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Analog Devices Inc. LT1991CDD#PBF
- Part No.:
- LT1991CDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT1991CDD#PBF.pdf
- Description:
- IC OPAMP PGA 1 CIRCUIT 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:200
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Product details
Overview
LT1991CDD#PBF from Analog Devices (formerly Linear Technology) is a precision, gain-selectable difference amplifier IC integrating eight matched thin-film resistors and a low-offset op amp in a single 10-lead DFN package. It delivers ±0.08% gain error at G = 1, 560kHz gain bandwidth product, rail-to-rail output swing within 40mV of rails, 50µV max input offset voltage, and operates from 2.7V to 36V supply. It is used in strain gauge signal conditioning and medical instrumentation where high CMRR (>75dB) and micropower (100µA at 5V) are critical.
For engineers reviewing the LT1991CDD#PBF datasheet, LT1991CDD#PBF pinout, LT1991CDD#PBF application, or LT1991CDD#PBF equivalent, key selection factors include verified resistor matching (0.04% for 450kΩ), guaranteed gain drift (<3ppm/°C), input voltage range (–0.5V to 5.1V at 5V supply), CMRR performance across temperature, and DFN package thermal limitations (TJMAX = 125°C).
Technical Context
The LT1991CDD#PBF implements a fixed-resistor-based difference amplifier architecture with three noninverting inputs (P1/P3/P9) and three inverting inputs (M1/M3/M9), enabling configurable gains from –13 to +14 without external components. Its internal SiChrome resistors (50kΩ/150kΩ/450kΩ) provide matched ratios that directly determine gain accuracy and CMRR.
It uses a precision bipolar input op amp with rail-to-rail output stage, 0.3µV/°C offset drift, and stability into capacitive loads up to 500pF at noise gain ≥2. The device is fully specified over –40°C to 85°C (I-grade), with absolute maximum ratings including ±60V on P1/M1 pins and 40V total supply voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Error | ±0.08% at G = 1 (LT1991C grade); ensures <100µV output error for 125mV differential input at 5V supply |
| CMRR | 75dB minimum at G = 1; rejects >5,600:1 common-mode interference in bridge sensor applications |
| Input Offset Voltage | 150µV max (LT1991CDD); contributes ≤1.95mV output error at G = 13 before trimming |
| Supply Current | 100µA typical at 5V; enables battery-powered handheld instrumentation with multi-year operation |
| Output Swing | 40mV from either rail at no load (5V supply); supports full-scale ADC interfacing without level-shifting |
| GBWP | 560kHz; allows stable 10kHz signal amplification at G = 56 or 100kHz at G = 5.6 |
| Operating Temp | –40°C to +85°C (I-grade); validated for industrial embedded systems with extended thermal cycling |
Pinout & Package
LT1991CDD#PBF is housed in a 10-lead, 3mm × 3mm plastic DFN package with exposed pad connected to VEE. Thermal resistance θJA = 43°C/W. Pin 1 is M1 (inverting gain-of-1 input); pin 10 is M1 (confirmed top-view orientation per DD package drawing).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| M1 (Pin 10) | Inverting gain-of-1 input | Connects 450kΩ resistor to op amp inverting input; supports ±60V overvoltage tolerance when P9/M9 grounded |
| M3 (Pin 9) | Inverting gain-of-3 input | Connects 150kΩ resistor to op amp inverting input; limited to VEE–0.2V to VCC+0.2V |
| M9 (Pin 8) | Inverting gain-of-9 input | Connects 50kΩ resistor to op amp inverting input; same voltage limit as M3 |
| VCC (Pin 7) | Positive power supply | Accepts 2.7V to 36V; supplies internal op amp and resistor network |
| OUT (Pin 6) | Amplifier output | Rail-to-rail capable; drives 10kΩ load with <40mV headroom at 5V supply |
| REF (Pin 5) | Reference input | Sets zero-differential output level; connects 450kΩ to op amp noninverting input |
