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Analog Devices Inc. AD7878JNZ
- Part No.:
- AD7878JNZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AD7878JNZ.pdf
- Description:
- IC ADC 12BIT SAR 28DIP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
AD7878JNZ from Analog Devices is a complete LC2MOS 12-bit analog-to-digital converter with integrated track/hold, 3 V Zener reference, and 8-word FIFO-designed for direct interfacing to high-speed DSPs (e.g., ADSP-2100, TMS32010). It delivers 100 kHz sampling rate, 72 dB SNR at 10 kHz input, and 41 ns data access time in a 28-pin plastic DIP package. Used in real-time spectrum analysis and speech synthesis systems requiring low-latency digitization of ±3 V bipolar signals.
For engineers reviewing the AD7878JNZ datasheet, AD7878JNZ pinout, AD7878JNZ application, or AD7878JNZ equivalent, key selection considerations include its 41 ns access time, FIFO programmability, bipolar ±3 V input range, on-chip 3 V reference, and compatibility with ADSP-2100/TMS320x DSP buses without external glue logic.
Technical Context
The AD7878JNZ implements a successive approximation ADC core with internal comparator strobe gating synchronized to CLK IN, enabling robust read/write operations during conversion via slippage-based timing arbitration. Its 8-word FIFO operates with ripple-down architecture, where reads shift data downward and the address pointer tracks the top valid location.
It features dual-function status/control register (accessible via ADD0-high reads/writes) supporting ALFL interrupt generation, FIFO overrun detection (FOVR), output disable during BUSY (DISO), and sample-out-of-range flagging (SOOR)-all tied to real-time conversion monitoring without CPU intervention.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit monotonic, no missing codes guaranteed - ensures full-scale linearity for precision measurement. |
| Sampling Rate | 100 kHz max - supports Nyquist-limited bandwidth up to 50 kHz for full-power signal conversion. |
| SNR @ 10 kHz | 72 dB min (J-grade) - enables high-fidelity audio and spectral analysis with low noise floor. |
| Data Access Time | 41 ns - allows direct connection to ADSP-2100 and TMS32010 without wait states. |
| Analog Input Range | ±3 V bipolar - simplifies interface to op-amp front-ends without level-shifting circuitry. |
| Reference Output | 3.0 V ±10 mV - stable on-chip Zener reference eliminates need for external voltage reference. |
| Power Dissipation | 60 mW typ (95.5 mW max) - suitable for thermally constrained embedded DSP subsystems. |
| FIFO Depth | 8 words - buffers consecutive samples to reduce interrupt overhead in real-time control loops. |
Pinout & Package
AD7878JNZ is housed in a 28-pin plastic dual-in-line package (N-28), compliant with JEDEC MS-001. Pin spacing is 0.3 inch, with standard through-hole mounting and 0.6 inch body width.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ADD0 | Address Select | Selects FIFO data (low) or status/control register (high) during read/write - enables single-bus access to both data and control space. |
| CS | Chip Select | Active-low enable for all digital I/O - synchronizes device access with system bus timing. |
| DMWR / DMRD | DSP Memory Write / Read | Directly maps to ADSP-2100 DMWR/DMRD pins - eliminates address decoding logic for DSP integration. |
| BUSY | Conversion Status | Active-low indicates track-to-hold transition and ongoing conversion - used to gate bus activity or trigger WAIT state. |
| ALFL | FIFO Almost Full Flag | Programmable interrupt output (1–8 word threshold) - enables deterministic data flow control in streaming applications. |
| VIN | Analog Input | ±3 V differential-capable input referenced to AGND - accepts directly coupled sensor or amplifier outputs. |
| REF OUT | Internal Reference | 3 V Zener output rated for ≤500 µA load - powers external circuitry or serves as DAC reference if isolated properly. |
| CONVST | Asynchronous Start | Rising-edge-triggered, independent of clock or bus - ensures precise, jitter-free sampling for time-critical acquisition. |
| DB11–DB0 | Data Bus | Three-state TTL outputs with twos-complement coding - compatible with 16-bit DSP data buses without level translation. |
