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Analog Devices Inc. LTC6268IS8#PBF
- Part No.:
- LTC6268IS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC6268IS8#PBF.pdf
- Description:
- IC OPAMP JFET 1 CIRCUIT 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,853
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Product details
Overview
LTC6268IS8#PBF from Analog Devices (formerly Linear Technology) is a single-channel, 500MHz FET-input operational amplifier optimized for ultra-low input bias current (±3fA typ. at 25°C), 450fF common-mode input capacitance, and rail-to-rail output swing. It operates from 3.1V to 5.25V, draws 16.5mA quiescent current, and features shutdown control-making it ideal for high-impedance photodiode transimpedance amplifiers in optical sensing systems.
For engineers reviewing the LTC6268IS8#PBF datasheet, LTC6268IS8#PBF pinout, LTC6268IS8#PBF application, or LTC6268IS8#PBF equivalent, key selection criteria include its 350MHz –3dB bandwidth (AV = 1), 4.3nV/√Hz voltage noise at 1MHz, 5.5fA/√Hz current noise at 100kHz, ±40°C to +85°C operating range, and SOIC-8 package with two NC pins usable as guard ring terminals.
Technical Context
The LTC6268IS8#PBF employs a CMOS input buffer stage that bootstraps ESD protection diodes to achieve femtoamp-level bias current. Its complementary differential input stage splits operation across two ranges-main amplifier active up to ~1.55V below V+, secondary amplifier covering the remaining 0.5V to V+–0.5V-enabling full rail-to-rail input common-mode range while maintaining low distortion.
Internally compensated for unity-gain stability, it delivers 400V/µs slew rate and –100dB harmonic distortion at 1MHz (2VP-P), supporting high-fidelity driving of SAR ADCs. The SOIC-8 package includes two unconnected pins (Pin 5 and Pin 8) specifically intended for guard ring routing to suppress PCB surface leakage currents in ultra-high-impedance signal paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Bandwidth Product | 500MHz - enables stable closed-loop gain ≥10 up to ~50MHz without peaking. |
| –3dB Bandwidth (AV = 1) | 350MHz - supports wideband signal conditioning and fast pulse amplification. |
| Input Bias Current | ±3fA typical at 25°C - preserves signal integrity in picoamp-level photodiode and electrophysiology sensor interfaces. |
| Input Capacitance (CM) | 450fF - minimizes phase shift and instability in transimpedance amplifier feedback networks. |
| Slew Rate | 400V/µs - ensures <17ns settling time to 0.1% for 3V step, critical for high-speed data acquisition. |
| Supply Range | 3.1V to 5.25V - compatible with standard 3.3V and 5V logic/system rails without level-shifting. |
| Operating Temp Range | –40°C to +85°C - qualified for industrial-grade embedded optical measurement equipment. |
Pinout & Package
Package: 8-lead plastic SOIC (SO-8), 5.0mm × 6.2mm body, 1.27mm pitch. Two unconnected pins (Pin 5 and Pin 8) are provided to implement an input guard ring around +IN and –IN traces, reducing board leakage current in high-impedance applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SHDN) | Active-low shutdown control | Pulled low ≤0.75V (relative to V–) disables amplifier; open or >1.5V enables operation. |
| 2 (V+) | Positive supply rail | Accepts 3.1V–5.25V; requires local 0.1µF bypass capacitor to ground. |
| 3 (OUT) | Amplifier output | Rail-to-rail swing; capable of sourcing/sinking 25mA with <370mV saturation voltage. |
| 4 (V–) | Negative supply rail | Typically grounded; must maintain 3.1V–5.25V total supply differential with V+. |
| 5 (NC) | No connect | Reserved for guard ring trace-electrically isolated copper surrounding input nodes to block surface leakage. |
| 6 (–IN) | Inverting input | Voltage range: V– to V+–0.5V; 450fF common-mode capacitance limits TIA bandwidth sensitivity. |
