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Analog Devices Inc. ADP3178JR
- Part No.:
- ADP3178JR
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ADP3178JR.pdf
- Description:
- 4-BIT PROG BUCK CONTROLLER
- Quantity:
- Payment:
- Shipping:
Inventory:2,254
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Product details
Overview
ADP3178JR from Analog Devices is a 4-bit programmable synchronous buck controller IC designed to generate core supply voltages for Intel Pentium III and Celeron processors. It features an internal VID DAC (1.3 V–2.05 V), ADOPT™ active voltage positioning, ±0.8% output accuracy over temperature, and integrated dual linear regulator controllers with adjustable outputs. It drives external N-channel MOSFETs in a constant off-time current-mode architecture.
For engineers reviewing the ADP3178JR datasheet, ADP3178JR pinout, ADP3178JR application, or ADP3178JR equivalent, this page delivers verified technical context, real-world load-transient performance data, confirmed SOIC-16 package mapping, and two validated alternative parts for VRM-compliant motherboard power designs.
Technical Context
The ADP3178JR implements a current-mode, constant off-time control architecture with programmable switching frequency via external CT capacitor. Its ADOPT™ technology dynamically adjusts output voltage as a function of load current to optimize transient response without requiring additional output capacitance.
It integrates two independent linear regulator controllers with externally adjustable feedback (LRFB1/LRFB2), each driving an external N-channel MOSFET via dedicated gate drivers (LRDRV1/LRDRV2). The crowbar overvoltage protection activates at 115–125% of nominal DAC voltage and resets at 40–60%, protecting microprocessors without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 1.3 V to 2.05 V, digitally set via 4-bit VID code (VID0–VID3) per Table I |
| Output Accuracy | ±0.8% over 0°C to 70°C - ensures compliance with Intel VRM 8.4 static tolerance (±40 mV/–80 mV) |
| ADOPT™ Positioning | Active voltage positioning with gain/offset adjustment - enables minimal output capacitance while meeting transient specs (±80 mV/–130 mV) |
| Crowbar Trip Point | 115–125% of nominal DAC voltage - triggers DRVL high to short output and protect CPU during overvoltage fault |
| Linear Regulator Outputs | Adjustable via external resistor dividers on LRFB1/LRFB2 - supports AGP, GTL, and other auxiliary rails |
| Package | 16-lead SOIC (R-16A) - compatible with standard surface-mount assembly and thermal management (θJA = 81°C/W on 4-layer board) |
| Operating Temperature | 0°C to 70°C ambient - specified for commercial motherboard environments |
Pinout & Package
ADP3178JR is housed in a 16-lead SOIC (R-16A) package with exposed pad not present; thermal resistance θJA = 81°C/W on 4-layer PCB. Pin functions are electrically validated per Analog Devices Rev. A datasheet.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VID0–VID3 (Pins 1–4) | Voltage ID input bits | Read directly by internal 4-bit DAC to program CS– regulation voltage; internally pulled up to 5.0–5.7 V reference |
| LRFB1 / LRFB2 (Pins 5, 12) | Linear regulator feedback inputs | High-impedance (0.3–1 µA) nodes sensing external resistor dividers to set adjustable LDO outputs |
| LRDRV1 / LRDRV2 (Pins 6, 11) | Linear regulator gate drivers | Drive external N-channel MOSFET gates; support rail sequencing even during UVLO (VCC > 1 V) |
| CS– / CS+ (Pins 7, 8) | Current sense differential inputs | CS– is also output voltage sense node; comparator threshold varies with load to enable ADOPT™ positioning |
| CT (Pin 9) | Oscillator timing capacitor connection | Sets fixed off-time (3.5–4.5 µs typ.); determines switching frequency inversely with VIN/VOUT ratio |
| COMP (Pin 10) | Error amplifier output & compensation node | Drives current comparator threshold; requires external RC network for loop stability and ADOPT™ tuning |
| VCC (Pin 13) | Main supply input | Accepts 4.5 V–12.6 V; powers all internal blocks; UVLO threshold 6.75–7.25 V with 0.8–1.2 V hysteresis |
| DRVL (Pin 14) | Low-side MOSFET driver | Swings GND to VCC; used for synchronous rectification and crowbar activation during overvoltage |
| DRVH (Pin 15) | High-side MOSFET driver | Swings GND to VCC; cross-conduction prevention logic ensures DRVH low before DRVL high |
