AD7228ACPZ-REEL

Overview

The AD7228ACPZ-REEL is an octal 8-bit digital-to-analog converter (DAC) manufactured by Analog Devices Inc. It integrates eight voltage-mode DACs with output buffer amplifiers and interface logic on a single monolithic chip fabricated using LC2MOS technology. The device operates with dual supplies (VDD: 10.8 V to 16.5 V, VSS: -5 V ± 10%) or a single supply. Key electrical specifications include a settling time of 5 µs for positive full-scale changes and 7 µs for negative changes, a maximum power dissipation of 1 W, and a typical supply current of 16 mA at 25°C. It features a common 8-bit parallel data bus with individual latches controlled by A0, A1, and A2 address inputs.

Feature Summary

• Octal architecture containing eight independent 8-bit DACs with integrated output buffer amplifiers.
• LC2MOS process technology enabling high-speed digital logic and precision analog circuits on one chip.
• Microprocessor-compatible interface with TTL/CMOS levels and 95 ns write pulse capability.
• No user trims required; guaranteed monotonicity with specified static and dynamic performance.

Applications

• Automated test equipment requiring timing deskew and coarse/fine adjustment functions.
• Multi-channel signal generation systems utilizing single or dual supply configurations.
• Microprocessor-based control systems interfacing via standard 8-bit parallel buses.

Procurement Notes

Verify the specific grade suffix (e.g., K, B, L, C) against the datasheet's Ordering Guide, as performance parameters such as Total Unadjusted Error vary between versions. Confirm that the PLCC-28 package matches the design footprint, noting that some pins are designated as Do Not Connect (DNC). Ensure the reel quantity aligns with production requirements, as packaging formats differ from tube options.

Selection Notes

Select this component when board space reduction is critical due to its integration of eight converters and buffers. Choose based on the required accuracy grade; 'L' and 'C' versions offer tighter error specifications compared to 'K' and 'B'. Verify supply voltage compatibility, as single-supply operation affects negative-going settling times and sink current capabilities near ground. Ensure the external reference source can handle the code-dependent input impedance variations.

Part Context

The AD7228 series belongs to Analog Devices' family of octal CMOS DACs. The ACPZ suffix denotes the 28-lead Plastic Leadless Chip Carrier (PLCC) surface-mount package variant. This package style differs from the PDIP, CERDIP, and SOIC options available in the same product line, offering a compact solution for high-density PCB layouts while maintaining identical internal circuitry and pin functionality for active connections.

Replacement Considerations

Direct pin-for-pin replacements within the AD7228 family include other package variants like AD7228ACRZ (SOIC-24) or AD7228ABNZ (PDIP-24), provided the package outline fits the design. Performance differences exist between grade suffixes (K/B vs. L/C); verify if the stricter accuracy of L/C grades is necessary or if K/B grades suffice for cost optimization.

FAQ

How does single-supply operation affect the output sink current?

In single-supply mode, the sink capability reduces as the output voltage approaches 0 V due to a passive pull-down transistor. In dual-supply mode, the full 400 µA sink current is maintained across the entire output range.

What is the function of the DNC pins in the PLCC package?

Pins 1, 8, 15, and 22 in the 28-lead PLCC package are marked DNC (Do Not Connect). They must not be connected to any voltage or ground potential.

Can the AD7228 operate with an AC reference signal?

Yes, it supports multiplying operations with AC signals applied to the VREF input, provided the signal is AC-coupled and biased to remain within the 2 V to 10 V range relative to GND.