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Analog Devices Inc. LT1228CS8#TRPBF
- Part No.:
- LT1228CS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1228CS8#TRPBF.pdf
- Description:
- IC OPAMP CFA 1 CIRCUIT 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,176
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Product details
Overview
LT1228CS8#TRPBF from Analog Devices (formerly Linear Technology) is a dual-function 8-pin SOIC current feedback amplifier with integrated transconductance amplifier, enabling electronic DC-to-video gain control. It delivers 100MHz small-signal bandwidth, 1000V/µs slew rate, and ±15V supply operation. It is used in video keyer/fader circuits, AGC amplifiers, and tunable filter designs requiring wide dynamic range and high-speed analog signal conditioning.
For engineers reviewing the LT1228CS8#TRPBF datasheet, LT1228CS8#TRPBF pinout, LT1228CS8#TRPBF application, or LT1228CS8#TRPBF equivalent, this page provides verified specifications, package mapping, real-world use scenarios, validated alternatives, and supply-chain support for industrial and video signal-path design.
Technical Context
The LT1228CS8#TRPBF integrates two functionally distinct amplifiers on one die: a high-impedance differential-input transconductance amplifier (gm amp) with ISET-controlled gain (gm = 10 × ISET), and a high-input-impedance current feedback amplifier (CFA) optimized for low-impedance loads. The gm amp's output current drives the CFA's noninverting input (Pin 1), forming a complete variable-gain voltage amplifier without external interstage coupling.
Its architecture supports wide supply range (±2V to ±15V), rail-to-rail input common-mode range (within 1.5V of supplies), and output swing within 0.8V of rails. Gain control is implemented via externally sourced current into Pin 5 (ISET), with gm linear over 1µA–1mA and temperature-compensatable using a 2.5V reference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Small-signal bandwidth | 100MHz at ±15V, RF = RG = 750Ω, RL = 100Ω - enables NTSC/PAL video signal amplification without phase distortion |
| Slew rate | 1000V/µs - supports fast transient response in keyer/fader switching and pulse-amplitude modulation |
| Transconductance (gm) | gm = 10 × ISET (e.g., 1mA ISET → 10mS) - provides precise, linear, externally programmable gain scaling |
| Differential gain/phase error | 0.04% / 0.1° at ±15V, RL = 150Ω - meets broadcast-grade video fidelity requirements |
| Supply voltage range | ±2V to ±15V - supports single-supply (4V–30V) or split-supply operation in mixed-signal systems |
| Input impedance | 25MΩ || 6pF - minimizes loading on high-Z sensor or filter networks |
| Output drive current | 30mA - directly drives 75Ω coaxial cables or multiple parallel loads without buffering |
Pinout & Package
LT1228CS8#TRPBF is housed in an 8-lead plastic SO (SOIC-8) package, RoHS-compliant and tape-and-reel packaged (TRPBF suffix). Dimensions: 4.9mm × 3.9mm × 1.45mm, standard JEDEC MS-012AC footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | gm Amp Output / CFA Noninverting Input | Current-source output of transconductance stage; directly connected to high-Z noninverting input of CFA - no external coupling required |
| 2 | gm Amp Inverting Input (–IN) | Differential input node; high common-mode rejection (60dB min) up to ±13V with ±15V supplies |
| 3 | gm Amp Noninverting Input (+IN) | Differential input node; matched to Pin 2 for precision DC-coupled gain control |
| 4 | Negative Supply (V–) | Reference for ISET bias (Pin 5 sits ~1.2V above V–); must be stable and low-noise for gm accuracy |
| 5 | ISET Control Terminal | Current-sink input setting transconductance; destruction risk if shorted to ground or V+ - requires series limiting resistor |
| 6 | CFA Output (VOUT) | Low-impedance voltage output capable of 30mA sink/source; swings within 0.8V of rails into 400Ω |
| 7 | Positive Supply (V+) | Power rail; supports ±2V to ±15V operation; PSRR ≥60dB across full supply range |
| 8 | CFA Inverting Input (–IN) | Current-summing node for feedback; requires resistive (not capacitive) feedback path to ensure stability |
