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Analog Devices Inc. LT1228IN8#PBF
- Part No.:
- LT1228IN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1228IN8#PBF.pdf
- Description:
- IC OPAMP CFA 1 CIRCUIT 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,139
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Product details
Overview
LT1228IN8#PBF from Analog Devices (formerly Linear Technology) is a dual-function 8-pin current feedback amplifier with integrated transconductance stage, designed for high-speed video and precision gain-control applications. It delivers 100MHz small-signal bandwidth, 1000V/µs slew rate, ±15V supply operation, and gm = 10 × ISET transconductance scaling - enabling DC-to-video-frequency electronic gain control in AGC amplifiers, video keyers, and tunable filters.
For engineers reviewing the LT1228IN8#PBF datasheet, LT1228IN8#PBF pinout, LT1228IN8#PBF application, or LT1228IN8#PBF equivalent, this page provides verified pin functions, confirmed temperature range (–40°C to +85°C), validated differential-phase performance (0.1° at 150Ω load), real-world THD (0.2% at 30mVRMS), and two documented alternative parts with explicit functional trade-offs.
Technical Context
The LT1228IN8#PBF integrates two independent amplifier blocks: a high-impedance differential-input transconductance amplifier (Pins 1–3,5) with gm programmable via ISET current into Pin 5, and a high-input-impedance current feedback amplifier (Pins 1,6,8) optimized for driving low-Z loads like coaxial cables. Its architecture decouples gain control (via external ISET) from signal path bandwidth - enabling stable wideband operation across voltage gains from 2 to 100.
Both sections operate over ±2V to ±15V supplies, share common V+ (Pin 7) and V– (Pin 4), and feature rail-to-rail input common-mode range (within 1.5V of supplies) and output swing within 0.8V of rails. The transconductance stage exhibits <1% gm variation over ±30mV differential input, while the CFA maintains <0.04% differential gain error under NTSC video conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Small-signal bandwidth | 100MHz at ±15V, RF = RG = 750Ω, RL = 100Ω - supports full NTSC/PAL video baseband without attenuation |
| Slew rate | 1000V/µs - enables clean 10Vpp signals at >10MHz without slewing distortion |
| Transconductance (gm) | gm = 10 × ISET (A/V); e.g., 100µA ISET → 1mS gm - provides linear, decade-scalable gain control |
| Total harmonic distortion | 0.2% at 30mVRMS input, 1kHz - meets broadcast-grade analog video linearity requirements |
| Differential phase error | 0.1° at ±15V, RL = 150Ω - preserves color fidelity in composite video systems |
| Supply voltage range | ±2V to ±15V - supports single-supply (4V–30V) or split-rail operation in industrial and video gear |
| Operating temperature | –40°C to +85°C - qualified for extended-temperature industrial and automotive cabin applications |
Pinout & Package
LT1228IN8#PBF is housed in an 8-lead plastic DIP (N8) package with through-hole mounting and 0.3-inch width. Pin spacing is 0.1 inch, body dimensions are 0.395 × 0.245 inches, and thermal resistance θJA = 100°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (IOUT) | Transconductance amplifier output current source | Drives noninverting input of CFA; requires external resistor to convert to voltage; high-voltage compliance (±13V) |
| Pin 2 (+IN) | Transconductance amplifier noninverting input | Differential pair input; high-Z (≥50MΩ common-mode), ±13V input range at ±15V supply |
| Pin 3 (–IN) | Transconductance amplifier inverting input | Differential pair input; ESD-protected (back-to-back Zeners vs Pin 2); same specs as Pin 2 |
| Pin 4 (V–) | Negative supply rail | Reference for internal biasing; Pin 5 voltage = V– + ~1.2V (two diode drops) |
| Pin 5 (ISET) | Transconductance set current input | Current sink; gm = 10 × ISET; must be limited to <15mA; shorting to ground destroys device |
| Pin 6 (VOUT) | Current feedback amplifier output | Capable of ±12V swing into 400Ω; 30mA drive capability; optimized for cable driving |
| Pin 7 (V+) | Positive supply rail | Accepts up to ±15V; supplies both amplifier sections; decoupling recommended |
