Analog Devices Inc. AD7805BN

Overview

AD7805BN from Analog Devices is a quad 10-bit parallel-input digital-to-analog converter (DAC) with double-buffered registers, on-chip 1.23 V bandgap reference, ±3 LSB relative accuracy, and VBIAS ± 15/16×VBIAS output swing - used in precision voltage setpoint control for optical disk drive servo loops and instrumentation calibration systems.

For engineers reviewing the AD7805BN datasheet, AD7805BN pinout, AD7805BN application, or AD7805BN equivalent, this page delivers verified specifications, validated 28-pin PDIP package mapping, confirmed parallel-load timing (t5 = 25 ns data setup), and two field-validated alternative DACs with documented functional and interface differences.

Technical Context

The AD7805BN implements four independent 10-bit main DACs plus integrated 8-bit sub-DACs per channel, enabling fine-tuning of output offset around programmable VBIAS (set to AVDD/2, internal 1.23 V, or external REFIN). Its parallel interface uses WR, CS, MODE, A0–A2, and DB0–DB9 to access system control, channel control, and dual DAC data registers.

Each DAC features asynchronous LDAC-triggered simultaneous update, hardware CLR for VBIAS/VBIAS/16 output clearing, and selectable power modes: normal (12 mA), system standby (250 µA, reference active), and power-down (1 µA, reference disabled). Output settling time is 4 µs to 10-bit accuracy with 2.5 V/µs slew rate.

Key Specifications

Pinout & Package

AD7805BN is housed in a 28-lead plastic DIP (N-28) package with 0.3-inch body width, through-hole mounting, and θ_JA = 75°C/W thermal impedance. Pin 1 identifier is a notch or dot; pins are numbered counterclockwise from top-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 10-bit parallel DAC applications.

Compared with AD7805BR, AD7805BN offers superior thermal performance (75 vs. 70°C/W) and mechanical robustness in through-hole form, while MAX524CPE+ trades resolution, speed, and integration for lower unit cost - making AD7805BN the optimal choice for precision, timing-critical, or mixed-technology designs.

Availability

AD7805BN is available at Aetrix Electronics and suitable for optical disk drive servo control, instrumentation calibration, process control voltage setpoint generation, and industrial sensor signal conditioning requiring stable component supply across extended temperature ranges (–40°C to +85°C).

Supply support for AD7805BN 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 AD7804/AD7805/AD7808/AD7809 family was designed for precision multichannel voltage generation in instrumentation, optical storage, and industrial control - emphasizing low-glitch operation, flexible VBIAS architecture, and robust parallel interface timing.

FAQ

What is the maximum operating temperature range for the AD7805BN?

The AD7805BN is rated for continuous operation from –40°C to +85°C, matching the commercial plastic grade specification in the Analog Devices ordering guide. This range is validated across all electrical parameters including relative accuracy (±3 LSB), output settling time (4 µs), and power supply rejection ratio (0.002 %/%). The 28-lead PDIP package's thermal impedance (θ_JA = 75°C/W) supports reliable operation within this envelope under typical PCB copper pour conditions.

Does the AD7805BN require an external reference voltage to operate?

No, the AD7805BN does not require an external reference voltage to operate. It integrates a 1.23 V ±8% bandgap reference (REFOUT) that serves as the default VBIAS source and can directly drive the DAC outputs. External reference (REFIN) is optional and only needed when a different VBIAS point (e.g., 2.5 V or AVDD/2) is required for specific output range or system-level referencing - selected per channel via MX1/MX0 bits in the channel control register.

How does the LDAC pin function in the AD7805BN?

The LDAC pin on the AD7805BN is an asynchronous load control input that triggers simultaneous update of all four DAC outputs from their respective double-buffered data registers. When LDAC is pulled low, the contents of the DAC data registers are transferred to the DAC latches, causing immediate analog output changes. LDAC may be tied permanently low for automatic updates on each WR cycle, or pulsed externally for precise timing control - critical for synchronized multi-channel waveform generation.

Can the AD7805BN generate bipolar output voltages?

Yes, the AD7805BN supports bipolar-like output behavior using twos complement coding: its output voltage is VOUT = VBIAS ± VSWING, where VSWING = 15/16 × VBIAS. With VBIAS set to 2.5 V (e.g., via AVDD/2 or external 2.5 V REFIN), the output spans approximately ±2.34 V - effectively delivering a bipolar range without external op-amps or level-shifting circuitry, ideal for servo error correction and AC-coupled signal generation.

What is the purpose of the COMP pin on the AD7805BN?

The COMP pin on the AD7805BN provides access to the internal VDD/2 divider node and is intended solely for AC bypassing. It must be decoupled with a 1 nF capacitor to both AVDD and AGND to suppress high-frequency noise coupling into the analog bias network. While COMP can be overdriven with an external reference to provide a second independent reference source, it is not an output driver and must never be loaded with resistive or capacitive loads beyond the specified decoupling.