My Inquiry
My Account
Analog Devices Inc. AD977AR
- Part No.:
- AD977AR
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AD977AR.pdf
- Description:
- IC ADC 16BIT SAR 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,778
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
AD977AR from Analog Devices is a 16-bit, 100 kSPS successive-approximation ADC operating from a single 5 V supply, featuring internal 2.5 V reference, ±10 V/0 V–10 V input ranges, and high-speed serial interface in a 20-lead SOIC package. It delivers 83 dB SNR, ±3 LSB INL (A grade), and 100 mW max power dissipation for precision data acquisition in industrial instrumentation.
For engineers reviewing the AD977AR datasheet, AD977AR pinout, AD977AR application, or AD977AR equivalent, this page provides verified technical context, real-world design meanings of key specs, validated pin functions, confirmed alternative parts with documented functional differences, and supply-chain support details specific to OEM and embedded system deployments.
Technical Context
The AD977AR implements a factory-calibrated switched-capacitor SAR architecture with on-chip clock generation and dual-mode serial interface (internal or external DATACLK). Its conversion control relies on R/C and CS signals, supporting both continuous and discontinuous clock read modes with SYNC frame synchronization when EXT/INT = HIGH.
It supports configurable analog input ranges (±10 V, ±5 V, ±3.3 V, 0 V–10 V, 0 V–5 V, 0 V–4 V) via external resistor networks, and includes power-down mode (50 µW) with 1 ms recovery to rated accuracy using a 2.2 µF capacitor on CAP pin. Reference selection is flexible: internal 2.5 V (±2 mV tolerance) or external 2.3 V–2.7 V source.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit - delivers 305 µV LSB step size at ±10 V full scale for high-precision sensor signal digitization. |
| Throughput Rate | 100 kSPS - enables real-time sampling of signals up to 700 kHz full-power bandwidth without aliasing in control-loop applications. |
| INL (A Grade) | ±3 LSB - ensures monotonicity and <0.05% end-point linearity error across temperature for calibrated measurement systems. |
| SNR / THD | 83 dB / –90 dB - supports >13.5 ENOB for clean spectral analysis in vibration monitoring and power quality analyzers. |
| Power Dissipation | 100 mW max - compatible with thermally constrained PCB layouts in sealed industrial enclosures without forced cooling. |
| Analog Input Ranges | ±10 V, ±5 V, ±3.3 V, 0 V–10 V, 0 V–5 V, 0 V–4 V - eliminates need for external level-shifting op-amps in multi-range PLC I/O modules. |
| Reference | Internal 2.5 V ±2 mV or external 2.3 V–2.7 V - allows traceable calibration using metrology-grade references while reducing BOM count. |
Pinout & Package
AD977AR is packaged in a 20-lead skinny SOIC (SOIC_N) with 0.3" body width and standard 0.050" lead pitch. Pin 1 is marked with a dot; pin numbering follows JEDEC MS-012AA.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| R1IN, R2IN, R3IN | Analog input terminals | Accept differential or single-ended inputs; configuration determines bipolar/unipolar range per Table 8 in datasheet Rev. E. |
| AGND1, AGND2 | Analog ground references | Separate ground pins isolate reference buffer (AGND1) and ADC core (AGND2); mandatory star grounding prevents digital noise coupling. |
| CAP | Reference buffer output | Requires 2.2 µF tantalum capacitor to AGND2 to stabilize internal reference; omission causes >10 LSB drift and gain error. |
| REF | Reference I/O | Supplies internal 2.5 V reference or accepts external reference; must be decoupled with 2.2 µF cap to AGND2 regardless of mode. |
| SB/BTC | Data format select | LOW = two's complement (±10 V mode); HIGH = straight binary (0 V–10 V mode); sets MSB polarity for firmware interpretation. |
| EXT/INT | Serial clock source select | LOW = internal DATACLK generation; HIGH = external clock sync; determines whether SYNC output is active and timing constraints for BUSY handling. |
| DATACLK | Serial clock I/O | Output when EXT/INT = LOW; input when EXT/INT = HIGH; edge-sensitive - data valid on both edges only in internal-clock mode. |
| DATA | Serial data output | MSB-first 16-bit stream; holds TAG state between conversions in internal-clock mode; supports daisy-chaining via TAG in external-clock mode. |
| R/C | Read/Convert control | Falling edge initiates sample-and-hold + conversion when CS = LOW; rising edge enables serial readout when CS = HIGH. |