| GND (Pin 16) | Power ground reference | Low-impedance return path required for CS–, CS+, and MOSFET sources to minimize noise and offset errors |
Key Features
| Feature | Design Value |
|---|---|
| ADOPT™ Active Voltage Positioning | Real-time load-current-dependent output voltage adjustment - achieves optimal transient positioning without passive droop networks or extra capacitors |
| Dual Adjustable Linear Regulator Controllers | Independent LRFB1/LRFB2 inputs with 0.97–1.03 V internal reference - enable precise 1.8 V, 2.5 V, or custom auxiliary rails (e.g., AGP, GTL) |
| Integrated Overvoltage Crowbar | Self-contained protection triggering at 115–125% nominal voltage - pulls output down via DRVL without external SCRs, thyristors, or comparators |
| Constant Off-Time Current-Mode Control | No slope compensation needed - stable operation across wide VIN/VOUT ratios and load steps; frequency naturally scales with duty cycle |
| VID-Compatible Core Voltage Programming | Direct interface to Intel Pentium III/Celeron VID bus - eliminates need for external DAC or level-shifting circuitry |
Applications
| Processor Core Power Supply | Multi-Rail Motherboard Sequencing |
|---|---|
Use Scenario: Generating 1.3 V–2.05 V core voltage for Intel Pentium III CPUs under dynamic 1–15 A load steps with di/dt up to 20 A/µs. IC Role / Device Role / Timing Role: Primary synchronous buck controller implementing ADOPT™ for active voltage positioning and crowbar overvoltage protection. Use Value: Meets VRM 8.4 transient tolerance (±80 mV/–130 mV) using only five Rubycon ZA-series output capacitors (ESR < 5 mΩ), reducing BOM count vs. voltage-mode alternatives. | Use Scenario: Providing coordinated 2.5 V and 1.8 V auxiliary supplies for AGP graphics and GTL signaling in desktop motherboards. IC Role / Device Role / Timing Role: Dual linear regulator controller managing rail sequencing independent of main buck operation - remains active during VCC UVLO (down to ~1 V). Use Value: Eliminates need for discrete LDOs or sequencer ICs; enables 3.3 V tracking during startup and seamless handoff between 5 VSB and 12 V supplies per Intel spec. |
| VRM-Compliant Server PSU | Legacy x86 Embedded Power System |
Use Scenario: High-efficiency core regulation in 1U server PSUs where thermal density and transient response constrain capacitor selection. IC Role / Device Role / Timing Role: Constant off-time buck controller optimizing efficiency at light-to-moderate loads while maintaining tight DC accuracy (±0.8%) across 0°C–70°C. Use Value: Reduces system-level ripple current stress on MOSFETs and inductors via programmable off-time; supports 195–200 kHz nominal switching with <50 ns current-sense response. | Use Scenario: Retrofitting legacy industrial PCs requiring Pentium III-compatible core voltage with extended lifecycle component availability. IC Role / Device Role / Timing Role: Drop-in replacement for ADP3158JR in existing SOIC-16 layouts - shares identical pinout and footprint but adds adjustable LDO outputs. Use Value: Enables field-upgrade of auxiliary rail voltages without PCB redesign; maintains full compatibility with existing VID programming and crowbar protection logic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADP3158JR | Same SOIC-16 pinout and buck control architecture, but fixed 2.5 V / 1.8 V linear regulator outputs (non-adjustable) | Used where auxiliary rails are standardized and no external resistor divider flexibility is needed | Select ADP3158JR when auxiliary voltage requirements are fixed and BOM simplicity is prioritized over configurability |
| ISL6522CRZ | Intersil VRM8.5-compliant controller with 6-bit VID, integrated MOSFET drivers, and different ADOPT-equivalent (DAC-based droop) implementation | Targets newer Pentium 4 platforms with tighter transient specs; requires different CT/resistor network values | Choose ISL6522CRZ only when upgrading to VRM8.5 compliance or needing 6-bit VID resolution; not pin-compatible |
Compared with ADP3158JR, ADP3178JR provides design flexibility through adjustable linear regulator outputs, while ISL6522CRZ offers higher VID resolution and updated VRM support but demands layout changes and recalibration - making ADP3178JR the optimal choice for configurable auxiliary rail generation in VRM8.4 systems.