| Pin 8 (–IN) | Current feedback amplifier inverting input | High-impedance node; feedback resistor connects here; sensitive to stray capacitance |
Key Features
| Feature | Design Value |
|---|---|
| Integrated transconductor + CFA | Eliminates inter-stage coupling errors and layout sensitivity in gain-controlled video paths |
| Programmable transconductance | gm scales linearly with ISET (1µA–1mA), enabling precise, monotonic gain adjustment over 60dB range |
| Video-optimized linearity | 0.04% differential gain / 0.1° differential phase error ensures broadcast-compliant color reproduction |
| Rail-compatible inputs/outputs | Inputs operate within 1.5V of rails; outputs swing within 0.8V - maximizes dynamic range in ±15V systems |
| Wide supply flexibility | Operates from ±2V to ±15V (4V–30V total) - supports legacy ±12V, modern ±5V, and battery-powered designs |
Applications
| Video Keyer/Fader Amplifier | AGC Amplifier |
|---|---|
Use Scenario: Real-time mixing of multiple video sources with adjustable opacity/fade depth in broadcast switchers. IC Role / Device Role / Timing Role: LT1228IN8#PBF serves as the core gain-controlled amplifier, where ISET current sets key/fade level while preserving sync timing integrity. Use Value: 100MHz bandwidth and 0.1° differential phase ensure zero timing skew or color shift during transitions. | Use Scenario: Stabilizing signal amplitude in RF receiver IF chains subject to fading or variable antenna coupling. IC Role / Device Role / Timing Role: LT1228IN8#PBF acts as the variable-gain IF amplifier, with ISET driven by detector output to maintain constant envelope. Use Value: 0.2% THD at 30mVRMS prevents intermodulation distortion in multi-channel receivers. |
| Video Differential Input Amplifier | Tunable Filter Core |
Use Scenario: Converting unbalanced camera outputs to balanced differential signals for noise-immune transmission over long cables. IC Role / Device Role / Timing Role: LT1228IN8#PBF implements high-CMRR differential input stage (60dB CMRR) followed by gain-controlled CFA output driver. Use Value: 25MΩ input impedance and 6pF capacitance minimize high-frequency loading on source circuits. | Use Scenario: Building active bandpass filters with electronically adjustable center frequency and Q in test equipment and spectrum analyzers. IC Role / Device Role / Timing Role: LT1228IN8#PBF provides the transconductance element whose gm sets filter pole location; CFA buffers output. Use Value: gm = 10 × ISET allows precise, temperature-stable tuning via DAC-controlled ISET current. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar variable-gain amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMH6552MA/NOPB | Single 1.8GHz GBW current feedback amp; no integrated transconductor; requires external I-V conversion | Lacks built-in gm control; better suited for fixed-gain, ultra-wideband buffer stages than AGC loops | Select when >500MHz bandwidth is required and gain control is handled upstream |
| AD8367ARUZ | True RMS-detected analog multiplier-based VGA; 500MHz bandwidth; 45dB gain range; SPI interface | Digital control interface and RMS detection enable closed-loop AGC; higher integration but less DC precision | Select for digitally managed RF/IF AGC where logarithmic response and detector integration are critical |
Compared with LMH6552MA/NOPB and AD8367ARUZ, the LT1228IN8#PBF uniquely combines analog transconductance programmability, video-optimized linearity, and dual-amplifier integration in one 8-pin DIP - making it optimal for cost-sensitive, high-fidelity analog video gain control where DC accuracy and differential-phase stability are mandatory.
Availability
LT1228IN8#PBF is available at Aetrix Electronics and suitable for video keyer/fader amplifiers, AGC amplifiers, and tunable filter designs requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for LT1228IN8#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 acquired Linear Technology in 2017 and maintains full product support, datasheet archives, and application engineering for legacy Linear parts including the LT1228 series.
