Analog Devices Inc. DC776A

Overview

DC776A from Analog Devices (formerly Linear Technology) is a demonstration circuit board implementing a 36V–72V_IN isolated forward converter using the LTC3705 primary-side driver and LTC3706 secondary-side controller to deliver 1.5V/45A output with 1500V_DC isolation, ±1% output regulation, and 84.75% typical efficiency at 48V_IN/45A. It targets high-step-down telecom power systems.

For engineers reviewing the DC776A datasheet, DC776A pinout, DC776A application, or DC776A equivalent, this page provides verified performance data, thermal behavior under 400LFM airflow, load transient response (65mV/50µs), input current measurement guidance, and secondary-side control architecture details critical for telecom PSU validation and layout review.

Technical Context

The DC776A implements a synchronous forward topology with primary-side gate driving (LTC3705) and isolated secondary-side voltage regulation (LTC3706), enabling optocoupler-free feedback via small-signal transformer T3. Control handoff occurs seamlessly below 10% of nominal output voltage.

It operates at a fixed 215kHz switching frequency, supports input undervoltage lockout (36V min), output overvoltage protection, and self-starting soft-start. Isolation meets basic insulation requirements at 1500V_DC, and output ripple is specified at 30mV_P–P (20MHz BW) under 48V_IN/30A conditions.

Key Specifications

Availability

DC776A is available at Aetrix Electronics and suitable for telecom power system validation, high-density DC-DC converter reference design evaluation, and isolated 1.5V supply qualification requiring stable component supply and documented thermal performance.

Supply support for DC776A 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. (including legacy Linear Technology products) designs high-performance analog, mixed-signal, and power management ICs for precision signal chain and power applications.

The DC776A belongs to Linear Technology's Demonstration Circuit series, developed to provide fully tested, application-optimized hardware platforms that accelerate power supply design verification and reduce time-to-market for isolated DC-DC converters.

FAQ

What is the purpose of the DC776A demonstration circuit?

The DC776A demonstration circuit is a fully assembled and tested 36V–72V_IN isolated forward converter board designed to validate the LTC3705/LTC3706 controller pair in high-step-down telecom applications. It delivers 1.5V/45A with secondary-side regulation, 1500V_DC isolation, and documented thermal and dynamic performance - enabling rapid evaluation without prototyping. The DC776A serves as a functional reference for system-level integration and layout verification.

How is output voltage regulated on the DC776A?

The DC776A uses secondary-side control: the LTC3706 senses the 1.5V output directly on the secondary winding and transmits encoded PWM pulses via small-signal transformer T3 to the primary-side LTC3705 driver. This eliminates optocouplers, reduces latency, improves large-signal transient response, and simplifies loop compensation. The DC776A achieves ±0.18% load regulation and ±0.01% line regulation per test data.

What thermal performance data is available for the DC776A?

Measured thermal data for the DC776A is provided across multiple operating points: Figures 7–10 show component temperatures on front/back sides at 48V_IN/45A (400LFM) and 48V_IN/40A (200LFM). Peak MOSFET and inductor temperatures remain within safe limits under rated load and airflow, confirming suitability for compact telecom chassis. The DC776A thermal profile supports continuous operation at full 45A with adequate forced-air cooling.

Can the DC776A be used to measure input current accurately?

Yes - the Quick Start Guide explicitly instructs users to place a DC ammeter capable of measuring 3A_dc in series with the input supply to measure the DC776A's input current for efficiency calculations. Input current varies with load and input voltage (e.g., ~3.2A at 48V_IN/45A); measurements must avoid ground-loop errors and use proper probe technique per Figure 2. The DC776A's input current behavior is repeatable and documented in its efficiency curves (Figure 3).

Does the DC776A support On/Off control, and what are the logic thresholds?

Yes, the DC776A implements digital On/Off control compatible with standard logic levels: a voltage ≤1V applied to the control pin disables the converter (Logic Low-Off), while ≥2.5V enables it (Logic High-On). This interface allows integration with system supervisors or microcontrollers. The DC776A's control pin is directly tied to the LTC3705's RUN pin, preserving the controller's built-in soft-start and fault-handling behavior during toggling.