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Analog Devices Inc. AD7871KP
- Part No.:
- AD7871KP
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-LCC (J-Lead)
- Datasheet:
-
AD7871KP.pdf
- Description:
- IC ADC 14BIT SAR 28PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,215
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Product details
Overview
AD7871KP from Analog Devices is a complete monolithic 14-bit LC2MOS successive approximation analog-to-digital converter with integrated track-and-hold amplifier, 3 V buried Zener reference, and versatile parallel/byte/serial interface. It delivers 80 dB SNR at 10 kHz, 57 ns data access time, 83 kSPS throughput, and operates from ±5 V supplies with ±3 V bipolar input range. It is used in high-speed DSP servo control and spectrum analysis systems requiring precise sampling timing.
For engineers reviewing the AD7871KP datasheet, AD7871KP pinout, AD7871KP application, or AD7871KP equivalent, key selection considerations include its 14-bit resolution with ±1 LSB integral nonlinearity, dual-mode interface (14-bit parallel or byte/serial), internal 2 MHz clock option, ±3 V analog input compliance, and 28-pin PDIP package compatibility with industrial temperature range (0°C to +70°C).
Technical Context
The AD7871KP implements a self-contained SAR architecture with laser-trimmed internal clock and on-chip 3 V temperature-compensated Zener reference. Its track-and-hold acquires signals to 14-bit accuracy in ≤2 μs, enabling full-scale conversion of 41.5 kHz input signals.
It supports three output formats via the 14/8/CLK pin: 14-bit parallel (DB13–DB0), two 8-bit bytes (HBEN-controlled), or 14-bit serial stream (SSTRB/SCLK/SDATA). Control logic allows Mode 1 (CONVST-triggered sampling) or Mode 2 (CS/RD-initiated conversion), with BUSY/INT indicating conversion status.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 14-bit - guarantees no missing codes; ideal for high-fidelity signal capture in DSP and spectrum analysis. |
| SNR @ 10 kHz | 80 dB min - enables clean digitization of audio and communication band signals with low noise floor. |
| Throughput Rate | 83 kSPS - supports real-time acquisition in modems and speech synthesis without undersampling. |
| Data Access Time | 57 ns max - ensures fast readout compatible with 8-bit and 16-bit microprocessor buses. |
| Analog Input Range | ±3 V - matches standard bipolar sensor outputs and op-amp stages without external level-shifting. |
| Power Dissipation | 50 mW typ - suitable for thermally constrained embedded systems with minimal heatsinking. |
| Reference Output | 3.00 V ±10 mV - stable on-chip Zener reference eliminates need for external precision voltage source. |
| Operating Temp | 0°C to +70°C - commercial-grade rating appropriate for industrial instrumentation and test equipment. |
Pinout & Package
AD7871KP is housed in a 28-pin plastic DIP (PDIP) package with 0.6-inch width, through-hole mounting, and industry-standard pin spacing (0.1 inch). Pin functions are validated per Analog Devices Rev. F datasheet Figures 5 and Table 4.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CONVST (Pin 1) | Asynchronous convert start | Triggers track-to-hold transition on rising edge; enables jitter-free sampling synchronized to external timer. |
| CS (Pin 2) | Chip select enable | Active-low input that initiates conversion in Mode 2 and enables data bus drivers during read cycles. |
| RD (Pin 3) | Data read strobe | Active-low signal that gates DB0–DB13 outputs; defines data valid window with 57 ns access time. |
| BUSY/INT (Pin 4) | Status indicator | Open-drain logic-low output signals conversion completion or serves as interrupt to host processor. |
| CLK (Pin 5) | Clock input/control | Accepts external TTL clock or connects to VSS to enable internal 2 MHz oscillator-no external timing components needed. |
| 14/8/CLK (Pin 28) | Interface mode selector | Configures output format: +5 V = 14-bit parallel only; 0 V = byte/serial with gated SCLK; −5 V = byte/serial with continuous SCLK. |
| VIN (Pin 26) | Analog input | ±3 V differential-capable input with 15 kΩ typical impedance; accepts bipolar signals directly without external scaling. |
| REFOUT (Pin 25) | Reference output | Provides 3.00 V ±10 mV reference for external circuitry; load-limited to 500 μA with 50 pF max capacitance. |
