Analog Devices Inc. AD7896BNZ

Overview

AD7896BNZ from Analog Devices is a fast, single-supply 12-bit successive-approximation ADC with 8 µs conversion time, on-chip track-and-hold and serial interface, operating from 2.7 V to 5.5 V and consuming only 9 mW typical. It accepts 0 V to VDD analog input, uses VDD as internal reference, and targets space-constrained data acquisition in portable instrumentation and sensor interfaces.

For engineers reviewing the AD7896BNZ datasheet, AD7896BNZ pinout, AD7896BNZ application, or AD7896BNZ equivalent, key selection criteria include its 100 kHz throughput rate, auto power-down mode for battery operation, 8-lead PDIP package, 70 dB SNR at 10 kHz input, and 2-wire serial interface timing compatibility with microcontrollers.

Technical Context

The AD7896BNZ implements an R-2R ladder-based SAR architecture with laser-trimmed internal clock, eliminating external timing components. Its track-and-hold amplifier achieves 1.5 µs acquisition time to 12-bit accuracy and supports full-scale sine-wave inputs up to 50 kHz.

It operates in two modes: Mode 1 (high-speed, 8 µs conversion, BUSY-driven timing) and Mode 2 (auto-sleep, 14 µs total cycle including 6 µs wake-up), both using edge-triggered CONVST and falling-edge–clocked SDATA output with 16-bit frame (4 leading zeros + 12-bit straight binary).

Key Specifications

Pinout & Package

AD7896BNZ is housed in an 8-lead, 0.3" wide plastic dual-in-line package (PDIP) with through-hole mounting and standard JEDEC MO-019 footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7892BRZ-1 and ADS7822U, the AD7896BNZ uniquely combines 8-lead PDIP packaging, VDD-as-reference simplicity, and guaranteed 70 dB SNR in a single-supply, low-power configuration - making it optimal for cost-sensitive, space-constrained, battery-operated measurement nodes where minimal external components are critical.

Availability

AD7896BNZ is available at Aetrix Electronics and suitable for portable instrumentation, industrial sensor interfaces, and medical vital sign monitors requiring stable component supply and long-term manufacturability.

Supply support for AD7896BNZ 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 AD7896BNZ belongs to Analog Devices' legacy precision SAR ADC product line, designed specifically for low-power, single-supply data acquisition in space- and energy-constrained embedded systems.

FAQ

What is the maximum sampling rate achievable with the AD7896BNZ?

The AD7896BNZ supports a maximum sustained throughput rate of 100 kHz in Mode 1 operation. This requires 8 µs conversion time, 1.6 µs serial read (at 10 MHz SCLK), and 400 ns minimum inter-conversion delay for track-and-hold settling. In Mode 2 (auto-sleep), the effective rate is lower due to 6 µs wake-up overhead, but power consumption drops significantly between conversions. The AD7896BNZ datasheet specifies timing margins that must be strictly observed to maintain 12-bit accuracy at this rate.

Does the AD7896BNZ require an external voltage reference?

No, the AD7896BNZ does not require an external voltage reference. Its internal reference is derived directly from the VDD supply pin, enabling a true single-supply 0 V to VDD analog input range. This eliminates the need for external reference ICs, associated decoupling, and layout area - a key advantage for compact, low-cost designs. The AD7896BNZ specification assumes VDD is stable and well-bypassed; reference performance tracks VDD regulation and noise.

How does the auto power-down mode work on the AD7896BNZ?

The AD7896BNZ enters auto power-down mode when the CONVST pin remains low after conversion completes (i.e., BUSY goes low). In this state, IDD drops to 5 µA typical (2.7–3.6 V) or 50 µA typical (5 V). The part "wakes up" on the rising edge of the next CONVST pulse, with a 6 µs wake-up time before track-and-hold enters hold mode. This feature is enabled by default in Mode 2 operation and is confirmed in the AD7896BNZ timing diagrams and power specifications tables.

What are the logic voltage levels for the AD7896BNZ digital interface?

The AD7896BNZ digital inputs (CONVST, SCLK) accept VIH ≥ 2.0 V (2.7–3.6 V VDD) or ≥ 2.4 V (5 V ±10% VDD), and VIL ≤ 0.8 V across all supply conditions. Outputs (SDATA, BUSY) drive VOH ≥ 2.4 V (ISOURCE = 400 µA) and VOL ≤ 0.4 V (ISINK = 1.6 mA). These levels are fully compatible with 3.3 V and 5 V CMOS logic families. All timing parameters - including t1 (40 ns CONVST pulsewidth), t2/t3 (402 ns SCLK pulsewidth) - are specified under these voltage conditions and must be met for reliable operation.

Can the AD7896BNZ interface directly with a microcontroller SPI peripheral?

The AD7896BNZ uses a 2-wire serial interface (SCLK and SDATA only) without chip select (CS), so it is not natively SPI-compatible. However, many microcontrollers can emulate the protocol using GPIO-controlled bit-banging or configure SPI hardware in master mode with CS disabled and software-managed timing. The AD7896BNZ outputs 16 bits per conversion (4 zeros + 12-bit result), with data valid on the falling edge of SCLK. Successful integration requires strict adherence to t4 (60–100 ns data access time) and t5 (10 ns data hold time) to avoid read errors - details confirmed in the AD7896BNZ timing characteristics table.