AD7477SRTZ-REEL - 10-Bit 1MSPS SAR ADC | Analog Devices
MPN: AD7477SRTZ-REEL ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.85 | $3.85 |
| 10 | $3.42 | $34.20 |
| 100 | $2.96 | $296.00 |
| 500 | $2.55 | $1,275.00 |
| 1,000 | $2.18 | $2,180.00 |
AD7477SRTZ-REEL Overview
A SAR ADC is a type of data converter that uses a binary-search successive-approximation algorithm to digitize an analog input one bit at a time within a single clock cycle per bit. SAR ADCs occupy the middle ground between flash ADCs (fastest, lowest resolution) and sigma-delta ADCs (highest resolution, lower speed). They are widely used in industrial, instrumentation, and motor-control applications where deterministic latency, low latency-to-sample delay, and moderate-to-high sampling rates are required without the cost of higher-end delta-sigma parts. The AD7477 family sits in the precision Analog Devices portfolio alongside its 8-bit (AD7478) and 12-bit (AD7476) siblings.
Key features of the AD7477SRTZ-REEL include throughput up to 1 MSPS, an analog input range of 0 V to VDD, true bipolar input capability with a resistor network, an on-chip track-and-hold amplifier, and a high-speed serial interface. The device includes an on-chip reference input (REF) and a low-noise, wide-bandwidth track-and-hold capable of handling input frequencies well above the Nyquist limit. Power-down current is typically 1 µA, making the part suitable for battery-powered and portable designs.
Architecturally, the AD7477 uses a charge-redistribution DAC array controlled by a SAR logic core. The analog input is sampled on an internal capacitor array, then compared against binary-weighted capacitors in successive approximation cycles, yielding 10 bits in 10 conversion cycles. The serial output appears MSB-first on SDOUT, clocked by SCLK. The compact SOT-23-6 footprint measures only 2.9 mm × 1.6 mm and offers an exposed pad for thermal dissipation and reduced ground inductance.
Typical applications include industrial process control, portable data acquisition, battery-powered instruments, motor control feedback, and transducer interfacing. The wide 2.35 V – 5.25 V supply range allows direct interfacing to 3.3 V and 5 V microcontrollers, while the SPI-compatible serial interface ensures easy connection to DSPs and microcontrollers without glue logic.
When designing with the AD7477, ensure the reference voltage source has low impedance at the REF pin - a 10 µF decoupling capacitor close to the pin is recommended. Keep analog input traces short and away from digital switching signals to minimize crosstalk, and place a small RC anti-aliasing filter at AIN when sampling broadband signals.
This page synthesizes distributor pricing, drop-in alternatives, application circuits, and practical PCB layout guidance not found in the manufacturer datasheet alone, optimized for design engineers and procurement specialists.
Drop-in alternatives for AD7477SRTZ-REEL — 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 AD7477SRTZ-REEL (same form factor and footprint) — differing in Package, Resolution, Architecture, Data Interface, Number of Channels.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AD7476SRTZ-REEL
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
AD7478SRTZ-REEL
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
AD7477SRTZ-REEL7
✅ Drop-In📋 Reference alternative (not in catalog)
AD7467BRTZ-REEL
✅ Drop-In📋 Reference alternative (not in catalog)
AD7466BRT-R2
✅ Drop-In✓ In Stock
$2.42 / Unit
View Datasheet →AD7477SRTZ-REEL Maximum Ratings & Electrical Characteristics
| Resolution | 10 bits |
| Number of Channels | 1 |
| Converter Type | SAR (Successive Approximation Register) |
| Sampling Rate | 1 MSPS |
| Supply Voltage (Single) | 2.35 V to 5.25 V |
| Supply Current (1 MSPS, VDD=3V) | 4 mA (typical) |
| Power-Down Current | 1 µA (typical) |
| Analog Input Range | 0 V to VDD |
| Data Interface | SPI, QSPI, MICROWIRE, DSP-compatible serial |
| Package | SOT-23-6 (RT) |
| Operating Temperature | -40C to +85C |
| Mounting Type | Surface Mount |
| Input Type | Single-ended, true bipolar with external resistor network |
| RoHS Status | Compliant |
| MSL Level | 1 (unlimited) |
| Packaging | Tape & Reel (REEL) |
| Architecture | Charge-redistribution SAR with on-chip track-and-hold |
AD7477SRTZ-REEL Pin Configuration
| Pin 1 | AIN — Analog input (single-ended, 0 V to VDD) |
| Pin 2 | GND — Ground reference |
| Pin 3 | REF — Reference voltage input (decouple with 10 µF capacitor) |
| Pin 4 | SCLK — Serial clock input (SPI/QSPI/MICROWIRE) |
| Pin 5 | SDOUT — Serial data output (MSB-first, clocked on SCLK falling edge) |
| Pin 6 | VDD — Power supply input (2.35 V to 5.25 V) |
Typical Applications
AD7477SRTZ-REEL is suitable for 6 applications: Industrial Process Control, Portable Data Acquisition Systems, Motor Control Feedback Loops, Transducer Signal Conditioning, Battery-Powered Instrumentation, Medical Monitoring Devices.
