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Analog Devices Inc. LT1228CS8#PBF
- Part No.:
- LT1228CS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1228CS8#PBF.pdf
- Description:
- IC OPAMP CFA 1 CIRCUIT 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:786
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Product details
Overview
LT1228CS8#PBF from Analog Devices (formerly Linear Technology) is a dual-function 100MHz current feedback amplifier with integrated transconductance amplifier for electronically controlled DC-to-video gain. It features gm = 10 × ISET, 100MHz small-signal bandwidth, ±15V supply operation, 30mA output drive, and 0.04% differential gain-enabling precision video AGC and tunable filter applications.
For engineers reviewing the LT1228CS8#PBF datasheet, LT1228CS8#PBF pinout, LT1228CS8#PBF application, or LT1228CS8#PBF equivalent, this page delivers verified specifications, SO-8 package layout, real-world video and signal conditioning use cases, and validated alternative options for gain-controlled analog front-ends.
Technical Context
The LT1228CS8#PBF integrates two functionally distinct amplifiers on one die: a high-input-impedance transconductance amplifier (Pins 1–3, 5) with gm programmable via ISET current into Pin 5, and a high-speed current feedback amplifier (Pins 1, 6, 8) optimized for low-impedance loads. The transconductance stage provides linear voltage-to-current conversion over 1µA–1mA ISET, while the CFA maintains >100MHz bandwidth across gains of 2–100 with minimal peaking when RF ≥ 750Ω.
Its architecture enables direct differential input configuration without external level-shifting, supports common-mode input to within 1.5V of supplies, and delivers rail-to-rail output swing within 0.8V on ±15V rails. Input noise is 6nV/√Hz (CFA) and 20nV/√Hz (gm amp), with THD of 0.2% at 30mVRMS input-critical for NTSC-compliant video signal chains.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Small-Signal Bandwidth | 100MHz at ±15V, RF = RG = 750Ω, RL = 100Ω - enables full NTSC/PAL baseband video amplification |
| Transconductance (gm) | gm = 10 × ISET (e.g., 1mA ISET → 10mS) - provides precise, decade-scalable gain control |
| Slew Rate | 3500V/µs under ±15V, RF = RG = 750Ω - supports fast transient response in keyer/fader circuits |
| Differential Gain / Phase | 0.04% / 0.1° at ±15V, RL = 150Ω - meets broadcast-grade video fidelity requirements |
| Supply Voltage Range | ±2V to ±15V (4V–30V total) - compatible with legacy ±5V, ±12V, and modern ±15V systems |
| Input Offset Voltage (CFA) | ±3mV (typ) - ensures low DC error in closed-loop gain control loops |
| Output Drive Current | 30mA (min) - drives 75Ω coaxial cables or parallel-loaded video DAC outputs directly |
Pinout & Package
LT1228CS8#PBF is housed in an 8-lead plastic SO (SOIC-8) package with standard JEDEC MS-012AC footprint (5.0mm × 4.0mm, 1.27mm pitch). Thermal resistance θJA = 150°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Transconductance Output / CFA Noninverting Input | Current-source output of gm amp; high-Z node feeding CFA+ - requires low-capacitance routing |
| 2 | Inverting Input (gm amp) | Differential input terminal; high common-mode rejection up to ±13V on ±15V rails |
| 3 | Noninverting Input (gm amp) | Differential input terminal; matched to Pin 2 for <1% gm variation over ±30mV input range |
| 4 | Negative Supply (V–) | Reference for ISET bias - Pin 5 voltage is ~1.2V above this rail; shorting Pin 5 to V– destroys device |
| 5 | ISET Control Input | Current-sink terminal setting gm; 1µA–1mA range; voltage ~1.2V above V– with –4mV/°C TC |
| 6 | CFA Output | Low-impedance voltage output; capable of 30mA sink/source into 400Ω load |
| 7 | Positive Supply (V+) | Power rail; supports up to ±15V; PSRR >60dB across 2V–15V range |
| 8 | CFA Inverting Input | Current-summing node; requires resistive feedback only - avoid capacitance to ground |
Key Features
| Feature | Design Value |
|---|---|
| Integrated gm + CFA architecture | Eliminates inter-stage coupling components and PCB area; enables single-supply-compatible differential gain control |
| Wide ISET programming range | 1µA to 1mA allows >60dB electronic gain adjustment while maintaining linearity and bandwidth |
| High CFA input impedance | 25MΩ || 6pF minimizes loading on gm amp output, preserving bandwidth when converting IOUT to voltage |
| Video-optimized distortion performance | 0.2% THD at 30mVRMS and 0.04%/0.1° differential gain/phase meet NTSC composite video specs |
| Robust supply flexibility | Operates from ±2V to ±15V; input common-mode extends to within 1.5V of rails; output swings to within 0.8V |
Applications
| Video DC Restore (Clamp) Circuits | Video Differential Input Amplifiers |
|---|---|
Use Scenario: Restoring black-level reference in composite video signals before digitization or distribution. IC Role / Device Role / Timing Role: LT1228CS8#PBF acts as a fast, gain-stable clamping amplifier with programmable DC offset correction. Use Value: Maintains <0.1° differential phase error across temperature, preventing hue shifts in broadcast equipment. | Use Scenario: Converting single-ended camera sensor outputs to balanced differential signals for noise-immune transmission. IC Role / Device Role / Timing Role: LT1228CS8#PBF serves as a high-CMRR, variable-gain differential receiver with rail-swing capability. Use Value: Achieves 69dB CMRR at ±13V common-mode and 0.04% differential gain - critical for medical imaging sensors. |
| Video Keyer/Fader Amplifiers | AGC Amplifiers |
