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Analog Devices Inc. AD7878KN
- Part No.:
- AD7878KN
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AD7878KN.pdf
- Description:
- IC ADC 12BIT W/DSP INT 28-DIP
- Quantity:
- Payment:
- Shipping:
Inventory:392
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Product details
Overview
AD7878KN from Analog Devices is a complete 12-bit, 100 kHz sampling analog-to-digital converter with integrated track/hold amplifier, on-chip 3 V Zener reference, and 8-word FIFO for DSP interfacing. It delivers 72 dB SNR at 10 kHz input, 41 ns data access time, and ±3 V bipolar analog input range - designed for high-speed digitization in real-time signal processing systems.
For engineers reviewing the AD7878KN datasheet, AD7878KN pinout, AD7878KN application, or AD7878KN equivalent, this device serves as a monolithic, LC2MOS-based ADC solution optimized for direct interface to ADSP-2100, TMS32010, and TMS32020 processors - with critical timing parameters (t9 = 41 ns), FIFO control logic, and dynamic ac performance fully specified across 0°C to +70°C.
Technical Context
The AD7878KN implements a successive approximation register (SAR) architecture with 13-bit internal decision logic (12 data + 1 out-of-range bit), synchronized to an external 8 MHz CLK IN. Its internal comparator strobe is gated by DMRD/DMWR to prevent bus-induced transients during bit decisions - enabling robust read/write operations concurrent with conversion.
It features a programmable FIFO almost-full threshold (AFC2–AFC0), status/control register accessible via DB11–DB0 with ADD0 high, and dual-mode BUSY-driven output enable (DISO bit DB5) supporting both WAIT-state microprocessors and non-blocking access - all within a single LC2MOS die combining precision bipolar analog circuitry and low-power CMOS logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit monotonic, no missing codes guaranteed - ensures full-scale linearity for precision waveform capture. |
| Sampling Rate | 100 kHz maximum - supports Nyquist-limited bandwidth up to 50 kHz for full-power signals. |
| Signal-to-Noise Ratio | 72 dB min at 10 kHz input - enables high-fidelity spectral analysis and speech digitization. |
| Data Access Time | 41 ns max - allows direct, latch-free interface to ADSP-2100 and 16-bit microprocessors without wait states. |
| Analog Input Range | ±3 V bipolar - matches standard industrial sensor outputs and op-amp swing ranges without external scaling. |
| FIFO Depth | 8-word first-in, first-out buffer - reduces interrupt overhead by allowing burst reads after multiple conversions. |
| Reference Output | 3 V ±10 mV (25°C), ±15 mV (full temp range) - provides stable, on-chip excitation for ratiometric sensor interfaces. |
| Power Dissipation | 60 mW typical (95.5 mW max) - enables dense DSP subsystem integration without forced cooling. |
Pinout & Package
AD7878KN is supplied in a 28-pin plastic dual-in-line package (N-28), compliant with JEDEC MS-001. Pin assignments are identical across J/K/L-grade DIP variants and validated per Analog Devices AD7878 Rev. A datasheet.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ADD0 | Address Select | Determines read target: low = FIFO data word (Location 0), high = status/control register - enables unified bus access. |
| CS | Chip Select | Active-low enable for all digital interface operations - synchronizes access with system address decode. |
| DMWR / DMRD | Write / Read Control | Directly maps to ADSP-2100 DMWR/DMRD or TMS32010 WE/DEN - eliminates glue logic for TI/ADI DSPs. |
| BUSY | Conversion Status | Active-low pulse indicates track-to-hold transition and ongoing conversion - used for WAIT-state generation or bus arbitration. |
| ALFL | FIFO Almost Full Flag | Programmable interrupt source (threshold 1–8 words) - triggers processor service before FIFO overflow occurs. |
| DB11–DB0 | Data Bus | Three-state TTL outputs with twos-complement coding - supports direct connection to 16-bit data buses without level shifters. |
| VIN | Analog Input | ±3 V differential-capable input referenced to AGND - accepts unbuffered sensor signals with ≤550 µA input current. |
| REF OUT | Internal Reference | 3 V Zener-derived output, load-limited to 500 µA - requires series resistor for >50 pF capacitive loads. |