| 7 (+IN) | Non-inverting input | Same voltage range and capacitance as –IN; matched to minimize offset drift vs. common-mode voltage. |
| 8 (NC) | No connect | Second guard ring terminal-used with Pin 5 to enclose both inputs symmetrically. |
Key Features
| Feature | Design Value |
|---|---|
| Femtoamp input bias current | ±3fA typ. at 25°C enables accurate integration of sub-picoamp photocurrents over seconds without significant error accumulation. |
| Ultra-low input capacitance | 450fF common-mode capacitance reduces feedback pole frequency in TIAs, preserving bandwidth when using large RF values. |
| Rail-to-rail output swing | Drives full 0–5V range into 10kΩ load with <200mV saturation, maximizing dynamic range for ADC interfacing. |
| Integrated shutdown control | Reduces quiescent current to ≤1.2mA per amplifier, enabling power-gating in battery-powered optical modules. |
| Guard-ring-compatible SOIC package | Two NC pins allow PCB-level guarding of input traces-critical for achieving <1pA leakage in high-humidity environments. |
Applications
| Photodiode Transimpedance Amplifier | SAR ADC Driver |
|---|---|
Use Scenario: Converting weak photocurrent from silicon photodiodes or avalanche photodiodes into measurable voltage signals in spectrometers and laser rangefinders. IC Role / Device Role / Timing Role: Primary transimpedance amplifier with 20kΩ–499kΩ feedback resistor, setting gain and bandwidth via RF and CIN interaction. Use Value: 450fF input capacitance and ±3fA bias current enable >65MHz bandwidth at 20kΩ gain while minimizing dark-current-induced offset drift. | Use Scenario: Buffering and driving analog inputs of 16-bit+ successive approximation register (SAR) ADCs in precision data acquisition systems. IC Role / Device Role / Timing Role: High-speed, low-distortion driver ensuring full-scale settling within ADC aperture time. Use Value: –100dB THD+N at 1MHz and 400V/µs slew rate guarantee <0.1% settling in <17ns, preventing missing codes during fast sampling. |
| CCD Output Buffer | Photomultiplier Tube Post-Amplifier |
Use Scenario: Amplifying low-noise, low-slew-rate analog outputs from charge-coupled device (CCD) image sensors in scientific cameras. IC Role / Device Role / Timing Role: Low-noise, DC-coupled buffer isolating CCD pixel readout from downstream processing circuitry. Use Value: 4.3nV/√Hz voltage noise and 5.5fA/√Hz current noise preserve SNR across pixel clock frequencies up to 10MHz. | Use Scenario: Amplifying microamp-level anode pulses from photomultiplier tubes (PMTs) in radiation detection and fluorescence lifetime systems. IC Role / Device Role / Timing Role: Fast, low-capacitance post-amplifier capturing PMT pulse rise times <2ns without overshoot. Use Value: 350MHz –3dB bandwidth and 400V/µs slew rate resolve sub-10ns pulses with <1% amplitude error and minimal timing jitter. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar ultra-low-bias-current op amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADA4817-1ARMZ | Higher input bias current (2pA max), lower GBW (1GHz), no shutdown pin, MSOP-8 package | Better suited for general-purpose high-speed buffering where femtoamp bias is unnecessary | Select when >1pA bias is acceptable and shutdown control is not required |
| OPA828ID | Lower voltage noise (1.8nV/√Hz), higher input bias current (1pA typ.), no guard-ring pins, SOIC-8 | Preferred for low-noise voltage amplification rather than ultra-high-Z current-to-voltage conversion | Select when voltage noise dominates system noise budget and input impedance >100GΩ is not mandatory |
Compared with ADA4817-1ARMZ and OPA828ID, the LTC6268IS8#PBF uniquely combines femtoamp bias current, guard-ring SOIC packaging, and integrated shutdown-making it irreplaceable in photodiode-based optical receivers requiring long integration times and environmental robustness.
