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Analog Devices Inc. AD7870KN
- Part No.:
- AD7870KN
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 24-DIP (0.300", 7.62mm)
- Datasheet:
-
AD7870KN.pdf
- Description:
- IC ADC 12BIT SAR 24DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,645
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Product details
Overview
AD7870KN from Analog Devices is a complete monolithic 12-bit successive approximation analog-to-digital converter (ADC) with integrated track-and-hold amplifier, laser-trimmed internal clock, and on-chip 3 V buried Zener reference. It supports ±3 V bipolar input range, achieves 100 kHz sampling rate, delivers 72 dB SNR at 10 kHz input, and features 57 ns data access time. It is used in precision data acquisition systems requiring high dynamic performance and minimal external components.
For engineers reviewing the AD7870KN datasheet, AD7870KN pinout, AD7870KN application, or AD7870KN equivalent, this page provides verified technical context, real-world interface timing constraints, confirmed package mapping to 24-pin DIP, and validated alternative options for industrial signal conditioning and DSP-adjacent measurement systems.
Technical Context
The AD7870KN implements a SAR architecture with a fast-settling DAC, high-speed comparator, and internal 3 V temperature-compensated Zener reference. Its track-and-hold acquires signals to 12-bit accuracy in ≤2 μs, enabling full-power conversion up to 50 kHz while maintaining dc accuracy (±1/2 LSB INL typ, ±5 LSB zero/full-scale error).
It supports three digital output formats-parallel 12-bit word, two 8-bit bytes, or serial data-with mode selection via the 12/8/CLK pin. Control logic accepts asynchronous CONVST triggering or CS-initiated conversion, and BUSY/INT provides status feedback. Internal clock operates at 2.5 MHz (6.5/9 μs min/max conversion time), and external clock override is supported.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit - guarantees no missing codes; defines 4096 discrete output levels for ±3 V input (1.46 mV/LSB) |
| Sampling Rate | 100 kHz - maximum sustained throughput with 8 μs conversion + 2 μs acquisition time |
| SNR @ 10 kHz | 72 dB min - enables >11.6 effective bits for low-distortion audio and instrumentation band signals |
| Input Range | ±3 V - bipolar operation compatible with op-amp-driven sensor interfaces and industrial transducers |
| Data Access Time | 57 ns max - supports direct interfacing to 8-bit/16-bit microprocessors without wait states |
| Reference Output | 3.00 V ±10 mV - factory-laser-trimmed buried Zener; stable ±35 ppm/°C (L grade); loadable to 500 μA |
| Power Dissipation | 60 mW typical - dual ±5 V supplies (IDD = 8 mA, ISS = 4 mA); suitable for thermally constrained embedded designs |
Pinout & Package
AD7870KN is housed in a 24-pin, 0.3-inch-wide plastic dual-in-line package (DIP). Pin 1 is identified by a notch or dot; pins are numbered counterclockwise from the notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 RD | Read strobe input | Active-low control enabling parallel data output; must be asserted with CS to drive DB0–DB11 |
| 2 BUSY/INT | Status output | Open-drain active-low signal indicating conversion in progress (BUSY) or completion (INT) |
| 3 CLK | Clock select input | Tie to VSS to enable internal 2.5 MHz laser-trimmed oscillator; accept external TTL clock otherwise |
| 4 DB11/HBEN | MSB output / byte-mode control | Functions as DB11 in 12-bit mode; becomes HBEN (high-byte enable) in byte mode for 8-bit bus interfacing |
| 5 DB10/SSTRB | Data bit / serial strobe | DB10 output in parallel mode; open-drain serial framing pulse (requires 4.7 kΩ pull-up) |
| 6 DB9/SCLK | Data bit / serial clock | DB9 output in parallel mode; gated open-drain serial clock (requires 2 kΩ pull-up) |
| 7 DB8/SDATA | Data bit / serial data | DB8 output in parallel mode; open-drain serial data output (valid on SCLK falling edge, SSTRB low) |
| 8–11 DB7/LOW–DB4/LOW | Configurable data outputs | Function depends on 12/8/CLK and HBEN state; used for lower or upper byte in byte mode |
| 12 DGND | Digital ground | Reference for all digital I/O; must be isolated from AGND except at single-point star ground |
| 13–16 DB3/DB11–DB0/DB8 | Configurable data outputs | Same functional dependency as pins 8–11; collectively provide full 12-bit parallel or byte-aligned outputs |
| 17 VDD | Positive supply | +5 V ±5% - powers digital logic and reference buffer; requires local 0.1 μF ceramic decoupling |
| 18 AGND | Analog ground | Reference for track-and-hold, DAC, and comparator; separate from DGND to minimize noise coupling |