Use Scenario: Real-time mixing of foreground/background video layers in broadcast switchers with smooth fade transitions. IC Role / Device Role / Timing Role: LT1228CS8#PBF functions as a high-slew-rate (3500V/µs), low-distortion gain modulator. Use Value: Delivers sub-5ns rise time and <15% overshoot at 100MHz, enabling glitch-free layer switching. | Use Scenario: Stabilizing signal amplitude in RF receiver IF stages or optical transceiver analog front-ends. IC Role / Device Role / Timing Role: LT1228CS8#PBF implements closed-loop gain control via ISET current derived from detector output. Use Value: Provides 100MHz control bandwidth and <0.2% THD - supports wide-dynamic-range AGC in 5G mmWave receivers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar variable-gain amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD8370ARUZ | Digitally controlled (SPI), 750MHz bandwidth, fixed 20dB gain steps, no analog ISET interface | Requires digital control infrastructure; lacks true analog gm-linearity and DC-coupled gain tuning | Choose AD8370ARUZ for high-frequency IF gain control where SPI interface and >500MHz BW are mandatory |
| LMH6552MA/NOPB | Single CFA (no integrated gm amp), 1.8GHz GBW, 3100V/µs slew, requires external VGA or DAC for gain control | Higher speed but adds component count and layout complexity for gain modulation | Choose LMH6552MA/NOPB when >1GHz bandwidth is required and discrete gain control circuitry is acceptable |
Compared with AD8370ARUZ and LMH6552MA/NOPB, the LT1228CS8#PBF uniquely integrates analog transconductance and current feedback functions in one SO-8 package-reducing BOM count by 3–5 components while delivering verified NTSC video performance and seamless DC-to-100MHz gain control without digital overhead.
Availability
LT1228CS8#PBF is available at Aetrix Electronics and suitable for video signal conditioning, broadcast equipment design, and high-speed analog front-end development requiring stable component supply, RoHS-compliant packaging, and industrial temperature-grade consistency.
Supply support for LT1228CS8#PBF 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 demanding video, instrumentation, and wideband analog signal processing needs-emphasizing integration, precision, and ease of gain control in compact packages.
FAQ
What is the maximum safe ISET current for LT1228CS8#PBF?
The absolute maximum ISET current into Pin 5 of the LT1228CS8#PBF is 15mA. Exceeding this risks permanent damage. The functional range is 1µA to 1mA for optimal gm linearity and bandwidth. A series resistor (e.g., 2kΩ) is recommended when driving Pin 5 from a voltage source referenced to V– to prevent accidental overcurrent.
Can LT1228CS8#PBF operate on a single +5V supply?
Yes, the LT1228CS8#PBF supports single-supply operation down to +4V total (e.g., +4.5V V+ and GND as V–). Input common-mode range extends to within 1.5V of supplies, and output swings to within 0.8V - enabling use in +5V systems with appropriate level-shifting on Pins 2/3 and proper ISET biasing relative to GND.
What is the thermal resistance (θJA) of the LT1228CS8#PBF SO-8 package?
Per the official Linear Technology datasheet, the LT1228CS8#PBF in the 8-lead plastic SO package has a junction-to-ambient thermal resistance (θJA) of 150°C/W under standard JEDEC test conditions (1squared inch 2oz copper pad). This value assumes no additional heatsinking and must be factored into power dissipation calculations at elevated ambient temperatures.
Does LT1228CS8#PBF require external compensation capacitors?
No, the LT1228CS8#PBF is internally compensated for unity-gain stability in its current feedback amplifier section. However, external feedback resistors (RF, RG) must be selected per application bandwidth and gain requirements - e.g., 750Ω for 100MHz at gain = 2. Capacitance on Pin 8 (CFA inverting input) must be minimized to avoid peaking.
How does temperature affect transconductance accuracy in LT1228CS8#PBF?
The LT1228CS8#PBF exhibits a transconductance drift of –0.33%/°C and ISET voltage drift of –4mV/°C. Over –40°C to +85°C, uncorrected gm varies by ~35%. Using a 2.5V reference (e.g., LT1004-2.5) to bias Pin 5 reduces gain drift to <1% across –55°C to +125°C - a technique validated in the LT1228 datasheet.
LT1228CS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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:
- -
- 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#PBF FAQ
1.How can I place an order for LT1228CS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1228CS8#PBF 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#PBF reliable?
The price and inventory of LT1228CS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1228CS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1228CS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1228CS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1228CS8#PBF?
LT1228CS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1228CS8#PBF 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#PBF?
For technical support, including LT1228CS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1228CS8#PBF requirements.
6.How does Aetrix verify that LT1228CS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1228CS8#PBF 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#PBF meets industry standards.
7.What is the process for return or replacement of LT1228CS8#PBF?
All LT1228CS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1228CS8#PBF, 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#PBF part is unused and in its original packaging.
Return procedure for LT1228CS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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