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Analog Devices Inc. LT1251CS#TRPBF
- Part No.:
- LT1251CS#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Video Amps and Modules
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1251CS#TRPBF.pdf
- Description:
- IC AMP CURRENT FEEDBACK 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,730
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Product details
Overview
LT1251CS#TRPBF from Analog Devices (formerly Linear Technology) is a 40MHz current-feedback video fader and DC gain-controlled amplifier in a 14-lead SOIC package. It provides accurate linear gain control (±3% max), 300V/µs slew rate, ±2.5V to ±15V dual-supply operation, and low differential gain/phase error (0.02%/0.02°) for composite video applications.
For engineers reviewing the LT1251CS#TRPBF datasheet, LT1251CS#TRPBF pinout, LT1251CS#TRPBF application, or LT1251CS#TRPBF equivalent, key selection criteria include its 10MHz control-path bandwidth, 2.5mV control feedthrough, 40mA output drive, ±1% typical gain accuracy, and guaranteed 0–100% linear fade behavior with internal zero/full-scale clamping.
Technical Context
The LT1251CS#TRPBF implements a dual-input, single-output current-feedback architecture with independent control and full-scale amplifiers. Its gain is set by a voltage-controlled current (VC) applied to Pin 3, referenced to an internal 5kΩ resistor (RC), while VFS on Pin 12 sets full-scale reference via another 5kΩ resistor (RFS).
Unlike the LT1256, the LT1251CS#TRPBF includes automatic zero/full-scale clamping: at VC ≤ 0.05V or ≥ 2.45V, it fully disables one input and enables the other-eliminating off-channel feedthrough due to control signal offset or gain errors. This makes it ideal for video fader and keyer circuits requiring clean channel switching.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Small-signal bandwidth | 40MHz at ±15V supply - supports high-definition video signal paths without attenuation |
| Slew rate | 300V/µs - enables distortion-free reproduction of fast video transients and sync pulses |
| Control path bandwidth | 10MHz - ensures rapid, stable response to analog fade control signals |
| Gain accuracy | ±3% maximum over 0–100% control range - guarantees precise, repeatable mixing ratios |
| Differential gain/phase | 0.02%/0.02° at 0% or 100% control - preserves color fidelity in NTSC/PAL composite video |
| Output current | ±40mA - drives 75Ω video lines directly or supports multi-load distribution |
| Supply range | ±2.5V to ±15V (or 5V to 30V single-ended) - accommodates legacy and modern video system rails |
Pinout & Package
LT1251CS#TRPBF is housed in a 14-lead plastic SOIC (S package) with θJA = 100°C/W, rated for –40°C to +85°C operating temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN1) | Noninverting input of first amplifier stage | Accepts primary video source; high-Z (17MΩ || 1.5pF) for minimal loading |
| 2 (FB1) | Inverting input of first amplifier stage | Connects to feedback resistor (RF1); internal 27Ω series resistance affects loop gain matching |
| 3 (VC) | Control voltage input | 0–2.5V analog signal sets fade ratio; LT1251 clamps at <2% and >98% for clean channel isolation |
| 4 (IC) | Control amplifier inverting input | Internally connected to RC; used with external op-amp for precision control current generation |
| 5 (RC) | Internal control resistor terminal | 5kΩ (typ) resistor to ground; defines control current scaling (IC = VC / RC) |
| 6 (NULL) | Offset null adjustment node | Adjusts internal current mirror bias; open-circuit voltage ≈ V– + 100mV when IFS = 2.5V/5kΩ |
| 7 (V–) | Negative supply rail | Supports ±2.5V minimum; powers all internal amplifiers and bias networks |
| 8 (VOUT) | Composite output | Single-ended, rail-to-rail capable (±3.5V into 150Ω); drives 75Ω coaxial loads directly |
| 9 (V+) | Positive supply rail | Supports up to ±15V; must be ≥4.5V for proper 2.5V control/reference operation |
| 10 (IFS) | Full-scale current input | Accepts current derived from VFS (Pin 12); sets reference gain scale |
| 11 (VFS) | Full-scale reference voltage | 2.5V nominal input; develops IFS through internal 5kΩ RFS resistor |
| 12 (RFS) | Internal full-scale resistor terminal | 5kΩ (typ) resistor to ground; defines full-scale current scaling (IFS = VFS / RFS) |
| 13 (FB2) | Inverting input of second amplifier stage | Connects to RF2; matches FB1 impedance for linear fade performance |
| 14 (IN2) | Noninverting input of second amplifier stage | Accepts secondary video source; identical input structure to IN1 |
Key Features
| Feature | Design Value |
|---|---|
| Zero/full-scale clamping | Automatically disables one input below 2% or above 98% VC - eliminates off-channel leakage in fader applications |
| Low control feedthrough | 2.5mVP-P - prevents control signal coupling into video output path |
| Temperature-stable gain | 400ppm/°C worst-case drift in SOIC package - maintains fade accuracy across industrial temperature range |
| High output drive | ±40mA into 150Ω - supports driving multiple video loads or long cables without external buffers |
| Wide supply flexibility | Operates from ±2.5V to ±15V or single 5V–30V - simplifies integration into mixed-voltage video systems |
Applications
| Composite Video Gain Control | RGB/YUV Video Gain Control |
|---|---|
Use Scenario: Adjusting brightness and contrast of standard-definition analog video signals in broadcast equipment. IC Role / Device Role / Timing Role: Dual-input fader IC performing real-time analog mixing of baseband CVBS signals with sub-10ns settling time. Use Value: 0.02% differential gain error preserves NTSC color saturation; ±3% gain accuracy ensures consistent luminance levels across units. | Use Scenario: Independently scaling red, green, and blue component video channels in professional video switchers. IC Role / Device Role / Timing Role: Precision DC-coupled gain controller for RGB/YUV signals, using matched feedback resistors for channel-to-channel tracking. Use Value: 40MHz bandwidth supports 1080p60 component video; low 270nV/√Hz noise at AV=100 avoids degrading SNR in high-gain stages. |