| AGND (Pin 22) | Analog ground | Separate ground return for analog section; must be isolated from DGND to maintain 80 dB SNR performance. |
| DGND (Pin 14) | Digital ground | Dedicated ground for digital I/O and logic; decoupled from AGND to prevent digital noise coupling into ADC core. |
Key Features
| Feature | Design Value |
|---|---|
| Complete monolithic ADC | Integrates track-and-hold, 14-bit SAR, 3 V Zener reference, and interface logic-no external DAC, reference, or clock required. |
| Three output formats | Configurable via single pin (14/8/CLK): 14-bit parallel, two 8-bit bytes (HBEN-selectable), or 14-bit serial stream. |
| Internal clock option | Laser-trimmed 2 MHz oscillator eliminates external crystal/capacitor; reduces BOM count and layout complexity. |
| Dynamic performance spec | Guaranteed 80 dB SNR and −86 dB THD at 10 kHz-validated for demanding DSP applications, not just DC accuracy. |
| Bipolar/unipolar flexibility | Supports ±3 V bipolar input by default; unipolar operation enabled using REFOUT offset (0 V to 5 V or 0 V to 10 V ranges). |
| Low power operation | 50 mW typical dissipation at 83 kSPS-enables use in portable or fanless instrumentation without thermal derating. |
Applications
| Digital Signal Processing | High-Speed Modems |
|---|---|
Use Scenario: Real-time acquisition of baseband I/Q signals in software-defined radio front-ends operating up to 41.5 kHz full-power bandwidth. IC Role / Device Role / Timing Role: Primary ADC capturing analog IF samples with precise CONVST-synchronized sampling to minimize aperture jitter. Use Value: 80 dB SNR and 83 kSPS throughput ensure accurate reconstruction of multi-tone signals without aliasing or quantization distortion. | Use Scenario: Digitizing analog line signals in V.34/V.90 modem data pumps where spectral purity and low harmonic distortion are critical. IC Role / Device Role / Timing Role: High-fidelity analog front-end ADC converting conditioned line voltage to 14-bit samples for adaptive equalization and echo cancellation. Use Value: −86 dB THD and ±1 LSB INL preserve signal integrity across 0–3.4 kHz telephony band, reducing bit error rate. |
| Spectrum Analysis | DSP Servo Control |
Use Scenario: Embedded FFT-based spectral monitoring in industrial vibration analyzers requiring 14-bit dynamic range over 0–20 kHz. IC Role / Device Role / Timing Role: Precision sampling engine feeding real-time DSP engine; uses internal clock for deterministic latency and repeatable timing. Use Value: 2 μs track/hold acquisition time and 57 ns data access enable tight loop timing in multi-channel acquisition systems. | Use Scenario: Closed-loop position/velocity feedback in CNC motion controllers using resolver or LVDT sensors with ±3 V output. IC Role / Device Role / Timing Role: Bipolar ADC interfacing directly to conditioned sensor outputs; operates in Mode 1 for deterministic sample timing aligned to servo cycle. Use Value: ±3 V input range and on-chip 3 V reference eliminate external signal conditioning, reducing component count and drift errors. |
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 |
|---|---|---|---|
| AD7871JP | Same architecture and pinout; J-grade rated for 0°C to +70°C, but specified with looser ±1.3 LSB INL (vs. ±1 LSB for KP) and 79 dB SNR min. | Acceptable for cost-sensitive industrial applications where 79 dB SNR suffices and ±1.3 LSB INL is within system calibration budget. | Select AD7871JP only if SNR and INL margins allow relaxation; AD7871KP maintains tighter specs across full temperature range. |
| ADS8320U | 16-bit SAR ADC with SPI interface only; no parallel/byte modes; requires external reference; 100 kSPS max; 85 dB SNR. | Used in higher-resolution, lower-throughput applications where serial interface simplifies routing and 16-bit depth improves dynamic range. | Choose ADS8320U when resolution >14 bits is mandatory and system design favors SPI over parallel bus; not drop-in compatible due to interface and pinout differences. |
Compared with AD7871JP, AD7871KP offers tighter DC and AC specs (±1 LSB INL, 80 dB SNR) for demanding DSP tasks; versus ADS8320U, it provides flexible parallel/serial interface and integrated reference at the cost of 2-bit resolution and 17 kSPS lower speed.
