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Analog Devices Inc. LT1251CN#PBF
- Part No.:
- LT1251CN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Video Amps and Modules
- Package:
- 14-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1251CN#PBF.pdf
- Description:
- IC AMP CURRENT FEEDBACK 14DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,280
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Product details
Overview
LT1251CN#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 between two inputs with ±1% typical accuracy, 300V/µs slew rate, and <0.02% differential gain/phase-enabling precise composite video mixing and RGB gain adjustment in broadcast equipment.
For engineers reviewing the LT1251CN#PBF datasheet, LT1251CN#PBF pinout, LT1251CN#PBF application, or LT1251CN#PBF equivalent, key selection criteria include its 40MHz bandwidth, 2.5mV control feedthrough, ±2.5V to ±15V dual-supply operation, and guaranteed 0–100% linear fade response with zero/full-scale hard-switching behavior unique to the LT1251 variant.
Technical Context
The LT1251CN#PBF implements a dual-input current-feedback architecture with independent unity-gain buffers driving inverting nodes, enabling simultaneous signal routing and precise gain interpolation. Its control path uses internal 5kΩ RC and RFS resistors referenced to VFS=2.5V, delivering 10MHz small-signal bandwidth and 150ns 0–100% transition time.
Unlike the LT1256, the LT1251CN#PBF includes hard-switch logic that forces K=0% at VC ≤50mV and K=100% at VC ≥2.45V-eliminating off-channel feedthrough due to control offset errors. This makes it optimal for video fader applications requiring clean channel isolation at endpoints.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Bandwidth | 40MHz at ±15V supply - supports full NTSC/PAL video baseband without attenuation |
| Slew Rate | 300V/µs - ensures distortion-free 1Vpp video signals up to 5MHz |
| Gain Accuracy | ±1% typ, ±3% max - enables calibrated gain matching across production units without trimming |
| Control Feedthrough | 2.5mV peak-to-peak - minimizes unwanted control-signal coupling into output path |
| Differential Gain/Phase | 0.02%/0.02° at 0% or 100% control - meets broadcast-grade color fidelity requirements |
| Supply Range | ±2.5V to ±15V (or single 5V–30V) - supports legacy ±5V and modern low-voltage systems |
| Output Current | ±40mA - drives 150Ω video loads directly without external buffer |
Pinout & Package
LT1251CN#PBF is housed in a 14-lead plastic DIP (PDIP) package with 0.3-inch width, JEDEC MS-001 compliant, θJA = 70°C/W, rated for 0°C to 70°C commercial operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN1) | Noninverting input of first amplifier stage | Accepts primary video source; high-Z (17MΩ || 1.5pF) interface compatible with passive video lines |
| 2 (FB1) | Inverting input of first amplifier stage | Feedback node for RF1; requires low-stray-capacitance layout to prevent peaking above 10MHz |
| 3 (VC) | Control voltage input | 0–2.5V analog fader position; LT1251 hard-switches at 2% and 98% to eliminate endpoint feedthrough |
| 4 (IC) | Control current reference input | Internal 5kΩ resistor converts VC to control current; open-circuit default for standard operation |
| 5 (RC) | Internal control resistor tap | Connect to ground for standard 2.5V full-scale operation; used with external resistor for custom scaling |
| 6 (NULL) | Offset null adjustment terminal | Adjusts internal current mirror to trim output DC offset; driven by op amp within 10mV of V− |
| 7 (V−) | Negative supply rail | Must be ≥4.5V below V+ to support 2.5V control range; bypass with 0.01µF + 4.7µF near pin |
| 8 (VOUT) | Composite output node | Delivers weighted sum of IN1 and IN2; capable of ±3.5V swing into 150Ω load |
| 9 (V+) | Positive supply rail | Supports up to ±15V; requires same bypassing as V− for stable settling |
| 10 (IFS) | Full-scale current reference input | Internal 5kΩ resistor sets full-scale gain; open-circuit default matches VFS=2.5V |
