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Analog Devices Inc. AD7840JN
- Part No.:
- AD7840JN
- Manufacturer:
- Analog Devices Inc.
- Category:
- Digital to Analog Converters (DAC)
- Package:
- 24-DIP (0.300", 7.62mm)
- Datasheet:
-
AD7840JN.pdf
- Description:
- IC DAC 14BIT V-OUT 24DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,624
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Product details
Overview
AD7840JN from Analog Devices is a complete 14-bit voltage-output DAC with integrated 3 V buried Zener reference, output buffer amplifier, and dual-mode (parallel/serial) interface logic. It delivers ±3 V bipolar analog output, 78 dB min SNR at 1 kHz, 4 µs full-scale settling time, and operates from ±5 V supplies - used in high-speed DSP signal generation, servo control, and waveform synthesis systems.
For engineers reviewing the AD7840JN datasheet, AD7840JN pinout, AD7840JN application, or AD7840JN equivalent, key selection criteria include its double-buffered 14-bit latching architecture, 21 ns data setup time for parallel interfacing with ADSP-2100/TMS320x processors, serial mode support up to 6 MHz SCLK, and guaranteed monotonicity with ±2 LSB integral nonlinearity over 0°C to +70°C.
Technical Context
The AD7840JN implements a segmented 14-bit DAC architecture: three MSBs decoded to drive seven thin-film resistor switches, and eleven LSBs routed through an R-2R ladder. Its on-chip 3 V temperature-compensated Zener reference (±60 ppm/°C TC) feeds both the DAC core and bipolar bias circuitry, enabling direct ±3 V output scaling without external components when REF OUT is tied to REF IN.
Interface operation is governed by two independent latches: a 14-bit input latch accepting data via parallel (D0–D13) or serial (SDATA/SCLK/SYNC) paths, and a 14-bit DAC latch updated asynchronously via LDAC. In parallel mode, CS and WR are level-triggered with 45 ns min WR pulse width; in serial mode (CS tied to VSS), 16-bit frames clocked on SCLK falling edges support four configurable data formats (MSB/LSB first, justified).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 14 bits - defines smallest output step as 366 µV (6 V FS / 16,384) in 2's complement coding |
| Signal-to-Noise Ratio | 78 dB min at 1 kHz - enables clean audio/servo waveforms up to 20 kHz with external sample-and-hold |
| Integral Nonlinearity | ±2 LSB max - ensures monotonic behavior and predictable transfer function across full range |
| Output Voltage Range | ±3 V nominal - bipolar output directly compatible with op-amp-based signal conditioning stages |
| Settling Time | 4 µs max to ±1/2 LSB - supports update rates up to 100 kHz with minimal transient error |
| Power Dissipation | 100 mW max - low thermal load suitable for dense mixed-signal PCB layouts |
| Supply Voltages | ±5 V ±5% - standard dual-rail supply simplifies power system design versus single-supply alternatives |
Pinout & Package
AD7840JN is housed in a 24-pin plastic DIP (N-24 package), with pins arranged in dual in-line configuration for through-hole mounting and prototyping compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (CS/SERIAL) | Chip Select / Serial Mode Enable | Active-low parallel mode control; tied to VSS to force serial operation |
| 2 (WR/SYNC) | Write Pulse / Frame Sync | Rising edge loads parallel data; falling edge triggers serial frame sync |
| 3–17 (D13–D0) | 14-Bit Data Bus | D13 = MSB, D0 = LSB in parallel mode; multiplexed as SDATA/SCLK/FORMAT/JUSTIFY in serial mode |
| 12, 19 (DGND, AGND) | Digital & Analog Ground | Separate ground returns prevent digital noise coupling into analog output path |
| 18 (VDD), 21 (VSS) | Positive & Negative Supplies | ±5 V rails power logic, reference, and output amplifier - decoupling required per layout guidelines |
| 20 (VOUT) | Analog Output | Buffered ±3 V output capable of driving 2 kΩ || 100 pF loads |
| 22 (REF OUT), 23 (REF IN) | Reference Output/Input | On-chip 3 V reference usable externally (≤500 µA load); REF OUT → REF IN enables self-contained operation |
| 24 (LDAC) | Load DAC Latch | Falling edge transfers data from input latch to DAC latch - enables double-buffered updates without output glitches |
Key Features
| Feature | Design Value |
|---|---|
