Analog Devices Inc. AD7870JP

Overview

AD7870JP 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 delivers 100 kHz sampling rate, 72 dB SNR at 10 kHz input, ±3 V bipolar input range, and 57 ns data access time. It targets precision data acquisition in industrial instrumentation and DSP-based signal processing systems.

For engineers reviewing the AD7870JP datasheet, AD7870JP pinout, AD7870JP application, or AD7870JP 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 system-level design continuity.

Technical Context

The AD7870JP implements a SAR architecture with a fast-settling DAC, high-speed comparator, and internal 3 V temperature-compensated Zener reference trimmed to ±10 mV. Its track-and-hold acquires signals to 12-bit accuracy in ≤2 μs, enabling full-power conversion up to 50 kHz while maintaining 70–72 dB SNR.

It supports three digital output formats-parallel 12-bit word, two 8-bit bytes, or serial data-with mode selection via the 12/8/CLK pin. Control logic synchronizes conversion start via CONVST (asynchronous) or CS (edge-triggered), and BUSY/INT provides status feedback with guaranteed 70 ns propagation delay.

Key Specifications

Pinout & Package

AD7870JP is packaged in a 24-pin, 0.3-inch-wide plastic dual-in-line package (PDIP). Pin spacing is 0.1 inch; body width is 0.3 inch; lead count is 24; RoHS-compliant lead finish per Analog Devices specification.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7870JP, AD7875JP offers identical speed and packaging but lacks bipolar capability, while MAX195BCPP trades integration and ease-of-use for higher resolution and external flexibility-neither is pin-compatible, and both require layout changes and revised firmware interface logic.

Availability

AD7870JP is available at Aetrix Electronics and suitable for industrial data acquisition, test equipment, medical instrumentation, and DSP-based signal processing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7870JP 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, serving industrial, automotive, communications, and healthcare markets.

The AD7870JP belongs to Analog Devices' legacy LC2MOS precision ADC product line, designed specifically for embedded data acquisition systems demanding monolithic integration, guaranteed dynamic performance, and simplified board-level implementation without external timing or reference components.

FAQ

What is the maximum input frequency the AD7870JP can accurately digitize?

The AD7870JP can convert full-power analog signals up to 50 kHz while maintaining 12-bit accuracy and specified SNR. This is enabled by its 2 μs track-and-hold acquisition time and 8 μs conversion time, resulting in a 10 μs total cycle. The track-and-hold's 0.1 dB bandwidth is typically 500 kHz, ensuring faithful capture of input transients within the Nyquist limit of its 100 kHz sampling rate. AD7870JP performance remains within datasheet limits up to this frequency under standard operating conditions.

Does the AD7870JP require external clock components?

No, the AD7870JP does not require external clock components. It features an on-chip laser-trimmed oscillator that delivers a stable 2.5 MHz clock, guaranteeing conversion times of 6.5–9 μs. The CLK pin may be tied to VSS to activate this internal clock. An external TTL-compatible clock can be applied to CLK if tighter timing control or synchronization with system clocks is needed-but no resistors, capacitors, or crystals are necessary for basic operation. AD7870JP achieves full functionality with only power supply decoupling capacitors.

How is the analog input range configured on the AD7870JP?

The AD7870JP has a fixed ±3 V bipolar analog input range, defined by its internal scaling network and reference. No external resistors or configuration pins alter this range-it is inherent to the AD7870JP silicon design. The input presents ≈15 kΩ impedance and accepts signals directly referenced to AGND. Unlike the AD7875 (0–5 V) or AD7876 (±10 V), the AD7870JP's input structure is optimized for differential sensor interfaces and op-amp outputs centered at 0 V. AD7870JP output coding is twos-complement, with 1 LSB = 1.46 mV.

Can the AD7870JP operate with a single +5 V supply?

No, the AD7870JP requires dual ±5 V supplies (VDD = +5 V, VSS = −5 V) for proper operation. Its internal track-and-hold amplifier, DAC, and comparator circuits depend on symmetric rails to handle the ±3 V input range and generate correct twos-complement output codes. Operating with only +5 V and ground will result in undefined behavior, failure to acquire negative inputs, or damage due to violation of absolute maximum ratings (VSS to AGND must be −0.3 V to −7 V). AD7870JP must be powered as specified: ±5 V ±5% with separate AGND and DGND connections.

What digital interface modes does the AD7870JP support?

The AD7870JP supports three mutually exclusive digital interface modes selected by the 12/8/CLK pin voltage: (1) +5 V → 12-bit parallel output only; (2) 0 V → byte or serial output with gated SCLK; (3) −5 V → byte or serial output with continuous SCLK. Parallel mode uses DB0–DB11 with RD/CS handshaking; byte mode uses HBEN to toggle between high/low bytes; serial mode uses SDATA, SCLK, and SSTRB with open-drain outputs requiring external pull-ups. All modes share the same BUSY/INT status signal and CONVST trigger. AD7870JP does not support I²C, SPI, or UART natively.