| CLK IN | Master Clock Input | TTL-compatible 8 MHz input (35/65 duty cycle) - drives internal 2 MHz SAR clock and synchronizes FIFO read/write propagation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated FIFO + Control Logic | 8-word depth with programmable ALFL threshold and status flags (FOVR, SOOR, FEMP) reduces software interrupt latency by >60% vs. polled ADCs. |
| On-Chip 3 V Reference | ±10 mV accuracy at 25°C eliminates external reference IC and associated layout sensitivity, saving BOM cost and board area. |
| 41 ns Data Access Time | Fastest monolithic ADC access time at introduction - enables zero-wait-state interface to ADSP-2100 and TMS32010 without external latches. |
| Asynchronous CONVST | Independent of CLK IN and bus timing - supports externally timed sampling for phase-coherent multi-channel systems. |
| Dynamic Parameter Testing | 100% production-tested SNR, THD, IMD, and peak spurious - provides guaranteed ac performance for spectral integrity-critical applications. |
| LC2MOS Process | Combines bipolar precision (track/hold, reference) with CMOS logic density and low power - achieves 60 mW typical dissipation at full speed. |
Applications
| Spectrum Analysis | Speech Synthesis |
|---|---|
Use Scenario: Real-time FFT-based frequency domain analysis of vibration or RF signals sampled at 100 kHz. IC Role / Device Role / Timing Role: Primary ADC capturing ±3 V analog inputs with 72 dB SNR and minimal harmonic distortion to preserve spectral fidelity. Use Value: On-chip FIFO buffers eight consecutive samples, allowing burst-mode acquisition and reducing host processor interrupt load by 8× versus single-sample mode. | Use Scenario: Digitizing voice waveforms in embedded TTS (text-to-speech) engines for industrial HMI or telecom gateways. IC Role / Device Role / Timing Role: High-speed, low-jitter ADC feeding ADSP-2100 DSP core with 12-bit resolution and 41 ns access for real-time LPC coefficient computation. Use Value: Asynchronous CONVST enables precise sample alignment across multiple channels, critical for phase-coherent speech reconstruction. |
| DSP Servo Control | High-Speed Modem |
Use Scenario: Closed-loop motor position feedback in industrial servo drives using resolver or encoder analog outputs. IC Role / Device Role / Timing Role: Bipolar ±3 V input accepts differential amplifier outputs from analog position sensors; FIFO decouples sampling from control loop execution. Use Value: Programmable ALFL flag triggers DMA transfer at fixed sample count (e.g., 4 words), ensuring deterministic latency for PID update cycles. | Use Scenario: Analog front-end for V.34/V.90 modems requiring high-SNR digitization of baseband QAM signals. IC Role / Device Role / Timing Role: ADC providing 72 dB SNR and –80 dB THD at 10 kHz to support 32-QAM symbol recovery under noisy line conditions. Use Value: On-chip 3 V reference ensures stable full-scale definition across temperature, minimizing gain drift-induced constellation rotation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit DSP-interfaced ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7865BSUZ | 4-channel simultaneous-sampling 12-bit ADC; 3 µs conversion time; SPI interface; no FIFO; requires external reference. | Designed for multi-channel synchronized acquisition (e.g., motor phase currents), not single-channel high-throughput streaming. | Choose AD7865BSUZ when simultaneous sampling across ≥2 channels is required; AD7878JNZ remains optimal for single-channel, FIFO-buffered, DSP-bus-native designs. |
| ADS8325IPFBT | 16-bit, 100 kSPS SAR ADC; serial SPI interface; internal reference; no FIFO; 1.5 µs conversion time. | Targets higher-resolution metrology over DSP throughput; lacks parallel bus and FIFO for low-latency streaming. | Choose ADS8325IPFBT for DC-precision applications needing >12-bit resolution; AD7878JNZ is preferred when DSP bus compatibility and hardware FIFO buffering are mandatory. |
Compared with AD7865BSUZ and ADS8325IPFBT, the AD7878JNZ uniquely combines parallel DSP bus interface, on-chip FIFO, asynchronous sampling trigger, and guaranteed dynamic performance - making it irreplaceable in legacy ADSP-2100/TMS320x-based real-time signal processing systems where timing determinism and interrupt reduction are critical.
Availability
AD7878JNZ is available at Aetrix Electronics and suitable for digital signal processing, speech synthesis, and spectrum analysis applications requiring stable component supply and long-term obsolescence management.
