Analog Devices Inc. AD7895ANZ-3

Overview

AD7895ANZ-3 from Analog Devices is a 12-bit successive-approximation ADC with ±2.5 V bipolar input range, 3.8 µs conversion time in high-sampling mode, single +5 V supply operation, and high-speed two-wire serial interface (SCLK/SDATA). It integrates on-chip track/hold, internal clock, and 2's complement output coding-designed for precision data acquisition in industrial sensor interfaces and portable instrumentation.

For engineers reviewing the AD7895ANZ-3 datasheet, AD7895ANZ-3 pinout, AD7895ANZ-3 application, or AD7895ANZ-3 equivalent, key selection criteria include its 70 dB SNR at 50 kHz, ±1 LSB relative accuracy, 0.5 µs track/hold acquisition time, automatic power-down mode (5 µA standby), and compatibility with microcontrollers via edge-triggered CONVST and BUSY status signaling.

Technical Context

The AD7895ANZ-3 implements a laser-trimmed R-2R ladder DAC-based SAR architecture with integrated track/hold amplifier and buffered reference input (2.375 V to 2.625 V). Its analog front-end uses resistor-scaling networks (R1 = R2 = 6.5 kΩ, R3 open) to support ±2.5 V input while maintaining 9 kΩ minimum input resistance.

It operates in two modes: Mode 1 (3.8 µs conversion, CONVST falling-edge triggered) for high-throughput applications up to 192 kHz, and Mode 2 (9.8 µs total cycle, auto-wake from power-down on CONVST rising edge) for low-power systems. Serial data output is 16-bit (4 leading zeros + 12-bit 2's complement result), synchronized to SCLK falling edges with 10 ns data hold time.

Key Specifications

Pinout & Package

AD7895ANZ-3 is housed in an 8-pin plastic DIP (0.3" wide, N-8 package) with standard through-hole mounting and 130°C/W thermal impedance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7895ANZ-3, AD7894ARZ offers higher resolution at the cost of dual-supply complexity, while ADS7822U reduces power and cost but sacrifices integrated signal conditioning and DC accuracy-making AD7895ANZ-3 optimal for space-constrained, single-supply bipolar DAQ where track/hold and ±1 LSB linearity are essential.

Availability

AD7895ANZ-3 is available at Aetrix Electronics and suitable for industrial sensor interfaces, portable data loggers, test equipment front-ends, and motor control current sensing requiring stable component supply and long-term obsolescence management.

Supply support for AD7895ANZ-3 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 AD7895ANZ-3 belongs to Analog Devices' precision data acquisition IC family, engineered specifically for high-speed, low-power, single-supply 12-bit conversion in space- and power-constrained industrial and instrumentation systems.

FAQ

What is the maximum sampling rate achievable with the AD7895ANZ-3?

The AD7895ANZ-3 achieves a maximum throughput rate of 192 kHz in Mode 1 operation. This is calculated from its 3.8 µs conversion time, 1.1 µs serial read time (at 15 MHz SCLK), 0.3 µs track/hold acquisition time, and mandatory 300 ns guard band before the next CONVST falling edge. The AD7895ANZ-3 must be operated within these timing constraints to maintain specified SNR and linearity performance.

Does the AD7895ANZ-3 require an external reference voltage?

Yes, the AD7895ANZ-3 requires an external 2.5 V reference applied to the REF IN pin. The device specifies a 2.375 V to 2.625 V input range (±5%) and draws ≤1 µA from this source. Precision references such as the AD780 or AD680 are recommended to maintain the AD7895ANZ-3's ±1 LSB relative accuracy and 70 dB SNR performance across temperature.

How does the power-down mode work on the AD7895ANZ-3?

In Mode 2 (auto-sleep), the AD7895ANZ-3 enters power-down automatically when CONVST remains low after conversion completes (BUSY goes low). It draws only 5 µA at +25°C. The rising edge of the next CONVST pulse "wakes up" the device, initiating a 6 µs wake-up period before conversion begins. This feature reduces average power in low-duty-cycle applications-critical for battery-powered AD7895ANZ-3 deployments.

What is the purpose of the four leading zeros in the AD7895ANZ-3 serial output?

The AD7895ANZ-3 outputs 16 serial bits per conversion: four leading zeros followed by twelve 2's complement data bits. These zeros provide fixed-format alignment, ensuring consistent bit positioning regardless of input magnitude. They simplify firmware parsing-microcontrollers can shift or mask the upper nibble to extract the 12-bit result without conditional logic, improving deterministic timing in real-time AD7895ANZ-3 read routines.

Can the AD7895ANZ-3 interface directly with a 3.3 V microcontroller?

Yes, the AD7895ANZ-3's digital outputs (SDATA, BUSY) are compatible with 3.3 V logic when VDD = 5 V: VOH is guaranteed ≥4.0 V (exceeding 3.3 V VIH), and VOL is ≤0.4 V (within 3.3 V VIL). However, SCLK and CONVST inputs require VIH ≥2.4 V-fully compatible with 3.3 V CMOS outputs. Level-shifting is unnecessary, but clean power supply decoupling and controlled slew rates are essential to maintain AD7895ANZ-3 timing margins.