LT1634AIS8-1.25 - 1.25V Micropower Shunt Voltage Reference | ADI
N.º de pieza: LT1634AIS8-1.25 ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $4.2 | $4,20 |
| 10 | $3.78 | $37,80 |
| 100 | $3.36 | $336,00 |
| 500 | $2.97 | $1.485,00 |
| 1.000 | $2.65 | $2.650,00 |
LT1634AIS8-1.25 Descripción general
A shunt voltage reference is a two-terminal device that maintains a constant voltage drop across itself, similar to a Zener diode but with far tighter initial accuracy and temperature stability. In the broader component hierarchy, the LT1634AIS8-1.25 belongs to the voltage reference family, which is a subset of power management ICs. Shunt references are commonly used as parallel-connected references in low-current applications, where they are biased by a resistor from a higher supply rail.
Key features include 0.05% initial voltage accuracy achieved through trimmed precision thin-film resistors, 10 ppm/°C maximum drift using an improved curvature correction technique, and micropower operation at just 10 µA. The wide operating current range from 10 µA to 100 mA supports both battery-powered and higher-power analog systems. Low temperature cycling hysteresis is also guaranteed through advanced processing techniques.
The LT1634 family uses a bandgap reference architecture with on-chip thin-film trimming to achieve its precision. Because it is a shunt (not series) topology, the same pinout handles multiple fixed voltage options including 1.25V, 2.5V, and 4.096V variants. This allows designers to standardize PCB layouts across product variants that require different reference voltages, simplifying both design and inventory.
Typical applications include portable battery-powered instrumentation, precision data acquisition systems, 12-bit to 16-bit ADC/DAC reference rails, and industrial loop-powered sensors. The 1.25V output is particularly well suited for low-voltage ADC full-scale references and as a bias point for low-voltage analog front ends. Its low quiescent current makes it ideal for always-on monitoring circuits.
When designing with the LT1634AIS8-1.25, select the bias resistor such that cathode current stays between 10 µA minimum and 100 mA maximum across all operating conditions. Place a 0.1 µF bypass capacitor close to the reference pins to maintain stability and reduce high-frequency noise. Avoid capacitive loads exceeding the datasheet recommendation, as this may cause oscillation.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, giving engineers a single source for sourcing and design decisions.
Alternativas directas para LT1634AIS8-1.25 — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
LT1634ACS8-1.25
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LT1634BCS8-1.25
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LT1634BIS8-1.25
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LT1634AIS8-1.25#TRPBF
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LT1634AIS8-1.25#PBF
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LT1634AIS8-1.25 Especificaciones
| Reference Type | Shunt Voltage Reference |
| Tensión de salida | 1.25 V (fixed) |
| Initial Voltage Accuracy | 0.05 % |
| Temperature Drift | 10 ppm/°C (max) |
| Minimum Cathode Current | 10 µA |
| Maximum Cathode Current | 100 mA |
| Dynamic Impedance | < 1 ohm |
| Rango de temperatura de funcionamiento | -40°C to +85°C (Industrial grade) |
| Encapsulado | 8-pin SOIC (S8) |
| Tipo de montaje | Surface Mount |
| Topología | Bandgap with thin-film trim |
| Lead Free / RoHS | Yes (PBF suffix) |
| Recuento de pines | 8 |
| Nivel MSL | 1 (per JEDEC J-STD-020) |
| Polarity | Two-terminal (anode, cathode) |
Configuración de pines de LT1634AIS8-1.25
| Pin 1 | NC — No internal connection (per datasheet) |
| Pin 2 | NC — No internal connection (per datasheet) |
| Pin 3 | NC — No internal connection (per datasheet) |
| Pin 4 | ANODE — Anode (positive terminal) |
| Pin 5 | NC — No internal connection (per datasheet) |
| Pin 6 | NC — No internal connection (per datasheet) |
| Pin 7 | NC — No internal connection (per datasheet) |
| Pin 8 | CATHODE — Cathode (1.25V output reference) |
Aplicaciones típicas
LT1634AIS8-1.25 es adecuado para 6 aplicacións: 12-bit ADC Voltage Reference, Portable Battery-Powered Instrumentation, Industrial Loop-Powered Sensor Transmitter, Precision Data Acquisition Front End, Precision Threshold Detection Circuit, Strain Gauge / Weigh Scale Amplifier.
