Analog Devices Inc. AD7858BRZ

Overview

AD7858BRZ from Analog Devices is a 12-bit, 200 kSPS, 8-channel SAR analog-to-digital converter operating from a single 3 V to 5.5 V supply. It features on-chip track-and-hold, internal reference buffer, system/self-calibration, and flexible serial interface (SPI/QSPI/µP-compatible). Designed for precision data acquisition in portable instrumentation and embedded control systems, it delivers ±1 LSB integral nonlinearity, 71 dB SNR at 10 kHz input, and 0.4 µs track/hold acquisition time.

For engineers reviewing the AD7858BRZ datasheet, AD7858BRZ pinout, AD7858BRZ application, or AD7858BRZ equivalent, this page provides verified technical context, validated pin functions, confirmed timing behavior under 4 MHz CLKIN, calibrated DC accuracy specs, and real-world substitution guidance - all grounded in Analog Devices' Rev. B datasheet and official ordering guide.

Technical Context

The AD7858BRZ implements a charge-redistribution SAR architecture with integrated calibration memory and controller, enabling automatic self-calibration on power-up and optional system calibration. Its pseudo-differential input multiplexer supports eight single-ended or four pseudo-differential channels, with channel selection controlled via a 14-bit write-only control register.

Conversion is initiated by CONVST or software command; BUSY signals completion; and SLEEP enables full or partial power-down (as low as 5 µA with external clock off). The serial interface operates in Mode 2 (SYNC-frame + SCLK), supporting read/write during or after conversion to sustain 200 kSPS throughput.

Key Specifications

Pinout & Package

AD7858BRZ is housed in a 24-lead SOIC (R-24) package with 0.3-inch width, RoHS-compliant lead finish, and standard JEDEC MS-013AC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7858ARZ, AD7858BRZ offers identical speed, resolution, and package but with B-grade screening - making it optimal for commercial-temperature applications where cost sensitivity matters. Versus ADS7822U, AD7858BRZ adds integrated reference, calibration, and pseudo-differential support at higher power, justifying its use in precision portable instrumentation.

Availability

AD7858BRZ is available at Aetrix Electronics and suitable for portable medical instrumentation, industrial sensor signal conditioning, handheld test equipment, and communications baseband monitoring requiring stable component supply, long-lifecycle availability, and guaranteed RoHS-compliant sourcing.

Supply support for AD7858BRZ 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, with design centers worldwide and ISO 9001-certified manufacturing.

The AD7858BRZ belongs to Analog Devices' precision SAR ADC product line, engineered for high-speed, low-power, multi-channel data acquisition in battery-operated and thermally constrained environments - emphasizing calibration integrity, interface flexibility, and supply voltage robustness.

FAQ

What is the maximum sampling rate supported by the AD7858BRZ?

The AD7858BRZ supports a maximum throughput rate of 200 kSPS when operated with a 4 MHz master clock (CLKIN). This rate is achievable across the full industrial temperature range (–40°C to +85°C) and requires proper timing alignment per Interface Mode 2, including ≥400 ns acquisition time between BUSY falling edge and next CONVST rising edge. The AD7858BRZ achieves this using a charge-redistribution SAR architecture with 4.6 µs conversion time.

Does the AD7858BRZ require an external reference voltage?

No, the AD7858BRZ does not require an external reference voltage. It features an internal 2.5 V reference buffer accessible via the REFIN/REFOUT pin, which can be used directly as the conversion reference. However, the device also supports external reference voltages from 1.2 V to AVDD, allowing flexible scaling for applications needing different input ranges. When using the internal reference, CREF1 (0.1 µF) and CREF2 (0.01 µF) capacitors must be connected to AGND as specified.

How does the AD7858BRZ handle channel selection and input configuration?

The AD7858BRZ supports eight single-ended or four pseudo-differential analog inputs (AIN1–AIN8), configured via the 14-bit Control Register. The SGL/DIFF bit selects mode, while CH2–CH0 bits define active channel. Configuration is performed through the SPI-compatible serial interface: writing to ADDR1=1, ADDR0=1 addresses the Control Register. Default power-up state enables single-ended mode on AIN1, requiring no initial register write for basic operation.

What power-down modes are available on the AD7858BRZ?

The AD7858BRZ offers three configurable power-down states controlled by PMGT1 and PMGT0 bits in the Control Register: full power-down (10 µA typ with external clock on), partial power-down (400 µA typ), and ultra-low-power sleep with external clock disabled (5 µA max). In all modes, calibration data is retained, and the internal reference is disabled only in full power-down. SLEEP pin assertion overrides register settings for immediate entry into lowest-power state.

Is the AD7858BRZ pin-compatible with other members of the AD7858 family?

Yes, the AD7858BRZ is pin-compatible with all AD7858 and AD7858L variants in the same package type (e.g., R-24 SOIC). Pin functions, layout, and mechanical dimensions match across AD7858AN, AD7858BN, AD7858AR, AD7858BR, AD7858LAN, AD7858LBN, AD7858LAR, and AD7858LBR. Differences lie solely in grade (A/B), speed (200 kSPS vs. 100 kSPS), and INL specification (±1 LSB vs. ±0.5 LSB), not pinout or interface behavior.