Analog Devices Inc. AD7870KPZ

Overview

AD7870KPZ from Analog Devices is a complete monolithic 12-bit sampling analog-to-digital converter (ADC) with integrated track-and-hold amplifier, laser-trimmed internal clock, and on-chip 3 V buried Zener reference. It delivers 100 kHz sampling rate, 72 dB SNR at 10 kHz input, and ±3 V bipolar input range. Designed for high-fidelity data acquisition in industrial instrumentation and DSP systems, it operates from ±5 V supplies and achieves 57 ns data access time.

For engineers reviewing the AD7870KPZ datasheet, AD7870KPZ pinout, AD7870KPZ application, or AD7870KPZ equivalent, this page provides verified technical context, real-world interface timing constraints, confirmed dynamic and dc accuracy specs, package-specific layout guidance, and validated alternative options for signal chain design continuity.

Technical Context

The AD7870KPZ implements a successive approximation register (SAR) architecture with a dedicated 2 μs track-and-hold amplifier and internal 3 V temperature-compensated Zener reference. Its self-contained 2.5 MHz laser-trimmed clock guarantees 8 μs max conversion time without external timing components.

It supports three digital output formats-12-bit parallel, two 8-bit bytes, or serial-via configurable pins (12/8/CLK, HBEN, SSTRB, SCLK, SDATA). Control logic enables asynchronous conversion start via CONVST or CS, with BUSY/INT signaling completion and RD-gated data readout.

Key Specifications

Pinout & Package

AD7870KPZ is housed in a 24-pin, 0.3-inch-wide plastic dual-in-line package (PDIP), pin-compatible with industry-standard DIP-24 footprints and socketable for prototyping and test.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit sampling ADC applications.

Compared with AD7870KPZ, AD7871KPZ offers identical packaging and timing but mandates hardware changes for bipolar operation, while ADS7822U trades integration for size and interface flexibility - making AD7870KPZ optimal for legacy-compatible, low-component-count 12-bit acquisition.

Availability

AD7870KPZ is available at Aetrix Electronics and suitable for industrial data acquisition, test equipment manufacturing, and medical device production requiring stable component supply and long-term lifecycle assurance.

Supply support for AD7870KPZ 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 AD7870KPZ belongs to Analog Devices' legacy LC2MOS precision ADC family, engineered for turnkey signal digitization in industrial and instrumentation applications where integration, dc accuracy, and dynamic performance are jointly critical.

FAQ

What is the maximum analog input frequency supported by the AD7870KPZ while maintaining 12-bit accuracy?

The AD7870KPZ maintains full 12-bit accuracy for input signals up to 50 kHz, as confirmed by its 100 kHz sampling rate and Nyquist criterion. Its track-and-hold amplifier has a 0.1 dB cutoff at ~500 kHz, ensuring minimal aperture error and distortion even at full throughput - enabling faithful digitization of fast transients in motor current or vibration sensing.

Does the AD7870KPZ require external clock components when using its internal oscillator?

No, the AD7870KPZ does not require external clock components when using its internal oscillator. Tying the CLK pin to VSS activates the laser-trimmed on-chip clock, guaranteeing 8 μs max conversion time with no external crystals, capacitors, or resistors - a key advantage for reducing bill-of-materials and board space in cost-sensitive instrumentation designs.

How is the AD7870KPZ's 3 V reference used internally, and can it drive external circuitry?

The AD7870KPZ's 3 V buried Zener reference powers the internal DAC and provides dc bias for bipolar operation. It is accessible at REF OUT and rated for up to 500 μA load current with ±10 mV initial tolerance and ±60 ppm/°C tempco. External use is permitted but requires strict 50 pF max capacitance and recommended RC decoupling (200 Ω + 10 μF || 0.1 μF) to suppress switching noise.

What digital interface modes does the AD7870KPZ support, and how are they selected?

The AD7870KPZ supports three interface modes: 12-bit parallel, two 8-bit bytes, or serial. Selection is controlled by the 12/8/CLK pin voltage (+5 V = parallel only; 0 V = byte/serial with gated SCLK; −5 V = byte/serial with continuous SCLK) and HBEN state. All modes share the same RD, CS, and CONVST control timing, enabling flexible integration across processor architectures.

Is the AD7870KPZ pin-compatible with other members of the AD7870/AD7875/AD7876 family?

The AD7870KPZ shares the same 24-pin PDIP package and pinout with AD7875KPZ and AD7876KPZ variants, but analog input ranges differ (±3 V, 0–5 V, ±10 V respectively). Digital interface pins, power, ground, and control signals are fully aligned - allowing PCB reuse across variants when input conditioning circuitry is adapted for the target range.