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Analog Devices Inc. AD7871JP
- Part No.:
- AD7871JP
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-LCC (J-Lead)
- Datasheet:
-
AD7871JP.pdf
- Description:
- IC ADC 14BIT SAR 28PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,614
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Product details
Overview
AD7871JP from Analog Devices is a complete monolithic 14-bit LC2MOS analog-to-digital converter with integrated track-and-hold amplifier, 3 V buried Zener reference, and self-contained laser-trimmed internal clock. It delivers 80 dB SNR at 10 kHz, 57 ns data access time, and 83 kSPS throughput while operating from ±5 V supplies with ±3 V bipolar analog input range. It is used in high-speed DSP servo control and spectrum analysis systems requiring precise sampling timing.
For engineers reviewing the AD7871JP datasheet, AD7871JP pinout, AD7871JP application, or AD7871JP equivalent, this page provides verified technical context, real-world interface behavior (parallel/byte/serial), dynamic performance metrics (SNR, THD, IMD), DC accuracy specs (INL ±1 LSB max), and validated alternative options for ADC replacement in embedded signal acquisition designs.
Technical Context
The AD7871JP implements a successive approximation register (SAR) architecture with a voltage-output DAC and high-speed comparator. Its on-chip 3 V buried Zener reference is temperature-compensated (±40 ppm/°C) and provides both DAC reference and bipolar bias, eliminating external reference components.
It supports three synchronous output formats-14-bit parallel, two 8-bit bytes, or 14-bit serial-selected via the 14/8/CLK pin. Conversion is initiated either by CONVST rising edge (Mode 1, for jitter-critical sampling) or CS falling edge (Mode 2, microprocessor-controlled), with BUSY/INT indicating conversion status.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 14-bit monotonic, no missing codes guaranteed - enables full-scale precision in 16384-step measurement systems. |
| Throughput Rate | 83 kSPS - supports real-time digitization of signals up to 41.5 kHz full-power bandwidth. |
| Signal-to-Noise Ratio | 80 dB min at 10 kHz - ensures clean spectral representation for speech recognition and DSP servo applications. |
| Analog Input Range | ±3 V bipolar - directly interfaces with industrial sensor outputs without external level-shifting amplifiers. |
| Power Dissipation | 50 mW typical at ±5 V - suitable for thermally constrained embedded systems with limited heatsinking. |
| Data Access Time | 57 ns max after RD - meets tight timing budgets for 8051, Z80, and early DSP bus cycles. |
| Reference Output | 3.00 V ±10 mV, 500 μA load capability - powers external circuitry (e.g., op-amp bias networks) without added regulators. |
Pinout & Package
AD7871JP is housed in a 28-pin plastic DIP (PDIP) package with 0.6-inch width and through-hole mounting. Pin 1 is marked with a notch or dot; pins are numbered counterclockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 CONVST | Asynchronous convert start | Rising-edge-triggered hold command - enables precise sampling instants independent of system clock domain. |
| 2 CS | Chip select | Active-low enable for data bus drivers - allows shared 8/16-bit data bus operation with other peripherals. |
| 3 RD | Read strobe | Active-low latch control - gates DB0–DB13 outputs only when CS and RD are low, preventing bus contention. |
| 4 BUSY/INT | Status output | Open-drain logic-low during conversion - serves as interrupt source or wait-state generator for microprocessors. |
| 5 CLK | Clock input | Accepts TTL-level external clock or connects to VSS to enable internal 2 MHz oscillator - removes need for external timing components. |
| 6 DB13/HBEN | MSB data / byte enable | Configurable: DB13 output in 14-bit mode; HBEN control for upper/lower byte selection in 8-bit bus interfacing. |
| 26 VIN | Analog input | ±3 V differential-capable input with 15 kΩ impedance - accepts direct connection to transducer bridges and op-amp outputs. |
| 25 REFOUT | Reference output | Stable 3.00 V source - powers external gain-setting resistors or reference buffers without loading internal Zener. |
| 23 CREF | Reference decoupling | Connection point for 10 nF capacitor to AGND - suppresses internal reference noise and improves AC performance. |
| 28 14/8/CLK | Format control | Selects output mode: +5 V = 14-bit parallel only; 0 V = byte/serial with gated SCLK; −5 V = byte/serial with continuous SCLK. |
Key Features
| Feature | Design Value |
|---|---|
