AD7451BRT-R2 - 12-Bit 1MSPS Pseudo-Diff SAR ADC | ADI
N.º da peça: AD7451BRT-R2 ✓ Ativo| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $6.5 | $6,50 |
| 10 | $5.85 | $58,50 |
| 100 | $5.2 | $520,00 |
| 500 | $4.65 | $2.325,00 |
| 1.000 | $4.1 | $4.100,00 |
AD7451BRT-R2 Visão geral
A successive-approximation ADC (SAR ADC) is a type of Nyquist-rate converter that uses an internal binary-search capacitor array to resolve one bit per clock cycle, producing deterministic latency, no pipeline delay, and excellent DC accuracy. SAR ADCs sit beneath the broader ADC hierarchy (SAR > Nyquist-rate > data converter > mixed-signal IC > semiconductor) and are favored when applications need simultaneous high accuracy, low latency, and small package size. The AD7451 family extends that architecture into an ultra-miniature 8-pin SOT-23, making it the smallest true 12-bit 1 MSPS ADC in ADI's catalog at release.
Key specifications include 12-bit resolution, 1 MSPS throughput, pseudo-differential input (IN+ and IN- with IN- usable as ground sense), 4 mW power dissipation at 1 MSPS with VDD = 3 V (9.25 mW with VDD = 5 V), SPI/QSPI/MICROWIRE/DSP-compatible serial interface, and an operating temperature range suitable for industrial environments. The pseudo-differential topology rejects small common-mode noise and supports rail-to-rail single-ended sources with proper reference design.
Typical applications include precision industrial process control, portable and battery-powered instrumentation, optical sensor front-ends (photodiode/phototransistor read-out), data acquisition boards, motor control current sensing, and medical patient-monitoring front-ends. The SOT-23-8 footprint is particularly attractive for space-constrained PCB designs where a 12-bit accurate signal chain must fit alongside dense digital logic.
When designing with this part, place a 100 nF decoupling capacitor within 2 mm of the VDD pin and a 10 µF bulk capacitor on the supply trace; the reference input (REF) requires a low-impedance 2.5 V reference such as the ADR01 or ADR02 for full 12-bit performance. The -R2 tape-and-reel suffix designates packaging only and does not affect electrical behavior.
This page synthesizes cross-reference alternatives, distributor pricing, application guidance, and practical PCB notes that go beyond what the bare datasheet reveals.
Alternativas drop-in para AD7451BRT-R2 — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Variantes desta série
Modelos da mesma série compatíveis como drop-in com AD7451BRT-R2 (mesmo formato e footprint) — diferindo em Architecture, Number of Channels, Packaging.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
AD7450BRTZ
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
AD7451BRTZ
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
AD7451BRT
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
AD7441BRTZ
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
AD7452BRTZ
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
AD7451BRT-R2 Classificações máximas e características elétricas
| Resolução | 12 bits |
| Taxa de amostragem | 1 MSPS |
| Architecture | Successive Approximation (SAR) |
| Number of Channels | 1 |
| Input Configuration | Pseudo-differential |
| Supply Voltage (VDD) | 2.7 V to 5.25 V |
| Power Dissipation at 1 MSPS (VDD=3V) | 4 mW maximum |
| Power Dissipation at 1 MSPS (VDD=5V) | 9.25 mW maximum |
| Data Interface | SPI, QSPI, MICROWIRE, DSP-compatible serial |
| Encapsulamento / Caixa | SOT-23-8 |
| Temperatura de operação | -40C to +85C (industrial) |
| Packaging | Tape & Reel (R2 = 7-inch reel) |
| Tipo de montagem | Surface Mount |
| Reference Input | External, typ. 2.5 V |
| Status RoHS | Compliant |
Configuração de pinos do AD7451BRT-R2
| Pino 1 | REF — External reference voltage input (typ. 2.5 V) |
| Pino 2 | IN- — Negative pseudo-differential analog input |
| Pino 3 | IN+ — Positive pseudo-differential analog input |
| Pino 4 | GND — Ground return |
| Pino 5 | VDD — Positive supply (2.7 V to 5.25 V) |
| Pino 6 | CS — Chip-select input (active low) |
| Pino 7 | SCLK — Serial clock input |
| Pino 8 | SDATA — Serial data output |
Aplicações típicas
AD7451BRT-R2 é adequado para 6 aplicaçãos: Industrial Process Control Signal Acquisition, Portable Battery-Powered Instrumentation, Optical Sensor Photodiode Read-Out, Motor Control Current Sensing, Medical Patient Monitoring Front-End, Data Acquisition Modules.
Industrial Process Control Signal Acquisition
The AD7451BRT-R2 fits 4-20 mA loop receivers and isolated sensor front-ends where 12-bit accuracy at 1 MSPS is sufficient for closed-loop control. Its pseudo-differential input rejects small ground-loop common-mode noise that develops across long sensor cables, while the 2.7 V to 5.25 V supply accepts the common 3.3 V and 5 V industrial rails. The SOT-23-8 package enables dense I/O modules with multiple channels per board. Typical performance trade-off is bandwidth-limited input conditioning above 100 kHz where an external amplifier would be required.
Recomendado
Portable Battery-Powered Instrumentation
The AD7451BRT-R2's 4 mW dissipation at 1 MSPS (VDD=3 V) makes it ideal for handheld multimeters and field instruments that run on Li-ion or 2xAA cells. The SOT-23-8 footprint leaves board area for wireless modules and OLED displays, and the SPI-compatible serial interface connects directly to low-power microcontrollers such as those in the MSP430 or PIC families. Trade-off: at higher supply voltages (5 V) power rises to 9.25 mW, which designers must budget against battery life.
