Analog Devices Inc. AD7870KP

Overview

AD7870KP from Analog Devices is a complete monolithic 12-bit successive approximation analog-to-digital converter (ADC) with integrated track-and-hold amplifier, laser-trimmed internal clock, and on-chip 3 V buried Zener reference. It supports ±3 V bipolar input range, achieves 100 kHz sampling rate, delivers 72 dB SNR at 10 kHz input, and features 57 ns data access time for microprocessor interfacing.

For engineers reviewing the AD7870KP datasheet, AD7870KP pinout, AD7870KP application, or AD7870KP equivalent, this page provides verified technical context, real-world interface timing constraints, confirmed dynamic and dc accuracy specs, package-specific layout considerations, and validated alternative options for data acquisition systems requiring stable 12-bit resolution and sub-10 μs conversion cycles.

Technical Context

The AD7870KP implements a SAR architecture with a fast-settling DAC, high-speed comparator, and internal 3 V temperature-compensated Zener reference. Its track-and-hold acquires signals to 12-bit accuracy in ≤2 μs, enabling full-power conversion up to 50 kHz while maintaining 72 dB SNR at 10 kHz.

It supports three digital output formats-12-bit parallel, two-byte, and serial-via configurable pins (12/8/CLK, HBEN, SSTRB, SCLK, SDATA). Conversion is initiated asynchronously by CONVST or CS, and the internal clock (laser-trimmed to 2.5 MHz) guarantees 6.5–9 μs conversion time without external components.

Key Specifications

Pinout & Package

The AD7870KP is housed in a 24-pin, 0.3-inch-wide plastic dual-in-line package (PDIP), with pin 1 identified by notch or dot. All pins are TTL-compatible; AGND and DGND must be separated and connected at single point.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7870JN, the AD7870KP offers extended temperature reliability without sacrificing speed or interface flexibility; versus MAX195BCPP, it trades resolution for integration, reducing design risk and time-to-market in cost-sensitive industrial DAQ systems.

Availability

AD7870KP is available at Aetrix Electronics and suitable for industrial data acquisition, test equipment, DSP-based signal processing, and medical instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7870KP 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, headquartered in Norwood, MA.

The AD7870KP belongs to the LC2MOS 12-bit sampling ADC product line, designed specifically for embedded data acquisition systems needing self-contained, low-power, high-accuracy digitization without external timing or reference components.

FAQ

What is the maximum analog input frequency the AD7870KP can accurately digitize?

The AD7870KP supports full-power signal conversion up to 50 kHz while maintaining 12-bit accuracy and 72 dB SNR at 10 kHz. Its track-and-hold amplifier has a 0.1 dB cutoff typically at 500 kHz, ensuring faithful capture of transient-rich waveforms within its Nyquist band. The AD7870KP is not specified for RF or IF sampling beyond baseband audio and instrumentation frequencies.

Does the AD7870KP require external components to operate?

No, the AD7870KP is a complete ADC requiring only power supply decoupling capacitors (typically 0.1 μF ceramic + 10 μF tantalum per supply rail). It integrates a 3 V buried Zener reference, laser-trimmed clock oscillator, and track-and-hold amplifier - eliminating external op-amps, references, crystals, or timing ICs needed by discrete ADC solutions.

How does the AD7870KP handle bipolar offset error in system calibration?

The AD7870KP specifies ±5 LSB bipolar zero error (max) at full temperature range. Offset adjustment is performed in the analog domain - typically via ac coupling or an external op-amp summing junction - before VIN. The AD7870KP itself does not include digital offset trim registers; system-level calibration compensates for this error during startup or periodic maintenance.

Can the AD7870KP interface directly with a 3.3 V microcontroller?

No - the AD7870KP operates from ±5 V supplies and all digital I/Os are TTL-compatible (VOH ≥ 4.0 V, VOL ≤ 0.4 V), requiring level translation for safe interfacing with 3.3 V logic. Direct connection risks damaging the microcontroller inputs due to 5 V output swing; a dedicated level shifter or buffer IC (e.g., 74LVC245) must be used in the data and control paths.

What package type is used for the AD7870KP and what are its key mechanical constraints?

The AD7870KP uses a 24-pin plastic dual-in-line package (PDIP) with 0.3 inch body width and 0.1 inch pin pitch. Its lead frame is tin-lead plated, and the package meets JEDEC MS-001 standards. Key constraints include mandatory separation of AGND and DGND planes, strict decoupling near VDD/VSS pins, and avoidance of thermal vias under the package body to prevent solder joint stress during reflow.