Analog Devices Inc. AD781ANZ

Overview

AD781ANZ from Analog Devices is a monolithic sample-and-hold amplifier (SHA) designed for high-speed, high-accuracy data acquisition systems. It achieves 12-bit accuracy with ≤700 ns acquisition time for a 10 V step to 0.01%, supports ±5 V input range, delivers ≤125 µV rms hold mode noise, and operates across –40°C to +85°C - enabling direct interface with 12-bit ADCs such as AD674 in multichannel instrumentation.

For engineers reviewing the AD781ANZ datasheet, AD781ANZ pinout, AD781ANZ application, or AD781ANZ equivalent, key selection criteria include aperture jitter (≤75 ps), droop rate (≤1 µV/µs), hold settling to 1 mV (≤500 ns), and self-correcting architecture that compensates for charge injection and gain/offset errors in hold mode.

Technical Context

The AD781ANZ implements a proprietary self-correcting architecture that reconfigures internal circuitry after the hold command to nullify amplifier gain/offset errors and switch-induced charge injection - ensuring accurate held output despite inaccurate sample-mode output. Its single-ended analog I/O referenced to COMMON eliminates need for external hold capacitors or trimming components.

It features dual ±12 V supply operation (±10.8 V to ±13.2 V), 4–7 mA total supply current, and integrated power supply rejection (≥70 dB PSRR at ±12 V). The device uses CMOS-compatible digital control inputs (S/H pin) with TTL/CMOS logic thresholds and diode-protected inputs for ESD robustness.

Key Specifications

Pinout & Package

AD781ANZ is housed in an 8-pin plastic DIP (N-8) package with 0.3-inch width, lead finish Sn/Pb, and JEDEC MS-001 compliant outline. Pin 1 is VCC (+12 V), Pin 2 is analog INPUT, Pin 3 is COMMON (analog/digital ground reference), Pins 4 and 7 are no-connect (NC), Pin 5 is analog OUTPUT, Pin 6 is S/H control input (active-high), and Pin 8 is VEE (–12 V).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar sample-and-hold amplifier applications.

Compared with LF398N and HA5351IBZ, the AD781ANZ uniquely integrates hold capacitance and self-correction - reducing BOM count and calibration effort while delivering guaranteed 12-bit performance across its industrial temperature range without external components.

Availability

AD781ANZ is available at Aetrix Electronics and suitable for high-speed data acquisition, 12-bit ADC front-end interfacing, precision instrumentation, and industrial process monitoring requiring stable component supply across extended temperature ranges.

Supply support for AD781ANZ 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, founded in 1965 and headquartered in Wilmington, MA.

The AD781ANZ belongs to Analog Devices' precision sample-and-hold amplifier product line, engineered specifically for 12-bit data acquisition systems demanding low aperture jitter, autonomous operation, and guaranteed accuracy without external tuning.

FAQ

What is the operating temperature range of the AD781ANZ?

The AD781ANZ is rated for operation from –40°C to +85°C, meeting industrial temperature requirements. This range is explicitly specified in the ordering guide for the "AN" grade and confirmed across all DC and AC performance parameters in the datasheet's AD781A column. The AD781ANZ maintains full 12-bit accuracy, including nonlinearity (±0.003% FS) and hold mode offset (–4 mV to +3 mV), across this entire range without derating.

Does the AD781ANZ require an external hold capacitor?

No, the AD781ANZ does not require an external hold capacitor. It integrates a precision on-chip hold capacitor as part of its monolithic design, eliminating external component dependencies and layout sensitivity. This is confirmed in the Functional Description section, which states the device is "completely self-contained, including an on-chip hold capacitor, and requires no external components or adjustments." The AD781ANZ achieves ≤1 µV/µs droop rate using this internal capacitor.

How does the self-correcting architecture of the AD781ANZ improve accuracy?

The AD781ANZ's self-correcting architecture actively compensates for internal errors - including amplifier gain/offset and charge injection - after the hold command is issued. This correction occurs within the hold path, ensuring the final held output reflects the true input value with minimal residual error. As documented in the Functional Description, this design enables guaranteed 12-bit accuracy without external trimming, directly addressing hold mode offset drift and nonlinearity limitations found in conventional SHAs like the LF398N.

Can the AD781ANZ drive a 12-bit ADC directly without a buffer amplifier?

Yes, the AD781ANZ can drive a 12-bit ADC directly. Its output drive capability (±5 mA), low output resistance (0.3–0.5 Ω), and fast hold settling (≤500 ns to 1 mV) allow it to interface directly with converters such as the AD674 without intermediate buffering. The datasheet's AD781 to AD674 Interface diagram (Figure 9) confirms this configuration, and the "Dynamic Performance" section explicitly states the AD781ANZ "can directly drive an A-to-D converter without the need for an added 'start convert' delay."

What is the maximum input voltage range supported by the AD781ANZ?

The AD781ANZ supports an analog input voltage range of ±5 V, referenced to the COMMON pin. This is explicitly stated in the "INPUT CHARACTERISTICS" table under "Input Voltage Range" and further qualified in Note 1 of the Accuracy Characteristics section: "Specified and tested over an input range of ±5 V." Exceeding ±5 V risks violating absolute maximum ratings (±12 V on analog input), potentially causing damage or parametric shift.