12-bit ADC Voltage Reference
The LT1634AIS8-1.25 provides a precision 1.25V reference rail for 12-bit successive-approximation ADCs. Its 0.05% initial accuracy equates to roughly 1 LSB at 12 bits, while 10 ppm/°C drift limits temperature-induced error to less than 0.5 LSB across a 50°C swing. Connected from a 3.3V or 5V system supply through a bias resistor sized for 1mA nominal cathode current, the reference maintains accuracy even as supply voltage varies. Compared to internal ADC references, the LT1634AIS8-1.25 offers tighter temperature stability and lower long-term drift. Designers should place a 0.1µF ceramic bypass capacitor close to the reference pins to suppress switching noise from digital logic.
Recomendado
Portable Battery-Powered Instrumentation
Battery-powered handheld meters and data loggers benefit from the LT1634AIS8-1.25's micropower 10 µA minimum cathode current, extending runtime by orders of magnitude compared to series-mode references. The shunt topology also eliminates the quiescent overhead of internal LDO regulators used as references. In a typical 3V lithium-powered design, the reference is biased from the battery through a 1.5 MΩ resistor, drawing only 1 µA average. The 1.25V output is ideal for full-scale references on low-voltage ADCs and for biasing precision analog front ends. The SOIC-8 package is well-suited to compact handheld layouts.
Recomendado
Industrial Loop-Powered Sensor Transmitter
In 4-20 mA industrial loop-powered transmitters, the LT1634AIS8-1.25 supplies a stable 1.25V reference to the ADC or DAC that converts sensor measurements into loop current. Its -40°C to +85°C industrial temperature range covers harsh factory environments, and its 10 ppm/°C drift maintains calibration over long deployment periods. The shunt topology is particularly well-suited to loop-powered designs because the reference can be biased directly from the loop supply without adding series voltage drop. With less than 1 ohm dynamic impedance, the reference holds accuracy even as the ADC's sample-and-hold capacitor switches.
Recomendado
Precision Data Acquisition Front End
Multi-channel data acquisition systems use the LT1634AIS8-1.25 as a common reference for simultaneous-sampling ADCs across all input channels. The 0.05% initial accuracy and 10 ppm/°C drift ensure that channel-to-channel gain matching is preserved across the entire signal chain. With 100 mA maximum cathode current, the reference can support multiple ADCs, DACs, and scaling amplifiers in parallel. The shunt topology also simplifies power-supply design because the same 5V or 12V rail that powers the analog section biases the reference through a single resistor. Place a 1µF or larger bypass capacitor at the reference output for low-noise performance.
Recomendado
Precision Threshold Detection Circuit
Comparator-based voltage threshold detectors benefit from the LT1634AIS8-1.25's stable 1.25V reference for setting precise trigger points. In over-voltage, under-voltage, and window comparator circuits, the reference defines the comparison threshold against an unknown input voltage. With 10 ppm/°C drift, the threshold remains stable across wide temperature variations, avoiding false trips. The shunt topology allows the reference to be biased directly from the supply being monitored, simplifying circuit topology. A typical configuration uses a single comparator with hysteresis resistor network and the LT1634AIS8-1.25 as the threshold reference.