| 19 REF OUT | Reference voltage output | 3.00 V ±10 mV; capable of sourcing 500 μA; max 50 pF capacitive load; decoupling required for external use |
| 20 VIN | Analog input | ±3 V differential input range (15 kΩ typical impedance); accepts dc-coupled or ac-coupled sensor signals |
| 21 VSS | Negative supply | −5 V ±5% - powers analog circuitry including track-and-hold and comparator; decouple locally |
| 22 12/8/CLK | Mode select input | +5 V = 12-bit parallel only; 0 V = byte/serial with gated SCLK; −5 V = byte/serial with continuous SCLK |
| 23 CONVST | Convert start input | Rising-edge-triggered asynchronous command; initiates track→hold transition and starts conversion |
| 24 CS | Chip select input | Active-low enable; when tied low with CONVST grounded, initiates auto-conversion on CS falling edge |
Key Features
| Feature | Design Value |
|---|---|
| Monolithic 12-bit ADC with T/H, ref, clock | Eliminates need for external sample-hold IC, reference IC, or timing components - reduces BOM and layout complexity |
| Laser-trimmed internal clock | Guarantees 2.5 MHz operation and precise 8 μs conversion time - removes clock generator design effort and tolerance stack-up |
| Three configurable data interfaces | Parallel 12-bit, two-byte, or serial output - enables flexible integration with 8-bit microcontrollers, FPGAs, or space-constrained PCBs |
| 72 dB SNR at 10 kHz | Supports high-fidelity digitization of audio-band and vibration signals without external anti-alias filtering beyond Nyquist |
| ±3 V bipolar input range | Direct compatibility with industrial current-loop receivers, strain-gauge bridges, and op-amp-based signal chains |
| Low power: 60 mW typical | Enables use in fanless industrial controllers and portable test equipment where thermal management is critical |
Applications
| Industrial Process Monitoring | Test & Measurement Equipment |
|---|---|
|
Use Scenario: Continuous digitization of 4–20 mA loop outputs conditioned by precision op-amps in PLC analog input modules. IC Role / Device Role / Timing Role: Primary ADC capturing ±3 V sensor-derived signals at 100 kHz with minimal latency and guaranteed monotonicity. Use Value: Delivers 12-bit resolution and 72 dB SNR without external reference or clock, reducing calibration overhead and board area. |
Use Scenario: High-speed waveform capture in benchtop oscilloscopes and spectrum analyzers with real-time FFT processing. IC Role / Device Role / Timing Role: Front-end ADC providing 100 kHz sampled data to DSP engines; BUSY/INT synchronizes DMA transfers. Use Value: 57 ns data access time enables direct connection to 80C188 or ADSP-2100 buses without glue logic or wait-state insertion. |
| DSP-Based Motor Control | Medical Instrumentation |
|
Use Scenario: Sampling phase currents and DC bus voltage in servo drives using isolated amplifiers with ±3 V output swing. IC Role / Device Role / Timing Role: Precision ADC feeding position/speed feedback loops; internal clock ensures deterministic conversion timing. Use Value: Laser-trimmed clock eliminates jitter-induced harmonic distortion, preserving torque ripple measurement fidelity. |
Use Scenario: Digitizing ECG and EEG biopotential signals amplified by low-noise instrumentation amps with ±3 V headroom. IC Role / Device Role / Timing Role: Final-stage ADC in analog front-end; AGND/DGND separation maintains >80 dB CMRR in noisy hospital environments. Use Value: On-chip 3 V reference with ±35 ppm/°C tempco ensures stable gain over operating temperature without external trimming. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit sampling ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7875KN | Unipolar 0 V to +5 V input range; same 12-bit SAR core, timing, and interface; identical package and pinout | Designed for single-supply systems with positive-only sensors (e.g., RTDs, potentiometers); lacks bipolar offset handling | Select AD7875KN only when input signals are strictly unipolar and system ground-referenced. |
| MAX195BCPP | 16-bit resolution, 100 kSPS, external reference required, no integrated T/H, SPI-only interface, 20-pin SOIC | Higher resolution but demands external precision reference, driver amp, and clock; no parallel/byte modes | Choose MAX195BCPP only when 16-bit accuracy is mandatory and board space allows added support components. |
Compared with AD7870KN, AD7875KN offers identical speed and packaging but restricts input to 0 V–+5 V, while MAX195BCPP trades integration and interface flexibility for higher resolution - making AD7870KN optimal for cost-sensitive, space-constrained bipolar measurement systems needing drop-in readiness.