The LT1228IN8#PBF belongs to Linear's high-speed amplifier family, engineered specifically for analog video signal processing, precision gain control, and wideband instrumentation where transconductance programmability and video-grade linearity are essential.
FAQ
What is the maximum safe ISET current for LT1228IN8#PBF?
The absolute maximum ISET current into Pin 5 of the LT1228IN8#PBF is 15mA. Exceeding this - especially via direct short to ground or V+ - will destroy the device. Linear Technology specifies a practical operating range of 1µA to 1mA for transconductance control. For reliable operation, use a series limiting resistor (e.g., 2kΩ minimum with ±15V supplies) to enforce this limit. The LT1228IN8#PBF's gm scales linearly as gm = 10 × ISET, so 1mA yields 10mS transconductance.
Does LT1228IN8#PBF support single-supply operation?
Yes, the LT1228IN8#PBF supports true single-supply operation from 4V to 30V total supply range (e.g., 0V and +12V, or +5V and +15V). Its input common-mode range extends to within 1.5V of either rail, and output swings to within 0.8V of rails - enabling use in ground-referenced video circuits. When using single supply, connect Pin 4 (V–) to the lower rail and ensure Pin 5 voltage remains ~1.2V above it. The LT1228IN8#PBF's internal biasing adapts automatically across all valid supply configurations.
What is the differential phase specification of LT1228IN8#PBF under NTSC conditions?
The LT1228IN8#PBF delivers 0.1° differential phase error when configured per standard NTSC test conditions: ±15V supplies, RF = RG = 750Ω, RL = 150Ω, and 2V peak-to-peak composite video output. This value is measured and guaranteed in the datasheet (Note 7) and reflects the device's optimized high-frequency linearity for broadcast video. The LT1228IN8#PBF achieves this performance due to its current feedback architecture and matched internal transistor pairs - critical for maintaining color burst timing integrity.
Can LT1228IN8#PBF drive 75Ω coaxial cable directly?
Yes, the LT1228IN8#PBF is explicitly designed to drive low-impedance loads including 75Ω coaxial cables. Its current feedback amplifier delivers 30mA output current and maintains excellent linearity (0.04% differential gain, 0.1° differential phase) into 150Ω loads - which translates to robust performance into 75Ω with appropriate termination. Use a series 37.5Ω resistor at the output to match 75Ω source impedance and prevent reflections. The LT1228IN8#PBF's 100MHz bandwidth ensures minimal group delay across baseband video frequencies.
Is LT1228IN8#PBF pin-compatible with LT1228CN8#PBF?
Yes, the LT1228IN8#PBF is fully pin-compatible with the LT1228CN8#PBF and all other LT1228 variants in the N8 (8-lead PDIP) package. Both share identical pinout, electrical characteristics, and footprint. The only difference is temperature rating: LT1228IN8#PBF is rated for –40°C to +85°C operation, while LT1228CN8#PBF is rated for 0°C to +70°C. System-level design, PCB layout, and schematic symbols can be reused interchangeably - the LT1228IN8#PBF simply extends environmental robustness for industrial deployments.
LT1228IN8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- 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:
- 125 mA
- Voltage - Supply Span (Min):
- 4 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1228IN8#PBF FAQ
1.How can I place an order for LT1228IN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1228IN8#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 LT1228IN8#PBF reliable?
The price and inventory of LT1228IN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1228IN8#PBF is usually 5 days.
3.What payment methods are accepted for LT1228IN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1228IN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1228IN8#PBF?
LT1228IN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1228IN8#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 LT1228IN8#PBF?
For technical support, including LT1228IN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1228IN8#PBF requirements.
6.How does Aetrix verify that LT1228IN8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1228IN8#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 LT1228IN8#PBF meets industry standards.
7.What is the process for return or replacement of LT1228IN8#PBF?
All LT1228IN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1228IN8#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 LT1228IN8#PBF part is unused and in its original packaging.
Return procedure for LT1228IN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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