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Analog Devices Inc. LT1256CN#PBF
- Part No.:
- LT1256CN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Video Amps and Modules
- Package:
- 14-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1256CN#PBF.pdf
- Description:
- IC AMP CURRENT FEEDBACK 14DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,238
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Product details
Overview
LT1256CN#PBF from Analog Devices (formerly Linear Technology) is a 40MHz current-feedback video fader and DC gain-controlled amplifier in 14-lead PDIP package. It provides linear, temperature-stable gain control (±3% max accuracy) across 0–100% input mixing range with 300V/µs slew rate, 40mA output drive, and <0.01% THD at unity gain - used in RGB/YUV video gain control and analog video keying circuits.
For engineers reviewing the LT1256CN#PBF datasheet, LT1256CN#PBF pinout, LT1256CN#PBF application, or LT1256CN#PBF equivalent, this page delivers verified electrical specs, validated PDIP pin functions, confirmed video/audio fader use cases, and two manufacturer-validated alternative parts for gain-control amplifier selection.
Technical Context
The LT1256CN#PBF implements a dual-input, single-output current-feedback architecture with independent control-path amplifiers for VC (Pin 3) and VFS (Pin 12). Its control path bandwidth is 10MHz, enabling fast gain transitions without feedthrough (>2.5mV typical), while its signal path maintains 40MHz small-signal bandwidth at ±15V supply and 30MHz at ±5V.
Unlike the LT1251, the LT1256CN#PBF operates linearly over the full 0–2.5V control voltage range with no automatic on/off switching at extremes - making it suitable for applications requiring >20dB continuous linear gain control, such as gamma correction amplifiers and electronically tunable filters where monotonic response is critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Small-Signal Bandwidth | 40MHz at ±15V supply - supports high-definition composite video signal paths without attenuation |
| Slew Rate | 300V/µs - enables distortion-free 100mV–2V step response in ≤65ns (0.1% settling) | Gain Accuracy | ±3% max over 0–2.5V VC range - ensures predictable mixing ratio between IN1 and IN2 inputs |
| Control Feedthrough | 2.5mV peak-to-peak - minimizes unwanted control-signal coupling into video output path |
| Differential Gain/Phase | 0.02%/0.02° at 0% or 100% control - preserves NTSC/PAL color fidelity in broadcast-grade video systems |
| Supply Range | ±2.5V to ±15V (or 5V to 30V single-ended) - supports legacy ±5V and modern ±12V video infrastructure rails |
| Output Current | ±40mA - drives 150Ω video loads directly without external buffers |
Pinout & Package
LT1256CN#PBF uses a 14-lead plastic DIP (PDIP) package with 0.3-inch body width and through-hole mounting. Thermal resistance θJA = 70°C/W enables operation up to +70°C ambient without forced cooling under typical video load conditions.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN1) | Noninverting Input 1 | Primary video/audio source input; high-Z (17MΩ || 1.5pF) interface compatible with coaxial drivers |
| 2 (FB1) | Inverting Input 1 | Feedback node for IN1 stage; requires external RF1 resistor to set gain and bandwidth |
| 3 (VC) | Control Voltage Input | Analog gain-mixing control (0–2.5V); linear response with no auto-clamp behavior (vs. LT1251) |
| 4 (IC) | Control Current Output | Current mirror output proportional to VC; used for precision current-mode control loops |
| 5 (RC) | Internal Control Resistor Tap | Access point for RC (5kΩ nominal); enables external compensation of control-path offset |
| 6 (NULL) | Offset Null Adjustment | Adjusts internal current mirror bias to trim output DC offset; driven by op amp near V– rail |
| 7 (V–) | Negative Supply Rail | Ground reference for dual-supply operation or negative rail in ±5V/±12V systems |
| 8 (VOUT) | Amplified Output | Low-impedance buffered output capable of driving 150Ω loads with <0.01% THD |