| 11 (VFS) | Full-scale reference voltage input | 2.5V reference for gain scaling; deviation alters full-scale point linearly |
| 12 (RFS) | Internal full-scale resistor tap | Ground connection enables standard 2.5V full-scale mode; used with external resistor for scaling |
| 13 (FB2) | Inverting input of second amplifier stage | Feedback node for RF2; matched layout with FB1 required for linear fade response |
| 14 (IN2) | Noninverting input of second amplifier stage | Accepts secondary video source; identical impedance and bandwidth to IN1 |
Key Features
| Feature | Design Value |
|---|---|
| Hard-switch fader logic | Forces full ON/OFF states at VC ≤50mV and ≥2.45V-eliminates off-channel leakage in broadcast switchers |
| Temperature-compensated gain | 50ppm/°C worst-case drift at 30% gain-maintains calibration across industrial ambient ranges |
| Low-distortion video path | 0.01% THD at 100% gain-preserves luminance/chrominance integrity in RGB/YUV processing |
| Fast control path | 10MHz bandwidth and 150ns 0–100% transition-enables real-time digital fader control via DAC |
| Wide supply flexibility | Operates from ±2.5V to ±15V or single 5V–30V-supports both legacy and low-power embedded designs |
Applications
| Composite Video Switcher | RGB Gain Calibration |
|---|---|
Use Scenario: Real-time switching between two SD/HD video sources in broadcast production switchers. IC Role / Device Role / Timing Role: Dual-input fader providing seamless cross-fade with <0.02% differential gain error. Use Value: Eliminates color shift during transitions by maintaining constant group delay and phase linearity across fade range. | Use Scenario: Precision gain matching of red, green, and blue channels in professional monitors and projectors. IC Role / Device Role / Timing Role: DC-controlled variable-gain amplifier with ±1% accuracy per channel. Use Value: Enables factory calibration without manual potentiometers; drift <50ppm/°C ensures long-term color stability. |
| Video Keyer (Chroma Key) | Gamma Correction Amplifier |
Use Scenario: Generating alpha matte signals in chroma key compositing systems using green-screen footage. IC Role / Device Role / Timing Role: Fast-response fader blending foreground and background video streams. Use Value: 300V/µs slew rate prevents edge smearing on high-contrast key boundaries; 10MHz control path syncs with FPGA timing. | Use Scenario: Applying nonlinear transfer functions to correct display gamma in medical imaging and digital signage. IC Role / Device Role / Timing Role: Programmable gain block implementing piecewise-linear gamma curves. Use Value: 40MHz bandwidth preserves sharpness in corrected images; low 45nV/√Hz noise avoids amplifying sensor dark-current artifacts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar video fader and gain control applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1256CN#PBF | No hard-switch logic; linear control over full 0–100% range; ±3% gain accuracy maintained across entire scale | Better suited for applications requiring >20dB continuous linear control (e.g., analog multipliers, tunable filters) | Select LT1256CN#PBF when endpoint precision is less critical than mid-scale linearity |
| AD8340ACPZ-R7 | RF digital step attenuator (DC–2.5GHz); 6-bit serial interface; 31.5dB range in 0.5dB steps; no analog fader function | Used in RF signal chains (e.g., transmitter output leveling), not baseband video mixing | Select AD8340ACPZ-R7 only for RF amplitude control; incompatible for video fader topology |
Compared with LT1256CN#PBF and AD8340ACPZ-R7, the LT1251CN#PBF uniquely delivers hard-switched endpoint behavior essential for broadcast switchers, while retaining full 40MHz video bandwidth and sub-0.02° differential phase-making it irreplaceable in applications demanding clean channel isolation at fade extremes.
Availability
LT1251CN#PBF is available at Aetrix Electronics and suitable for broadcast video switchers, RGB monitor calibration systems, chroma key compositors, and gamma correction circuits requiring stable component supply and long-lifecycle availability.
