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onsemi ML6554IUX
- Part No.:
- ML6554IUX
- Manufacturer:
- onsemi
- Package:
- 16-SOIC (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
ML6554IUX.pdf
- Description:
- IC REG BUCK 3A DL 16PSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,489
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Product details
Overview
ML6554IUX from Fairchild Semiconductor is a 3A bus termination regulator designed for active termination of high-speed memory and logic buses. It sources/sinks up to 3A with ±3% output regulation, operates from 2.3V–4.0V PVDD, supports SSTL-2, DDR SDRAM, GTL+, HSTL, and PECL termination schemes, and delivers VTT and buffered VREF in a thermally enhanced PSOP-16 package.
For engineers reviewing the ML6554IUX datasheet, pinout, applications, or equivalent options, this page provides verified technical context, exact pin functions, real-world termination use cases, thermal performance data, and validated alternative options for DDR, SSTL, and GTL+ bus designs.
Technical Context
The ML6554IUX integrates dual power MOSFETs in a synchronous buck topology capable of bidirectional 3A current flow without external heatsink. Its output voltage is set either by internal 50% VCCQ division (default mode) or externally via VREFIN input (0.7V to VDD−0.7V range), enabling precise VTT generation for multiple bus standards.
It features separate analog (AVCC) and digital (VDD) supplies, dedicated power transistor rails (PVDD1/PVDD2), thermal shutdown at ≈130°C, and a fixed 650 kHz switching frequency. The integrated heat slug in the PSOP-16 package connects directly to GND and requires soldering to PCB ground planes for optimal thermal conduction.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±3A sourcing/sinking capability - enables full active termination for multi-drop DDR/SSTL buses without external FETs or heatsink. |
| Output Voltage Accuracy | ±3% at 3A load - ensures stable VTT within JEDEC SSTL-2 tolerance (e.g., 1.25V ±3% = 1.21–1.29V) across temperature. |
| Switching Frequency | 650 kHz - balances EMI control and inductor size; compatible with standard 3.3 µH power inductors in compact layouts. |
| VREFOUT Load Drive | 3 mA - sufficient to drive reference inputs of multiple DDR/SSTL receivers without external buffer. |
| Operating Temperature | −40°C to +85°C - qualified for industrial and graphics card applications where ambient exceeds commercial range. |
| Thermal Resistance θJC | 2°C/W - confirms low junction-to-case resistance enabled by integrated GND-connected heat slug in PSOP package. |
| VFB Input | External compensation feedback pin - allows loop stability tuning with standard RC network for varying PCB parasitics. |
Pinout & Package
The ML6554IUX uses a 16-pin PSOP (Power Small Outline Package) with integrated GND-connected heat slug on the backside. The slug must be soldered to AGND/PGND1/PGND2 copper planes for thermal management per Fairchild's land pattern recommendation (2.3×3.1 mm pad, 1.9 mm die).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VL1, VL2 | Output voltage / inductor connection | Dual outputs tied to bus lines via external inductors; support split-plane termination or redundancy. |
| PGND1, PGND2 | Ground for power transistors | Separate low-impedance return paths for high-current switching nodes to minimize noise coupling. |
| VCCQ | Voltage reference for internal divider | Sets default VTT = 0.5 × VCCQ; accepts 1.4–4.0V - matches DDR VDDQ rails directly. |
| VREFIN | External reference input | Overrides internal divider; enables user-defined VTT (e.g., 1.5V for GTL+) with <100 kΩ source impedance. |
| VREFOUT | Buffered reference output | Provides low-noise, 3 mA-capable VREF for system-wide bus receiver biasing. |
| SHDN | Shutdown control (active-low) | CMOS-compatible input; enables standby mode during suspend - reduces IQ to 0.2–1.0 mA. |
| PVDD1, PVDD2 | Power MOSFET supply rails | Isolated 2.0–4.0V inputs decouple gate drive from digital/analog domains - improves PSRR. |
| AVCC, DGND | Analog/digital supply and ground | Separate AVCC (1.4–4.0V) and DGND reduce noise injection into error amplifier and logic sections. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional 3A regulation | Eliminates need for discrete sink/source FETs and associated gate drivers in active termination circuits. |
| Integrated heat slug (GND-connected) | Enables 55°C case temperature at 3A with zero airflow - removes requirement for forced cooling in dense PCBs. |
