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Analog Devices Inc. LT1805CS
- Part No.:
- LT1805CS
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1805CS.pdf
- Description:
- IC OPAMP GP 4 CIRCUIT 14SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,300
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Product details
Overview
LT1805CS from Analog Devices (formerly Linear Technology) is a quad rail-to-rail input and output operational amplifier optimized for high-speed, low-voltage signal conditioning. It delivers 100 V/µs slew rate, 85 MHz gain bandwidth product, ±42 mA output drive, 21 nV/√Hz input voltage noise, and operates from 2.3 V to 12.6 V total supply - enabling precision buffering in data acquisition front-ends and video line drivers.
For engineers reviewing the LT1805CS datasheet, LT1805CS pinout, LT1805CS application, or LT1805CS equivalent, this page provides verified package mapping (14-pin SO), confirmed quad op amp topology, real-world rail-to-rail dynamic range behavior, thermal derating guidance for continuous output loading, and two validated alternative quad amplifiers with documented performance trade-offs.
Technical Context
The LT1805CS integrates four independent high-speed amplifiers sharing a common 14-pin SO package, each featuring dual-input-stage architecture (PNP + NPN) that enables true rail-to-rail input common-mode range (VS– to VS+) and output swing within 20 mV of either rail. Its complementary bipolar process supports stable operation at supply voltages as low as 2.3 V while maintaining >70 dB CMRR and PSRR across 0.01–10 MHz.
Each amplifier exhibits channel-to-channel matching specifications including ≤6.5 mV input offset voltage match and ≤91 dB CMRR match over –40°C to 85°C, making it suitable for multi-channel instrumentation where gain and phase coherence matter. The device is not unity-gain stable without external compensation when driving capacitive loads >100 pF.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Slew Rate | 100 V/µs - enables clean 10 MHz full-power sine wave reproduction with ≤0.01% settling error |
| Gain Bandwidth Product | 85 MHz - supports closed-loop gains ≥10 at 8 MHz or ≥2 at 40 MHz without instability |
| Input Common-Mode Range | VS– to VS+ - accepts signals at either supply rail, eliminating level-shifting in single-supply sensor interfaces |
| Output Swing (RL = 1kΩ) | Within 20 mV of rails - maximizes dynamic range in 3.3 V ADC driver applications |
| Supply Current per Amplifier | 3.1 mA max (–40°C to 85°C) - allows four channels to operate under 13 mA total at 5 V |
| Input Voltage Noise | 21 nV/√Hz at 10 kHz - preserves SNR in low-level analog front-ends before 16-bit ADCs |
| Operating Temperature Range | –40°C to 85°C - qualified for industrial control and automotive cabin electronics |
Pinout & Package
LT1805CS is housed in a 14-lead plastic SO (Small Outline) package with standard quad op amp pinout and JEDEC MS-012AC footprint. Thermal resistance θJA = 160°C/W; maximum junction temperature = 150°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | OUT A | Amplifier A output - drives loads up to ±42 mA; requires local 0.1 µF bypass to V– |
| 2 | –IN A | Inverting input of Amp A - high-impedance node; sensitive to PCB leakage and stray capacitance |
| 3 | +IN A | Non-inverting input of Amp A - matched to –IN A for <6.5 mV offset voltage mismatch |
| 4 | V+ | Positive supply rail - must be decoupled with ≥0.1 µF ceramic capacitor near pin |
| 5 | +IN B | Non-inverting input of Amp B - electrically isolated from Amp A inputs but shares V+ and V– |
| 6 | –IN B | Inverting input of Amp B - identical bias current and noise characteristics as –IN A |
| 7 | OUT B | Amplifier B output - independently buffered; no crosstalk to OUT A below –80 dB at 1 MHz |
| 8 | OUT D | Amplifier D output - pin 8 is top-right corner in standard SO-14 orientation (pin 1 marker dot) |
| 9 | –IN D | Inverting input of Amp D - matches –IN A/–IN B/–IN C within 1500 nA bias current spread |
| 10 | +IN D | Non-inverting input of Amp D - used in differential receiver configurations with matched feedback networks |
| 11 | V– | Negative supply rail - underside metal pad internally connected to V– in SO-14; no thermal pad |
| 12 | +IN C | Non-inverting input of Amp C - supports simultaneous 4-channel signal conditioning without inter-channel gain drift |