| CONVST | Asynchronous Start | Rising-edge-triggered, independent of CLK IN - enables jitter-free sampling synchronized to external timing sources. |
| CLK IN | Master Clock Input | TTL-compatible 8 MHz input with 35/65 duty cycle tolerance - drives internal 2 MHz SAR clock and FIFO synchronization. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated DSP Interface | On-chip 8-word FIFO + status/control register eliminates external memory and address logic for burst-mode acquisition. |
| Dynamic Performance Guarantee | 100% production-tested SNR (72 dB), THD (–80 dB), and IMD - ensures spectral integrity in communication and audio applications. |
| Robust Timing Architecture | Comparator strobe gating prevents bus-induced conversion errors - allows safe concurrent read/write and conversion. |
| Flexible BUSY Handling | DISO bit (DB5) enables either WAIT-state extension or non-blocking access - adapts to ADSP-2100, TMS32020, or 68000 timing models. |
| Programmable FIFO Threshold | AFC2–AFC0 bits set ALFL trigger point from 1 to 8 words - optimizes interrupt latency vs. buffer utilization trade-off. |
| LC2MOS Process Integration | Monolithic combination of precision bipolar analog front-end and low-power CMOS logic - achieves 60 mW power at 100 kSPS. |
Applications
| Digital Signal Processing Systems | Speech Recognition Front-End |
|---|---|
Use Scenario: Real-time acquisition of microphone or codec output for FFT-based feature extraction in embedded voice command units. IC Role / Device Role / Timing Role: Primary ADC capturing 10–16 kHz audio band with 72 dB SNR and minimal group delay; FIFO buffers samples during DSP kernel execution. Use Value: 41 ns access time enables zero-wait-state reads into ADSP-2100 internal RAM, reducing instruction cycle overhead by >30% vs. slower ADCs. | Use Scenario: Digitizing analog speech waveforms in telephony gateways or VoIP endpoint devices requiring low-latency, high-SNR conversion. IC Role / Device Role / Timing Role: Bipolar ±3 V input directly interfaces electret mic preamp; on-chip 3 V reference ensures ratiometric accuracy across temperature. Use Value: 72 dB SNR at 10 kHz meets ITU-T G.711 wideband requirements without external dither or oversampling. |
| Spectrum Analysis Instruments | DSP-Based Servo Control |
Use Scenario: High-resolution frequency-domain measurement in portable analyzers where 50 kHz analog bandwidth and harmonic distortion < –80 dB are mandatory. IC Role / Device Role / Timing Role: ADC core in swept-frequency or real-time FFT engine; FIFO decouples sampling from display update rate. Use Value: Fully tested IMD (second/third order ≤ –80 dB) guarantees clean intermodulation-free spectra for two-tone testing per IEEE Std 1057. | Use Scenario: Closed-loop position/velocity feedback in industrial motion controllers using resolver or LVDT sensors with ±3 V output range. IC Role / Device Role / Timing Role: Synchronized sampling of analog feedback signals at servo loop rates up to 10 kHz; CONVST edge-triggering ensures deterministic jitter < 1 ns. Use Value: Asynchronous CONVST allows precise alignment with PWM dead-time intervals - critical for minimizing torque ripple in PMSM drives. |
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 |
|---|---|---|---|
| AD7878LN | Same package (N-28), identical specs except 41 ns data access time (vs. 57 ns in AD7878KN); same 72 dB SNR and 0°C to +70°C grade. | Optimized for tighter timing-critical DSP interfaces where sub-50 ns access is mandatory. | Select AD7878LN only if system timing margin requires guaranteed 41 ns t9 - otherwise AD7878KN offers identical dynamic performance at lower cost. |
| AD7879KN | Pin-compatible 12-bit ADC with 100 kHz sampling, but uses external reference and lacks FIFO; 70 dB SNR (vs. 72 dB), 60 ns access time. | Suitable for cost-sensitive designs where external reference control or FIFO-free architecture is preferred. | Choose AD7879KN when reference flexibility or reduced die complexity outweighs need for on-chip FIFO and highest SNR. |
Compared with AD7878LN, AD7878KN trades 16 ns slower data access for broader availability and lower unit cost, while retaining identical SNR, THD, and FIFO functionality; versus AD7879KN, it adds integrated reference and FIFO at the expense of slightly higher power and fixed reference voltage - making AD7878KN optimal for turnkey DSP-acquisition subsystems.
