AD8420ARMZ - Micropower Rail-to-Rail In-Amp | Analog Devices
MPN: AD8420ARMZ ✓ Hoạt độngAD8420ARMZ Tóm tắt
An instrumentation amplifier (INA) is a precision differential amplifier with high common-mode rejection ratio (CMRR), high input impedance, and user-settable gain - typically realized through one gain-setting resistor. INAs are specialized building blocks in the analog signal chain, sitting between a sensor (bridge, thermocouple, biopotential electrode) and an analog-to-digital converter. They belong to the broader amplifier-IC family and are widely used where small signals must be extracted in the presence of large common-mode noise or DC offsets.
Key features of the AD8420ARMZ include 100 dB minimum DC CMRR (G = 100), a maximum input offset voltage of 250 µV, 30 nV/√Hz input voltage noise density, and ±18 V dual supply operation. The rail-to-rail output swing maximizes dynamic range when operating from low supply voltages, while the novel architecture eliminates the need for level shifting in single-supply designs. A single external resistor sets the gain from 1 to 1000, simplifying BOM and layout.
Typical applications for the AD8420ARMZ include battery-powered sensor signal conditioning, ECG/biomedical front ends, industrial process-control transducers (pressure, strain gauge, load cell), and thermocouple/RTD amplifiers. The wide supply range and 90 µA quiescent current make it suitable for portable instrumentation, while ±18 V capability addresses industrial instrumentation.
When designing with this part, place the gain-setting resistor close to the RG pin to minimize parasitic effects, use 0.1 µF decoupling capacitors at the supply pins, and follow proper PCB layout for high-CMRR performance (matched input traces, guard ring around inputs). For new designs consider the AD8421ARMZ (higher precision) or AD8237ARMZ (zero-drift) if your application demands tighter offset or lower noise.
Bộ thay thế dễ dàng lắp đặt cho AD8420ARMZ — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với AD8420ARMZ (cùng hình factor và footprint) — khác nhau ở Gain Range, Input Common-Mode Range, Input Offset Voltage (max), Input Voltage Noise Density, Operating Temperature Range.
AD8420ARMZ-R7
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
AD8420ARMZ-RL
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
AD8421ARMZ
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
AD8237ARMZ
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →AD8420ARMZ Tỷ lệ tối đa & tính chất điện
| Product Type | Instrumentation Amplifier |
| Number of Channels | 1 |
| Hộp | 8-MSOP (RM-8) |
| Supply Voltage Range (Single) | 2.7 V to 36 V |
| Supply Voltage Range (Dual) | ±2.5 V to ±18 V |
| Quiescent Current (typical) | 90 µA |
| Bandwidth (-3 dB, G=1) | 6 MHz |
| Input Offset Voltage (max) | 250 µV |
| Input Voltage Noise Density | 30 nV/√Hz |
| CMRR (DC, G=100) | 100 dB minimum |
| Gain Range | 1 to 1000 (set by single external resistor) |
| Kiểu đầu ra | Rail-to-Rail |
| Slew Rate | 1 V/µs (typical) |
| Khoảng nhiệt độ hoạt động | -40 °C to +85 °C |
| Input Common-Mode Range | Includes ground; below ground on single supply |
| Kiểu lắp đặt | Surface Mount |
| Cấp MSL | 1 (Unlimited) |
| RoHS Compliance | RoHS3 Compliant |
| REACH Status | REACH Unaffected |
| Lead-Free | Yes |
Cấu hình chân AD8420ARMZ
| Chân 1 | RG — Gain-setting resistor pin (RG between pins 1 and 8) |
| Chân 2 | -IN — Inverting input |
| Chân 3 | +IN — Noninverting input |
| Chân 4 | VS- — Negative supply (or ground for single supply) |
| Chân 5 | REF — Reference input (sets output mid-scale; typically tied to mid-supply or ground) |
| Chân 6 | OUT — Amplifier output (rail-to-rail) |
| Chân 7 | VS+ — Positive supply |
| Chân 8 | RG — Gain-setting resistor pin (RG between pins 1 and 8) |
Ứng dụng tiêu biểu
AD8420ARMZ phù hợp cho 6 Áp dụngs: Battery-Powered Sensor Signal Conditioning, ECG and Biopotential Front End, Industrial Process-Control Transducers, Thermocouple and RTD Amplification, Portable Instrumentation and Handheld Meters, Current-Sense and Shunt Amplifiers.
Battery-Powered Sensor Signal Conditioning
The AD8420ARMZ is well-suited to battery-powered sensor front ends because of its 90 µA typical quiescent current and wide single-supply range of 2.7 V to 36 V. In a portable pressure or strain-gauge system, it sits between a bridge sensor and an ADC, where its 100 dB minimum DC CMRR (G = 100) rejects common-mode DC and 50/60 Hz interference on the bridge output. The rail-to-rail output maximizes dynamic range on 3.3 V or 5 V rails, and the 6 MHz bandwidth at G = 1 supports signal rates well beyond typical sensor bandwidths. Single-resistor gain setting (G = 1 + 19.8 kΩ / RG) minimizes BOM cost.
Được đề xuất
ECG and Biopotential Front End
In ECG and other biopotential applications, the AD8420ARMZ amplifies small differential electrode voltages (typically 0.5 mV to 5 mV) in the presence of large DC common-mode voltages (often ±300 mV or more from skin-electrode half-cell potentials). Its indirect current-feedback architecture amplifies signals at or below ground without dual supplies - a critical requirement for single-supply ECG designs where one electrode is near ground. The 100 dB minimum DC CMRR and 30 nV/√Hz input noise density support diagnostic-grade signal-to-noise. Pair with right-leg-drive feedback for best common-mode rejection.