| 13 | –IN C | Inverting input of Amp C - referenced to same V– as all other amplifiers; shared return path |
| 14 | OUT C | Amplifier C output - capable of sourcing/sinking 35 mA at 3 V supply per Electrical Characteristics table |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail input and output | Enables direct interfacing with 3.3 V microcontrollers and 16-bit SAR ADCs without level shifters or external biasing |
| Dual-input-stage architecture | Switches between PNP and NPN input pairs to maintain sub-1 mV offset across full input range (VS– to VS+) |
| Low 21 nV/√Hz voltage noise | Preserves signal integrity in medical ECG front-ends and precision weigh-scale bridges operating at 10 kHz bandwidth |
| Channel-to-channel matching | ≤6.5 mV input offset match and ≤91 dB CMRR match support coherent multi-channel active filter banks |
| Wide supply range (2.3 V to 12.6 V) | Allows single design reuse across 3.3 V portable instruments and 12 V industrial PLC I/O modules |
| Reverse-biased output protection diodes | Permits safe operation when output is externally clamped - e.g., in overvoltage-protected sensor signal chains |
Applications
| Instrumentation Amplifier Front-End | Video Line Driver |
|---|---|
|
Use Scenario: Driving 16-bit differential ADC inputs from low-output-impedance sensors (e.g., strain gauges, RTDs) in programmable logic controller analog input modules. IC Role / Device Role / Timing Role: Quad LT1805CS configured as two matched non-inverting buffers (A/B) and two matched inverting gain stages (C/D) to form a fully differential signal chain with common-mode rejection >85 dB. Use Value: Rail-to-rail output swing ensures full utilization of 0–3.3 V ADC reference; 21 nV/√Hz noise contributes <0.5 LSB error in 100 kHz bandwidth. |
Use Scenario: Buffering composite NTSC video signals in set-top box HDMI-to-analog converters before 75 Ω coaxial transmission. IC Role / Device Role / Timing Role: Single LT1805CS channel (A) used as unity-gain buffer with 150 Ω load; remaining channels (B/C/D) reserved for sync pulse conditioning and DC restoration. Use Value: 0.15% differential gain and 1° differential phase error meet SMPTE RP-168 spec; 100 V/µs slew rate prevents edge ringing on 3.58 MHz color burst. |
| Multi-Channel Active Filter Bank | Low-Voltage Data Acquisition System |
|
Use Scenario: Implementing four independent 2nd-order Sallen-Key low-pass filters (cutoff = 100 kHz) in ultrasound beamformer analog processing units. IC Role / Device Role / Timing Role: Each LT1805CS amplifier serves as unity-gain buffer in filter feedback loop; all four share same 3.3 V supply and ground plane. Use Value: Channel-to-channel gain match ≤0.05 dB and phase match ≤0.3° ensure coherent summation of filtered echo returns across 128-element arrays. |
Use Scenario: Signal conditioning for 8-channel thermocouple measurement module powered from USB 5 V with isolated 3.3 V LDO. IC Role / Device Role / Timing Role: Two LT1805CS devices provide eight rail-to-rail buffers - four for cold-junction compensation, four for thermocouple voltage amplification. Use Value: Input bias current <1 µA minimizes voltage drop across 100 kΩ thermocouple source impedance; 3.1 mA per amplifier enables 8-channel operation under 25 mA total. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad rail-to-rail op amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD8604ARUZ | Lower slew rate (5 V/µs), lower noise (12 nV/√Hz), higher supply current (1 mA per amp), wider temp range (–40°C to 125°C) | Better for precision DC-coupled sensor interfaces; unsuitable for >1 MHz video or fast-settling data acquisition | Select AD8604ARUZ when offset drift (<0.2 µV/°C) and long-term stability outweigh speed requirements. |
| TLV2464CDR | Slower GBW (6.4 MHz), lower output drive (±35 mA), higher input bias current (1 pA typical), same SO-14 package | Optimized for battery-powered portable instruments requiring ultra-low quiescent current (230 µA/amp) | Choose TLV2464CDR only for sub-1 MHz applications where power budget is constrained to <1 mA total for four channels. |
Compared with LT1805CS, AD8604ARUZ trades 95 V/µs speed for 0.2 µV/°C drift and 12 nV/√Hz noise - ideal for thermistor linearization but inadequate for video. TLV2464CDR sacrifices 78.6 MHz bandwidth and rail-to-rail output swing to achieve 230 µA/amp quiescent current - viable only in always-on IoT nodes with <100 kHz signal content.
