Analog Devices Inc. AD7880BN

Overview

AD7880BN from Analog Devices is a 12-bit monolithic successive-approximation analog-to-digital converter (ADC) operating from a single +5 V supply, featuring 66 kHz throughput rate, 12 µs conversion time, and 3 µs track/hold acquisition. It supports unipolar (0 V to +5 V, 0 V to +10 V) and bipolar (±5 V) input ranges using internal resistor networks, and is used in battery-powered portable instrumentation and digital signal processing systems.

For engineers reviewing the AD7880BN datasheet, AD7880BN pinout, AD7880BN application, or AD7880BN equivalent, this page delivers verified technical context, real-world interface timing constraints, confirmed dynamic performance (70 dB SNR, –80 dB THD), package-specific thermal and layout guidance for the 24-pin plastic DIP (N-24), and validated alternative options for signal chain redesign.

Technical Context

The AD7880BN integrates a charge-balanced comparator-based track/hold amplifier with 3 µs acquisition time and a 12-bit SAR ADC core clocked at 2.5 MHz, delivering 15 µs total throughput. Its LC2MOS process enables mixed-signal integration of precision bipolar front-end and low-power CMOS logic on a single die.

Interface logic supports asynchronous CONVST-triggered conversion initiation and synchronous parallel data readout via CS/RD-controlled three-state DB0–DB11 outputs. The MODE pin selects between normal operation (IDD = 7.5 mA max) and power-save mode (IDD = 750 µA max), with BUSY indicating active conversion status.

Key Specifications

Pinout & Package

AD7880BN is housed in a 24-pin, 0.3-inch-wide plastic dual-in-line package (N-24), compatible with standard through-hole PCB assembly and socketing. Thermal resistance θ_JA = 65°C/W (JEDEC std). Pin 1 is located at top-left corner when notch faces upward.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7880BN, AD7888BRZ trades parallel speed for serial footprint reduction and higher sampling rate, while MAX1113ECPP sacrifices bus timing predictability for integrated reference and simpler firmware - neither offers the same combination of 3 µs track/hold, 0–10 V unipolar range, and hardware-controlled power-save mode.

Availability

AD7880BN is available at Aetrix Electronics and suitable for battery-powered instrumentation, digital signal processing front-ends, and industrial control loop sampling requiring stable component supply across extended temperature ranges (–40°C to +85°C).

Supply support for AD7880BN 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 AD7880BN belongs to Analog Devices' legacy LC2MOS precision ADC family, designed specifically for low-power, single-supply data acquisition in portable and embedded systems where dc accuracy and dynamic performance must coexist.

FAQ

What is the maximum clock frequency supported by the AD7880BN?

The AD7880BN is specified for operation with a 2.5 MHz CLKIN signal. While it may function at slightly higher frequencies, accuracy degrades due to hold capacitor leakage - normalized linearity error increases above 2.5 MHz per Figure 10. For guaranteed 12-bit performance, maintain CLKIN at exactly 2.5 MHz with 40/60–60/40 duty cycle. The AD7880BN's conversion time remains fixed at 12 µs regardless of minor clock variation.

Does the AD7880BN require external calibration for offset and full-scale errors?

The AD7880BN does not require factory calibration, but system-level offset and full-scale adjustment may be needed for metrology-grade applications. Figures 11–14 detail op-amp-based trim procedures: apply 0.61 mV (1/2 LSB) for unipolar offset nulling, and 4.9982 V (FS–3/2 LSB) for full-scale tuning. These adjustments compensate for the AD7880BN's ±15 LSB full-scale error (B-grade) and ±10 LSB bipolar zero error.

Can the AD7880BN interface directly with an 8086 microprocessor?

Yes - the AD7880BN interfaces directly with the 8086 using WR-gated CONVST and AS/RD-derived read strobes, as shown in Figure 19. No glue logic is required beyond address decoding. The AD7880BN's 57 ns data access time satisfies 8086's 100 ns minimum read setup, and its three-state outputs prevent bus contention. Ensure VDD decoupling (0.1 µF ceramic + 10 µF tantalum) is placed within 5 mm of AD7880BN pins 24 and 3.

What is the purpose of the MODE pin on the AD7880BN?

The MODE pin controls power state: logic high (VDD) enables normal operation (7.5 mA IDD), while logic low (0 V) activates power-save mode (750 µA IDD). This feature is essential for intermittent-sampling applications like portable data loggers. Unlike software-controlled sleep modes, AD7880BN's MODE pin reduces current instantly without clock gating or register writes - critical for sub-millisecond wake-up latency.

How does the AD7880BN achieve bipolar (±5 V) input range with only a +5 V supply?

The AD7880BN achieves ±5 V input range using an internal resistor network that configures VINA and VINB as differential inputs referenced to VREF (tied to VDD). As shown in Figure 7, connecting VINB to VREF and VINA to the signal creates a level-shifted topology where the 12-bit DAC compares against ±VREF. This eliminates need for external op-amps or negative supplies - a key differentiator of the AD7880BN versus generic 12-bit ADCs.