Key Features
| Feature | Design Value |
|---|---|
| Integrated gm + CFA architecture | Eliminates interstage coupling components and layout sensitivity - reduces board area and parasitic phase shift |
| Wide ISET control range (1µA–1mA) | Enables >60dB analog gain adjustment range while maintaining linearity and bandwidth scalability |
| High input impedance (25MΩ) | Preserves signal integrity when interfacing with passive filters, crystal networks, or high-Z sensors |
| Video-optimized distortion performance | 0.2% THD at 30mVRMS input and 0.04%/0.1° differential gain/phase - suitable for broadcast and medical imaging front-ends |
| Temperature-stable gm control | Supports 2.5V reference-based compensation achieving <1% gain drift from –55°C to 125°C |
Applications
| Video Keyer/Fader Amplifier | AGC Amplifier |
|---|---|
Use Scenario: Real-time mixing of video sources during live broadcast, requiring smooth fade transitions and precise level matching between RGB or YUV channels. IC Role / Device Role / Timing Role: LT1228CS8#TRPBF serves as the core gain-controlled amplifier in the keyer's analog matrix, where ISET current modulates opacity in sub-microsecond timescales. Use Value: 100MHz bandwidth and 1000V/µs slew rate enable artifact-free transitions; 0.04% differential gain error preserves color fidelity across fade range. | Use Scenario: Maintaining constant output amplitude in RF receiver IF stages despite varying signal strength, especially in terrestrial TV tuners and satellite demodulators. IC Role / Device Role / Timing Role: LT1228CS8#TRPBF acts as the variable-gain IF amplifier, with envelope-detected DC voltage converted to ISET current for closed-loop gain adjustment. Use Value: Wide ISET range (1µA–1mA) supports >60dB AGC range; low THD (0.2%) prevents intermodulation distortion in multi-channel systems. |
| Tunable Active Filter | Video DC Restore (Clamp) Circuit |
Use Scenario: Adaptive filtering in software-defined radio (SDR) front-ends or medical ultrasound beamformers, where center frequency and Q are dynamically adjusted. IC Role / Device Role / Timing Role: LT1228CS8#TRPBF implements the gain-controllable integrator or resonator stage in state-variable or biquad topologies, with ISET tuning filter Q and bandwidth. Use Value: gm proportional to ISET allows direct Q control; 80MHz gm-amp bandwidth (at 500µA) supports >10MHz filter center frequencies with low group delay variation. | Use Scenario: Restoring DC level of composite video signals after AC coupling in monitor inputs or video processing pipelines. IC Role / Device Role / Timing Role: LT1228CS8#TRPBF functions as a fast, high-impedance clamp amplifier that injects correction current into sync-tip clamping diodes during blanking intervals. Use Value: High input impedance (25MΩ) avoids loading video source; 3.5ns rise time ensures accurate clamping within tight horizontal blanking windows. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar variable-gain amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD8367ARUZ | 500MHz gain-bandwidth, logarithmic dB-linear transfer function, internal RMS detector; requires external power-down control | Designed for RF/IF automatic gain control, not video baseband; lacks differential input and DC-coupled capability | Select AD8367ARUZ for RF AGC above 10MHz; avoid for DC-coupled video or precision differential applications. |
| THS7530DR | Triple-channel, fully differential, 300MHz bandwidth, fixed-gain options only; no ISET-based gain control | Targeted at RGB video routing and distribution; no analog gain programming interface | Select THS7530DR for multi-channel video routing with fixed gain; use LT1228CS8#TRPBF when per-channel electronic gain adjustment is required. |
Compared with AD8367ARUZ and THS7530DR, the LT1228CS8#TRPBF uniquely combines DC-coupled differential input, ISET-programmable transconductance, and current-feedback output drive - making it the only option among the three for precision analog video gain control with sub-1% distortion and microsecond settling.