Supply support for LT1251CN#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, serving industrial, automotive, communications, and healthcare markets.
The LT1251CN#PBF belongs to ADI's legacy Linear Technology video amplifier product line, engineered specifically for broadcast-quality analog video signal processing-including fader, keyer, and gain-control functions where differential gain/phase and transient fidelity are critical.
FAQ
What is the guaranteed gain accuracy of the LT1251CN#PBF over temperature?
The LT1251CN#PBF guarantees ±3% maximum gain accuracy across 0°C to 70°C, with ±1% typical performance. Gain drift is specified at 50ppm/°C (N-package, worst case at 30% gain), ensuring stable calibration in commercial video equipment without active compensation. This accuracy is achieved through wafer-level trimming and full temperature compensation of the control circuitry inside the LT1251CN#PBF.
Can the LT1251CN#PBF operate from a single 5V supply?
Yes, the LT1251CN#PBF supports single 5V operation (V+ = 5V, V− = 0V), but input common-mode range is limited to within 2V of each rail. For noninverting operation, the noninverting inputs must be biased at 2.5V. The control voltage VC must remain within 0–2.5V, and VFS should be set to 2.5V. Full functionality-including 40MHz bandwidth and 300V/µs slew rate-is preserved under single 5V conditions, as confirmed in the LT1251CN#PBF datasheet AC characteristics table.
How does the LT1251CN#PBF differ from the LT1256CN#PBF in fader applications?
The LT1251CN#PBF includes hard-switch logic that forces complete ON/OFF states at VC ≤50mV and ≥2.45V, eliminating off-channel feedthrough caused by control signal offsets-critical for broadcast switchers. The LT1256CN#PBF lacks this feature and operates linearly across the full 0–100% range, offering better mid-scale linearity (>20dB control range) but higher endpoint leakage. This functional distinction is intrinsic to the LT1251CN#PBF design and is not achievable via external circuitry.
What is the maximum capacitive load the LT1251CN#PBF can drive stably?
The LT1251CN#PBF can drive any capacitive load when paralleled with a minimum 150Ω resistive load. Without DC resistance, stability requires adding a 100Ω resistor in series with 200pF from output to ground, then selecting an appropriate feedback resistor (e.g., ≥2.2kΩ) to suppress peaking. This requirement stems from the current-feedback architecture's sensitivity to inverting-node capacitance, as documented in the LT1251CN#PBF Applications Information section on capacitive loads.
Does the LT1251CN#PBF require external resistors for basic fader operation?
No-basic two-input fader operation requires only power supply bypass capacitors (0.01µF + 4.7µF per rail) and external feedback resistors RF1 and RF2 (e.g., 1.5kΩ each). The LT1251CN#PBF integrates internal 5kΩ RC and RFS resistors, and pins 4 (IC), 5 (RC), 10 (IFS), and 12 (RFS) may be left open for standard 2.5V full-scale operation. No external gain-setting resistors are needed beyond RF1/RF2, simplifying PCB layout and reducing bill-of-materials cost for the LT1251CN#PBF.
LT1251CN#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
LT1251CN#PBF FAQ
1.How can I place an order for LT1251CN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1251CN#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 LT1251CN#PBF reliable?
The price and inventory of LT1251CN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1251CN#PBF is usually 5 days.
3.What payment methods are accepted for LT1251CN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1251CN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1251CN#PBF?
LT1251CN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1251CN#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 LT1251CN#PBF?
For technical support, including LT1251CN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1251CN#PBF requirements.
6.How does Aetrix verify that LT1251CN#PBF is sourced from the original manufacturer or authorized distributors?
All LT1251CN#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 LT1251CN#PBF meets industry standards.
7.What is the process for return or replacement of LT1251CN#PBF?
All LT1251CN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1251CN#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 LT1251CN#PBF part is unused and in its original packaging.
Return procedure for LT1251CN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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