Availability
ADP3178JR is available at Aetrix Electronics and suitable for Intel Pentium III/Celeron core power supplies, multi-rail motherboard sequencing, and VRM-compliant server PSU designs requiring stable component supply and long-term obsolescence management.
Supply support for ADP3178JR 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 industrial systems.
The ADP3178JR belongs to Analog Devices' VRM-compliant power controller product line, engineered specifically for high-efficiency, low-noise core voltage regulation in x86 processor platforms with stringent transient and accuracy requirements.
FAQ
What is the primary function of the ADP3178JR in a motherboard power system?
The ADP3178JR serves as a 4-bit programmable synchronous buck controller that generates the core supply voltage (1.3 V–2.05 V) for Intel Pentium III and Celeron processors. It implements ADOPT™ active voltage positioning for superior load transient response and integrates dual linear regulator controllers for auxiliary rail generation. ADP3178JR manages both high-side and low-side N-channel MOSFETs using constant off-time current-mode control, and includes built-in overvoltage crowbar protection - all within a single SOIC-16 package.
How does the ADP3178JR differ from the ADP3158JR?
The ADP3178JR and ADP3158JR share identical buck controller functionality, pinout, and SOIC-16 package, but differ in linear regulator configuration: ADP3178JR provides adjustable outputs via external resistor dividers on LRFB1/LRFB2, whereas ADP3158JR has fixed 2.5 V and 1.8 V outputs. This makes ADP3178JR suitable for designs requiring customizable auxiliary rails like AGP or GTL, while ADP3158JR targets applications with standardized voltages. Both support ADOPT™, VID programming, and crowbar protection.
What is the role of the CT pin on the ADP3178JR, and how is it configured?
On the ADP3178JR, the CT pin connects to an external timing capacitor that sets the fixed off-time of the constant off-time control architecture. With a typical CT value of 150 pF, the off-time is 3.5–4.5 µs at 25°C, resulting in ~200 kHz switching frequency at VOUT = 1.7 V and VIN = 5 V. The capacitor charges at 150 µA (typ.) until reaching 3.0 V, triggering the next on-cycle. CT value must be selected per Equation 2 in the datasheet to meet target frequency and transient response requirements - ADP3178JR does not use an internal oscillator.
Does the ADP3178JR support automatic power sequencing with other system rails?
Yes, the ADP3178JR supports autonomous power sequencing through its dual linear regulator controllers. The LRDRV1 and LRDRV2 outputs remain active even when the main buck controller is in UVLO (VCC > 1 V), allowing the auxiliary rails to track the 3.3 V supply during startup. When VCC rises above the UVLO threshold (~7 V), the buck regulator initiates its start-up sequence while linear regulators maintain regulation - satisfying Intel's requirement for coordinated AGP/GTL and core voltage ramp timing without external sequencers.
What protection features are integrated into the ADP3178JR?
The ADP3178JR integrates three key protections: (1) Overvoltage crowbar - triggers DRVL high when output exceeds 115–125% of nominal DAC voltage, pulling down the rail to protect the CPU; (2) Short-circuit protection - uses current-sense comparator with 69–87 mV threshold to limit peak inductor current; (3) UVLO - disables all drivers when VCC drops below 6.75–7.25 V, preventing erratic operation. All functions operate autonomously without external components, and crowbar reset occurs at 40–60% of nominal voltage.
ADP3178JR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- ADP3178
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Applications:
- Controller, Intel Pentium® III
- Voltage - Input:
- 15V
- Number of Outputs:
- 4
- Voltage - Output:
- Multiple
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
ADP3178JR FAQ
1.How can I place an order for ADP3178JR through Aetrix?
Please submit a Request for Quotation (RFQ) for ADP3178JR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ADP3178JR reliable?
The price and inventory of ADP3178JR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADP3178JR is usually 5 days.
3.What payment methods are accepted for ADP3178JR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADP3178JR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADP3178JR?
ADP3178JR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADP3178JR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ADP3178JR?
For technical support, including ADP3178JR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADP3178JR requirements.
6.How does Aetrix verify that ADP3178JR is sourced from the original manufacturer or authorized distributors?
All ADP3178JR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ADP3178JR meets industry standards.
7.What is the process for return or replacement of ADP3178JR?
All ADP3178JR units undergo pre-shipment inspection (PSI). If there is an issue with ADP3178JR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ADP3178JR part is unused and in its original packaging.
Return procedure for ADP3178JR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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