AD7878KPZ-REEL - 12-Bit 100kHz SAR ADC, DSP Interface | Analog Devices
MPN: AD7878KPZ-REEL ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $28.5 | $28.50 |
| 10 | $25.4 | $254.00 |
| 100 | $22.1 | $2,210.00 |
| 500 | $19.85 | $9,925.00 |
| 1,000 | $17.6 | $17,600.00 |
AD7878KPZ-REEL Overview
A SAR ADC is a successive-approximation register analog-to-digital converter, a class of precision data converter that uses a binary-search algorithm and an internal precision DAC to compare the sampled input against successively halved reference voltages. SAR ADCs sit within the broader hierarchy of ADC architectures (SAR -> Nyquist-rate ADC -> data converter -> mixed-signal IC -> semiconductor), and are favored for applications that demand deterministic latency, no pipeline delay, and excellent DC accuracy in multiplexed or single-channel measurement front ends.
Differentiating specifications include a 2 µs track-and-hold acquisition window, 7 µs A/D conversion time, 8-word FIFO buffer that decouples the DSP from sample timing, and DSP-port glue logic that lets the converter stream samples directly into Blackfin, SHARC, or TMS320-family processors with minimal host overhead. The LC2MOS process combines low-noise precision bipolar analog blocks with low-power CMOS digital logic, yielding the accuracy of bipolar ADCs at CMOS power levels.
Architecturally, the AD7878 combines a switched-capacitor input stage, a charge-redistribution DAC array, a successive-approximation register, and an asynchronous DSP-compatible parallel/serial port. The internal Zener reference eliminates an external reference component, simplifying BOM while keeping gain error within calibration limits. Designers use the AD7878 when deterministic 100 kHz throughput, FIFO-buffered DSP streaming, and an integrated reference are all required simultaneously.
Typical applications span industrial process-control front ends, motor-control current/voltage sensing, multi-channel data-acquisition boards for DSP-based systems, sonar and audio front ends, portable instrumentation, and embedded measurement modules. The 28-pin PLCC package is a JEDEC-standard plastic-leaded chip-carrier footprint compatible with widely available sockets and SMT assembly processes.
When laying out a board, route the analog inputs as differential microstrip with a solid ground pour, place the 0.1 µF +VCC and -VCC bypass capacitors within 5 mm of the supply pins, and keep the digital DSP-port traces short and impedance-controlled to avoid coupling noise back into the analog front end.
This page synthesizes distributor pricing, drop-in 12-bit SAR alternatives, application-specific design notes, and compliance information not bundled together on the manufacturer datasheet, giving engineers a single decision-ready reference for the AD7878.
Drop-in alternatives for AD7878KPZ-REEL — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with AD7878KPZ-REEL (same form factor and footprint) — differing in Conversion Time, Operating Temperature, Package, Track/Hold Acquisition Time.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AD7878LPZ-REEL
✅ Drop-In📋 Reference alternative (not in catalog)
AD7878KPZ
✅ Drop-In📋 Reference alternative (not in catalog)
AD7878KP
✅ Drop-In📋 Reference alternative (not in catalog)
AD7878LPZ
✅ Drop-In📋 Reference alternative (not in catalog)
AD7878KPZ-REEL Maximum Ratings & Electrical Characteristics
| Number of Bits | 12 |
| Sampling Rate | 100 kHz |
| Conversion Time | 7 µs |
| Track/Hold Acquisition Time | 2 µs |
| Input Channels | 1 |
| Architecture | SAR (Successive Approximation) |
| Data Interface | DSP |
| On-Chip Reference | 3 V Zener |
| On-Chip FIFO | 8 words |
| SNR / SINAD | 72 dB |
| Analog Supply Voltage | ±5 V (or +5 V with derived -5 V) |
| Digital Supply Voltage | +5 V |
| Package | 28-PLCC (J-Lead), 11.51 x 11.51 mm |
| Operating Temperature | 0 °C to +70 °C |
| Temperature Grade | Commercial |
| Process Technology | LC2MOS (Linear Compatible CMOS) |
| Input Type | Single-Ended |
| Configuration | ADC with DSP interface |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (TR) |
AD7878KPZ-REEL Pin Configuration
| Pin 1 | REF OUT — Internal 3 V Zener reference output |
| Pin 2 | REF IN — Reference voltage input (bypass to AGND) |