Availability
LT1228CS8#TRPBF is available at Aetrix Electronics and suitable for video keyer/fader circuits, AGC amplifiers, and tunable active filters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LT1228CS8#TRPBF 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
Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.
The LT1228 product line was originally developed by Linear Technology (acquired by ADI in 2017) to address high-speed analog signal conditioning needs in professional video, test equipment, and instrumentation - emphasizing wide bandwidth, low distortion, and flexible gain control.
FAQ
What is the maximum safe ISET current for LT1228CS8#TRPBF?
The absolute maximum ISET current into Pin 5 is 15mA, but operation above 1mA degrades gm linearity and increases thermal stress. The datasheet specifies optimal performance across 1µA–1mA, with gm = 10 × ISET holding within ±5% over this range. Exceeding 15mA will destroy the LT1228CS8#TRPBF due to internal junction failure.
Can LT1228CS8#TRPBF operate from a single 5V supply?
Yes, LT1228CS8#TRPBF supports single-supply operation from 4V to 30V (i.e., +4V to +30V with ground referenced). At +5V, input common-mode range is ±2V to ±3.5V, output swing is ±2.5V into 150Ω, and supply current is ~7mA. Pin 4 (V–) connects to ground, and Pin 5 bias remains ~1.2V above ground - requiring appropriate ISET resistor sizing.
Does LT1228CS8#TRPBF require external compensation capacitors?
No, LT1228CS8#TRPBF is internally compensated for unity-gain stability with resistive feedback. However, capacitive load driving (>100pF) or peaking enhancement in high-gain configurations may require a series isolation resistor (10–20Ω) at Pin 6 or controlled capacitance at Pin 8. The datasheet provides "Maximum Capacitive Load vs Feedback Resistor" curves to guide selection without instability.
What is the typical THD performance of LT1228CS8#TRPBF at video frequencies?
LT1228CS8#TRPBF achieves 0.2% total harmonic distortion at 30mVRMS input and 1kHz, and maintains <0.5% THD up to 10MHz under ±15V supply conditions. This performance is validated with 75Ω termination and matches broadcast video requirements - confirmed in TPC20 and TPC21 plots showing distortion ≤ –40dBc through NTSC bandwidth.
How does temperature affect the transconductance (gm) of LT1228CS8#TRPBF?
LT1228CS8#TRPBF exhibits –3300ppm/°C transconductance drift versus absolute temperature. However, its Pin 5 bias voltage has a compensating +3300ppm/°C coefficient. When combined with a 2.5V reference (e.g., LT1004-2.5), the net gm drift is reduced to <1% over –55°C to 125°C - a design feature explicitly documented in the Applications Information section of the LT1228 datasheet.
LT1228CS8#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Amplifier Type:
- Current Feedback
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 3500V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 100 MHz
- Current - Input Bias:
- 10 µA
- Voltage - Input Offset:
- 3 mV
- Current - Supply:
- 6mA
- Current - Output / Channel:
- 125 mA
- Voltage - Supply Span (Min):
- 4 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1228CS8#TRPBF FAQ
1.How can I place an order for LT1228CS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1228CS8#TRPBF 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 LT1228CS8#TRPBF reliable?
The price and inventory of LT1228CS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1228CS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1228CS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1228CS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1228CS8#TRPBF?
LT1228CS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1228CS8#TRPBF 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 LT1228CS8#TRPBF?
For technical support, including LT1228CS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1228CS8#TRPBF requirements.
6.How does Aetrix verify that LT1228CS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1228CS8#TRPBF 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 LT1228CS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1228CS8#TRPBF?
All LT1228CS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1228CS8#TRPBF, 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 LT1228CS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1228CS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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