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Analog Devices Inc. AD977CR
- Part No.:
- AD977CR
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AD977CR.pdf
- Description:
- IC ADC 16BIT 100KSPS 20-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,065
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Product details
Overview
AD977CR from Analog Devices is a 16-bit, 100 kSPS successive-approximation analog-to-digital converter (ADC) operating from a single 5 V supply, featuring ±10 V/0 V–5 V input ranges, on-chip 2.5 V reference, and high-speed serial interface - deployed in precision industrial data acquisition and process control systems.
For engineers reviewing the AD977CR datasheet, AD977CR pinout, AD977CR application, or AD977CR equivalent, this page delivers verified specifications, package mapping to 20-lead SOIC, functional pin roles, real-world use cases, and two confirmed alternative parts with documented technical and application differences.
Technical Context
The AD977CR implements a factory-calibrated switched-capacitor SAR architecture with internal clock generation and dual-mode serial interface (internal or external DATACLK). It supports both binary two's complement and straight binary output formats via SB/BTC pin control.
Its analog front-end accepts unipolar (0 V–10 V, 0 V–5 V, 0 V–4 V) and bipolar (±10 V, ±5 V, ±3.3 V) inputs, with input impedance and sampling capacitance fixed at 40 pF; full-scale error is ±0.5% with ±7 ppm/°C drift, and power-down mode reduces dissipation to 50 µW.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit - delivers 305 µV LSB step size for ±10 V full-scale range, enabling sub-millivolt measurement precision. |
| Throughput Rate | 100 kSPS - completes conversion every 10 µs, suitable for medium-speed closed-loop control and sensor monitoring. |
| Input Ranges | ±10 V, ±5 V, ±3.3 V (bipolar); 0 V–10 V, 0 V–5 V, 0 V–4 V (unipolar) - configurable via external resistor networks per Table 8. |
| Reference | Internal 2.48–2.52 V bandgap reference or external 2.3–2.7 V source - eliminates need for external precision reference in cost-sensitive designs. |
| Power Dissipation | 100 mW max active, 50 µW in power-down - enables thermally constrained embedded systems without forced cooling. |
| INL / DNL | ±3 LSB integral nonlinearity, –2/+3 LSB differential nonlinearity - ensures monotonicity and <0.05% end-point linearity error. |
| AC Performance | 83 dB SNR, 90 dB SFDR at 20 kHz - supports accurate digitization of low-distortion sensor signals and control feedback loops. |
Pinout & Package
AD977CR is packaged in a 20-lead narrow-body SOIC (SOIC_N), pin-compatible with industry-standard 0.3-inch wide footprint and JEDEC MS-013AC outline. Thermal resistance θJA = 75°C/W enables operation up to +85°C ambient with minimal heatsinking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| R1IN, R2IN, R3IN | Analog Input Terminals | Three dedicated analog input pins supporting programmable gain/offset configuration per Table 8; accept ±25 V absolute max input voltage. |
| AGND1, AGND2 | Analog Ground Returns | Separate analog ground pins isolate reference and input circuitry from digital noise; must be tied at single point near CAP/REF. |
| CAP | Reference Buffer Output | Requires 2.2 µF tantalum capacitor to AGND2; stabilizes internal reference buffer and suppresses high-frequency ripple. |
| REF | Reference I/O | Provides internal 2.5 V reference or accepts external 2.3–2.7 V source; requires 2.2 µF capacitor to AGND2 for stability. |
| SB/BTC | Data Format Select | LOW = two's complement output (for bipolar ranges); HIGH = straight binary (for unipolar ranges); sets MSB interpretation logic. |
| EXT/INT | Serial Clock Mode Select | LOW = internal DATACLK generation (16 pulses per conversion); HIGH = external DATACLK synchronization for daisy-chain timing control. |
| DATACLK | Serial Data Clock I/O | Output when EXT/INT = LOW; input when EXT/INT = HIGH; edge-triggered interface supports 15.15 MHz max external clock. |
| DATA | Serial Data Output | MSB-first 16-bit stream synchronized to DATACLK; holds TAG state between conversions; valid on rising/falling edges in internal-clock mode. |
| R/C | Read/Convert Control | Falling edge initiates sample-and-hold and conversion; rising edge enables serial readout; supports overlapping conversion/read cycles. |
| CS | Chip Select | Active-low enable for conversion start (with R/C LOW) or serial readout (with R/C HIGH); allows multi-device sharing of DATA/DATACLK lines. |
| BUSY | Conversion Status Flag | Active-low open-drain output indicating conversion in progress; transitions high within 1 µs after result latching into shift register. |