| VEE (Pin 4) | Negative power supply | May be ground (single-supply) or negative rail; exposed pad must be soldered to PCB ground plane |
| P9 (Pin 3) | Noninverting gain-of-9 input | Connects 50kΩ resistor to op amp noninverting input; same voltage limit as M9 |
| P3 (Pin 2) | Noninverting gain-of-3 input | Connects 150kΩ resistor to op amp noninverting input; same voltage limit as M3 |
| P1 (Pin 1) | Noninverting gain-of-1 input | Connects 450kΩ resistor to op amp noninverting input; supports ±60V overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| Integrated precision resistor network | Eight SiChrome resistors (50k/150k/450k) with 0.04% matching enables <0.08% gain error without calibration |
| Rail-to-rail output stage | Swings to within 40mV of VCC or VEE at no load, preserving dynamic range for low-voltage ADCs |
| Wide supply range | Operates from 2.7V single supply to ±18V split supply, supporting portable and industrial power architectures |
| High CMRR over temperature | Guaranteed >75dB from –40°C to +85°C due to <3ppm/°C resistor matching TC |
| Low-power precision | 100µA supply current at 5V with 50µV max VOS enables high-accuracy sensing in energy-constrained designs |
Applications
| Strain Gauge Amplifier | Differential-to-SE Conversion |
|---|---|
Use Scenario: Amplifying µV-level Wheatstone bridge outputs from load cells in industrial weighing systems. IC Role / Device Role / Timing Role: Difference amplifier with G = 1000 configured via external resistors and internal P1/M1 path; REF tied to mid-supply. Use Value: 75dB CMRR rejects 60Hz line noise and thermal EMF; 0.08% gain error eliminates factory calibration per unit. | Use Scenario: Converting differential sensor outputs (e.g., MEMS accelerometers) to single-ended signals for SAR ADC input. IC Role / Device Role / Timing Role: Precision gain-of-1 difference amplifier with REF = VCM; P1/M1 inputs accept differential pair, OUT drives ADC reference point. Use Value: Rail-to-rail output swing (40mV headroom) maximizes SNR into 5V ADC; 100µA quiescent current extends battery life. |
| Medical ECG Front-End | Handheld Multimeter Input Stage |
Use Scenario: First-stage amplification of mV-level biopotential signals with high common-mode interference rejection. IC Role / Device Role / Timing Role: Difference amplifier with G = 10 using P3/M3 inputs; REF biased at 1.25V for 3.3V supply rail-to-rail compatibility. Use Value: 50µV max VOS prevents DC baseline drift; 0.3µV/°C drift ensures stable gain across operating temperature range. | Use Scenario: High-impedance, low-noise front-end for autoranging digital multimeters measuring µV–10V signals. IC Role / Device Role / Timing Role: Configurable noninverting amplifier (G = 0.07 to 14) using P1/P3/P9 and REF; M1 grounded for Hi-Z input. Use Value: 900kΩ input impedance (P1) minimizes loading on high-RTH divider networks; 10ppm gain nonlinearity preserves measurement linearity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar difference amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| INA128UA | Fixed G = 5, 10, 100, or 1000; no internal resistor selection; higher 125µV VOS max; 700µA IQ | Requires external gain-setting resistor; less flexible for multi-gain systems | Choose for cost-sensitive, fixed-gain industrial transmitters where board space is not constrained |
| AD8271ARMZ | G = 0.2 to 10; 0.05% gain error; 125µV VOS; 250µA IQ; SOIC-8 package | Wider gain range but no overvoltage-tolerant inputs; no P1/M1 ±60V capability | Choose when G = 0.2–10 suffices and ±60V input protection is unnecessary |
Compared with INA128UA and AD8271ARMZ, LT1991CDD#PBF offers unique pin-configurable gain (–13 to +14), ±60V input tolerance on P1/M1, and micropower operation - making it optimal for compact, multi-function sensor interfaces requiring field-reconfigurable gain and robust input protection.