| Video Faders and Keyers | Gamma Correction Amplifiers |
Use Scenario: Smoothly transitioning between two live video sources during live production with no visible glitches or cross-talk. IC Role / Device Role / Timing Role: Analog video fader implementing linear 0–100% fade curves with automatic hard-switching at endpoints. Use Value: Internal zero/full-scale clamping eliminates need for external comparators; <2.5mV control feedthrough prevents fade artifacts. | Use Scenario: Applying non-linear transfer functions to correct display gamma in CRT/LCD monitor calibration circuits. IC Role / Device Role / Timing Role: Programmable gain amplifier where control voltage follows gamma curve (e.g., V2.2) to linearize output luminance. Use Value: 10MHz control bandwidth allows real-time gamma adjustment; ±1% typical gain accuracy ensures calibrated output consistency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar video fader and gain-controlled amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1256CS#TRPBF | No zero/full-scale clamping; operates linearly across full 0–100% VC range; ±3% gain accuracy same | Better suited for applications needing >20dB continuous linear control (e.g., tunable filters, modulators) | Select LT1256CS#TRPBF when precise analog interpolation across entire range is required, not endpoint switching |
| AD8340ACPZ-R7 | RF digital VGA (0.1–2.5GHz); 30dB gain range; SPI interface; 50Ω I/O; no analog VC input | Designed for RF IF gain control, not baseband video; requires digital control and impedance matching | Choose AD8340ACPZ-R7 only for RF/IF signal chains; not a functional substitute for baseband video fading |
Compared with LT1256CS#TRPBF, the LT1251CS#TRPBF adds endpoint clamping for cleaner video switching but sacrifices full-range linearity; compared with AD8340ACPZ-R7, it offers direct analog control and baseband optimization but lacks RF bandwidth and digital interface.
Availability
LT1251CS#TRPBF is available at Aetrix Electronics and suitable for broadcast video equipment, professional video switchers, medical imaging displays, and industrial vision systems requiring stable component supply and guaranteed long-term availability.
Supply support for LT1251CS#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 LT1251CS#TRPBF belongs to ADI's legacy Linear Technology video amplifier product line, engineered specifically for high-fidelity analog video signal conditioning-including fading, gain control, and composite signal processing-with emphasis on low distortion and color fidelity.
FAQ
What is the guaranteed operating temperature range for the LT1251CS#TRPBF?
The LT1251CS#TRPBF is specified for operation from –40°C to +85°C and tested across this full industrial temperature range. Its SOIC package has a thermal resistance θJA of 100°C/W, and junction temperature must remain ≤150°C under all conditions. The device maintains ±3% gain accuracy and 0.02% differential gain performance across this range.
How does the LT1251CS#TRPBF differ from the LT1256CS#TRPBF in control behavior?
The LT1251CS#TRPBF includes internal circuitry that clamps gain to 0% or 100% when the control voltage (VC) falls below 0.05V or exceeds 2.45V-ensuring clean channel isolation in fader applications. The LT1256CS#TRPBF lacks this feature and operates linearly across the full 0–2.5V VC range, making it better for continuous analog control like tunable filters.
Can the LT1251CS#TRPBF drive a 75Ω video load directly?
Yes, the LT1251CS#TRPBF delivers ±40mA output current and supports ±3.5V swing into a 150Ω load, which covers standard 75Ω video termination when configured with appropriate feedback and gain-setting resistors. For optimal differential gain/phase performance (0.02%/0.02°), use matched 1.5kΩ feedback resistors and maintain clean layout practices per the datasheet.
What is the purpose of the NULL pin (Pin 6) on the LT1251CS#TRPBF?
The NULL pin (Pin 6) adjusts the offset of an internal current mirror to fine-tune output DC offset. With IFS = 500µA (from 2.5V across 5kΩ RFS), the open-circuit voltage at NULL is ~100mV above V–. An op amp such as the LT1077 can drive this pin to null residual DC offset in precision video applications, improving black-level stability.
Does the LT1251CS#TRPBF require external feedback resistors, and what values are recommended?
Yes, the LT1251CS#TRPBF requires external feedback resistors RF1 and RF2 (Pins 2 and 13) to set gain and bandwidth. For 40MHz bandwidth at ±5V supply, 1.5kΩ is recommended. To ensure linear fade response, RF1 and RF2 must be matched and selected based on Thevenin impedance at each inverting input-especially critical when gains differ between inputs.
LT1251CS#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- 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:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 14-SO
LT1251CS#TRPBF FAQ
1.How can I place an order for LT1251CS#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1251CS#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 LT1251CS#TRPBF reliable?
The price and inventory of LT1251CS#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1251CS#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1251CS#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1251CS#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1251CS#TRPBF?
LT1251CS#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1251CS#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 LT1251CS#TRPBF?
For technical support, including LT1251CS#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1251CS#TRPBF requirements.
6.How does Aetrix verify that LT1251CS#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1251CS#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 LT1251CS#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1251CS#TRPBF?
All LT1251CS#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1251CS#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 LT1251CS#TRPBF part is unused and in its original packaging.
Return procedure for LT1251CS#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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