AD8251ARMZ-R7 - 10MHz Digitally Programmable Gain In-Amp | ADI
MPN: AD8251ARMZ-R7 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.92 | $8.92 |
| 10 | $8.03 | $80.30 |
| 100 | $7.14 | $714.00 |
| 500 | $6.43 | $3,215.00 |
| 1,000 | $5.71 | $5,710.00 |
AD8251ARMZ-R7 Overview
An instrumentation amplifier (in-amp) is a precision differential amplifier optimized for accurate, low-noise amplification of small differential signals riding on large common-mode voltages. In-amps sit in the analog signal chain between sensors (thermocouples, strain gauges, bridge transducers, biopotential electrodes) and downstream ADCs, combining high common-mode rejection ratio (CMRR), high input impedance, and user-adjustable gain. Within the broader taxonomy, in-amps belong to the amplifier IC family, which is itself a subset of linear ICs and signal-conditioning components. The AD8251's iCMOS™ process enables ±15 V supply operation in a small surface-mount footprint.
Key differentiating features of the AD8251 include its parallel digital gain-control interface (two logic inputs select G = 1, 2, 4, or 8) allowing microsecond gain switching without analog glitches, a maximum input bias current of 50 pA, integrated overvoltage protection up to ±40 V on the inputs, and low offset drift of 1 μV/°C. The 10 MHz small-signal bandwidth and 20 V/μs slew rate are preserved at all gain settings, which is uncommon in programmable-gain in-amps. An exposed thermal pad on the MSOP-10 footprint improves θJA for continuous industrial-temperature operation.
Architecturally, the AD8251 uses a classic three-op-amp in-amp topology with precision thin-film gain-setting resistors and laser-trimmed input stages, then digitizes the gain selection via CMOS switches on the feedback network. The result is a single device that replaces discrete in-amp designs with manual relay or analog-gain-switch circuitry, reducing PCB area and improving gain-set repeatability. Power dissipation is approximately 30 mW at ±5 V supply, well within the MSOP-10 thermal budget.
Typical applications include medical instrumentation (ECG, EEG front ends), industrial process control (PLC analog input modules, weigh scales), automated test equipment (ATE) scanner cards, and wideband data-acquisition systems driving 16-/18-bit SAR ADCs. Designers pair the AD8251 with high-impedance sensors and high-CMRR front-end filters to extract millivolt-level signals from noisy industrial environments.
A key design consideration is that the digital gain-control pins (A0, A1) require clean CMOS-level logic; any ringing or slow edges can inject charge into the input stage. Decouple both supply rails with 0.1 μF X7R ceramic capacitors placed within 5 mm of the supply pins. For best CMRR above 10 kHz, keep source impedances balanced to within 1 Ω and place the common-mode filter capacitor directly across the input pins.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for AD8251ARMZ-R7 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with AD8251ARMZ-R7 (same form factor and footprint) — differing in Package, Slew Rate, Bandwidth (-3 dB), Supply Voltage Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AD8250ARMZ-R7
✅ Drop-In📋 Reference alternative (not in catalog)
AD8253ARMZ-R7
✅ Drop-In📋 Reference alternative (not in catalog)
AD8251ARMZ-RL
✅ Drop-In✓ In Stock
$7.05 / Unit
View Datasheet →AD8421ARMZ
✅ Drop-In📋 Reference alternative (not in catalog)
INA128UA
✅ Drop-In📋 Reference alternative (not in catalog)
AD8221ARMZ
✅ Drop-In📋 Reference alternative (not in catalog)
AD8251ARMZ-R7 Maximum Ratings & Electrical Characteristics
| Part Number | AD8251ARMZ-R7 |
| Manufacturer | Analog Devices Inc. |
| Function | Instrumentation Amplifier |
| Number of Channels | 1 |
| Programmable Gains | G = 1, 2, 4, 8 |
| Bandwidth (Small-Signal, -3 dB) | 10 MHz |
| Slew Rate | 20 V/μs |
| Settling Time to 0.001% | 785 ns (max) |
| Total Harmonic Distortion (THD) | -110 dB |