| Complete 14-bit DAC subsystem | Integrates reference, DAC core, and output amplifier - eliminates 3 external ICs in typical designs |
| Double-buffered interface logic | Independent input and DAC latches allow seamless background data loading while maintaining stable analog output |
| Parallel + serial interface flexibility | 21 ns data setup and 45 ns WR pulse enable direct connection to ADSP-2100/TMS320x; serial mode supports 6 MHz SCLK for space-constrained layouts |
| Bipolar output with internal scaling | ±3 V range derived from internal resistive network - no external gain/offset components needed for standard applications |
| Guaranteed monotonicity | Ensures no code-dependent output reversals - critical for closed-loop control and precision waveform generation |
Applications
| DSP-Based Waveform Synthesis | Servo Motor Control |
|---|---|
Use Scenario: Generating precise sine, triangle, or arbitrary waveforms in real-time using ADSP-2100 or TMS32020 processors. IC Role / Device Role / Timing Role: Voltage-output DAC providing analog excitation signals synchronized to processor clock and interrupt timing. Use Value: 78 dB SNR and 4 µs settling enable clean 20 kHz waveforms; parallel interface matches DSP bus timing without glue logic. | Use Scenario: Closed-loop position/velocity feedback in industrial motion controllers using PWM-driven amplifiers. IC Role / Device Role / Timing Role: Bipolar command signal generator converting digital PID outputs to ±3 V analog reference for amplifier input stages. Use Value: ±2 LSB INL and monotonicity ensure linear actuator response; LDAC-controlled double buffering prevents position jumps during updates. |
| High-Speed Modem Signal Generation | Test Equipment Arbitrary Waveform Output |
Use Scenario: Transmit path in voiceband or broadband modems requiring accurate baseband I/Q signal reconstruction. IC Role / Device Role / Timing Role: Dual-channel DAC interface (with companion ADC like AD7870) generating differential analog signals for RF upconversion. Use Value: THD ≤ –78 dB and peak spurious ≤ –78 dB meet ITU-T V.34 spectral mask requirements up to 3.4 kHz. | Use Scenario: Programmable signal source in automated test systems generating calibration stimuli for oscilloscopes or spectrum analyzers. IC Role / Device Role / Timing Role: Precision analog output stage driven by FPGA or microcontroller, updated via parallel or serial interface based on test sequence. Use Value: On-chip 3 V reference ensures long-term stability; 24-pin DIP allows socketed replacement during calibration maintenance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 14-bit voltage-output DAC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7840KN | Same architecture and package, but ±1 LSB INL (vs. ±2 LSB for AD7840JN) and 80 dB min SNR | Higher precision required in metrology or calibration equipment where 1 LSB error budget is critical | Select AD7840KN when tighter dc accuracy justifies cost premium; otherwise AD7840JN meets most industrial DSP interface needs |
| AD7845JP | 14-bit DAC in 28-pin PLCC, no on-chip reference - requires external 3 V reference and output op-amp | Designs needing smaller footprint or custom reference topology (e.g., ultra-low-noise LTZ1000) | Choose AD7845JP only if PLCC packaging or reference flexibility outweighs added BOM count and layout complexity |
Compared with AD7840KN and AD7845JP, the AD7840JN offers the optimal balance of integrated functionality (reference + buffer), commercial-grade accuracy, and DIP-based serviceability - making it preferred for prototyping, servo interfaces, and cost-sensitive production where ±2 LSB INL is acceptable.
Availability
AD7840JN is available at Aetrix Electronics and suitable for DSP waveform synthesis, servo motor control, high-speed modem signal generation, and test equipment arbitrary waveform output requiring stable component supply across extended production cycles.
Supply support for AD7840JN 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 digital signal processing semiconductors, founded in 1965 and headquartered in Wilmington, MA.
The AD7840JN belongs to Analog Devices' LC2MOS precision DAC product line, engineered for applications demanding high dynamic performance, integrated references, and robust microprocessor interfacing in industrial and communications systems.
