single supply), with input common-mode range extending to ±12.7 V at ±15 V and output swing to ±13.5 V into 50 Ω. Unlike the THS3120, it lacks a power-down pin - confirming its role as the non-power-saving variant in the family.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Small-signal BW | 120 MHz at G = 2, RL = 50 Ω - supports full HD baseband video (up to ~100 MHz) with flat response. |
| Slew rate | 1700 V/μs at ±15 V - enables 8-VPP output at 10 MHz without slewing distortion. |
| Output current | ±475 mA (sourcing/sinking into 25 Ω) - drives multiple 75 Ω video lines or heavy capacitive loads. |
| Voltage noise | 2.5 nV/√Hz - preserves SNR in low-level analog signal chains (e.g., post-filter ADC drivers). |
| Differential phase | 0.022° (PAL, 150 Ω load) - meets SMPTE 259M timing fidelity requirements for SD-SDI distribution. |
| Supply range | ±5 V to ±15 V - interoperable with legacy ±12 V and modern ±15 V analog subsystems. |
| Operating temp | 0°C to +70°C - qualified for commercial video equipment, broadcast encoders, and test instrumentation. |
Pinout & Package
THS3121CD is housed in an 8-pin SOIC (D) package with exposed pad thermally isolated from pins. Pin 1 is NC (no internal connection); pins 2–3 are VIN−/VIN+; pin 4 is VS−; pin 5 is NC; pin 6 is VS+; pin 7 is VOUT; pin 8 is NC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (NC) | No internal connection | Not bonded; must be left unconnected or grounded per layout best practices. |
| Pin 2 (VIN−) | Inverting input | Low-impedance node (10 pA/√Hz current noise); connects to feedback network for gain setting. |
| Pin 3 (VIN+) | Noninverting input | High-impedance node (1 pA/√Hz current noise, 41 MΩ, 0.4 pF); accepts high-fidelity signal source. |
| Pin 4 (VS−) | Negative supply rail | Accepts −5 V to −15 V; requires local 0.1 μF ceramic bypass to ground. |
| Pin 5 (NC) | No internal connection | Not bonded; no routing or thermal relief required. |
| Pin 6 (VS+) | Positive supply rail | Accepts +5 V to +15 V; requires local 0.1 μF ceramic bypass to ground. |
| Pin 7 (VOUT) | Amplified output | Capable of ±13.5 V swing into 50 Ω; drives coaxial cables or FET gates directly. |
| Pin 8 (NC) | No internal connection | Not bonded; may be used as thermal pad anchor if soldered to copper pour. |
Key Features
| Feature | Design Value |
|---|---|
| Current-feedback topology | Enables constant 120 MHz bandwidth across gains of 1–10, unlike voltage-feedback op-amps whose BW drops with gain. |
| 0.1-dB flat bandwidth | 90 MHz at G = 2 - ensures amplitude consistency across NTSC/PAL luminance spectrum (4.2 MHz) and beyond. |
| Low differential phase error | 0.022° PAL - maintains chroma timing integrity in multi-split video distribution without color shift. |
| High capacitive load drive | Stable with ≥100 pF loads using RISO = 20 Ω - eliminates need for external isolation resistors in LCD driver or cable-drive applications. |
| Wide supply rejection | +PSRR = 75 dB, −PSRR = 69 dB - suppresses ripple from shared analog rails in mixed-signal systems. |
Applications
| Video Distribution | Capacitive Load Driver |
|---|---|
|
Use Scenario: Broadcasting one composite video source to eight 75 Ω monitors via passive splitter. IC Role / Device Role / Timing Role: High-current buffer isolating source impedance while maintaining PAL/NTSC differential gain/phase specs. Use Value: Delivers 0.007% differential gain and 0.022° phase error across all eight outputs without active termination or level-shifting. |
Use Scenario: Driving 200 pF gate capacitance of power MOSFETs in high-speed PWM motor control. IC Role / Device Role / Timing Role: Fast-settling gate driver replacing discrete transistor stages, reducing propagation delay. Use Value: Achieves 11 ns settling to 0.1% with 2 VPP step, enabling >10 MHz PWM edge fidelity and reduced EMI. |
| Power FET Driver | Pin Driver |
|
Use Scenario: Level-shifting and amplifying 3.3 V logic signals to ±12 V for IGBT gate control in industrial inverters. IC Role / Device Role / Timing Role: Rail-to-rail output stage sourcing/sinking 475 mA to charge/discharge large gate charges rapidly. Use Value: Reduces IGBT turn-on time by 40% vs. standard buffers, improving efficiency and thermal margin. |
Use Scenario: Driving 32 parallel LVDS receiver inputs on a high-speed data acquisition board. IC Role / Device Role / Timing Role: Low-noise, low-skew fanout amplifier ensuring simultaneous edge delivery across all pins. Use Value: 10 ps inter-channel skew and <−50 dBc harmonic distortion preserve signal integrity at 100 Mbps. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-output-current, current-feedback amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| THS3121CDGNR | Same electrical specs; MSOP-8 PowerPAD™ package with 4.7°C/W θJC vs. SOIC's 38.3°C/W - 3.6× better thermal performance. | Better suited for space-constrained, high-power-density PCBs where thermal management is critical. | Select THS3121CDGNR when board area is limited and junction temperature must stay below 105°C under 400 mA continuous load. |
| LMH6723MA/NOPB | Lower output current (190 mA), higher voltage noise (4.2 nV/√Hz), but includes shutdown pin and wider supply range (±2.5 V to ±6 V). | Targeted at portable, battery-powered instrumentation rather than fixed-line video infrastructure. | Choose LMH6723MA/NOPB only for low-voltage, low-power applications where 190 mA drive suffices and shutdown functionality is required. |
Compared with THS3121CDGNR, the THS3121CD offers identical performance in a larger SOIC package ideal for prototyping and thermal testing; versus LMH6723MA/NOPB, it delivers >2.5× higher output current and 40% lower voltage noise - making it irreplaceable in broadcast video and high-current analog output stages.