| Input Impedance | GΩ |
| Input Bias Current (max) | 50 pA |
| Offset Voltage Drift (typ) | 1 μV/°C |
| Supply Voltage Range | ±5 V to ±15 V (dual) / +5 V to +30 V (single-equivalent) |
| Quiescent Supply Current (typ) | 4.5 mA |
| Input Overvoltage Protection | ±40 V (continuous) |
| Operating Temperature Range | -40°C to +85°C |
| Package | 10-pin MSOP (RM) |
| Mounting Type | Surface Mount |
| MSL (Moisture Sensitivity Level) | 1 (unlimited) |
| Lead-Free / RoHS | Yes / Compliant |
| Gain-Selection Interface | 2-bit parallel CMOS logic (A0, A1) |
| Process Technology | iCMOS™ |
AD8251ARMZ-R7 Pin Configuration
| Pin 1 | -IN — Inverting differential input |
| Pin 2 | +IN — Non-inverting differential input |
| Pin 3 | VS- — Negative supply voltage |
| Pin 4 | REF — Reference voltage for output level shifting |
| Pin 5 | A0 — Gain-select logic input (LSB) |
| Pin 6 | A1 — Gain-select logic input (MSB) |
| Pin 7 | VS+ — Positive supply voltage |
| Pin 8 | OUT — Amplifier output |
| Pin 9 | NC — Not connected (per datasheet) |
| Pin 10 | EPAD — Exposed thermal pad (connect to VS- or PCB ground) |
Typical Applications
AD8251ARMZ-R7 is suitable for 6 applications: Medical Instrumentation Front Ends, Industrial Process Control & PLC Analog Modules, Automated Test Equipment (ATE) Scanner Cards, Strain-Gauge and Bridge Sensor Signal Conditioning, High-Speed Data Acquisition Front Ends, Audio Test & Measurement Instrumentation.
Medical Instrumentation Front Ends
The AD8251ARMZ-R7 fits medical instrumentation front ends because of its 10 MHz bandwidth, GΩ input impedance, and 50 pA max input bias current that minimizes loading on high-impedance biopotential electrodes. Its 20 V/μs slew rate captures fast transient biosignals (paced ECG pulses, neural spikes) without slew-induced distortion. Digital gain switching lets a single-channel ECG/EEG design span 1× to 8× at runtime, replacing mechanical range relays. The ±40 V input overvoltage protection also tolerates defibrillator-pulse recovery transients seen in patient monitors.
Recommended
Industrial Process Control & PLC Analog Modules
The AD8251ARMZ-R7 is well matched to industrial PLC analog-input modules that digitize 4-20 mA, 0-10 V, and thermocouple/mV sensor signals. Its 10 MHz bandwidth supports 16-/18-bit SAR ADCs at full throughput, while digital gain programming (G=1, 2, 4, 8) auto-ranges the input to the ADC full-scale range, eliminating manual calibration across input types. The ±15 V supply capability and ±40 V input protection handle industrial common-mode and surge events. With 1 μV/°C offset drift and high CMRR, the AD8251 delivers accurate readings in electrically noisy factory environments.
Recommended
Automated Test Equipment (ATE) Scanner Cards
ATE scanner cards need fast settling and programmable gain, both of which the AD8251ARMZ-R7 delivers. Its 785 ns max settling to 0.001% combined with parallel digital gain switching allows per-channel range reconfiguration in microseconds, multiplying effective test throughput on multi-pin IC testers. The 10 MHz bandwidth preserves pulse fidelity for production test of high-speed serial interfaces, and the small MSOP-10 footprint enables dense scanner-card layouts. Offset drift of 1 μV/°C keeps calibration valid across extended thermal soak in ATE chambers.
Recommended
Strain-Gauge and Bridge Sensor Signal Conditioning
Bridge sensor signal chains benefit from the AD8251ARMZ-R7's high CMRR and GΩ input impedance, which extract low-level mV differential signals riding on large DC common-mode voltages typical of wheatstone bridges. With programmable gains of 1× to 8×, designers can use one in-amp for both low-mV strain gauges and higher-output load cells without hardware changes. The 20 V/μs slew rate handles dynamic strain events (impact, vibration), while ±40 V input protection survives miswiring in field-installable weigh scales. Pair with the AD7190 24-bit sigma-delta ADC for weigh-scale readout.