Availability
LTC6268IS8#PBF is available at Aetrix Electronics and suitable for photodiode transimpedance amplifiers, SAR ADC drivers, and CCD output buffers requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for LTC6268IS8#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 precision instrumentation, communications, and industrial markets.
The LTC6268 product line was designed specifically for ultra-high-impedance, wideband signal conditioning-targeting optical sensing, scientific instrumentation, and low-current measurement applications demanding femtoamp-level input bias and sub-picofarad input capacitance.
FAQ
What is the maximum input common-mode voltage range for LTC6268IS8#PBF?
The LTC6268IS8#PBF supports an input common-mode voltage range from V– to V+–0.5V. With a 5V supply (V+ = 5V, V– = 0V), this translates to 0V to 4.5V. This specification is guaranteed over the full –40°C to +85°C operating temperature range and enables direct interfacing with sensors operating near supply rails without attenuation or level-shifting circuitry.
Does LTC6268IS8#PBF require external compensation for unity-gain stability?
No, the LTC6268IS8#PBF is internally compensated for unity-gain stability. It achieves stable operation with closed-loop gains ≥1 without external compensation components. This simplifies design in transimpedance amplifier configurations where feedback networks dominate phase margin considerations, though proper layout-including guard rings and minimized parasitic capacitance-is essential to realize its full 350MHz bandwidth.
How does the guard ring feature on LTC6268IS8#PBF improve performance in high-impedance circuits?
The LTC6268IS8#PBF's two NC pins (Pin 5 and Pin 8) enable implementation of a PCB guard ring around the +IN and –IN traces. By routing this ring at the same potential as the inputs (typically via low-impedance op-amp follower), surface leakage currents across the PCB dielectric are shunted away from the sensitive input nodes-reducing effective input bias current by orders of magnitude in humid or contaminated environments where board leakage would otherwise dominate system error.
What is the typical power consumption of LTC6268IS8#PBF in shutdown mode?
In shutdown mode, the LTC6268IS8#PBF draws ≤1.2mA per amplifier at 25°C, dropping from 16.5mA active current. This reduction is achieved by disabling the input stage and output buffer while retaining bias for fast wake-up. Turn-on time is 580ns, allowing rapid reactivation for burst-mode optical sensing applications without sacrificing power efficiency.
Can LTC6268IS8#PBF drive capacitive loads directly?
The LTC6268IS8#PBF is specified for stability with 10pF capacitive load in unity-gain configuration. Driving larger capacitive loads (>20pF) may cause peaking or oscillation due to phase margin degradation. For loads exceeding 10pF, a small series resistor (10–50Ω) placed between the output and the load capacitance restores stability without significantly affecting bandwidth-verified in typical performance curves and application notes for photodiode amplifier layouts.
LTC6268IS8#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:
- J-FET
- Number of Circuits:
- 1
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 400V/µs
- Gain Bandwidth Product:
- 500 MHz
- -3db Bandwidth:
- 350 MHz
- Current - Input Bias:
- 0.9 pA
- Voltage - Input Offset:
- 200 µV
- Current - Supply:
- 16.5mA
- Current - Output / Channel:
- -
- Voltage - Supply Span (Min):
- 3.1 V
- Voltage - Supply Span (Max):
- 5.25 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC6268IS8#PBF FAQ
1.How can I place an order for LTC6268IS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC6268IS8#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 LTC6268IS8#PBF reliable?
The price and inventory of LTC6268IS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC6268IS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC6268IS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC6268IS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC6268IS8#PBF?
LTC6268IS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC6268IS8#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 LTC6268IS8#PBF?
For technical support, including LTC6268IS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC6268IS8#PBF requirements.
6.How does Aetrix verify that LTC6268IS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC6268IS8#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 LTC6268IS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC6268IS8#PBF?
All LTC6268IS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC6268IS8#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 LTC6268IS8#PBF part is unused and in its original packaging.
Return procedure for LTC6268IS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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