Availability
AD7878KN is available at Aetrix Electronics and suitable for digital signal processing systems, speech recognition front-ends, and spectrum analysis instruments requiring stable component supply across extended production cycles.
Supply support for AD7878KN 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 real-time control.
The AD7878KN belongs to Analog Devices' LC2MOS high-speed data acquisition product line, engineered specifically for seamless integration with digital signal processors - emphasizing low-jitter sampling, FIFO buffering, and production-tested ac performance over dc linearity.
FAQ
What is the operating temperature range for the AD7878KN?
The AD7878KN is rated for operation from 0°C to +70°C, matching the J/K/L-grade specification in the Analog Devices ordering guide. This commercial-grade temperature range is validated across all dynamic parameters including SNR, THD, and IMD, and applies to the N-28 plastic DIP package configuration shipped as AD7878KN. The part maintains full 72 dB SNR and 41 ns data access time across this entire range.
Does the AD7878KN require an external reference voltage?
No, the AD7878KN includes an on-chip 3 V Zener reference provided at the REF OUT pin, eliminating the need for external reference components. The reference is specified at ±10 mV error at 25°C and ±15 mV over the full 0°C to +70°C range, with load capability up to 500 µA. For capacitive loads exceeding 50 pF, a series resistor must be added per the AD7878KN datasheet Figure 1 guidelines.
How does the FIFO in the AD7878KN reduce software overhead in DSP applications?
The AD7878KN's 8-word FIFO allows up to eight consecutive conversions to complete before the DSP must service the ADC - decoupling sampling from processing. This eliminates frequent interrupt handling and enables burst reads at maximum processor speed, reducing instruction cycle count by up to 40% compared to single-sample ADCs. The ALFL flag and programmable threshold (AFC2–AFC0) further optimize interrupt scheduling.
Can the AD7878KN interface directly to the ADSP-2100 without level-shifting or timing adapters?
Yes, the AD7878KN is explicitly designed for direct interface to the ADSP-2100: DMWR and DMRD pins map one-to-one to ADSP-2100 control lines, BUSY and ALFL provide native interrupt signaling, and the 41 ns data access time meets ADSP-2100's minimum setup/hold requirements. No level shifters, latches, or glue logic are required - the AD7878KN operates natively at +5 V / –5 V supplies compatible with ADSP-2100 I/O voltage levels.
What is the purpose of the DISO bit (DB5) in the AD7878KN status/control register?
The DISO bit (DB5) controls whether AD7878KN's three-state outputs are enabled during BUSY low - i.e., while the track/hold is transitioning to hold mode. Writing '0' disables outputs to prevent bus transients from corrupting conversion; writing '1' allows non-blocking access. This enables compatibility with both WAIT-state processors (e.g., ADSP-2100 with DMACK) and non-WAIT architectures (e.g., TMS32010), making AD7878KN adaptable to diverse DSP timing models.
AD7878KN 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:
- -
- Input Type:
- -
- Data Interface:
- SPI, DSP
- Configuration:
- -
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- -
- Reference Type:
- -
- Voltage - Supply, Analog:
- -
- Voltage - Supply, Digital:
- -
- Features:
- -
- Operating Temperature:
- 0°C ~ 70°C
- Supplier Device Package:
- 28-PDIP
- Mounting Type:
- Through Hole
- Grade:
- -
- Qualification:
- -
AD7878KN FAQ
1.How can I place an order for AD7878KN through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7878KN 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 AD7878KN reliable?
The price and inventory of AD7878KN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7878KN is usually 5 days.
3.What payment methods are accepted for AD7878KN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7878KN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7878KN?
AD7878KN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7878KN 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 AD7878KN?
For technical support, including AD7878KN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7878KN requirements.
6.How does Aetrix verify that AD7878KN is sourced from the original manufacturer or authorized distributors?
All AD7878KN 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 AD7878KN meets industry standards.
7.What is the process for return or replacement of AD7878KN?
All AD7878KN units undergo pre-shipment inspection (PSI). If there is an issue with AD7878KN, 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 AD7878KN part is unused and in its original packaging.
Return procedure for AD7878KN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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