Industrial Process Control
The AD7477SRTZ-REEL fits industrial process control because its 1 MSPS throughput captures fast-changing sensor signals while its 10-bit resolution provides sufficient quantization for closed-loop control loops. A 4-20 mA current loop from a process transmitter is converted to a 0-5 V signal and fed to AIN, where the SAR architecture digitizes it with deterministic latency. The SPI-compatible serial interface streams conversion results directly to an industrial microcontroller or PLC, eliminating glue logic. Power-down mode (1 µA typical) allows battery-backed sensor nodes to conserve energy between samples. Wide 2.35 V - 5.25 V supply tolerance supports 24 V industrial bus rails after regulation.
Recommended
Portable Data Acquisition Systems
The AD7477SRTZ-REEL is well suited to portable data loggers because it consumes only 4 mA at 1 MSPS and drops to 1 µA in shutdown, extending battery life. The SOT-23-6 footprint (2.9 mm x 1.6 mm) fits handheld instruments where PCB area is constrained. The on-chip track-and-hold handles transient input changes, making the part suitable for digitizing thermocouple, strain-gauge, or accelerometer outputs. The serial SPI interface minimizes microcontroller pin count and enables simple DMA transfers. For multi-channel systems, multiple AD7477 parts can be synchronized via shared SCLK.
Recommended
Motor Control Feedback Loops
The AD7477SRTZ-REEL serves as the position/speed feedback ADC in BLDC and stepper motor drives, converting analog outputs from Hall-effect sensors or rotary encoders. Its 1 MSPS throughput easily captures the PWM-aligned current and position feedback signals used in field-oriented control loops. The low propagation delay of SAR architecture (10 clock cycles) ensures deterministic sampling, critical for commutation timing in high-speed motors. The single 2.35 V - 5.25 V supply works directly from 3.3 V or 5 V motor driver rails. SPI interface streams results to the motor-control DSP without bus contention.
Recommended
Transducer Signal Conditioning
The AD7477SRTZ-REEL digitizes analog transducer outputs from pressure sensors, load cells, temperature sensors (RTD/thermistor bridges), and gas sensors. The 10-bit resolution suits threshold-detection and feedback applications where sensor nonlinearity can be calibrated in firmware. The 0 V to VDD analog input range accepts common bridge outputs centered at mid-rail. The on-chip track-and-hold eliminates external sample-and-hold circuitry. The wide 5.25 V maximum supply allows direct connection to 5 V transducer excitation rails.
Recommended
Battery-Powered Instrumentation
The AD7477SRTZ-REEL's 1 µA power-down current makes it ideal for battery-powered multimeters, handheld oscilloscope probes, and field test instruments where idle current dominates battery life. The SAR ADC wakes from shutdown in microseconds, enabling duty-cycled sampling where the part is active for only a few microseconds per conversion. The wide 2.35 V - 5.25 V supply range allows direct operation from Li-ion (3.7 V) or two AA cells (3 V). The 6-pin SOT-23 footprint simplifies compact handheld PCB layouts where every square millimeter counts.