| CS | Chip select | Enables conversion start (R/C LOW) or serial read (R/C HIGH); must meet t16 setup time (10 ns) relative to R/C for reliable operation. |
| BUSY | Conversion status indicator | Active-low open-drain output; LOW duration = 4.0–8.0 µs (AD977); used by host MCU to avoid premature read attempts. |
| PWRD | Power-down enable | HIGH disables conversion and reduces current to 10 µA; retains last conversion result in shift register; requires 1 ms wake-up before next valid sample. |
| VANA, VDIG | Analog/digital supplies | Both require 4.75–5.25 V; separate pins allow independent decoupling - 0.1 µF ceramic + 10 µF tantalum per supply recommended. |
Key Features
| Feature | Design Value |
|---|---|
| Factory-calibrated SAR architecture | Eliminates field calibration for INL/DNL; guarantees ±3 LSB INL and no missing codes over –40°C to +85°C without user trimming. |
| Flexible reference options | Internal 2.5 V reference (±2 mV initial error) or external 2.3–2.7 V source - enables system-level calibration traceability to NIST standards. |
| High-speed serial interface | 16-bit MSB-first output with programmable data format (two's complement/straight binary) - reduces host MCU GPIO count and simplifies SPI-compatible firmware drivers. |
| Configurable input ranges | Hardware-selectable unipolar/bipolar ranges via external resistors - supports direct connection to strain gauges (±10 V), RTDs (0 V–5 V), and position sensors (0 V–4 V) without external amplifiers. |
| Power-down mode | 50 µW standby power with 1 ms wake-up - extends battery life in portable data loggers and enables duty-cycled sampling in energy-constrained IoT nodes. |
Applications
| Process Control Sensors | Industrial PLC Analog Inputs |
|---|---|
Use Scenario: Digitizing 4–20 mA current loop outputs from pressure, temperature, and flow transmitters in hazardous-area control cabinets. IC Role / Device Role / Timing Role: Precision front-end ADC capturing slow-varying process variables with 16-bit resolution and ±10 V bipolar input capability. Use Value: Enables sub-0.1% measurement accuracy across temperature without recalibration, meeting IEC 61000-6-2 immunity requirements for factory automation. | Use Scenario: Modular analog input cards in DIN-rail mounted PLCs accepting multiple voltage/current field signals. IC Role / Device Role / Timing Role: High-density, low-power ADC per channel with shared serial bus to reduce FPGA resource usage and PCB layer count. Use Value: 100 kSPS throughput supports 16-channel scanning at 6.25 kSPS/channel, satisfying IEC 61131-3 cycle-time constraints for motion control. |
| Portable Data Acquisition | Power Quality Analyzers |
Use Scenario: Battery-powered handheld meters measuring AC mains harmonics, THD, and RMS values in commercial buildings. IC Role / Device Role / Timing Role: Low-power ADC with internal reference and power-down mode enabling >8-hour runtime on Li-ion cells. Use Value: 83 dB SNR and 85 dB S/(N+D) ensure accurate 50/60 Hz fundamental and 25th harmonic detection per IEEE 519-2022. | Use Scenario: Real-time monitoring of voltage sags, swells, flicker, and interharmonics in utility substations and renewable inverters. IC Role / Device Role / Timing Role: High-fidelity digitizer capturing 1.5 MHz –3 dB bandwidth signals with 700 kHz full-power bandwidth. Use Value: ±3 LSB INL and 90 dB SFDR support Class A compliance per IEC 61000-4-30 Ed. 3 for revenue-grade metering. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 16-bit SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS8505IPW | 16-bit, 250 kSPS, external reference only, SPI interface, 28-pin TSSOP | Higher speed but no internal reference; requires external 2.5 V reference and level-shifting for 5 V logic | Select when throughput >150 kSPS is required and board space allows larger package and extra reference IC. |
| MAX11270ETJ+ | 16-bit, 10 kSPS, internal oscillator, 2.5 V reference, 24-pin TQFN | Lower speed, integrated oscillator, smaller footprint, but lacks bipolar input support | Select for ultra-low-power (<15 mW) portable applications where ±10 V input is not needed and size is critical. |
Compared with ADS8505IPW and MAX11270ETJ+, the AD977AR uniquely balances 100 kSPS throughput, internal reference, ±10 V bipolar input, and SOIC packaging - making it optimal for retrofitting legacy industrial systems requiring minimal layout changes and no reference redesign.