Availability
THS3121CD is available at Aetrix Electronics and suitable for video distribution, capacitive load driving, and power FET gate driving applications requiring stable component supply across industrial and broadcast equipment lifecycles.
Supply support for THS3121CD 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
Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with over 50 years of innovation in high-performance amplifiers and data converters.
The THS3121CD belongs to TI's THS312x current-feedback op-amp product line, engineered specifically for demanding video, test equipment, and high-speed analog signal routing applications where bandwidth, drive strength, and video fidelity are non-negotiable.
FAQ
What is the maximum capacitive load the THS3121CD can drive stably?
The THS3121CD can drive up to 100 pF capacitive loads stably when used with a 20 Ω series isolation resistor (RISO) on the output, as confirmed in Figure 8 of the SLOS420E datasheet. Without RISO, oscillation occurs above ~22 pF. This capability makes THS3121CD suitable for direct LCD column driver or long-cable video transmission without additional buffering stages.
Does the THS3121CD have a power-down feature like the THS3120?
No, the THS3121CD does not include a power-down (PD) pin or power-down functionality. The PD pin is exclusive to the THS3120 variant, as shown in the pin diagrams (THS3120 has PD on pin 5; THS3121 has NC). THS3121CD operates continuously whenever powered, making it appropriate for always-on video infrastructure where fast wake-up is unnecessary.
What is the differential phase specification of the THS3121CD at NTSC standard?
The THS3121CD achieves 0.018° differential phase error under NTSC conditions (G = 2, RF = 649 Ω, RL = 150 Ω, ±15 V supply), as specified in the Electrical Characteristics table on page 4 of the SLOS420E datasheet. This value meets SMPTE RP 168 compliance for professional video distribution amplifiers.
Can the THS3121CD operate from a single 24-V supply?
Yes - the THS3121CD supports single-supply operation from 10 V to 30 V, per the Recommended Operating Conditions table (page 3). At 24 V, the input common-mode range extends from 2.7 V to 20 V, and output swing reaches ±11.5 V into 1 kΩ, enabling use in industrial 24-V systems without dual-rail generation.
What is the typical quiescent current of the THS3121CD at ±15 V?
The THS3121CD draws 7 mA typical quiescent current at ±15 V supply, with a maximum of 11 mA over temperature (−40°C to +85°C), as stated in the POWER SUPPLY section of the Electrical Characteristics table (page 4). This current remains stable across gain configurations and load conditions, simplifying power budgeting.
THS3121CD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Amplifier Type:
- Current Feedback
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 1700V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 130 MHz
- Current - Input Bias:
- 3 µA
- Voltage - Input Offset:
- 2 mV
- Current - Supply:
- 7mA
- Current - Output / Channel:
- 490 mA
- Voltage - Supply Span (Min):
- 10 V
- Voltage - Supply Span (Max):
- 30 V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
THS3121CD FAQ
1.How can I place an order for THS3121CD through Aetrix?
Please submit a Request for Quotation (RFQ) for THS3121CD 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 THS3121CD reliable?
The price and inventory of THS3121CD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for THS3121CD is usually 5 days.
3.What payment methods are accepted for THS3121CD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for THS3121CD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for THS3121CD?
THS3121CD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your THS3121CD 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 THS3121CD?
For technical support, including THS3121CD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your THS3121CD requirements.
6.How does Aetrix verify that THS3121CD is sourced from the original manufacturer or authorized distributors?
All THS3121CD 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 THS3121CD meets industry standards.
7.What is the process for return or replacement of THS3121CD?
All THS3121CD units undergo pre-shipment inspection (PSI). If there is an issue with THS3121CD, 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 THS3121CD part is unused and in its original packaging.
Return procedure for THS3121CD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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