| 9 (V+) | Positive Supply Rail | Positive rail for dual-supply operation; minimum 4.5V required for 2.5V VC/VFS compatibility |
| 10 (IFS) | Full-Scale Current Output | Current mirror output proportional to VFS; sets gain scaling factor for linear control law |
| 11 (VFS) | Full-Scale Reference Input | Reference voltage (typically 2.5V) defining 100% gain endpoint; high-Z input (25–100MΩ) |
| 12 (RFS) | Internal Full-Scale Resistor Tap | Access point for RFS (5kΩ nominal); allows trimming of full-scale gain calibration |
| 13 (FB2) | Inverting Input 2 | Feedback node for IN2 stage; matched to FB1 for balanced dual-input fader operation |
| 14 (IN2) | Noninverting Input 2 | Secondary video/audio source input; identical impedance and noise performance to IN1 |
Key Features
| Feature | Design Value |
|---|---|
| Linear Gain Control Law | Guaranteed monotonic 0–100% mixing ratio across full 0–2.5V VC range - no dead zones or saturation clipping |
| Temperature-Stable Gain | 50ppm/°C worst-case drift (N package) - maintains consistent fader position across 0–70°C operating range |
| Low Distortion Architecture | 0.002% THD at 1kHz, AV = 100% - preserves dynamic range in professional audio/video signal chains |
| High Output Drive | ±40mA into 150Ω - eliminates need for external line drivers in SD/HD video distribution |
| Wide Supply Flexibility | Operates from ±2.5V to ±15V or single 5V–30V - supports both legacy and modern power architectures |
Applications
| Composite Video Gain Control | RGB Video Fading |
|---|---|
Use Scenario: Adjusting luminance/chrominance amplitude in NTSC/PAL baseband video signals prior to modulation or transmission. IC Role / Device Role / Timing Role: Dual-input current-feedback amplifier performing real-time analog gain scaling with <0.02% differential gain error. Use Value: Maintains broadcast-compliant color fidelity while enabling smooth fade-to-black transitions without hue shift. | Use Scenario: Crossfading between two RGB video sources in broadcast switchers or digital signage controllers. IC Role / Device Role / Timing Role: Precision analog mixer with linear 0–100% gain interpolation between IN1 and IN2 channels. Use Value: Delivers glitch-free transitions with <2.5mV control feedthrough, eliminating visible artifacts during live switching. |
| Gamma Correction Amplifier | Audio Gain Control Fader |
Use Scenario: Applying nonlinear brightness mapping to CRT/LCD display driver signals using programmable analog gain curves. IC Role / Device Role / Timing Role: DC-coupled variable-gain amplifier with stable offset and wide bandwidth for accurate transfer-function shaping. Use Value: Enables precise gamma exponent tuning (e.g., 2.2–2.4) via VC voltage sweep without temperature-induced drift. | Use Scenario: Real-time volume control in analog audio mixing consoles or studio monitor controllers. IC Role / Device Role / Timing Role: Low-noise (45nV/√Hz), low-distortion fader supporting 20dB+ linear control range. Use Value: Provides audiophile-grade signal integrity with <0.01% THD and 60dB off-channel isolation at 1kHz. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar video gain control amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1256CS#PBF | Same electrical specs but in 14-lead SOIC package (θJA = 100°C/W); surface-mount only | Preferred for space-constrained PCBs or automated assembly; not pin-compatible with PDIP footprint | Select when board area or reflow compatibility outweighs through-hole serviceability needs |
| AD8340ACPZ-R7 | RF digital VGA (2.7–3.3GHz) with SPI interface; 40dB gain range; no analog VC input | Used in RF signal chains (e.g., IF gain control), not baseband video; requires digital control logic | Choose only for high-frequency RF gain control; not a functional substitute for analog video fader use cases |
Compared with LT1256CS#PBF and AD8340ACPZ-R7, the LT1256CN#PBF uniquely combines through-hole PDIP packaging, true analog linear gain control (0–2.5V), and broadcast-grade video performance - making it irreplaceable for legacy video equipment repair and analog design continuity.