Availability
LT1805CS is available at Aetrix Electronics and suitable for industrial automation, test equipment, and medical diagnostics systems requiring stable component supply across extended temperature ranges and multi-year production cycles.
Supply support for LT1805CS 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 backward compatibility for all LT-series op amps, ensuring long-term availability and technical support for legacy designs.
The LT180x family was designed specifically for high-fidelity, wide-bandwidth signal conditioning in mixed-signal systems where rail-to-rail operation, low noise, and multi-channel matching are critical - especially in data acquisition, video, and instrumentation.
FAQ
What is the maximum capacitive load the LT1805CS can drive without oscillation?
The LT1805CS remains stable driving up to 100 pF with unity-gain configuration and proper PCB layout. For loads exceeding 100 pF, a series resistor (10–50 Ω) must be placed adjacent to the output pin to isolate capacitance - verified by overshoot measurements in Figure G30/G31 of the 180345f datasheet. This limitation applies to all four amplifiers identically in the LT1805CS.
Does the LT1805CS support true single-supply operation down to 2.3 V?
Yes - the LT1805CS is fully specified from 2.3 V to 12.6 V total supply, with rail-to-rail input and output functionality maintained across this range. At 2.3 V, minimum output swing is within 120 mV of each rail at 5 mA load, and gain bandwidth reduces to ~40 MHz. This capability is confirmed in the "Minimum Supply Voltage" row of the Electrical Characteristics tables (Note 6).
How does input stage crossover affect offset voltage in the LT1805CS?
The LT1805CS uses dual PNP/NPN input stages that switch near VS+ – 1.3 V; offset voltage shifts by ≤1 mV across the transition zone (VCM = 3.7 V to 5 V at 5 V supply). This behavior is documented in Figure G06 and the "Input Offset Shift" parameter (≤1.00 mV max over full VCM range), and must be accounted for in precision DC-coupled applications spanning the entire input range.
Can the LT1805CS replace the LT1805IS in industrial temperature-grade designs?
No - LT1805CS is rated for 0°C to 70°C operation only, while LT1805IS is guaranteed over –40°C to 85°C. Though LT1805CS may function at –40°C, its parameters (e.g., slew rate, GBW, offset match) are not tested or guaranteed outside 0°C–70°C. For industrial deployments requiring full-spec performance at extreme temperatures, LT1805IS is the qualified choice.
What thermal considerations apply when using all four amplifiers simultaneously in LT1805CS?
At 5 V supply and 3.1 mA per amplifier, total quiescent power is 62 mW. With θJA = 160°C/W, ambient temperature must stay below 135°C to keep junction temperature ≤150°C - but practical derating requires limiting continuous output current. Per the Power Dissipation section, driving 10 mA into 100 Ω loads raises power to 180 mW, requiring ambient <120°C or PCB copper area enhancement.
LT1805CS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- LT®
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- General Purpose
- Number of Circuits:
- 4
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 100V/µs
- Gain Bandwidth Product:
- 83 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 2.5 µA
- Voltage - Input Offset:
- 1.5 mV
- Current - Supply:
- 2.5mA (x4 Channels)
- Current - Output / Channel:
- 50 mA
- Voltage - Supply Span (Min):
- 2.3 V
- Voltage - Supply Span (Max):
- 12.6 V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SO
LT1805CS FAQ
1.How can I place an order for LT1805CS through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1805CS 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 LT1805CS reliable?
The price and inventory of LT1805CS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1805CS is usually 5 days.
3.What payment methods are accepted for LT1805CS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1805CS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1805CS?
LT1805CS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1805CS 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 LT1805CS?
For technical support, including LT1805CS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1805CS requirements.
6.How does Aetrix verify that LT1805CS is sourced from the original manufacturer or authorized distributors?
All LT1805CS 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 LT1805CS meets industry standards.
7.What is the process for return or replacement of LT1805CS?
All LT1805CS units undergo pre-shipment inspection (PSI). If there is an issue with LT1805CS, 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 LT1805CS part is unused and in its original packaging.
Return procedure for LT1805CS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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