Analog Devices Inc. AD7804BN

Overview

AD7804BN from Analog Devices is a quad 10-bit serial-input DAC with on-chip 1.23 V reference, ±3 LSB relative accuracy, and VBIAS ± 15/16 × VBIAS output swing. It supports dual external reference capability, double-buffered registers, and simultaneous update via asynchronous LDAC. Used in optical disk drive bias control and precision voltage setpoint generation.

For engineers reviewing the AD7804BN datasheet, AD7804BN pinout, AD7804BN application, or AD7804BN equivalent, key selection criteria include serial interface timing (FSIN/CLKIN/SDIN), 16-pin PDIP package constraints, VBIAS configuration flexibility (VDD/2, internal ref, or REFIN), and sub-DAC-assisted offset trimming for instrumentation calibration.

Technical Context

The AD7804BN implements a serial-load architecture with 16-bit frame synchronization (FSIN), falling-edge clocking (CLKIN), and MSB-first SDIN data transfer. Its register map includes a system control register (power-down, coding mode, standby) and per-channel control registers (MX1/MX0 for VBIAS source selection, STBY, CLR).

Each of the four main DACs features an 8-bit sub-DAC that shifts the full-scale transfer function around VBIAS to minimize bias offset error. Output settling time is ≤4 µs to 10-bit accuracy, with analog crosstalk limited to ±0.2 LSB and digital-to-analog glitch impulse at 1 nV·s (major carry transition).

Key Specifications

Pinout & Package

AD7804BN is housed in a 16-lead plastic DIP (N-16) package with 0.3-inch body width and through-hole mounting. Pin 16 is NC; all analog and digital grounds are separated (AGND/DGND); AVDD and DVDD accept +3.3 V to +5 V ±10%.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7804BR, AD7804BN offers identical performance in a through-hole package suited for manual assembly and thermal robustness in industrial enclosures; versus AD7805BN, it trades parallel speed and pin overhead for serial simplicity and reduced MCU resource usage - critical in cost-sensitive embedded designs.

Availability

AD7804BN is available at Aetrix Electronics and suitable for optical disk drive manufacturing, industrial process control instrumentation, and embedded power supply margining requiring stable component supply across extended temperature ranges.

Supply support for AD7804BN 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 semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The AD7804BN belongs to Analog Devices' precision DAC product line, engineered for applications demanding accurate, low-glitch, multi-channel voltage synthesis with integrated reference and flexible biasing architecture.

FAQ

What is the maximum clock frequency supported by the AD7804BN serial interface?

The AD7804BN requires a minimum CLKIN cycle time of 100 ns (t1), corresponding to a maximum clock frequency of 10 MHz. The clock duty cycle must be between 40% and 60%. This timing applies across the full operating temperature range (–40°C to +85°C) and ensures reliable 16-bit serial data capture into the input shift register for the AD7804BN.

How does the AD7804BN achieve VBIAS center-point adjustment, and what sources can be selected?

The AD7804BN uses MX1 and MX0 bits in each channel's control register to select VBIAS from three sources: internal VDD/2 divider, internal 1.23 V REFOUT, or external voltage applied to REFIN (1.0 V to VDD/2). The 8-bit sub-DAC then fine-tunes the main DAC's transfer function around that center point, reducing bias offset error to ±60 mV - a key capability of the AD7804BN.

Can the AD7804BN operate with a 3.3 V supply only, and what are the implications for REFOUT and output swing?

Yes, the AD7804BN operates from +3.3 V to +5 V ±10%, so 3.3 V is fully supported. At 3.3 V, REFOUT remains 1.23 V ±8% (nominal), and the output swing is VBIAS ± 15/16 × VBIAS - e.g., if VBIAS = VDD/2 = 1.65 V, the range is ~0.103 V to 3.197 V. All specifications, including settling time and glitch impulse, are guaranteed across this supply range for the AD7804BN.

What is the function of the COMP pin on the AD7804BN, and how should it be decoupled?

The COMP pin on the AD7804BN provides the internal VDD/2 divider output for AC bypass. It must be decoupled with a 1 nF capacitor to both AVDD and AGND. This stabilizes the internal bias network and suppresses high-frequency noise coupling into the DAC core. Overdriving COMP with an external reference is permitted and enables dual-reference configurations - a unique feature of the AD7804BN.

Does the AD7804BN retain register contents during power-down mode, and how is normal operation restored?

Yes, the AD7804BN retains all register contents (system, channel, and DAC data registers) during power-down mode. To restore normal operation, the PD bit in the system control register must be written to '1'. This re-enables the internal reference and all DAC circuitry without requiring reinitialization - ensuring seamless resumption of analog output control after low-power sleep, a critical behavior for the AD7804BN in battery-backed systems.