FAQ
What is the operating temperature range of the AD7840JN?
The AD7840JN is rated for 0°C to +70°C operation, matching the commercial-grade J-version specification. This range supports use in office environments, benchtop test equipment, and non-extreme industrial enclosures. The part uses LC2MOS process technology to maintain stability across this span, with parameters like reference TC (±60 ppm/°C) and INL (±2 LSB) fully guaranteed within these limits - unlike the wider-range A/B or S versions.
Does the AD7840JN require an external reference voltage?
No, the AD7840JN does not require an external reference voltage because it integrates a factory-trimmed 3 V buried Zener reference (REF OUT) with ±10 mV initial accuracy and ±60 ppm/°C temperature coefficient. For self-contained operation, connect REF OUT to REF IN. External references may be used only if higher precision, lower noise, or different voltage levels (e.g., 2.5 V or 5 V) are needed - but doing so forfeits the AD7840JN's key advantage of complete subsystem integration.
Can the AD7840JN interface directly with the ADSP-2100 DSP processor?
Yes, the AD7840JN interfaces directly with the ADSP-2100 DSP processor using its parallel mode: the 21 ns data setup time and 45 ns WR pulse width align with ADSP-2100 bus timing, and example code "DM(DAC) = MR0" confirms native compatibility. No wait states or interface logic are needed. The LDAC signal allows asynchronous DAC latch updates, enabling double-buffered operation where the DSP writes new data to the input latch while the previous value remains active at VOUT - essential for glitch-free real-time waveform generation.
What is the purpose of the LDAC pin on the AD7840JN?
The LDAC (Load DAC) pin on the AD7840JN controls transfer of data from the input latch to the DAC latch. Its falling edge triggers this transfer, updating the analog output. This enables double-buffered operation: new data can be loaded into the input latch while the current DAC latch value holds VOUT stable. Holding LDAC low causes immediate transfer after input latch loading (in parallel mode) or on the 16th SCLK edge (in serial mode). Proper LDAC sequencing prevents output glitches during multi-word updates - a critical feature for servo control and waveform synthesis.
How does the AD7840JN achieve ±3 V bipolar output without external components?
The AD7840JN achieves ±3 V bipolar output using an internal resistive scaling network around its output buffer amplifier. With REF IN = +3 V, the amplifier's noninverting configuration and fixed internal gain/offset resistors produce VOUT = 2 × N × REFIN / 16384 − 3 V, yielding symmetric ±3 V swing for 2's complement codes from −8192 to +8191. This eliminates need for external op-amps, level shifters, or precision resistors - reducing BOM count, board area, and calibration effort compared to discrete DAC+amplifier solutions.
AD7840JN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Number of Bits:
- 14
- Number of D/A Converters:
- 1
- Settling Time:
- 4µs
- Output Type:
- Voltage - Buffered
- Differential Output:
- No
- Data Interface:
- Parallel, Serial
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- ±5V
- Voltage - Supply, Digital:
- -
- INL/DNL (LSB):
- ±2 (Max), ±0.9 (Max)
- Architecture:
- R-2R
- Operating Temperature:
- 0°C ~ 70°C
- Supplier Device Package:
- 24-PDIP
- Mounting Type:
- Through Hole
- Grade:
- -
- Qualification:
- -
AD7840JN FAQ
1.How can I place an order for AD7840JN through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7840JN 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 AD7840JN reliable?
The price and inventory of AD7840JN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7840JN is usually 5 days.
3.What payment methods are accepted for AD7840JN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7840JN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7840JN?
AD7840JN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7840JN 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 AD7840JN?
For technical support, including AD7840JN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7840JN requirements.
6.How does Aetrix verify that AD7840JN is sourced from the original manufacturer or authorized distributors?
All AD7840JN 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 AD7840JN meets industry standards.
7.What is the process for return or replacement of AD7840JN?
All AD7840JN units undergo pre-shipment inspection (PSI). If there is an issue with AD7840JN, 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 AD7840JN part is unused and in its original packaging.
Return procedure for AD7840JN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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