| Complete monolithic ADC | Integrates SAR core, track-and-hold, 3 V reference, and interface logic - eliminates 7+ external components in data acquisition boards. |
| Three configurable output formats | 14-bit parallel, dual-byte, or serial stream - adapts to 8-bit microcontrollers (e.g., 8051), 16-bit DSPs (e.g., ADSP-2100), and space-constrained layouts. |
| Self-contained internal clock | 2 MHz laser-trimmed oscillator - removes crystal, capacitors, and clock buffer, reducing BOM cost and layout area by ~30%. |
| Bipolar input support | ±3 V range with twos-complement coding - enables direct digitization of AC-coupled sensor signals without external level shifters. |
| Low power consumption | 50 mW typical at 83 kSPS - extends battery life in portable test equipment and reduces thermal stress in stacked PCB assemblies. |
Applications
| Digital Signal Processing | High-Speed Modems |
|---|---|
Use Scenario: Real-time FFT-based spectral monitoring in vibration analysis equipment sampling at 83 kSPS. IC Role / Device Role / Timing Role: Primary ADC capturing time-domain waveforms with <2 μs track/hold acquisition and precise CONVST-synchronized sampling. Use Value: 80 dB SNR ensures detection of low-amplitude harmonics buried in noise floor; internal reference stability avoids drift-induced calibration errors over temperature. |
Use Scenario: Digitizing analog line signals in V.34 modems operating up to 33.6 kbps with adaptive equalization. IC Role / Device Role / Timing Role: High-fidelity front-end ADC providing 14-bit resolution for QAM constellation mapping and echo cancellation algorithms. Use Value: −86 dB THD preserves signal integrity across voiceband frequencies; 57 ns access time enables efficient DMA transfers to DSP memory. |
| Spectrum Analysis | DSP Servo Control |
Use Scenario: Portable RF spectrum analyzer measuring 0–20 MHz IF signals using undersampling techniques. IC Role / Device Role / Timing Role: Wideband ADC with 41.5 kHz full-power bandwidth and 83 kSPS sustained rate for real-time windowed FFT processing. Use Value: 80 dB SNR and −86 dB IMD prevent spurious tones from masking adjacent-channel interference in crowded RF environments. |
Use Scenario: Closed-loop motor position feedback in industrial CNC controllers requiring sub-micron resolution. IC Role / Device Role / Timing Role: Precision ADC converting resolver or LVDT analog outputs into 14-bit digital position values synchronized to motion control interrupts. Use Value: ±1 LSB INL and ±12 LSB gain error ensure repeatable positioning accuracy; BUSY/INT pin integrates cleanly with real-time OS task scheduling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 14-bit sampling ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7872JP | Serial-only output; 16-pin PDIP; no parallel/byte interface; identical core ADC, reference, and timing specs. | Used where board space is constrained and microcontroller has dedicated SPI peripheral - eliminates 12 data lines and associated routing. | Select AD7872JP when serial interface suffices and PCB real estate is premium; avoid if legacy 8/16-bit bus architecture requires parallel access. |
| ADS8320U | 16-bit resolution; SPI interface only; 100 kSPS; external reference required; 5 V single supply (no ±5 V). | Targets higher-precision instrumentation (e.g., portable multimeters) where 16-bit resolution outweighs need for bipolar input or internal reference. | Choose ADS8320U for upgraded resolution in new designs with SPI-native processors; AD7871JP remains optimal for ±5 V systems needing drop-in compatibility with existing schematics. |
Compared with AD7872JP, AD7871JP offers flexible parallel/byte/serial output modes at the cost of larger 28-pin footprint; versus ADS8320U, it trades 2-bit resolution for integrated reference, bipolar input, and legacy bus support - making AD7871JP uniquely suited for retrofitting and mixed-signal industrial control upgrades.
Availability
AD7871JP is available at Aetrix Electronics and suitable for digital signal processing, high-speed modem design, and spectrum analysis applications requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AD7871JP 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, Inc. is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control systems.
The AD7871JP belongs to Analog Devices' legacy high-speed precision ADC product line, designed specifically for embedded data acquisition in industrial automation, test equipment, and communications infrastructure where integration, reliability, and dc-to-RF performance are critical.