Được đề xuất
Industrial Process-Control Transducers
The AD8420ARMZ is widely used in industrial process-control transducer signal chains for pressure, strain-gauge, load-cell, and flow sensors. Its ±18 V dual-supply capability handles industrial ±15 V rails and provides extra headroom for high common-mode bridge excitation. The 100 dB minimum CMRR at high gain rejects ground-loop and 50/60 Hz line-frequency noise in plant-floor environments. The wide operating temperature range of -40 °C to +85 °C supports most industrial cabinets and field enclosures, while the MSOP-8 footprint enables compact, densely populated multi-channel PLC and DAQ modules.
Được đề xuất
Thermocouple and RTD Amplification
For thermocouple (J, K, T, E types) and RTD (PT100/PT1000) amplification, the AD8420ARMZ's high gain (up to 1000) and excellent DC CMRR extract microvolt-level thermoelectric voltages from millivolt-scale common-mode sensor bias. The wide-supply range accommodates 5 V excitation for the RTD bridge plus amplifier on a single rail, while the 250 µV maximum input offset is acceptable for non-thermocouple-junction applications where cold-junction compensation is performed in software or a dedicated temperature sensor. For Type T/K thermocouples requiring tighter offset, consider the AD8421ARMZ.
Được đề xuất
Portable Instrumentation and Handheld Meters
Battery-powered handheld multimeters, data loggers, and field instrumentation benefit from the AD8420ARMZ's 90 µA quiescent current and wide 2.7 V to 36 V supply range - directly accepting Li-ion, 9 V, and 12 V battery stacks. The rail-to-rail output swing maximizes dynamic range on 3.3 V ADC rails, while the 6 MHz bandwidth supports both DC measurement channels and modest-bandwidth AC signal chains. The MSOP-8 footprint keeps the analog front end under 9 mm² per channel, allowing 4- and 16-channel multi-function instruments to fit in compact handheld enclosures without sacrificing battery life.
Được đề xuất
Current-Sense and Shunt Amplifiers
While traditionally a dedicated current-sense amplifier, the AD8420ARMZ also serves well as a high-side or low-side shunt current amplifier in power-management and battery-monitoring circuits. With a small shunt resistor (10 mΩ to 100 mΩ) and G = 100, it amplifies currents from 10 mA to 10 A into a 0 V to 5 V output range suitable for an ADC. Its wide common-mode input range - extending below ground on single supply - accommodates low-side shunts without requiring dual supplies. The 90 µA Iq adds minimal load to the monitored rail.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho AD8420ARMZ — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | AD8420ARMZ-R7 | AD8420ARMZ-RL | AD8421ARMZ | AD8237ARMZ |
|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 8-MSOP (RM-8) | 8-MSOP (RM-8) - same | 8-MSOP (RM-8) - same | 8-MSOP (RM-8) - same | 8-MSOP (RM-8) - same |
| Input Offset Voltage (max) | 250 µV | 250 µV | 250 µV | 25 µV | 15 µV |
| Bandwidth (-3 dB, G=1) | 6 MHz | 6 MHz | 6 MHz | ~10 MHz | ~30 kHz |
| Supply Voltage Range (Single) | 2.7 V to 36 V | 2.7 V to 36 V | 2.7 V to 36 V | ~±2.5 V to ±18 V dual | 1.8 V to 5.5 V |
| Output Type | Rail-to-Rail | Rail-to-Rail | Rail-to-Rail | Rail-to-Rail | Rail-to-Rail |
| Pinout Compatibility | Reference | Identical pinout | Identical pinout | Same MSOP-8, verify gain pin config | Same MSOP-8, verify gain pin config |
Bảo phân biệt quan trọng
- Lowest quiescent current in its bandwidth class (vsAD8421ARMZ)
- Wide supply range up to 36 V single / ±18 V dual (vsAD8237ARMZ)
- Below-ground input common-mode on single supply (vsConventional 3-op-amp INAs)
- Single-resistor gain setting from 1 to 1000 (vsAD8421ARMZ)
Ghi chú thiết kế
Place the gain-setting resistor RG as close as possible to pins 1 and 8 to minimize parasitic capacitance. Use 0.1 µF decoupling capacitors on each supply pin (VS+ and VS-), placed within 2 mm of the IC. Keep input traces matched and short - the AD8420 datasheet recommends a guard ring tied to REF potential around the input traces to maximize CMRR, especially in high-impedance bridge applications.
Do not use a standard 1 % RG resistor if gain accuracy is critical - the gain error of the AD8420 directly adds the RG tolerance to the gain formula. For best CMRR, the REF pin should be driven by a low-impedance source (op-amp buffer or mid-supply rail), not left floating or driven by a resistor divider. Also note that the quiescent current spec of 90 µA is typical - worst-case may approach ~5 mA during transient conditions.
The MSOP-8 package has a thermal resistance (θJA) of approximately 150 °C/W. At maximum supply (36 V single, 18 V dual) and full output swing, internal dissipation can reach ~50 mW, resulting in ~7.5 °C junction rise - well within the 85 °C operating limit. For high-gain high-output-voltage applications in elevated-temperature environments, verify junction temperature with the latest AD8420 datasheet derating curves.
Input common-mode range extends below ground on single supply, but at high source impedance or high frequency, the indirect current-feedback architecture's input capacitance (~5 pF) can interact with source resistance to create a parasitic zero in the transfer function. Keep source impedances below 10 kΩ for best high-frequency CMRR, or add a buffer amp (e.g., AD8627ARMZ or similar) for higher-impedance sources.
Thông tin tuân thủ
RoHS3 compliant and REACH unaffected per PartGenie compliance records. Not AEC-Q100 qualified - this part targets industrial/medical/consumer applications, not automotive. Halogen-free status and conflict-minerals declaration should be confirmed with the manufacturer for specific lot requirements.
