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Analog Devices Inc. AD7870AQ
- Part No.:
- AD7870AQ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 24-CDIP (0.300", 7.62mm)
- Datasheet:
-
AD7870AQ.pdf
- Description:
- IC ADC 12BIT SAR 24CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,228
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Product details
Overview
AD7870AQ from Analog Devices is a complete monolithic 12-bit successive approximation ADC with integrated track-and-hold amplifier (2 μs acquisition), on-chip 3 V buried Zener reference, laser-trimmed internal clock, and parallel/byte/serial digital interface. It supports ±3 V bipolar input range, achieves 72 dB SNR at 10 kHz, and delivers 57 ns data access time. It is used in precision data acquisition systems requiring high dynamic performance and microprocessor compatibility.
For engineers reviewing the AD7870AQ datasheet, AD7870AQ pinout, AD7870AQ application, or AD7870AQ equivalent, key selection considerations include its LC2MOS process, guaranteed 8 μs conversion time with internal clock, ±1 LSB integral nonlinearity (max), −80 dB THD, and support for standalone or microprocessor-controlled operation across 0°C to +70°C.
Technical Context
The AD7870AQ implements a SAR architecture with a voltage-output DAC, high-speed comparator, and self-timed control logic. Its internal 3 V reference is laser-trimmed to ±10 mV and provides dc bias for bipolar operation while sourcing up to 500 μA.
Conversion is initiated asynchronously via CONVST rising edge or CS falling edge, triggering the track-and-hold to switch from track to hold mode. The internal clock (2.5 MHz nominal) eliminates external timing components, and conversion time is fixed at 6.5 μs (min) / 9 μs (max) - independent of temperature or supply variation within spec.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit - guarantees no missing codes; full 4096-level quantization for ±3 V input (1.46 mV/LSB) |
| Sampling Rate | 100 kHz - supports full-power signal conversion up to 50 kHz (Nyquist-limited) |
| SNR | 72 dB min @ 10 kHz - enables high-fidelity digitization of audio-band and instrumentation signals |
| THD | −80 dB max @ 10 kHz - ensures low harmonic contamination in spectral analysis applications |
| Conversion Time | 6.5 μs min / 9 μs max - deterministic timing with internal clock; no external timing components required |
| Data Access Time | 57 ns - compatible with fast 8-bit/16-bit microprocessors and DSPs without wait states |
| Input Range | ±3 V - matched to industrial sensor outputs and op-amp stages operating on ±5 V supplies |
| Power Dissipation | 60 mW typical - enables low-heat operation in dense mixed-signal PCB layouts |
Pinout & Package
AD7870AQ is housed in a 24-pin, 0.3-inch-wide hermetic dual-in-line package (DIP), rated for commercial temperature range (0°C to +70°C). Pin 1 identifier is marked by a notch or dot; pins are numbered counterclockwise from top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 RD | Digital output enable | Active-low read strobe; enables DB0–DB11 three-state drivers when CS is low |
| 2 BUSY/INT | Status indicator | Active-low open-drain output signaling conversion in progress (BUSY) or completion (INT) |
| 3 CLK | Clock source select | Tie to VSS to enable internal laser-trimmed oscillator; accept external 2.5 MHz TTL clock otherwise |
| 4 DB11/HBEN | MSB or byte control | Outputs DB11 in 12-bit mode; functions as High Byte Enable (HBEN) in byte mode |
| 5 DB10/SSTRB | Data bit or serial strobe | Outputs DB10 in parallel mode; provides active-low serial framing pulse (SSTRB) with 4.7 kΩ pull-up |
| 6 DB9/SCLK | Data bit or serial clock | Outputs DB9 in parallel mode; gated open-drain serial clock (SCLK) requiring 2 kΩ pull-up |
| 7 DB8/SDATA | Data bit or serial data | Outputs DB8 in parallel mode; open-drain serial data (SDATA) valid on SCLK falling edge |
| 8–11 DB7/LOW–DB4/LOW | Configurable data outputs | Function as DB7–DB4 (12-bit) or upper/lower byte bits depending on 12/8/CLK and HBEN state |
| 12 DGND | Digital ground reference | Isolated return path for logic circuitry; must be connected to system digital ground plane |
| 13–16 DB3/DB11–DB0/DB8 | Configurable data outputs | Function as DB3–DB0 (12-bit) or upper/lower byte bits; controlled by CS, RD, and HBEN |
| 17 VDD | Positive supply | +5 V ±5% analog/digital supply; requires local 0.1 μF ceramic decoupling to AGND |
