Analog Devices Inc. SDC1768411

Overview

SDC1768411 from Analog Devices is a 14-bit hybrid synchro/resolver-to-digital converter with ±5.3 arc minute accuracy, internal isolating transformers, and TTL-compatible parallel natural binary output. It operates over –55°C to +125°C, supports 400 Hz or 2.6 kHz reference frequency, and delivers analog velocity and error outputs for real-time shaft angle tracking in high-reliability servo systems.

For engineers reviewing the SDC1768411 datasheet, SDC1768411 pinout, SDC1768411 application, or SDC1768411 equivalent, this page provides verified technical context, pin-level design meaning, real-world use cases in avionics and fire control, and validated alternative options for resolver interface redesigns requiring hermetic sealing and MIL-qualified reliability.

Technical Context

The SDC1768411 implements a Type II servo loop architecture with phase-sensitive detection, integrator, and voltage-controlled oscillator (VCO) to continuously null Sin(θ − φ), enabling true continuous tracking even during data transfer. Its internal Scott-T transformer pair converts 3-wire synchro inputs to resolver format, while 4-wire resolver inputs pass through isolation only.

It features separate ENABLE_M (pins 29–32) and ENABLE_L (pins 25–28) controls for independent gating of MSB and LSB groups, and uses a dual-monostable latch clocking scheme synchronized to INHIBIT to preserve loop integrity - ensuring no disruption to internal conversion during digital readout.

Key Specifications

Pinout & Package

SDC1768411 is housed in a hermetically sealed metal 32-pin dual-in-line (DIP) package measuring 1.74″ × 1.14″ × 0.28″ (44.2 × 28.9 × 7.1 mm), with glass-bead standoffs and case-connected pin 32 for EMI shielding and thermal grounding.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar resolver-to-digital conversion applications.

Compared with SDC1768411, SDC1767411 offers identical interface and packaging but trades 2 bits of resolution and 3.2 arc min accuracy for lower cost and higher tracking rate; DRC1765 serves an inverse function entirely and lacks isolation, velocity, or error monitoring - making it unsuitable as a drop-in or functional alternative.

Availability

SDC1768411 is available at Aetrix Electronics and suitable for avionic flight control, artillery fire control, and engine controller feedback applications requiring stable component supply, long-lifecycle assurance, and MIL-qualified reliability.

Supply support for SDC1768411 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 company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The SDC/RDC1768 family was designed for demanding military and aerospace motion feedback systems requiring hermetic packaging, transformer isolation, and continuous tracking - targeting resolver/synchro interfacing where reliability trumps cost.

FAQ

What is the operating temperature range of the SDC1768411?

The SDC1768411 operates from –55°C to +125°C and is storage-rated from –65°C to +150°C. This extended range is achieved through hermetic metal packaging and MIL-STD-883 Class B screening when ordered with the /883B suffix. The SDC1768411 maintains its ±5.3 arc minute accuracy across this full range, making it suitable for deployment in jet engines, missile guidance, and tracked vehicle systems.

Does the SDC1768411 support both synchro and resolver inputs?

Yes, the SDC1768411 supports both 3-wire synchro (via S1–S3) and 4-wire resolver (via S1–S4) inputs, determined by the Z-option code in the part number. For SDC1768411, the "Z=1" option specifies 11.8 V signal and reference compatibility with resolver format. Internal Scott-T transformers convert synchro signals to resolver-equivalent format, while resolver inputs pass through isolation only.

How does the INHIBIT function affect the internal servo loop of the SDC1768411?

The INHIBIT input on the SDC1768411 freezes latch updates without disrupting the internal Type II servo loop - the VCO, integrator, and error amplifier continue running uninterrupted. When INHIBIT is asserted low, the up-down counter keeps tracking the input shaft angle, and data becomes valid 3 µs after assertion. This preserves dynamic performance during readout, unlike gated-clock approaches that break loop continuity.

What is the purpose of the ERROR output on the SDC1768411?

The ERROR output on the SDC1768411 is a built-in test point derived near the Sin(θ − φ) null point of the internal control loop. Under normal operation, it remains below ±30 mV; if tracking fails or input acceleration exceeds design limits, it rapidly transitions to >±200 mV. It is not linear with error and must not be used for closed-loop correction - only for fault detection and system-level diagnostics.

Can the SDC1768411 be used with non-standard signal or reference voltages?

Yes, the SDC1768411 supports resistive scaling of signal and reference inputs. For resolver mode, add 2.22 kΩ per extra volt in series with S1/S2, and 1 kΩ per extra volt in series with RHI. This allows adaptation to custom voltage levels without modifying the core converter - a key feature enabling reuse across platforms with varying synchro/resolver excitation standards.