Availability
AD7870KN is available at Aetrix Electronics and suitable for industrial process monitoring, test & measurement equipment, and DSP-based motor control requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AD7870KN 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 company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.
The AD7870KN belongs to the LC2MOS 12-bit sampling ADC product line, designed for embedded data acquisition systems demanding self-contained accuracy, low power, and minimal external components in harsh industrial environments.
FAQ
What is the maximum analog input frequency the AD7870KN can accurately digitize?
The AD7870KN supports full-power input signals up to 50 kHz while maintaining 12-bit accuracy and specified SNR. Its track-and-hold amplifier has a 0.1 dB bandwidth of ~500 kHz, ensuring faithful sampling well beyond the Nyquist limit at 100 kHz sampling. For signals above 50 kHz, amplitude accuracy degrades due to aperture uncertainty and bandwidth roll-off - the AD7870KN datasheet specifies dynamic performance only up to 50 kHz full-power input.
Does the AD7870KN require external components to operate?
No, the AD7870KN is a complete ADC requiring only power supply decoupling capacitors: 0.1 μF ceramic capacitors placed close to VDD and VSS pins, and proper grounding between AGND and DGND. It integrates a track-and-hold amplifier, 3 V buried Zener reference, laser-trimmed clock oscillator, and interface logic - eliminating need for external reference ICs, clock generators, or sample-hold circuits in standard configurations.
How does the AD7870KN handle bipolar offset and full-scale calibration?
The AD7870KN specifies ±5 LSB maximum bipolar zero error and ±5 LSB maximum positive/negative full-scale error at +25°C. These errors are factory trimmed and stable over temperature (±35 ppm/°C ref tempco). While not user-adjustable via dedicated pins, system-level calibration can be applied in firmware using known reference inputs - the AD7870KN's guaranteed monotonicity and no-missing-codes behavior ensure linear correction remains valid across the full ±3 V range.
Can the AD7870KN interface directly with an 8-bit microcontroller bus?
Yes, the AD7870KN supports byte-mode operation via HBEN and 12/8/CLK pins, allowing sequential read of upper and lower 8-bit bytes on an 8-bit data bus. With HBEN low, DB7–DB0 deliver the lower byte; with HBEN high, they deliver the upper byte. This eliminates need for external latches or address decoding logic - the AD7870KN's 57 ns access time and standard CS/RD timing comply with common 8-bit MPU timing requirements.
What is the purpose of the 12/8/CLK pin on the AD7870KN?
The 12/8/CLK pin configures both data format and serial clock behavior: at +5 V, it enables 12-bit parallel output only; at 0 V, it enables byte or serial output with gated SCLK (stops after transmission); at −5 V, it enables byte or serial output with continuous SCLK. This single pin eliminates external mode-select jumpers or configuration registers - the AD7870KN's hardware-defined interface simplifies PCB layout and firmware initialization.
AD7870KN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 100k
- 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:
- 24-PDIP
- Mounting Type:
- Through Hole
- Grade:
- -
- Qualification:
- -
AD7870KN FAQ
1.How can I place an order for AD7870KN through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7870KN 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 AD7870KN reliable?
The price and inventory of AD7870KN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7870KN is usually 5 days.
3.What payment methods are accepted for AD7870KN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7870KN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7870KN?
AD7870KN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7870KN 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 AD7870KN?
For technical support, including AD7870KN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7870KN requirements.
6.How does Aetrix verify that AD7870KN is sourced from the original manufacturer or authorized distributors?
All AD7870KN 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 AD7870KN meets industry standards.
7.What is the process for return or replacement of AD7870KN?
All AD7870KN units undergo pre-shipment inspection (PSI). If there is an issue with AD7870KN, 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 AD7870KN part is unused and in its original packaging.
Return procedure for AD7870KN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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