Availability
LT1991CDD#PBF is available at Aetrix Electronics and suitable for strain gauge amplifiers, medical instrumentation, handheld test equipment, and industrial process monitoring requiring stable component supply across extended temperature ranges.
Supply support for LT1991CDD#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.
The LT1991CDD#PBF belongs to ADI's precision amplifier portfolio designed for high-accuracy, low-power signal conditioning in instrumentation, medical, and industrial sensing applications where resistor matching, gain stability, and input protection are critical.
FAQ
What is the maximum input voltage allowed on the P1 and M1 pins of the LT1991CDD#PBF?
The LT1991CDD#PBF allows ±60V on P1 and M1 pins when P9 and M9 are grounded and supply is ±15V. This overvoltage tolerance is enabled by isolation of the 450kΩ resistors from the substrate. Exceeding this rating risks permanent damage, and other inputs (P3/M3/P9/M9) are limited to VEE–0.2V to VCC+0.2V.
Does the LT1991CDD#PBF support true rail-to-rail input operation?
No, the LT1991CDD#PBF op amp inputs are not rail-to-rail: they extend to within 1.2V of VCC and 1V of VEE. However, effective attenuation through internal resistors often enables rail-to-rail *common-mode* operation at the package pins - for example, P1/M1 can accept –0.5V to 5.1V at 5V supply while maintaining valid internal node voltages.
What is the thermal limitation of the LT1991CDD#PBF in its DFN package?
The LT1991CDD#PBF in the 10-lead 3mm × 3mm DFN package has a maximum junction temperature (TJMAX) of 125°C and thermal resistance θJA = 43°C/W. With 100µA supply current at 5V (0.5mW dissipation), junction rise is ~22°C above ambient - well within limits. Exposed pad soldering to PCB ground is mandatory for thermal and electrical integrity.
Can the LT1991CDD#PBF be used as a noninverting amplifier with high input impedance?
Yes - when configured with only P1 (or P3 or P9) and REF active, and M1 grounded, the LT1991CDD#PBF functions as a precision noninverting amplifier. Input impedance is 900kΩ (P1), 600kΩ (P3), or 500kΩ (P9), preserving high-Z characteristics essential for passive sensor interfaces and voltage dividers.
How does gain error vary with temperature for the LT1991CDD#PBF?
The LT1991CDD#PBF exhibits guaranteed gain drift of <3ppm/°C over –40°C to +85°C. At G = 1, this translates to <0.0003% error per °C - for a 50°C ambient shift, total gain variation remains under ±0.015%, far tighter than discrete resistor solutions with typical 25ppm/°C TC.
LT1991CDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- Programmable Gain
- Number of Circuits:
- 1
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 0.12V/µs
- Gain Bandwidth Product:
- 560 kHz
- -3db Bandwidth:
- 110 kHz
- Current - Input Bias:
- 2.5 nA
- Voltage - Input Offset:
- 25 µV
- Current - Supply:
- 130µA
- Current - Output / Channel:
- 21 mA
- Voltage - Supply Span (Min):
- 2.7 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT1991CDD#PBF FAQ
1.How can I place an order for LT1991CDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1991CDD#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 LT1991CDD#PBF reliable?
The price and inventory of LT1991CDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1991CDD#PBF is usually 5 days.
3.What payment methods are accepted for LT1991CDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1991CDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1991CDD#PBF?
LT1991CDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1991CDD#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 LT1991CDD#PBF?
For technical support, including LT1991CDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1991CDD#PBF requirements.
6.How does Aetrix verify that LT1991CDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT1991CDD#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 LT1991CDD#PBF meets industry standards.
7.What is the process for return or replacement of LT1991CDD#PBF?
All LT1991CDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1991CDD#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 LT1991CDD#PBF part is unused and in its original packaging.
Return procedure for LT1991CDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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