| 18 AGND | Analog ground reference | Return for track-and-hold, reference, and DAC; must be star-connected to minimize noise coupling |
| 19 REF OUT | Reference voltage output | 3.00 V ±10 mV buried Zener output; capable of sourcing 500 μA; max 50 pF capacitive load |
| 20 VIN | Analog input | ±3 V differential input range into 15 kΩ impedance; accepts signals directly from op-amps or sensors |
| 21 VSS | Negative supply | −5 V ±5% analog supply; requires local 0.1 μF ceramic decoupling to AGND |
| 22 12/8/CLK | Interface mode select | +5 V = 12-bit parallel only; 0 V = byte/serial with gated SCLK; −5 V = byte/serial with continuous SCLK |
| 23 CONVST | Conversion trigger | Rising-edge asynchronous start signal; initiates track-to-hold transition and conversion sequence |
| 24 CS | Chip select | Active-low device enable; falling edge can initiate conversion when CONVST is tied low |
Key Features
| Feature | Design Value |
|---|---|
| Complete monolithic ADC | Integrates track-and-hold, 12-bit SAR core, 3 V reference, and interface logic - zero external components needed beyond decoupling caps |
| Laser-trimmed internal clock | Guarantees 6.5–9 μs conversion time without external timing parts; eliminates clock jitter sensitivity in system design |
| Three interface modes | Supports 12-bit parallel, two-byte, or serial output - enables flexible bus interfacing with 8-bit, 16-bit, or low-pin-count controllers |
| 72 dB SNR at 10 kHz | Validated dynamic performance for DSP applications including spectral analysis, vibration monitoring, and audio digitization |
| ±1 LSB INL (max) | Ensures monotonicity and accurate dc measurement in closed-loop control and sensor calibration systems |
| LC2MOS process technology | Provides low power (60 mW typ), high noise immunity, and stable operation over temperature without external trimming |
Applications
| Industrial Data Acquisition | Test & Measurement Equipment |
|---|---|
Use Scenario: Digitizing outputs from strain gauges, RTDs, and pressure transducers in PLC I/O modules. IC Role / Device Role / Timing Role: Primary ADC capturing ±3 V sensor signals at 100 kSPS with minimal external circuitry. Use Value: Eliminates need for external reference, clock, or track-and-hold - reduces BOM count and layout area in space-constrained modules. |
Use Scenario: Capturing transient waveforms in portable oscilloscopes and spectrum analyzers. IC Role / Device Role / Timing Role: High-SNR front-end ADC synchronized to internal clock for repeatable sampling intervals. Use Value: 72 dB SNR and −80 dB THD enable accurate frequency-domain analysis of low-amplitude signals up to 50 kHz. |
| DSP-Based Signal Processing | Automated Test Systems |
Use Scenario: Feeding real-time sensor data into TI C5000 or Analog Devices SHARC processors for filtering and feature extraction. IC Role / Device Role / Timing Role: Microprocessor-compatible ADC delivering 57 ns data access to avoid wait states on 16-bit buses. Use Value: Parallel/byte/serial flexibility allows direct connection to diverse host interfaces without glue logic or FPGA bridging. |
Use Scenario: High-accuracy voltage/current measurement in ATE rack instruments performing parametric testing. IC Role / Device Role / Timing Role: Precision ADC with ±1 LSB INL and calibrated 3 V reference for traceable metrology-grade measurements. Use Value: On-chip reference stability (±35 ppm/°C) and low tempco reduce calibration drift between thermal cycles. |
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 |
|---|---|---|---|
| AD7875AQ | Unipolar 0 V to +5 V input range; identical timing, SNR, and interface; same package and pinout | Designed for single-supply systems with unipolar sensors (e.g., 4–20 mA receivers, potentiometers) | Select AD7875AQ when input signal is strictly non-negative and system lacks negative supply rail. |
| MAX195BCPP+ | 16-bit resolution; 100 kSPS; external reference required; no integrated track-and-hold; CMOS process | Higher resolution but higher power (120 mW); requires external clock, reference, and signal conditioning | Choose MAX195BCPP+ only when 16-bit accuracy is mandatory and board area/power budget permits added components. |
Compared with AD7870AQ, AD7875AQ offers identical speed and dynamic performance but targets unipolar systems, while MAX195BCPP+ trades integration and power efficiency for higher resolution - making AD7870AQ optimal for compact, low-power, ±3 V industrial DAQ where 12-bit fidelity suffices.