Recommended
High-Speed Data Acquisition Front Ends
High-speed data acquisition front ends rely on the AD8251ARMZ-R7's 10 MHz bandwidth and 20 V/μs slew rate to drive 16-/18-bit ADCs at maximum sample rates without introducing alias or harmonic distortion. The digitally programmable gain (G=1, 2, 4, 8) lets software-controlled autoranging stretch dynamic range to 16+ effective bits across wide input signal spans. The exposed thermal pad on MSOP-10 keeps θJA low enough for continuous multi-MSPS operation. With -110 dB THD the AD8251 is well below the noise floor of typical 18-bit ADCs.
Recommended
Audio Test & Measurement Instrumentation
Audio test and measurement instruments need wideband, low-distortion amplification, and the AD8251ARMZ-R7's -110 dB THD at 10 MHz bandwidth is well below audible and even studio-grade measurement thresholds. Its GΩ input impedance makes it transparent to high-Z audio sources (tape heads, condenser microphones), while 50 pA max input bias current prevents DC drift in capacitor-coupled front ends. The MSOP-10 footprint allows dense multi-channel audio analyzer designs, and the 1 μV/°C offset drift keeps THD+N measurements stable across warm-up.
Recommended
Recommended Products Summary
Engineering reference data for AD8251ARMZ-R7 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD8250ARMZ-R7 | AD8253ARMZ-R7 | AD8251ARMZ-RL | AD8421ARMZ | INA128UA | AD8221ARMZ |
|---|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Texas Instruments | Analog Devices |
| Package | MSOP-10 (RM) | MSOP-10 (RM) - same | MSOP-10 (RM) - same | MSOP-10 (RM) - same | MSOP-10 (RM) - same | MSOP-10 - same | MSOP-10 (RM) - same |
| Bandwidth | 10 MHz | 10 MHz | 10 MHz | 10 MHz | 10 MHz | 1.3 MHz | 825 kHz |
| Programmable Gains | 1, 2, 4, 8 | Fixed G=10 | 1, 10, 100, 1000 | 1, 2, 4, 8 (same die) | Fixed G=10 | External resistor (1 to 1000) | External resistor (1 to 1000) |
| Slew Rate | 20 V/μs | 20 V/μs | 20 V/μs | 20 V/μs | 35 V/μs | 0.4 V/μs | 2 V/μs |
| Input Bias Current (max) | 50 pA | 50 pA | 50 pA | 50 pA | 1 nA | 5 nA | 1.5 nA |
| Supply Voltage (Dual) | ±5 V to ±15 V | ±5 V to ±15 V | ±5 V to ±15 V | ±5 V to ±15 V | ±5 V to ±18 V | ±2.25 V to ±18 V | ±2.3 V to ±18 V |
Key Differentiators
- Digitally switchable gains in a single MSOP-10 IC (vs INA128UA)
- 10 MHz bandwidth preserved across all gain settings (vs AD8221ARMZ)
- 20 V/μs slew rate at all programmable gains (vs AD8253ARMZ-R7)
Design Notes
Place the AD8251ARMZ-R7's 0.1 μF X7R supply-decoupling capacitors within 5 mm of pins 3 (-Vs) and 7 (+Vs). Use a ground plane on the top layer directly under the part, and stitch the exposed thermal pad (pin 10) to that plane with at least 4 vias to lower θJA. This layout minimizes supply-induced gain error and keeps the 10 MHz bandwidth intact at all gain settings.
Route the differential inputs to the AD8251ARMZ-R7 as a tightly coupled pair with matched trace lengths, ideally with a balanced common-mode filter capacitor placed directly across pins 1 and 2. Source-impedance imbalance above 1 Ω degrades CMRR above 10 kHz, which matters for sensor front ends and ECG designs. Add an RFI filter at the connector if the inputs will see electrostatic discharge or RF interference.
Driven CMOS logic into the A0/A1 gain-control pins of the AD8251ARMZ-R7 should have clean edges (rise/fall times under 100 ns); slow or ringing logic injects charge into the input stage, causing transient gain errors and DC offset shift. Tie unused gain-control logic to a defined CMOS rail (don't float). Never exceed ±Vs on the inputs even though the part has ±40 V protection - sustained overvoltage outside the rails can damage internal ESD cells.
Compliance Information
RoHS compliant per Analog Devices product page. Industrial temperature range -40C to +85C. Not AEC-Q100 qualified - for automotive applications contact Analog Devices for qualified equivalents.
