Analog Devices Inc. AD7864BS-1

Overview

AD7864BS-1 from Analog Devices is a 4-channel, simultaneous-sampling, 12-bit analog-to-digital converter (ADC) with 1.65 μs conversion time, ±10 V/±5 V input ranges, on-chip 2.5 V reference, and high-speed parallel interface. It preserves phase coherence across channels and targets real-time control systems requiring synchronized acquisition of motor currents or voltage waveforms.

For engineers reviewing the AD7864BS-1 datasheet, AD7864BS-1 pinout, AD7864BS-1 application, or AD7864BS-1 equivalent, key selection criteria include simultaneous sampling capability, aperture delay matching ≤4 ns, bipolar input support, 130 kSPS four-channel throughput, and MQFP-44 package compatibility with industrial signal conditioning layouts.

Technical Context

The AD7864BS-1 integrates four independent track-and-hold amplifiers with ≤4 ns aperture delay matching and a single 12-bit successive approximation ADC core. Its internal 2.5 V reference (±20 mV error over temperature) and signal scaling circuitry enable direct interfacing to ±10 V or ±5 V industrial sensors without external level-shifting.

Conversion is triggered by a single CONVST edge, initiating simultaneous hold and sequential channel conversion. Channel selection is configurable via hardware (SL1–SL4 pins) or software (DB0–DB3 register write), with BUSY and EOC signals providing precise timing control for microprocessor or DSP synchronization.

Key Specifications

Pinout & Package

AD7864BS-1 is housed in a 44-lead MQFP (0.3 inch square) package with exposed thermal pad. Pin functions are fully defined in Analog Devices Rev. D datasheet Figure 3 and Table 4.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-channel simultaneous-sampling ADC applications.

Compared with AD7864BS-1, AD7656ASTZ trades 130 kSPS throughput and integrated reference for 4-bit resolution gain, while ADS8556IPMR adds two channels and SPI flexibility at the cost of deterministic parallel-read timing and on-chip reference convenience.

Availability

AD7864BS-1 is available at Aetrix Electronics and suitable for AC motor control, uninterruptible power supplies, and data acquisition systems requiring stable component supply, long-term obsolescence management, and traceable industrial-grade sourcing.

Supply support for AD7864BS-1 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.

The AD7864 product line delivers simultaneous-sampling ADCs optimized for real-time industrial control, featuring integrated signal conditioning, tight channel-to-channel timing alignment, and robust industrial packaging.

FAQ

What is the maximum sample rate for all four channels on the AD7864BS-1?

The AD7864BS-1 achieves a maximum throughput of 130 kSPS when converting all four channels in sequence using the read-during-conversion mode. This is determined by the 1.65 μs conversion time per channel plus inter-channel timing overhead. The device supports higher single-channel rates up to 500 kSPS, but full four-channel operation is capped at 130 kSPS to maintain simultaneous sampling integrity and bus timing compliance. AD7864BS-1 datasheet Rev. D Table 1 confirms this value under "Throughput Time".

Does the AD7864BS-1 require an external reference voltage?

No, the AD7864BS-1 includes an internal 2.5 V reference with ±20 mV error over temperature and 25 ppm/°C drift, eliminating the need for external reference components. The VREF pin serves as both output and input-users may overdrive it with an external 2.5 V source if higher stability is required. Reference decoupling with a 0.1 μF capacitor to AGND is mandatory per datasheet Section "Reference Input/Output". AD7864BS-1 operates fully functional with its internal reference enabled by default.

How does the AD7864BS-1 handle channel selection-hardware or software?

The AD7864BS-1 supports dual-mode channel selection: hardware via SL1–SL4 pins when H/S SEL = 0, or software via DB0–DB3 register writes when H/S SEL = 1. In hardware mode, the channel sequence is latched on the rising edge of CONVST; in software mode, WR pulses with CS low load the register. Both methods allow any subset of 1–4 channels to be converted, optimizing throughput. AD7864BS-1 pin function descriptions in Rev. D datasheet Table 4 explicitly define this behavior.

What is the aperture delay matching specification for the AD7864BS-1?

The AD7864BS-1 guarantees aperture delay matching of ≤4 ns maximum across all four track-and-hold amplifiers, as specified in Rev. D datasheet Table 1 under "Aperture Delay Matching". This tight matching ensures phase coherence between sampled channels-critical for vector control and power quality analysis. At 50 kHz, this translates to <0.02° phase error, enabling accurate real-time computation of active/reactive power without post-acquisition correction. AD7864BS-1 achieves this via matched on-chip amplifier design and shared clock distribution.

Can the AD7864BS-1 interface directly with 3 V microprocessors?

Yes, the AD7864BS-1 supports 3 V logic interfacing through its dedicated VDRIVE pin, which powers the DB0–DB11 data bus, BUSY, EOC, and FRSTDATA outputs. When VDRIVE is supplied with 3 V ±10%, the outputs meet 3 V TTL levels (VOH ≥ 2.4 V, VOL ≤ 0.4 V) while maintaining full timing compliance. This eliminates level-shifters in mixed-voltage systems. AD7864BS-1 timing characteristics in Rev. D Table 2 specify t5/t6 values for both 5 V and 3 V VDRIVE conditions.