Supply support for AD7878JNZ 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 DSP technology, founded in 1965 and headquartered in Wilmington, MA.
The AD7878JNZ belongs to Analog Devices' LC2MOS precision ADC product line, engineered specifically for seamless integration into real-time DSP systems requiring low-latency, high-fidelity analog capture with minimal external components.
FAQ
What is the maximum sampling rate supported by the AD7878JNZ?
The AD7878JNZ supports a maximum sampling rate of 100 kHz, achieved with an 8 MHz CLK IN. This rate is fully specified for dynamic parameters including SNR and THD across the operating temperature range. At this rate, the device can accurately digitize full-power signals up to 50 kHz while maintaining 72 dB SNR at 10 kHz input - a key specification confirmed in the Rev. A datasheet for the J-grade version. The AD7878JNZ maintains this performance without external timing components.
Does the AD7878JNZ require an external reference voltage?
No, the AD7878JNZ does not require an external reference voltage. It integrates a precision 3 V Zener reference (REF OUT) with ±10 mV accuracy at 25°C and ±15 mV over temperature. This reference is internally used for ADC conversion and is available at Pin 23 for external use, rated for up to 500 µA load. Using the internal reference eliminates external component count and improves system stability - a confirmed feature documented in the General Description and REF OUT specifications sections of the AD7878JNZ datasheet.
How does the FIFO in the AD7878JNZ reduce software overhead?
The AD7878JNZ's 8-word FIFO reduces software overhead by allowing up to eight consecutive conversions to complete before the host processor must service the device. Instead of generating an interrupt per sample, the system can read all eight words in burst mode at maximum bus speed. This cuts interrupt frequency by 8× and eliminates per-sample setup/teardown latency. The FIFO's ALFL flag further enables programmable interrupt thresholds (1–8 words), giving designers precise control over data flow - a capability explicitly highlighted in the Product Highlights and STATUS/CONTROL REGISTER sections of the AD7878JNZ datasheet.
Can the AD7878JNZ interface directly with the ADSP-2100 DSP?
Yes, the AD7878JNZ interfaces directly with the ADSP-2100 DSP without glue logic. Its DMRD and DMWR pins map one-to-one to the ADSP-2100's DMRD and DMWR signals, and its 41 ns data access time meets the ADSP-2100's timing requirements at full speed. The BUSY signal can be used to generate READY, and the asynchronous CONVST input aligns with the ADSP-2100's external event triggering model. This native compatibility is explicitly stated in the FEATURES and GENERAL DESCRIPTION sections of the AD7878JNZ datasheet.
What is the analog input voltage range of the AD7878JNZ?
The AD7878JNZ has a bipolar analog input voltage range of ±3 V, referenced to AGND (Pin 22). This range is fully specified for dynamic performance including SNR and THD, and applies across the entire operating temperature range of 0°C to +70°C for the J-grade device. Input current is limited to ±550 µA max, allowing direct connection to low-output-impedance op-amp drivers without attenuation or buffering - a parameter confirmed in the ANALOG INPUT section of the AD7878JNZ datasheet.
AD7878JNZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-DIP (0.600", 15.24mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 100k
- Number of Inputs:
- 1
- Input Type:
- Single Ended
- Data Interface:
- DSP
- 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-PDIP
- Mounting Type:
- Through Hole
- Grade:
- -
- Qualification:
- -
AD7878JNZ FAQ
1.How can I place an order for AD7878JNZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7878JNZ 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 AD7878JNZ reliable?
The price and inventory of AD7878JNZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7878JNZ is usually 5 days.
3.What payment methods are accepted for AD7878JNZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7878JNZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7878JNZ?
AD7878JNZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7878JNZ 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 AD7878JNZ?
For technical support, including AD7878JNZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7878JNZ requirements.
6.How does Aetrix verify that AD7878JNZ is sourced from the original manufacturer or authorized distributors?
All AD7878JNZ 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 AD7878JNZ meets industry standards.
7.What is the process for return or replacement of AD7878JNZ?
All AD7878JNZ units undergo pre-shipment inspection (PSI). If there is an issue with AD7878JNZ, 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 AD7878JNZ part is unused and in its original packaging.
Return procedure for AD7878JNZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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