Availability
AD7870AQ is available at Aetrix Electronics and suitable for industrial data acquisition, test equipment, DSP interfacing, and automated test systems requiring stable component supply across extended product lifecycles.
Supply support for AD7870AQ 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 AD7870AQ belongs to the AD787x family of complete sampling ADCs designed for precision, low-component-count data acquisition in industrial, instrumentation, and DSP-adjacent applications.
FAQ
What is the maximum input frequency the AD7870AQ can accurately digitize?
The AD7870AQ supports full-power signal conversion up to 50 kHz while maintaining 12-bit accuracy and specified SNR/THD. Its track-and-hold amplifier has a 0.1 dB bandwidth of ~500 kHz, enabling faithful capture of signals well above Nyquist when undersampling is applied. For baseband applications, the 100 kSPS sampling rate imposes a practical 50 kHz upper limit per Shannon-Nyquist criteria. The AD7870AQ achieves 72 dB SNR at 10 kHz input, confirming high-fidelity digitization within this band.
Does the AD7870AQ require external components to operate?
No, the AD7870AQ is a complete monolithic ADC requiring only power supply decoupling capacitors (0.1 μF ceramic from VDD and VSS to AGND). It integrates a 3 V buried Zener reference, laser-trimmed internal clock oscillator, and 2 μs track-and-hold amplifier - eliminating external reference ICs, timing crystals, or sample-hold circuits. The AD7870AQ datasheet confirms "no external components apart from power supply decoupling capacitors" are needed for basic operation.
How does the AD7870AQ handle bipolar versus unipolar input ranges?
The AD7870AQ is specifically configured for ±3 V bipolar input range, using its internal 3 V reference to establish symmetric full-scale boundaries. Its output code is twos complement binary, with 1 LSB = 1.46 mV and ideal transitions at ±½ LSB. This differs from the AD7875AQ (0 V to +5 V, straight binary) and AD7876AQ (±10 V, twos complement). The AD7870AQ's analog input structure includes scaling resistors optimized for ±3 V, and its offset/full-scale error specs (±5 LSB max) are validated under that range.
Can the AD7870AQ interface directly with an 8-bit microprocessor bus?
Yes, the AD7870AQ supports byte-mode operation via its HBEN (High Byte Enable) and 12/8/CLK pins, allowing 8-bit data transfers without external latches. When 12/8/CLK is low and HBEN is toggled, DB7–DB0 deliver lower or upper bytes sequentially. Its 57 ns data access time meets timing requirements of fast 8-bit CPUs like the 80C88 or Z80, and control signals (RD, CS, BUSY/INT) conform to standard microprocessor bus protocols. The AD7870AQ datasheet explicitly states compatibility with "modern 8-bit and 16-bit microprocessors."
What is the temperature range and packaging of the AD7870AQ?
The AD7870AQ is specified for 0°C to +70°C (commercial grade) and packaged in a 24-pin hermetic dual-in-line package (DIP) with 0.3 inch body width. This hermetic seal provides enhanced moisture and contamination resistance compared to plastic DIP variants, supporting reliability-critical applications in industrial environments. The "AQ" suffix denotes the hermetic DIP option per Analog Devices' ordering guide, distinct from plastic DIP (AD7870JN) or PLCC (AD7870KN) variants.
AD7870AQ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-CDIP (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:
- -40°C ~ 85°C
- Supplier Device Package:
- 24-CDIP
- Mounting Type:
- Through Hole
- Grade:
- -
- Qualification:
- -
AD7870AQ FAQ
1.How can I place an order for AD7870AQ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7870AQ 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 AD7870AQ reliable?
The price and inventory of AD7870AQ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7870AQ is usually 5 days.
3.What payment methods are accepted for AD7870AQ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7870AQ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7870AQ?
AD7870AQ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7870AQ 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 AD7870AQ?
For technical support, including AD7870AQ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7870AQ requirements.
6.How does Aetrix verify that AD7870AQ is sourced from the original manufacturer or authorized distributors?
All AD7870AQ 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 AD7870AQ meets industry standards.
7.What is the process for return or replacement of AD7870AQ?
All AD7870AQ units undergo pre-shipment inspection (PSI). If there is an issue with AD7870AQ, 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 AD7870AQ part is unused and in its original packaging.
Return procedure for AD7870AQ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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