Recommended
Medical Monitoring Devices
The AD7477SRTZ-REEL serves in medical monitoring peripherals for patient-side signal acquisition where its 10-bit resolution and 1 MSPS sampling rate are sufficient for pulse oximetry, ECG R-wave detection, and respiration rate monitoring front ends. The SAR architecture's deterministic latency supports real-time DSP filtering of bioelectric signals. The low 4 mA operating current is acceptable for compact bedside monitors. The SPI interface simplifies connection to medical microcontrollers. Compliance with RoHS supports medical device environmental requirements, though full medical certification requires system-level qualification.
Recommended
Recommended Products Summary
Engineering reference data for AD7477SRTZ-REEL — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD7476SRTZ-REEL | AD7478SRTZ-REEL | AD7477SRTZ-REEL7 | AD7467BRTZ-REEL | AD7466BRT-R2 |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | SOT-23-6 (RT) | SOT-23-6 (RT) - same | SOT-23-6 (RT) - same | SOT-23-6 (RT) - same | SOT-23-6 (RT) - same | SOT-23-6 (RT) - same |
| Resolution | 10 bits | 12 bits | 8 bits | 10 bits | 10 bits | 12 bits |
| Sampling Rate | 1 MSPS | 1 MSPS | 1 MSPS | 1 MSPS | 1 MSPS | 1 MSPS |
| Supply Voltage | 2.35 V to 5.25 V | 2.35 V to 5.25 V | 2.35 V to 5.25 V | 2.35 V to 5.25 V | 2.35 V to 5.25 V | 2.35 V to 5.25 V |
| Architecture | SAR | SAR | SAR | SAR | SAR | SAR |
| Data 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 |
| Lifecycle Status | Obsolete | Check distributor | Check distributor | Obsolete | Check distributor | Check distributor |
Key Differentiators
- Highest resolution in 1 MSPS SOT-23-6 SAR family (vs AD7478SRTZ-REEL)
- Lower resolution than 12-bit upgrade option in same family (vs AD7476SRTZ-REEL)
- Drop-in compatible with 12-bit upgrade without PCB rework (vs AD7466BRT-R2)
Design Notes
Estimated: Place a 10 µF decoupling capacitor within 3 mm of the VDD pin and a 0.1 µF bypass cap directly adjacent to the IC. Route the AIN trace as a short, guarded trace surrounded by GND copper pour to minimize digital crosstalk. The exposed thermal pad on the SOT-23-6 bottom must be soldered to a grounded copper pour of at least 10 mm² for mechanical and thermal performance.
The REF pin requires a low-impedance reference for accurate conversions - use a dedicated 10 µF ceramic bypass capacitor directly at REF. A noisy or high-impedance reference will inject error into the SAR comparator and degrade ADC linearity. If using an external reference IC, buffer it with a low-noise op-amp capable of driving the REF pin's dynamic load during sampling.
Keep SCLK traces short and route them away from analog inputs. The SDOUT signal edges during SCLK transitions can couple into the AIN trace through parasitic capacitance, causing conversion errors. For sampling rates above 500 kSPS, place a small anti-aliasing RC filter (typically 100 Ω + 100 pF) at the AIN pin to limit input bandwidth below the Nyquist frequency.
Estimated: Do not exceed the 5.25 V absolute maximum supply rating - even brief transients above this will permanently damage the IC. When using true bipolar input mode with an external resistor network, ensure the resistors have 0.1% or better tolerance to maintain INL. The part's CS (chip select) signal must be asserted before SCLK begins toggling, otherwise the first conversion will be invalid.
Compliance Information
RoHS and REACH compliant per Analog Devices product page. Not AEC-Q100 qualified - not suitable for automotive safety-critical applications. Lead-free and halogen-free per the SOT-23-6 RT package material declaration.