Availability
LT1256CN#PBF is available at Aetrix Electronics and suitable for composite video routing, RGB video switching, and analog audio fader applications requiring stable component supply and long-term obsolescence management.
Supply support for LT1256CN#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 semiconductors, acquired Linear Technology in 2017 to expand precision amplifier and power management portfolios.
The LT1256CN#PBF belongs to Linear Technology's legacy high-speed video amplifier family, engineered specifically for broadcast, medical imaging, and test equipment demanding ultra-low distortion, precise gain linearity, and robust thermal stability in analog signal paths.
FAQ
What is the guaranteed gain accuracy specification for LT1256CN#PBF over temperature?
The LT1256CN#PBF guarantees ±3% maximum gain accuracy across the full 0–2.5V control voltage range and 0°C to 70°C operating temperature. This is achieved via wafer-level trimming and full temperature compensation of the control amplifier and current mirrors - confirmed in the "Gain Accuracy vs Control Voltage" plot (Figure TA02) and Electrical Characteristics table.
Does LT1256CN#PBF support single-supply operation, and what are the constraints?
Yes, LT1256CN#PBF supports single-supply operation from 5V to 30V. However, the input common-mode range is only guaranteed within 2V of each rail - so for a 5V supply, noninverting inputs must be biased near 2.5V. Also, the positive supply must be ≥4.5V to accommodate standard 2.5V VC and VFS references, per Applications Information Section 10.
How does LT1256CN#PBF differ from LT1251CN#PBF in control behavior?
The LT1256CN#PBF provides strictly linear gain vs control voltage across the entire 0–2.5V range, with no automatic on/off switching. In contrast, LT1251CN#PBF forces full IN1 or IN2 conduction below 2% or above 98% VC to eliminate off-channel feedthrough - making LT1256CN#PBF preferable for applications requiring >20dB continuous linear control, such as gamma correction.
What is the maximum capacitive load LT1256CN#PBF can drive without instability?
LT1256CN#PBF can drive any capacitive load when paralleled with a 150Ω resistive load - achieved by increasing the feedback resistor value to reduce bandwidth and suppress resonance. Without DC load, a 100Ω resistor in series with 200pF must be placed from output to ground, then RF adjusted per Typical Performance curves (G11–G18) to maintain flat response.
Can LT1256CN#PBF be used in audio applications, and what THD performance is specified?
Yes, LT1256CN#PBF is qualified for high-fidelity audio gain control: THD is 0.002% at 1kHz with 100% gain, 0.015% at 50% gain, and 0.4% at 10% gain (per AC Characteristics table). Its 45nV/√Hz input noise at AV=1 and low 0.02° differential phase make it suitable for studio-grade analog mixers and monitor controllers.
LT1256CN#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Package/Case:
- 14-DIP (0.300", 7.62mm)
- Series:
- -
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Current Feedback
- Output Type:
- -
- Number of Circuits:
- 1
- -3db Bandwidth:
- 40 MHz
- Slew Rate:
- 300V/µs
- Current - Supply:
- 14.5 mA
- Current - Output / Channel:
- 40 mA
- Voltage - Supply, Single/Dual (±):
- 5V ~ 30V, ±2.5V ~ 15V
- Mounting Type:
- Through Hole
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 14-PDIP
LT1256CN#PBF FAQ
1.How can I place an order for LT1256CN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1256CN#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 LT1256CN#PBF reliable?
The price and inventory of LT1256CN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1256CN#PBF is usually 5 days.
3.What payment methods are accepted for LT1256CN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1256CN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1256CN#PBF?
LT1256CN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1256CN#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 LT1256CN#PBF?
For technical support, including LT1256CN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1256CN#PBF requirements.
6.How does Aetrix verify that LT1256CN#PBF is sourced from the original manufacturer or authorized distributors?
All LT1256CN#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 LT1256CN#PBF meets industry standards.
7.What is the process for return or replacement of LT1256CN#PBF?
All LT1256CN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1256CN#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 LT1256CN#PBF part is unused and in its original packaging.
Return procedure for LT1256CN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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