Recomendado
Optical Sensor Photodiode Read-Out
Photodiode and phototransistor front-ends benefit from the AD7451BRT-R2's pseudo-differential input, where IN+ connects to the photodiode cathode through a transimpedance amplifier and IN- senses local ground. The 1 MSPS throughput allows real-time optical power monitoring for safety applications, smoke detectors, and ambient light meters. Compact SOT-23-8 allows sensor integration directly at the optical head, minimizing pickup noise. Designers should note that photodiode capacitance combined with amplifier bandwidth may limit effective analog input frequency below 500 kHz.
Recomendado
Motor Control Current Sensing
Phase current sensing in BLDC and stepper motor drives is a natural fit for the AD7451BRT-R2's 1 MSPS conversion rate, which exceeds typical PWM switching frequencies of 20-100 kHz by a wide margin for oversampling. The pseudo-differential input accepts current-shunt voltages referenced to local ground at the half-bridge. SOT-23-8 packaging allows placement near the shunt resistor to minimize trace inductance. Trade-off: designers should add an anti-aliasing RC filter ahead of the ADC inputs for high-di/dt switching nodes.
Recomendado
Medical Patient Monitoring Front-End
Low-power patient monitors such as pulse oximeters, ECG acquisition boards, and body-temperature measurement systems use the AD7451BRT-R2 for 12-bit resolution of physiological sensor signals. The 4 mW low-power operation preserves battery life for bedside telemetry, while the small SOT-23-8 footprint suits wearable and patch designs. The pseudo-differential input supports common electrode configurations, and the SPI interface connects to low-power MCUs running real-time bio-signal processing algorithms. Trade-off: medical IEC 60601 isolation and EMI filtering are application-specific.
Recomendado
Data Acquisition Modules
Multi-channel data acquisition cards for industrial PCs and PLCs use the AD7451BRT-R2 as a compact per-channel or multiplexed ADC for digitizing 4-20 mA loops, thermocouple amplifiers, and pressure transducer outputs. The 1 MSPS speed accommodates multiplexed multi-channel scanning, and the SPI serial interface allows easy daisy-chaining of multiple AD7451 devices with separate CS lines. SOT-23-8 packaging supports high-density DAQ layouts with hundreds of channels per card. Trade-off: for higher precision (>14 bits), parts such as AD7264 in MSOP should be considered instead.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para AD7451BRT-R2 — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | AD7450BRTZ | AD7451BRTZ | AD7451BRT | AD7441BRTZ | AD7452BRTZ |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | SOT-23-8 | SOT-23-8 - same | SOT-23-8 - same | SOT-23-8 - same | SOT-23-8 - same | SOT-23-8 - same |
| Resolution | 12 bits | 10 bits | 12 bits | 12 bits | 10 bits | 12 bits |
| Sampling Rate | 1 MSPS | 1 MSPS | 1 MSPS | 1 MSPS | 1 MSPS | 1 MSPS |
| Input Configuration | Pseudo-differential | Pseudo-differential | Pseudo-differential | Pseudo-differential | Pseudo-differential | True differential |
| Supply Voltage | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V |
| Serial Interface | SPI / QSPI / MICROWIRE / DSP | SPI / QSPI / MICROWIRE / DSP | SPI / QSPI / MICROWIRE / DSP | SPI / QSPI / MICROWIRE / DSP | SPI / QSPI / MICROWIRE / DSP | SPI / QSPI / MICROWIRE / DSP |
Principais diferenciais
- Smallest 12-bit 1 MSPS SAR ADC in SOT-23-8 from ADI (vs AD7265BCPZ-REEL)
- True 12-bit no-missing-codes performance at 1 MSPS (vs AD7450BRTZ)
- Pseudo-differential input with high common-mode rejection (vs AD7452BRTZ)
Notas de projeto
Estimated: at 1 MSPS continuous conversion the AD7451BRT-R2 pulls ~1.5 mA from a 3 V supply (4 mW). A 100 nF ceramic decoupling capacitor must be placed within 2 mm of the VDD pin (pin 5) and a 10 µF bulk capacitor should sit on the supply trace near the IC. Use a wide, short ground return on pin 4 to keep digital return currents away from the analog reference - the reference input is high-impedance and easily disturbed by ground bounce.
The REF pin requires a low-impedance, low-noise external reference (such as ADR02 or ADR4525) buffered with at least 1 µF of ceramic capacitance for full 12-bit accuracy. Do not assume the AD7451's internal reference is sufficient - the datasheet specifies external reference only. A noisy or under-buffered reference will appear directly as ADC noise and degrade SNR by 6 to 10 dB. Verify reference settling time during worst-case CS toggling patterns.
Route the analog IN+ and IN- traces as a tightly-coupled differential pair with ground guarding on both sides, and avoid running them under or parallel to digital SPI traces. The SOT-23-8 package is small enough that trace length matters - keep both inputs under 10 mm and place the anti-aliasing RC (typically 100 ohm + 330 pF) within 2 mm of the input pins. Provide a solid ground plane on layer 2 for clean return paths.
Informações de conformidade
RoHS compliant per ADI product page. Not AEC-Q100 qualified - the part targets industrial-grade applications, not automotive. Reach and conflict-minerals declarations available from Analog Devices' compliance portal.