Recomendado
Strain Gauge / Weigh Scale Amplifier
Load cell and weigh scale signal conditioning circuits use the LT1634AIS8-1.25 as the excitation reference for strain gauge bridges and the ADC reference for digitizing the amplified output. Using the same reference for both functions achieves ratiometric measurement that cancels reference drift and initial accuracy errors. The 1.25V output is well-matched to low-voltage ADC full-scale ranges commonly used in weigh scale designs. With 10 µA minimum operating current, the reference adds negligible load to the bridge excitation supply. Less than 1 ohm dynamic impedance keeps the reference stable during ADC sampling transients.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para LT1634AIS8-1.25 — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | LT1634ACS8-1.25 | LT1634BCS8-1.25 | LT1634BIS8-1.25 | LT1634AIS8-1.25#TRPBF |
|---|---|---|---|---|---|
| Package | SOIC-8 | SOIC-8 (same) | SOIC-8 (same) | SOIC-8 (same) | SOIC-8 (same) |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Output Voltage | 1.25 V | 1.25 V | 1.25 V | 1.25 V | 1.25 V |
| Temperature Drift | 10 ppm/°C | 10 ppm/°C | 10 ppm/°C | 10 ppm/°C | 10 ppm/°C |
| Operating Temperature Range | -40°C to +85°C (Industrial) | 0°C to +70°C (Commercial) | 0°C to +70°C (Commercial) | -40°C to +85°C (Industrial) | -40°C to +85°C (Industrial) |
| Min Cathode Current | 10 µA | 10 µA | 10 µA | 10 µA | 10 µA |
| Max Cathode Current | 100 mA | 100 mA | 100 mA | 100 mA | 100 mA |
| Packaging Form | Tube (#PBF suffix) | Tube / Tape & Reel | Tube / Tape & Reel | Tube / Tape & Reel | Tape & Reel |
Diferenciadores clave
- Industrial temperature grade (-40°C to +85°C) (frente a LT1634ACS8-1.25)
- Micropower 10 µA minimum cathode current (frente a LM4040-1.2)
- 0.05% initial accuracy with thin-film trimming (frente a Generic 1.25V shunt references)
Notas de diseño
The LT1634AIS8-1.25 is a shunt reference that requires a bias resistor from a higher supply rail. Choose R_BIAS such that cathode current stays between 10 µA minimum and 100 mA maximum across all operating conditions. For a 5V supply producing 1.25V across the reference, with 1 mA nominal cathode current: R_BIAS = (5V - 1.25V) / 1mA = 3.75 kΩ. Always verify current remains above 10 µA at minimum supply and load conditions to prevent reference dropout. For battery-powered designs, R_BIAS in the MΩ range can extend battery life but at the cost of higher dynamic impedance.
Avoid placing capacitive loads exceeding the datasheet recommendation directly at the reference output, as this can cause oscillation. If a large filter capacitor is required for noise reduction, add a small series resistor (typically 10-100 Ω) between the reference and the capacitor to isolate the load. The reference is also sensitive to thermal gradients on the PCB; keep heat sources away from the SOIC-8 package to avoid drift errors from self-heating. Note that the SOIC-8 package has many no-connect pins that should not be used for signal routing.
Place a 0.1 µF ceramic bypass capacitor as close as possible to the cathode and anode pins of the LT1634AIS8-1.25. For low-noise applications, add a 1 µF to 10 µF tantalum or ceramic capacitor in parallel. Use a star-ground topology where the reference ground pin ties directly to the ADC or comparator ground reference point to minimize ground loop noise. Avoid running digital signals or high-current traces directly under or near the reference to prevent coupled noise from corrupting the 1.25V rail.
When using the LT1634AIS8-1.25 as an ADC reference, ensure the ADC's sample-and-hold capacitor does not excessively load the reference. For typical 12-bit and 16-bit ADCs with pF-range input capacitance, the reference's <1 ohm dynamic impedance is sufficient to maintain accuracy during sampling. For multi-channel ADCs with rapid switching, add a buffer amplifier (such as the LMV841) between the reference and the ADC reference pin to isolate the reference from switching transients. This is especially important in multiplexed data acquisition systems.
Información de cumplimiento
RoHS compliance indicated by #PBF suffix. Part is lead-free per Analog Devices product page. AEC-Q100 not explicitly stated in available data; this part is marketed for industrial/commercial applications rather than automotive. Halogen-free status not explicitly stated in available data.