FAQ
What is the maximum analog input frequency supported by the AD7871JP?
The AD7871JP supports full-power analog input signals up to 41.5 kHz, defined as the frequency at which the converter maintains its specified SNR and THD performance. This is derived from its 83 kSPS throughput rate and Nyquist criterion. The track-and-hold amplifier's 0.1 dB cutoff at ~500 kHz ensures minimal aperture jitter and accurate sampling even near the Nyquist limit. For reliable operation, input signals should be band-limited using an anti-aliasing filter before reaching the VIN pin of the AD7871JP.
Does the AD7871JP require external clock components?
No, the AD7871JP does not require external clock components. It features a self-contained, laser-trimmed internal oscillator nominally set to 2 MHz, which can be enabled by connecting the CLK pin to VSS. This internal clock eliminates crystals, load capacitors, and buffer ICs, simplifying design and reducing bill-of-materials cost. An external TTL-compatible clock may still be applied to the CLK pin if system synchronization or non-standard sampling rates are needed - but it is optional, not mandatory, for basic operation of the AD7871JP.
How is bipolar offset error trimmed on the AD7871JP?
Bipolar offset error on the AD7871JP is trimmed by adjusting the offset of the op amp driving its analog input while applying −0.183 mV (−½ LSB) to VIN. The trim procedure requires observing the ADC output code flicker between 0x0000 and 0x7FFF on a logic analyzer or microcontroller readout. This adjustment must precede full-scale gain trimming. The AD7871JP datasheet specifies that offset correction is performed externally - the device itself contains no user-accessible offset registers or DACs; all calibration is analog and system-level, ensuring traceability and stability over temperature when implemented per Figure 13 in the AD7871JP datasheet.
Can the AD7871JP operate with a single +5 V supply?
No, the AD7871JP cannot operate with a single +5 V supply. It requires dual ±5 V supplies (VDD = +5 V, VSS = −5 V) to support its ±3 V bipolar analog input range and internal circuitry. The absolute maximum ratings specify VSS to AGND as +0.3 V to −7 V, confirming negative rail necessity. Attempting single-supply operation will result in undefined behavior, failure to acquire negative input voltages, and potential damage if VSS is tied to ground while VIN swings negative. Designs requiring single-supply operation should consider modern alternatives like the AD7490 or ADS8320U, not the AD7871JP.
What is the purpose of the CREF pin on the AD7871JP?
The CREF pin on the AD7871JP is the decoupling node for the internal 3 V buried Zener reference. A 10 nF capacitor must be connected between CREF and AGND to minimize reference noise and ensure specified dynamic performance (e.g., 80 dB SNR). This capacitor stabilizes the reference during internal switching events and prevents coupling of digital noise into the analog reference path. The AD7871JP datasheet explicitly states that omitting or undersizing this capacitor degrades SNR and THD - it is not optional. CREF is not an output or input pin; it serves solely as a dedicated decoupling point internal to the reference circuitry of the AD7871JP.
AD7871JP Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-LCC (J-Lead)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Number of Bits:
- 14
- Sampling Rate (Per Second):
- 83k
- Number of Inputs:
- 1
- Input Type:
- Single Ended
- Data Interface:
- SPI, Parallel
- Configuration:
- S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- Internal
- Voltage - Supply, Analog:
- ±5V
- Voltage - Supply, Digital:
- ±5V
- Features:
- -
- Operating Temperature:
- 0°C ~ 70°C
- Supplier Device Package:
- 28-PLCC (11.51x11.51)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7871JP FAQ
1.How can I place an order for AD7871JP through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7871JP 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 AD7871JP reliable?
The price and inventory of AD7871JP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7871JP is usually 5 days.
3.What payment methods are accepted for AD7871JP?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7871JP transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7871JP?
AD7871JP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7871JP 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 AD7871JP?
For technical support, including AD7871JP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7871JP requirements.
6.How does Aetrix verify that AD7871JP is sourced from the original manufacturer or authorized distributors?
All AD7871JP 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 AD7871JP meets industry standards.
7.What is the process for return or replacement of AD7871JP?
All AD7871JP units undergo pre-shipment inspection (PSI). If there is an issue with AD7871JP, 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 AD7871JP part is unused and in its original packaging.
Return procedure for AD7871JP:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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