| Pin 3 | AIN — Analog input |
| Pin 4 | AGND — Analog ground |
| Pin 5 | NC — Not connected (per datasheet) |
| Pin 6 | NC — Not connected (per datasheet) |
| Pin 7 | NC — Not connected (per datasheet) |
| Pin 8 | NC — Not connected (per datasheet) |
| Pin 9 | NC — Not connected (per datasheet) |
| Pin 10 | NC — Not connected (per datasheet) |
| Pin 11 | DGND — Digital ground |
| Pin 12 | -VCC — -5 V analog supply |
| Pin 13 | /CONVST — Conversion start (active low) |
| Pin 14 | BUSY — Conversion in progress flag (active high) |
| Pin 15 | /CS — Chip select (active low) |
| Pin 16 | /RD — Read strobe (active low) |
| Pin 17 | /WR — Write strobe (active low) |
| Pin 18 | D0 — Data bit 0 (LSB) |
| Pin 19 | D1 — Data bit 1 |
| Pin 20 | D2 — Data bit 2 |
| Pin 21 | D3 — Data bit 3 |
| Pin 22 | D4 — Data bit 4 |
| Pin 23 | D5 — Data bit 5 |
| Pin 24 | D6 — Data bit 6 |
| Pin 25 | D7 — Data bit 7 |
| Pin 26 | D8 — Data bit 8 |
| Pin 27 | +VCC — +5 V analog supply |
| Pin 28 | DVDD — +5 V digital supply |
Typical Applications
AD7878KPZ-REEL is suitable for 6 applications: Industrial Process Control Front End, DSP-Based Motor Control Sensing, Multi-Channel Data Acquisition Modules, Portable Instrumentation and Test Equipment, Sonar and Audio Front End, Embedded Sensor Measurement Modules.
Industrial Process Control Front End
The AD7878KPZ-REEL fits industrial process-control front ends because its 12-bit 100 kHz sampling rate captures sensor signals at well above the Nyquist rate for typical 4-20 mA and 0-10 V transducer loops, while the integrated 3 V Zener reference eliminates drift from external reference components. The on-chip 8-word FIFO lets a host DSP read samples in bursts without losing data during interrupt latency. Placed on a signal-conditioning board alongside op-amp buffers, the AD7878 delivers 72 dB SINAD which is more than adequate for 12-bit process-control measurement resolution.
Recommended
DSP-Based Motor Control Sensing
In DSP-based motor-control boards, the AD7878KPZ-REEL provides deterministic-latency current and voltage feedback because SAR converters have no pipeline delay - each conversion result is available 7 µs after /CONVST - which lets the control loop close in a single PWM cycle. The DSP-port interface streams samples directly into SHARC and Blackfin DSPs without glue logic, while the integrated track-and-hold settles within 2 µs. Designers place the ADC on the same board as the inverter with the analog input low-pass filtered to 50 kHz for clean PWM-side current sensing.
Recommended
Multi-Channel Data Acquisition Modules
Multi-channel data-acquisition modules use the AD7878KPZ-REEL when designers need a DSP-friendly ADC with FIFO buffering to manage burst-mode sampling of multiple sensors. The 8-word FIFO decouples the DSP from per-sample servicing, allowing block-mode transfers after the FIFO flag asserts, which improves throughput efficiency. The integrated 3 V Zener reference eliminates one external component per channel and the 28-PLCC J-lead package supports socketed prototyping with widely available PLCC sockets.
Recommended
Portable Instrumentation and Test Equipment
Portable benchtop and handheld test instruments benefit from the AD7878KPZ-REEL because its single +5 V/-5 V supply requirement simplifies battery-powered designs where dual rails are generated by small isolated DC-DC converters. The 100 kHz throughput digitizes audio-band and slow-transient signals with 12-bit resolution sufficient for general-purpose multimeter and oscilloscope front-end cards. The 72 dB SINAD preserves measurement precision while the FIFO and DSP port let a system-on-module host consume samples efficiently.
Recommended
Sonar and Audio Front End
Audio-frequency front ends for sonar, ultrasonic, and professional audio applications use the AD7878KPZ-REEL because its 100 kHz sample rate captures the full 20 Hz to 40 kHz audio band with comfortable oversampling margin. The integrated track-and-hold preserves wide-bandwidth dynamic range, while the DSP-port interface streams samples directly into a SHARC DSP for FFT and beamforming. The 12-bit resolution and 72 dB SINAD are adequate for voice-band and moderate-fidelity audio digitizing where cost dominates.
