Analog Devices Inc. ADP3156JR-1.5-REEL

Overview

ADP3156JR-1.5-REEL from Analog Devices is a dual-output synchronous buck controller with integrated linear regulator controller, designed for desktop VRM8.4-compliant core voltage regulation. It delivers fixed 1.5 V ±1.33% output at up to 10 A, supports active voltage positioning, includes overvoltage crowbar protection (±15% trip), and operates in constant off-time current-mode control with SO-16 package.

For engineers reviewing the ADP3156JR-1.5-REEL datasheet, ADP3156JR-1.5-REEL pinout, ADP3156JR-1.5-REEL application, or ADP3156JR-1.5-REEL equivalent, key selection considerations include its 1.5 V fixed output accuracy, CT-programmable switching frequency, dual N-channel gate drive capability, integrated linear regulator control for auxiliary AGP/GTL rails, and crowbar-protected transient response in Pentium III motherboard power systems.

Technical Context

The ADP3156JR-1.5-REEL implements a current-mode, constant off-time architecture where t_OFF is set by an external CT capacitor (e.g., 150 pF yields 2.45 µs typical), enabling stable operation without slope compensation. Its active voltage positioning adjusts output DC level dynamically with load current to minimize required output capacitance.

It integrates two independent control paths: a primary synchronous buck controller (DRIVE1/DRIVE2) for main core voltage and a secondary linear regulator controller (VLDO/FB) for auxiliary 1.5 V outputs. The crowbar function triggers when V_OUT exceeds +15% nominal, forcing PGND conduction via DRIVE2 to protect microprocessors.

Key Specifications

Pinout & Package

ADP3156JR-1.5-REEL is housed in a 16-lead SOIC (R-16A/SO-16) package with exposed pad thermal design, rated for 0°C to +70°C ambient operation and θ_JA = 90°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck controller applications.

Compared with ADP3156JR-1.5-REEL, ADP3165JR-1.5-REEL offers enhanced thermal handling and integrated bootstrap functionality but demands board revision, while TPS51100PWR provides lower-cost voltage-mode control at the expense of VRM8.4-compliant transient performance and crowbar protection.

Availability

ADP3156JR-1.5-REEL is available at Aetrix Electronics and suitable for desktop motherboard power delivery, VRM8.4-compliant CPU supplies, and multi-rail chipset power systems requiring stable component supply and long-term lifecycle continuity.

Supply support for ADP3156JR-1.5-REEL 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The ADP3156JR-1.5-REEL belongs to Analog Devices' VRM controller product line, engineered specifically for Intel Pentium III-era desktop platforms requiring precise active voltage positioning, crowbar-protected overvoltage response, and dual-path regulation for core and auxiliary rails.

FAQ

What is the output voltage tolerance of the ADP3156JR-1.5-REEL over temperature?

The ADP3156JR-1.5-REEL guarantees a fixed 1.5 V output with ±13.3 mV (±0.89%) tolerance across 0°C to +70°C ambient, corresponding to 1.480 V minimum and 1.520 V maximum per the datasheet's "ADP3156-1.5 V" specification row. This tight tolerance ensures VRM8.4 compliance without external calibration. ADP3156JR-1.5-REEL maintains this accuracy through on-chip reference trimming and active voltage positioning compensation.

Does the ADP3156JR-1.5-REEL support adjustable output voltage?

No, the ADP3156JR-1.5-REEL is a fixed-output variant with factory-trimmed 1.5 V regulation; it does not support external VID or resistor-based adjustment. The "-1.5" suffix explicitly denotes the fixed 1.5 V version. For programmable outputs, Analog Devices offers the ADP3155 series with VID interface. ADP3156JR-1.5-REEL's FB pin only controls the auxiliary linear regulator, not the main 1.5 V buck output.

How does the crowbar protection function in the ADP3156JR-1.5-REEL?

The ADP3156JR-1.5-REEL activates crowbar protection when the sensed output voltage exceeds +9% to +24% above nominal (i.e., >1.635 V), forcing DRIVE2 high to fully turn on the synchronous rectifier MOSFET and short the output to PGND. This hardware-level response occurs without software or external components. ADP3156JR-1.5-REEL releases the crowbar when V_OUT falls below ~50% of nominal (e.g., <0.75 V), allowing safe recovery after fault removal.

What is the recommended timing capacitor value for 200 kHz operation with the ADP3156JR-1.5-REEL?

For nominal 200 kHz operation at 1.5 V output, the ADP3156JR-1.5-REEL requires a 208 pF timing capacitor on the CT pin, calculated from t_OFF = 3.2 µs and 65 µA discharge current. This value assumes continuous conduction mode and accounts for parasitic voltage drops. ADP3156JR-1.5-REEL's actual frequency varies with V_IN/V_OUT ratio and load; Figure 5 in the datasheet confirms 200 kHz at CT = 200 pF for V_OUT = 1.8 V, scaling proportionally for 1.5 V.

Can the ADP3156JR-1.5-REEL drive both high-side and low-side N-channel MOSFETs simultaneously?

No - the ADP3156JR-1.5-REEL employs non-overlapping drive logic that ensures DRIVE1 (high-side) and DRIVE2 (low-side) are never active simultaneously, preventing shoot-through. During each cycle, DRIVE1 turns off before DRIVE2 turns on, and vice versa, with built-in dead-time controlled by internal timing. ADP3156JR-1.5-REEL's functional block diagram explicitly shows "NONOVERLAP" logic between the two drivers, making simultaneous conduction impossible under normal operation.