Vishay Siliconix DG485DJ

Overview

DG485DJ from Vishay Siliconix is an octal SPST analog switch array with serial interface control, 55 Ω typical on-resistance, 170 ns typical turn-on time, and rail-to-rail analog signal range (±15 V). It functions as an 8-channel multiplexer in data acquisition and industrial process control systems requiring low distortion and daisy-chain expandability.

For engineers reviewing the DG485DJ datasheet, DG485DJ pinout, DG485DJ application, or DG485DJ equivalent, key selection criteria include serial shift-register control architecture, ±44 V supply rating, 18-pin plastic DIP package, and compatibility with TTL/CMOS logic levels at VL = 5 V.

Technical Context

The DG485DJ integrates an 8-bit serial shift register followed by an octal latch to control eight independent SPST analog switches. Each switch conducts bidirectionally with matched on-resistance and blocks rail-to-rail voltages when off, enabled by Vishay's high-voltage silicon gate process and epitaxial latchup protection.

Control is fully serial: DIN feeds data into the shift register on CLK rising edges; LD latches register contents into the output latch level-sensitively; RS resets all bits low. DOUT enables daisy-chaining multiple DG485DJ units for scalable channel expansion without parallel bus overhead.

Key Specifications

Pinout & Package

Package: 18-pin plastic dual-in-line (DIP), through-hole mount, operating temperature range –40 °C to +85 °C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar analog switch array applications.

Compared with ADG408BRZ and MAX485CPA+, the DG485DJ uniquely combines serial expandability, bipolar ±15 V analog handling, and 18-pin DIP packaging-making it optimal for space-constrained, multi-node analog routing where microcontroller pin count and supply flexibility are critical.

Availability

DG485DJ is available at Aetrix Electronics and suitable for data acquisition, industrial process control, and audio teleconferencing applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for DG485DJ 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

Vishay Siliconix is a global semiconductor manufacturer specializing in discrete components and analog ICs, with emphasis on high-reliability, high-voltage, and precision signal-path solutions.

The DG485DJ belongs to Vishay's high-voltage analog switch family designed for robust multiplexing in industrial, avionic, and test equipment where rail-to-rail signal integrity and serial configurability are essential.

FAQ

What is the maximum analog signal voltage the DG485DJ can handle?

The DG485DJ supports rail-to-rail analog input voltages up to ±15 V when operated with V+ = +15 V and V– = –15 V. Its absolute maximum ratings allow V+ up to +44 V and V– down to –44 V, enabling use with wider supply rails. Signal voltages beyond the supply rails are clamped by internal diodes, so applied analog signals must remain within (V–) to (V+) to avoid forward-biasing protection structures. This makes the DG485DJ suitable for industrial ±10 V and ±15 V systems without external clamping.

How does the serial interface of the DG485DJ work for controlling individual switches?

The DG485DJ uses a dedicated 8-bit serial shift register fed via DIN and CLK. Each rising CLK edge shifts one bit into the register; after eight clocks, the full 8-bit pattern resides in the register. Asserting LD (high) latches that pattern into the octal output latch, which directly controls S1–S8 switch states. RS (high) forces all latch bits low, turning all switches OFF. DOUT provides the Q8 output for daisy-chaining-allowing multiple DG485DJ units to be driven by a single serial stream without address decoding logic.

Is the DG485DJ pin-compatible with other variants like DG485DN or DG485AZ/883?

No, the DG485DJ is not pin-compatible with DG485DN or DG485AZ/883. The DG485DJ uses an 18-pin plastic DIP package with specific pin assignments (e.g., Pin 15 labeled S8 in the top-view diagram), while DG485DN uses a 20-pin PLCC and DG485AZ/883 uses a 20-pin LCC-both with different pinouts and thermal/mechanical footprints. Although functional behavior is identical, PCB layout, socketing, and thermal management differ significantly; redesign is required when substituting packages.

What is the significance of the 35 nW power dissipation specification for the DG485DJ?

The 35 nW typical power dissipation (PD) reflects ultra-low static power consumption in the logic section when idle-critical for battery-powered remote monitoring systems where years of operation are required on a single cell. This value results from CMOS logic design and low-leakage fabrication, not from reduced functionality: full analog performance (55 Ω rDS(on), ±15 V range) remains available. Actual total power depends on switching activity and supply voltages, but the 35 nW baseline enables energy budgeting for always-on sensor interfaces without compromising signal path integrity.

Can the DG485DJ be used in summing amplifier configurations?

Yes, the DG485DJ is explicitly referenced in its datasheet for summing amplifier applications (Figure 14). Its common-drain (D) architecture allows all eight sources (S1–S8) to feed a shared node-ideal for weighted current-summing or voltage-summing networks. With low on-resistance (55 Ω typ.) and matched channel characteristics, it introduces minimal gain error or offset when used with precision op-amps. The serial control also enables dynamic reconfiguration of active inputs-supporting adaptive filtering or programmable gain stages without hardware changes.