Analog Devices Inc. DC2138B

Overview

DC2138B from Analog Devices is a demonstration board for the LT8301 micropower isolated flyback controller IC, implementing a 5V/1.15A isolated output power supply operating from 2.7V–36V input. It integrates the LT8301 in a 5-lead TSOT-23 package with a 3:1 turns-ratio transformer, single RFB resistor programming, and no opto-isolator or third winding. Designed for auxiliary/housekeeping power in space-constrained industrial and automotive systems.

For engineers reviewing the DC2138B datasheet, DC2138B pinout, DC2138B application, or DC2138B equivalent, this page delivers verified board-level specifications, validated transformer selection, boundary-mode vs. burst-mode behavior under load, thermal performance at 150°C junction, and design guidance for AEC-Q100-compliant isolated supplies using the LT8301 controller.

Technical Context

The DC2138B implements the LT8301's primary-side sensing architecture, enabling regulation by sampling the reflected flyback voltage on the SW pin without optocouplers or auxiliary windings. It operates in boundary conduction mode above ~0.4A load and transitions to low-ripple Burst Mode below 6mA, maintaining >75% efficiency from 6mA to full load across 5V, 12V, 24V, and 36V inputs.

Board-level validation confirms compliance with AEC-Q100 Grade I (–40°C to 125°C) when populated with automotive-grade LT8301ES5#WTRPBF, uses Würth 750370047 transformer (30µH primary, 3:1 ratio), and achieves <0.5% minimum load requirement with 50mVpp output ripple at light load.

Key Specifications

Availability

DC2138B is available at Aetrix Electronics and suitable for isolated auxiliary power, automotive housekeeping supplies, and industrial sensor interface modules requiring stable component supply and AEC-Q100-aligned reference designs.

Supply support for DC2138B 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. is a global semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision instrumentation, power management, and isolation applications.

The DC2138B belongs to Analog Devices' Power by Linear™ demonstration board family, engineered to accelerate adoption of their no-opto isolated flyback controllers in safety-critical and space-constrained power systems.

FAQ

What is the purpose of the DC2138B evaluation board?

The DC2138B evaluation board demonstrates the LT8301 micropower isolated flyback controller in a fully assembled, tested 5V/1.15A auxiliary power supply. It validates primary-side regulation, boundary-mode stability, and low-ripple Burst Mode operation across 2.7V–36V input, serving as a turnkey reference for automotive and industrial isolated rail generation. The DC2138B includes layout-optimized transformer placement and EMI-reduced SW node routing.

Does DC2138B support AEC-Q100 automotive qualification?

Yes - when populated with the LT8301ES5#WTRPBF controller (automotive-grade variant), the DC2138B meets AEC-Q100 Grade I requirements (–40°C to 125°C). Its transformer, capacitors, and PCB layout are selected and validated for automotive temperature cycling, vibration, and long-term reliability. The DC2138B documentation includes test reports confirming operation at 150°C junction temperature during overload conditions.

What transformer is used on the DC2138B, and why is it critical?

The DC2138B uses Würth Electronik part 750370047: a 30µH primary, 3:1 turns-ratio flyback transformer with 60mΩ primary DCR and 12.5mΩ secondary DCR. This specific unit is pre-validated for boundary mode operation with the LT8301, ensures <450ns minimum off-time for accurate flyback sampling, and maintains <65V SW-pin stress at 36V_IN. Substituting transformers without matching LPRI, leakage inductance, and turns-ratio accuracy will degrade regulation and cause instability. The DC2138B relies on this exact part for its published 5V ±2% output tolerance.

How does DC2138B achieve regulation without an optocoupler or third winding?

The DC2138B leverages the LT8301's internal flyback pulse sense circuit to sample the isolated output voltage directly from the reflected voltage on the SW pin during zero-secondary-current events. This eliminates optocouplers and third windings while maintaining ±2% output regulation across line, load, and temperature. The DC2138B's RFB resistor (154kΩ) sets 5V output based on the 3:1 transformer ratio and diode forward voltage, with no external compensation required due to the LT8301's integrated error amplifier and soft-start.

Can DC2138B be modified for different output voltages?

Yes - output voltage on the DC2138B is set by changing the RFB resistor value per the formula V_OUT ≈ (100µA × RFB)/NPS – V_F, where NPS = 3 and V_F ≈ 0.3V. For example, a 301kΩ resistor yields ~12V output. However, transformer turns ratio must remain matched to avoid exceeding the LT8301's 65V SW-pin rating; increasing V_OUT beyond 12V requires verifying SW voltage stress under worst-case VIN and leakage spike conditions. The DC2138B schematic and bill of materials provide full modification guidelines.