Availability
AD7871KP is available at Aetrix Electronics and suitable for digital signal processing, high-speed modems, and spectrum analysis applications requiring stable component supply, long-term obsolescence management, and traceable sourcing.
Supply support for AD7871KP 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.
The AD7871KP belongs to the AD7871/AD7872 family of complete 14-bit sampling ADCs designed for high-speed, low-power, and high-dynamic-range applications in DSP, communications, and instrumentation.
FAQ
What is the maximum analog input frequency supported by the AD7871KP?
The AD7871KP can accurately convert full-power analog signals up to 41.5 kHz, as confirmed by its Nyquist-compliant design and 83 kSPS throughput rate. This capability is enabled by its track-and-hold amplifier's 500 kHz 0.1 dB bandwidth and ≤2 μs acquisition time. The 80 dB SNR specification is guaranteed at 10 kHz, but the device maintains usable performance across its entire input bandwidth. For optimal fidelity above 10 kHz, proper anti-alias filtering and PCB layout isolation remain essential.
Does the AD7871KP require an external clock to operate?
No, the AD7871KP does not require an external clock. It features a self-contained, laser-trimmed internal oscillator nominally set to 2 MHz, which can be enabled by connecting the CLK pin (Pin 5) to VSS. This eliminates the need for external timing components and simplifies system design. An external TTL-compatible clock may still be applied to CLK if precise synchronization or frequency adjustment is required, but it is optional-not mandatory-for basic operation of the AD7871KP.
How does the 14/8/CLK pin configure the AD7871KP interface modes?
The 14/8/CLK pin (Pin 28) configures three distinct interface behaviors: at +5 V, the AD7871KP outputs only 14-bit parallel data on DB0–DB13; at 0 V, it enables both byte-mode (via HBEN) and serial-mode (SSTRB/SCLK/SDATA) with gated SCLK; at −5 V, it enables byte and serial modes with continuous SCLK output. This single-pin control eliminates external mode-selection logic and allows runtime reconfiguration. All modes share the same CONVST, CS, RD, and BUSY/INT timing relationships as defined in the AD7871KP datasheet.
Can the AD7871KP operate in unipolar mode, and how is it implemented?
Yes, the AD7871KP supports unipolar operation by using its internal 3 V REFOUT to offset the analog input stage. As shown in Figure 14 of the AD7871KP datasheet, connecting REFOUT to the op-amp summing node shifts the input range from ±3 V to 0 V–5 V or 0 V–10 V depending on resistor ratios (R3/R4). The output remains twos-complement but can be converted to straight binary by inverting the MSB. No hardware modification to the AD7871KP is needed-only external passive components and proper grounding of AGND/DGND.
What is the purpose of the CREF pin on the AD7871KP, and how must it be connected?
The CREF pin (Pin 23) is the dedicated decoupling point for the AD7871KP's internal 3 V buried Zener reference. It must be connected to AGND via a 10 nF ceramic capacitor, as explicitly required in the AD7871KP datasheet (Page 10, "Internal Reference"). This capacitor minimizes reference noise and stabilizes the DAC reference voltage during conversion cycles. Failure to install this capacitor degrades SNR and increases INL. The capacitor must be placed as close as possible to Pins 23 and 22 (CREF and AGND) with short, low-inductance traces to maintain the specified 80 dB SNR performance.
AD7871KP 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:
- -
AD7871KP FAQ
1.How can I place an order for AD7871KP through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7871KP 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 AD7871KP reliable?
The price and inventory of AD7871KP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7871KP is usually 5 days.
3.What payment methods are accepted for AD7871KP?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7871KP transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7871KP?
AD7871KP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7871KP 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 AD7871KP?
For technical support, including AD7871KP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7871KP requirements.
6.How does Aetrix verify that AD7871KP is sourced from the original manufacturer or authorized distributors?
All AD7871KP 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 AD7871KP meets industry standards.
7.What is the process for return or replacement of AD7871KP?
All AD7871KP units undergo pre-shipment inspection (PSI). If there is an issue with AD7871KP, 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 AD7871KP part is unused and in its original packaging.
Return procedure for AD7871KP:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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