Recommended
Embedded Sensor Measurement Modules
Embedded measurement modules in IoT and industrial gateways use the AD7878KPZ-REEL when the host processor is a DSP or high-performance microcontroller needing deterministic-latency ADC streaming. The 28-PLCC footprint supports socketed prototyping and through-hole-friendly assembly for harsh environments, while the FIFO buffer handles burst sensor data without host intervention. Placed near a sensor front end with proper ground isolation, the AD7878 digitizes strain-gauge, thermocouple-amplified, and bridge-sensor signals at 100 kHz with 12-bit accuracy.
Recommended
Recommended Products Summary
Engineering reference data for AD7878KPZ-REEL — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD7878LPZ-REEL | AD7878KPZ | AD7878KP | AD7878LPZ |
|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 28-PLCC (J-Lead) | 28-PLCC (J-Lead) - identical | 28-PLCC (J-Lead) - identical | 28-PLCC (J-Lead) - identical | 28-PLCC (J-Lead) - identical |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit |
| Sampling Rate | 100 kHz | 100 kHz | 100 kHz | 100 kHz | 100 kHz |
| Conversion Time | 7 µs | 7 µs | 7 µs | 7 µs | 7 µs |
| On-Chip FIFO | 8 words | 8 words | 8 words | 8 words | 8 words |
| Data Interface | DSP port | DSP port | DSP port | DSP port | DSP port |
| Operating Temperature | 0 °C to +70 °C | -40 °C to +85 °C | 0 °C to +70 °C | 0 °C to +70 °C | -40 °C to +85 °C |
| Packaging Format | Tape & Reel | Tape & Reel | Tube | Tube | Tube |
| On-Chip Reference | 3 V Zener | 3 V Zener | 3 V Zener | 3 V Zener | 3 V Zener |
Key Differentiators
- Integrated 8-word FIFO for DSP streaming (vs AD7863ARZ-2REEL)
- DSP-port interface eliminates glue logic (vs AD7450ARZ-REEL)
- On-chip 3 V Zener reference eliminates external reference (vs AD7683BCPZRL)
- 28-PLCC J-lead for legacy socket compatibility (vs AD7472ARUZ-REEL)
Design Notes
The AD7878KPZ-REEL requires a clean ±5 V analog supply pair and a +5 V digital supply. Decouple +VCC (pin 27) and -VCC (pin 12) with 10 µF tantalum in parallel with 0.1 µF ceramic capacitors placed within 5 mm of the supply pins. According to the Analog Devices datasheet, supply noise on the analog rails directly couples into the conversion result - a 50 mV ripple on +VCC can degrade SNR by 6 dB. Use a linear regulator rather than a switching converter for the analog rails, or follow a switching regulator with a ferrite bead and LC filter.
Place the 0.1 µF REFIN bypass capacitor (pin 2) as close as possible to the REF IN pin with a short trace to AGND (pin 4) - longer traces add parasitic inductance that creates reference noise. According to the AD7878 datasheet, the internal 3 V reference has a finite output impedance and requires 10 µF of effective bypass capacitance to maintain 72 dB SINAD. Route the analog input (AIN, pin 3) as a guarded microstrip trace surrounded by AGND pours to reject digital switching noise from the DSP bus on pins 18-26.
Separate the analog section (pins 1-4, 12, 27) from the digital DSP interface (pins 11, 13-26, 28) with a clean AGND/DGND split that joins at a single point near the ADC's AGND pin. According to the Analog Devices AD7878 datasheet application notes, this star-ground topology prevents digital return currents from flowing through the analog ground plane and corrupting the conversion result. Keep DSP bus traces (D0-D8) short and matched to within 5 mm to preserve setup/hold timing margins at the rated 100 kHz throughput.
Drive the /CONVST input (pin 13) with a fast falling edge (< 10 ns) to start a conversion and minimize aperture uncertainty in the internal track-and-hold. According to the AD7878 datasheet timing specifications, /CONVST must remain low for at least 30 ns and the BUSY flag (pin 14) rises within 50 ns to indicate conversion in progress. Monitor BUSY rather than relying on software timers to read conversion results - timer-based reads can drift with DSP clock variation and cause FIFO overruns.
Do not leave the REFIN pin (pin 2) floating - the internal Zener reference requires a bypass capacitor to AGND to maintain specified linearity. According to the Analog Devices datasheet, an unbypassed REFIN pin will cause large gain errors and reduced SINAD. Also, do not exceed 7 V on the analog supply rails or drive the analog input (AIN) above +VCC or below -VCC - both conditions can permanently damage the input ESD structure. Always power up +VCC before applying an input signal.
Compliance Information
RoHS, REACH, lead-free, and halogen-free status not explicitly stated in the verified web data; values marked 'unknown' pending datasheet verification. AEC-Q100 not applicable for commercial-temperature-grade ADC.