Availability
AD977AR is available at Aetrix Electronics and suitable for process control sensors, industrial PLC analog inputs, portable data acquisition, and power quality analyzers requiring stable component supply, long-term obsolescence management, and traceable sourcing.
Supply support for AD977AR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.
The AD977AR belongs to Analog Devices' precision data acquisition product line, designed specifically for high-accuracy, low-power, single-supply 16-bit SAR ADC applications in harsh industrial environments.
FAQ
What is the maximum sampling rate supported by the AD977AR?
The AD977AR supports a maximum throughput rate of 100 kSPS, corresponding to a complete conversion cycle time of 10 µs. This is specified for all grades (A/B/C) across the –40°C to +85°C temperature range with 5 V supplies. The AD977AR achieves this using an internal clock; external clock mode does not increase the base conversion speed but enables flexible data read timing.
Does the AD977AR include an internal voltage reference?
Yes, the AD977AR integrates a precision 2.5 V internal reference with ±2 mV initial accuracy (2.48 V to 2.52 V) and ±2 ppm/°C drift over temperature. This reference is accessible at the REF pin and can be overridden by an external 2.3 V–2.7 V source. A 2.2 µF tantalum capacitor must be placed between REF and AGND2 for stability, regardless of reference mode.
How does the AD977AR handle bipolar versus unipolar input ranges?
The AD977AR supports both bipolar (±10 V, ±5 V, ±3.3 V) and unipolar (0 V–10 V, 0 V–5 V, 0 V–4 V) input ranges through external resistor networks connected to R1IN/R2IN/R3IN pins, as defined in Table 8 of the Rev. E datasheet. Data format (two's complement vs. straight binary) is selected via the SB/BTC pin to match the chosen range.
What is the purpose of the CAP pin on the AD977AR?
On the AD977AR, the CAP pin is the output of the internal reference buffer and must be connected to a 2.2 µF tantalum capacitor tied to AGND2. This capacitor stabilizes the reference voltage during conversion cycles; omitting it causes significant gain error (>0.5%) and increased INL due to reference droop under dynamic load.
Can the AD977AR operate with a 3.3 V digital interface?
No, the AD977AR requires 4.75 V–5.25 V on both VDIG and VANA pins for specified operation. Its digital inputs (VIH = 2.0 V min, VIL = +0.8 V max) are 5 V tolerant but not 3.3 V compatible without level-shifting. Driving CS, R/C, or EXT/INT directly from a 3.3 V MCU may cause unreliable logic recognition and intermittent conversion failures.
AD977AR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Number of Bits:
- 16
- Sampling Rate (Per Second):
- 100k
- Number of Inputs:
- 1
- Input Type:
- Single Ended
- Data Interface:
- SPI
- Configuration:
- ADC
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- 5V
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 20-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD977AR FAQ
1.How can I place an order for AD977AR through Aetrix?
Please submit a Request for Quotation (RFQ) for AD977AR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AD977AR reliable?
The price and inventory of AD977AR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD977AR is usually 5 days.
3.What payment methods are accepted for AD977AR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD977AR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD977AR?
AD977AR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD977AR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AD977AR?
For technical support, including AD977AR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD977AR requirements.
6.How does Aetrix verify that AD977AR is sourced from the original manufacturer or authorized distributors?
All AD977AR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AD977AR meets industry standards.
7.What is the process for return or replacement of AD977AR?
All AD977AR units undergo pre-shipment inspection (PSI). If there is an issue with AD977AR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AD977AR part is unused and in its original packaging.
Return procedure for AD977AR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AD977AR Tags
-
ADC081C021CIMKX/NOPB
Texas Instruments
-
MCP3021A5T-E/OT
Microchip Technology
-
TLA2024IRUGR
Texas Instruments
-
MCP3221A5T-E/OT
Microchip Technology
-
MCP3221A5T-I/OT
Microchip Technology
-
MCP3221A4T-E/OT
Microchip Technology
-
MCP3221A6T-E/OT
Microchip Technology
-
MCP3221A0T-E/OT
Microchip Technology
-
MCP3221A1T-E/OT
Microchip Technology
-
ADC121S021CIMFX/NOPB
Texas Instruments
-
MCP3001-I/MS
Microchip Technology
-
MCP3001-I/SN
Microchip Technology
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
