Analog Devices Inc. DC1171A-B

Overview

DC1171A-B from Analog Devices (formerly Linear Technology) is a demonstration circuit for the LTC3851EGN synchronous buck controller, configured with DCR current sensing to eliminate the external sense resistor-reducing cost, board area, and improving full-load efficiency by ≥2% at 15A output. It delivers 1.5V ±2% across 4.5V–14V input, operates at 400kHz nominal switching frequency, and supports CCM, pulse-skip, and externally synchronized modes.

For engineers reviewing the DC1171A-B datasheet, DC1171A-B pinout, DC1171A-B application, or DC1171A-B equivalent, this page provides verified design context, measured performance data (e.g., 90.0% typical efficiency at 12V_IN/1.5V_OUT/15A), mode-selection jumper configurations (JP1/JP3), and DCR-sense implementation details critical for power stage validation and layout reuse.

Technical Context

The DC1171A-B implements a single-output synchronous buck topology centered on the LTC3851EGN controller in 16-lead narrow SSOP package. It uses the inductor's DCR for current sensing via an RC network (R9/R10/C23), eliminating R_SENSE while maintaining accurate cycle-by-cycle current limiting and soft-start control.

It supports three operating modes via JP3: continuous conduction mode (CCM), pulse-skipping, and externally synchronized operation (with JP1 set to 'EXTCLK'). The board includes an internal 5V linear regulator for bias, TRK/SS pin for output tracking or soft-start ramp control, and thermal-aware layout optimized for 15A continuous load at 1.5V.

Key Specifications

Availability

DC1171A-B is available at Aetrix Electronics and suitable for power supply validation, FPGA core voltage qualification, high-current DC/DC reference design, and industrial embedded power system development requiring stable component supply and documented thermal performance.

Supply support for DC1171A-B 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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, communications, and power conversion markets.

The DC1171A-B belongs to Linear Technology's Demonstration Circuit (DC) series, designed specifically to accelerate evaluation and adoption of their power ICs-providing fully assembled, tested, and characterized hardware with documented performance and layout guidance.

FAQ

What is the key difference between DC1171A-B and DC1171A-A?

The DC1171A-B uses DCR current sensing via the power inductor's resistance, eliminating the onboard 3mΩ sense resistor found on DC1171A-A. This reduces component count and board space, and improves full-load efficiency by up to 2.7 percentage points - measured as 90.0% vs. 87.3% at 12V_IN/1.5V_OUT/15A. Both share identical LTC3851EGN control architecture and jumper-based mode selection.

How do I configure DC1171A-B for external clock synchronization?

To synchronize DC1171A-B to an external clock, set JP1 to 'EXTCLK' and JP3 to 'BURST', then apply the clock signal to the MODE/PLLIN pin (E4). The LTC3851EGN's PLL accepts 100kHz–750kHz input; ensure clean signal integrity and proper termination. No PCB modification is needed beyond jumper repositioning - the required routing and decoupling are already implemented on DC1171A-B.

What is the purpose of the TRK/SS pin on DC1171A-B?

The TRK/SS pin (E2) on DC1171A-B serves dual functions: soft-start ramp control (default configuration with C24 = 0.1µF) or output voltage tracking of an external reference. For tracking, remove C24 and apply a scaled reference to E2 via resistor dividers (R32/R35 per Table 3). This enables coordinated power-up sequencing in multi-rail systems - a verified capability documented in the DC1171A-B Quick Start Guide.

Does DC1171A-B support Burst Mode operation out of the box?

No - Burst Mode operation on DC1171A-B requires a bench modification: installing a 100kΩ resistor between JP4 pins 1 and 2, and removing the jumper from JP3. This is explicitly stated in Table 2 of the DC1171A-B Quick Start Guide. Unlike CCM and pulse-skip modes, Burst Mode is not enabled by jumper position alone and must be validated with light-load efficiency measurements post-modification.

What thermal performance can be expected from DC1171A-B at full load?

DC1171A-B achieves thermal equilibrium at ≤75°C case temperature under 12V_IN/1.5V_OUT/15A continuous load, as confirmed by the published thermal image (Figure 5) in the Quick Start Guide. The layout places high-current paths on top-side copper with minimal vias, and the MOSFETs (Q1/Q3: RJK0305DPB/RJK0301DPB) are thermally coupled to inner ground planes - enabling reliable operation without forced air in enclosed industrial enclosures.