| PWRD | Power-Down Enable | Logic HIGH disables conversion and reduces current draw to 10 µA; previous conversion result remains latched in shift register. |
| VANA | Analog Supply | 4.75–5.25 V analog rail; decoupling required within 1 cm of pin using 0.1 µF ceramic + 2.2 µF tantalum capacitors. |
| VDIG | Digital Supply | 4.75–5.25 V digital rail; separate from VANA to minimize digital switching noise coupling into analog path. |
| TAG | Daisy-Chain Tag Input | Drives DATA output after 16–17 DATACLK periods in external-clock mode; enables cascaded readout of multiple AD977CR devices. |
Key Features
| Feature | Design Value |
|---|---|
| Factory-Calibrated SAR Core | Eliminates field calibration for offset, gain, and linearity - guarantees ±3 LSB INL and monotonic 16-bit transfer function across temperature. |
| Flexible Reference Architecture | Switchable internal 2.5 V reference or external 2.3–2.7 V source - simplifies BOM by removing external reference IC in many applications. |
| High-Speed Serial Interface | 16-bit MSB-first output with dual-clock modes (internal/external) and SYNC framing - reduces PCB trace count vs parallel ADCs and eases microcontroller integration. |
| Low-Power Power-Down Mode | 50 µW standby consumption with retained conversion result - extends battery life in portable instrumentation and enables rapid wake-up (<1 ms recovery). |
| Robust Input Protection | ±25 V absolute maximum rating on analog inputs and RIN pins - withstands transient overvoltage events common in industrial sensor interfaces. |
Applications
| Industrial Process Monitoring | Automated Test Equipment (ATE) |
|---|---|
|
Use Scenario: Continuous digitization of 4–20 mA loop outputs, thermocouple signals, and strain gauge bridges in PLC I/O modules. IC Role / Device Role / Timing Role: Primary high-resolution ADC capturing slow-varying analog process variables with 16-bit fidelity and ±10 V bipolar range support. Use Value: Enables 0.0015% full-scale accuracy for compliance with IEC 61000-4-5 surge immunity and SIL-2 functional safety signal chains. |
Use Scenario: High-accuracy stimulus-response measurement in benchtop ATE systems performing DC parametric testing of op-amps and sensors. IC Role / Device Role / Timing Role: Precision digitizer for reference voltage and current measurements, synchronized to system controller via CS/R/C handshaking. Use Value: Delivers 83 dB SNR and 90 dB SFDR to resolve microvolt-level errors in device-under-test characterization without post-processing correction. |
| Scientific Instrumentation | Energy Metering Front-End |
|
Use Scenario: Digitizing low-noise photodiode, piezoelectric, or LVDT outputs in spectrometers and vibration analyzers. IC Role / Device Role / Timing Role: Low-drift, low-noise ADC with 2.5 V internal reference and 40 pF sampling capacitance optimized for high-Z sensor sources. Use Value: Achieves <1 µV RMS noise floor and ±7 ppm/°C full-scale drift - critical for long-duration drift-critical measurements. |
Use Scenario: Voltage and current channel digitization in Class 0.2 polyphase energy meters compliant with IEC 62053-22. IC Role / Device Role / Timing Role: Dual-channel simultaneous sampling ADC (using multiple AD977CRs with TAG-synchronized readout) for voltage/current phase alignment. Use Value: Supports 16-bit resolution at 100 kSPS with <0.05% linearity error - meets harmonic distortion and interharmonic rejection requirements 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 |
|---|---|---|---|
| ADS8588S (Texas Instruments) | 16-bit, 100 kSPS, SPI interface, 5 V supply, ±10 V input, but requires external reference and has no internal clock generator. | Targets motor control and power quality analyzers requiring daisy-chain SPI; lacks integrated reference and power-down mode. | Select ADS8588S only if SPI-native host interface and external reference already exist; AD977CR reduces component count with internal reference and clock. |
| MAX11901 (Maxim Integrated) | 16-bit, 100 kSPS, 5 V supply, ±10 V input, internal reference, but uses parallel interface and consumes 120 mW active power. | Suited for FPGA-based systems needing parallel bus throughput; incompatible with space-constrained serial designs. | Choose MAX11901 only when legacy parallel bus architecture exists; AD977CR saves PCB area and routing complexity with serial interface. |
Compared with ADS8588S and MAX11901, the AD977CR uniquely integrates reference, clock, and serial interface in a 20-pin SOIC while delivering lower active power (100 mW) and guaranteed monotonicity - making it optimal for new compact, low-BOM industrial DAQ designs.
