Analog Devices Inc. DC1785A

Overview

DC1785A from Analog Devices (formerly Linear Technology) is an evaluation board for the LTC2991 octal I²C voltage, current, and temperature monitor IC. It enables full functional validation of the LTC2991's 14-bit ADC, remote diode temperature sensing (±0.7°C typical TUE), differential current measurement (±0.1% TUE), and internal VCC monitoring across 3V–5.5V supply. Designed for thermal management in FPGA power domains and multi-rail server systems.

For engineers reviewing the DC1785A datasheet, DC1785A pinout, DC1785A application, or DC1785A equivalent, this page delivers verified hardware configuration details, I²C register mapping, jumper-controlled measurement modes (voltage/current/temperature), on-board sense resistor options (10 mΩ/50 mΩ), and validated layout practices for sub-millivolt noise immunity - critical when evaluating high-accuracy system monitoring.

Technical Context

The DC1785A implements the LTC2991 in a fully populated 16-lead MSOP footprint with configurable ADR0–ADR2 pull-up/down jumpers, dedicated V1–V8 test points, and dual-purpose PWM output routed to a fan control header. It integrates calibrated 10 ppm/°C reference support and ESD-hardened (6 kV HBM) input protection per channel.

Board-level design includes low-noise decoupling (0.1 µF X7R + 10 µF tantalum at VCC), Kelvin-connected sense resistor pads, shielded remote diode traces with 470 pF filtering, and isolated ground planes for analog/digital separation - directly reflecting LTC2991's specified 0.07 °RMS temperature noise with filter enabled.

Key Specifications

Availability

DC1785A is available at Aetrix Electronics and suitable for FPGA thermal validation, multi-rail server power monitoring, and industrial embedded environmental sensing requiring stable component supply and documented reference design fidelity.

Supply support for DC1785A 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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.

The DC1785A belongs to Analog Devices' Linear Technology Evaluation Board product line, engineered to accelerate accurate characterization of precision monitoring ICs like the LTC2991 in real-world thermal and power integrity scenarios.

FAQ

What is the primary function of the DC1785A evaluation board?

The DC1785A evaluation board is a fully assembled and tested platform designed exclusively to evaluate the LTC2991 octal I²C voltage, current, and temperature monitor. It provides immediate access to all eight analog inputs (V1–V8), supports differential current sensing with two precision shunt options, enables four-channel remote diode temperature measurement with optimized PCB layout, and validates the LTC2991's PWM temperature output functionality - all without requiring custom hardware development.

Does the DC1785A support both C-Grade and I-Grade versions of the LTC2991?

Yes, the DC1785A supports both LTC2991CMS#PBF (0°C to 70°C) and LTC2991IMS#PBF (–40°C to 85°C) variants. Its 16-lead MSOP footprint, thermal relief pad design, and decoupling network comply with the absolute maximum ratings and operating conditions specified for both temperature grades in the LTC2991 datasheet.

How is remote diode temperature accuracy maintained on the DC1785A?

The DC1785A maintains LTC2991's ±0.7°C typical remote diode temperature total unadjusted error through strict adherence to layout guidelines: GND-shielded differential traces for V7/V8, 470 pF filtering per the datasheet's Figure 2, Kelvin connections for sense resistors, and isolation of analog ground from digital return paths - directly implementing the noise-reduction techniques validated in LTC2991 Typical Performance Characteristics G16–G17.

Can the DC1785A be used to validate current measurement accuracy down to 14-bit resolution?

Yes. The DC1785A enables 14-bit current measurement validation using its dual 0805 shunt footprints (10 mΩ and 50 mΩ, both 1% tolerance) and Kelvin-connected pads. When paired with the LTC2991's differential voltage LSB of 19.075 µV and full-scale range of ±312.5 mV, this achieves ≤0.75% differential voltage TUE - meeting the 14-bit resolution requirement confirmed in LTC2991 Electrical Characteristics Table (VDIFF(TUE) and RES).

Is the PWM output on the DC1785A directly usable for fan control?

Yes, the DC1785A routes the LTC2991's PWM pin to a 2-pin header labeled "TO FAN" with CMOS-level drive capability (0.9–1.2 ms period, 0–99.8% duty cycle). This output is calibrated to the LTC2991's SCALEPWM = 32°C range and has been verified against the device's specified 0.0625°C/LSB temperature resolution and 0.07 °RMS noise with filter engaged - making it suitable for closed-loop thermal management without additional signal conditioning.