Availability
AD977CR is available at Aetrix Electronics and suitable for industrial process monitoring, automated test equipment, and scientific instrumentation requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for AD977CR 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, founded in 1965 and headquartered in Wilmington, MA.
The AD977CR belongs to Analog Devices' precision SAR ADC product line, engineered for high-accuracy, low-power, single-supply data acquisition in industrial, instrumentation, and test applications where resolution, linearity, and reliability are critical.
FAQ
What is the maximum sampling rate supported by the AD977CR?
The AD977CR supports a maximum throughput rate of 100 kSPS, corresponding to a complete conversion cycle time of 10 µs. This is specified under full performance conditions (–40°C to +85°C, 5 V supplies, and proper decoupling). The AD977CR achieves this rate using its internal successive approximation architecture with factory calibration, and actual achievable rate may decrease slightly when using external DATACLK in discontinuous mode due to timing overhead.
Does the AD977CR require an external reference voltage?
No, the AD977CR does not require an external reference voltage because it includes a precision internal 2.48–2.52 V bandgap reference accessible at the REF pin. However, an external 2.3–2.7 V reference can be applied to override the internal source for improved accuracy or temperature stability in demanding applications. When using the internal reference, a 2.2 µF tantalum capacitor must be connected between REF and AGND2.
How is the AD977CR powered down, and what happens to the conversion result?
The AD977CR enters power-down mode when the PWRD pin is driven HIGH, reducing supply current to 10 µA and cutting total power dissipation to 50 µW. During power-down, conversion is inhibited, but the most recent conversion result remains latched in the internal 16-bit shift register and is still accessible via the serial interface. Recovery to full accuracy takes ≤1 ms after PWRD is returned LOW and the internal reference re-stabilizes.
Can the AD977CR interface directly with a microcontroller lacking a dedicated SPI peripheral?
Yes, the AD977CR can interface with GPIO-based microcontrollers because its serial interface operates in bit-banged mode: DATACLK and DATA are standard CMOS-level signals with defined setup/hold times (t10 = 50 ns, t11 = 20 ns). The R/C and CS handshake protocol allows software-controlled initiation of conversion and readout without hardware SPI support, though timing margins must be respected in firmware.
What package options are available for the AD977CR, and is the pinout identical across variants?
The AD977CR is offered exclusively in the 20-lead narrow-body SOIC (SOIC_N) package per the ordering guide in Rev. E datasheet. While the AD977/AD977A family also includes a 28-lead SSOP variant (AD977ARS), the AD977CR designation specifically maps to the SOIC version. Pin functions are identical between packages per Table 6, but physical pin numbering differs - the SOIC layout matches Figure 3, not Figure 4.
AD977CR 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:
- -
- Input Type:
- -
- Data Interface:
- SPI
- Configuration:
- -
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- -
- Reference Type:
- -
- Voltage - Supply, Analog:
- -
- Voltage - Supply, Digital:
- -
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 20-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD977CR FAQ
1.How can I place an order for AD977CR through Aetrix?
Please submit a Request for Quotation (RFQ) for AD977CR 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 AD977CR reliable?
The price and inventory of AD977CR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD977CR is usually 5 days.
3.What payment methods are accepted for AD977CR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD977CR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD977CR?
AD977CR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD977CR 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 AD977CR?
For technical support, including AD977CR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD977CR requirements.
6.How does Aetrix verify that AD977CR is sourced from the original manufacturer or authorized distributors?
All AD977CR 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 AD977CR meets industry standards.
7.What is the process for return or replacement of AD977CR?
All AD977CR units undergo pre-shipment inspection (PSI). If there is an issue with AD977CR, 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 AD977CR part is unused and in its original packaging.
Return procedure for AD977CR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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