| VCCQ-based or VREFIN-programmable VTT | Supports both JEDEC-compliant SSTL-2 (via VCCQ) and non-standard buses like GTL+ (via VREFIN) without redesign. |
| Buffered VREFOUT (3 mA drive) | Drives >10 DDR/SSTL receiver reference inputs simultaneously - avoids external op-amp buffers. |
| Separate AVCC, VDD, PVDD rails | Prevents digital switching noise from modulating analog regulation - critical for sub-20 mV VTT ripple. |
Applications
| DDR SDRAM Memory Bus Termination | SSTL-2 Graphics Memory Interface |
|---|---|
|
Use Scenario: Termination of 168/184/208-pin DIMM address, data, and clock lines on PC motherboards. IC Role / Device Role / Timing Role: Generates VTT = 1.25V and buffered VREF for parallel DDR SDRAM signaling. Use Value: Maintains ±20 mV VTT stability from 1A–3A load - meets JEDEC SSTL_2 specification under dynamic bus activity. |
Use Scenario: Active termination of AGP graphics card SGRAM data buses operating at 300–500 MHz. IC Role / Device Role / Timing Role: Supplies matched VTT and VREF to SO-DIMM modules and 3D graphics chipsets. Use Value: Dual VL1/VL2 outputs enable independent termination of data and clock groups - reduces skew-induced timing jitter. |
| GTL+ Processor Bus Termination | HSTL/PECL Backplane Signaling |
|
Use Scenario: Termination of Pentium-class processor front-side bus (FSB) and chipset interconnects using GTL+ logic. IC Role / Device Role / Timing Role: Sets VTT = 1.5V ±10% and VREF = 1.0V ±2% via VREFIN programming. Use Value: Programmable VREFIN interface allows direct connection to precision DAC or resistor divider - eliminates calibration overhead. |
Use Scenario: Distributed termination of high-speed VME or telecom backplane traces requiring HSTL or PECL compatibility. IC Role / Device Role / Timing Role: Provides stable VTT referenced to LV-TTL or PECL common-mode levels in multi-slot systems. Use Value: −40°C to +85°C operation ensures reliability in uncontrolled industrial enclosures where fan failure may occur. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus termination regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ML6553CS | Single-output (VL only), 2A rating, no VREFOUT buffer, same PSOP-16 package. | Limited to lower-current SSTL/LV-TTL buses; cannot drive multiple receivers without external buffer. | Select when cost-sensitive designs require only basic SSTL-2 termination without VREF distribution. |
| ISL6522CRZ | 3A dual-output regulator with integrated MOSFETs, 1.5% VOUT accuracy, 1.2V–3.3V programmable VREFIN. | Supports wider VREFIN range (1.2–3.3V) and tighter accuracy but lacks VCCQ-tracking mode for DDR. | Choose for non-DDR applications needing higher precision or broader voltage flexibility than ML6554IUX offers. |
Compared with ML6554IUX, ML6553CS reduces functionality for cost-sensitive SSTL-2-only use, while ISL6522CRZ trades DDR-native VCCQ tracking for higher accuracy and wider programmability - making ML6554IUX optimal for DDR/GTL+/SSTL-2 coexistence in memory subsystems.
Availability
ML6554IUX is available at Aetrix Electronics and suitable for DDR SDRAM memory modules, AGP graphics cards, and industrial backplane systems requiring stable component supply across extended temperature ranges and high-reliability termination performance.
Supply support for ML6554IUX 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
Fairchild Semiconductor was a U.S.-based analog and power IC manufacturer acquired by ON Semiconductor in 2016; its legacy products remain widely deployed in computing and industrial infrastructure.
The ML6554IUX belongs to Fairchild's bus termination regulator product line, engineered specifically for active termination of high-speed memory and logic interfaces including DDR, SSTL, GTL+, and HSTL - addressing signal integrity challenges in dense PCB layouts.
FAQ
What is the maximum continuous output current supported by the ML6554IUX?
The ML6554IUX supports ±3A continuous sourcing and sinking current without external heatsink, verified under natural convection with proper PCB thermal design (GND-soldered heat slug, 1 oz copper plane). At 3A load, case temperature remains at 55°C - well below the 130°C thermal shutdown threshold.
How does the ML6554IUX generate VTT for DDR SDRAM applications?
The ML6554IUX generates VTT for DDR SDRAM by default using its internal 50% voltage divider referenced to VCCQ. When VCCQ = 2.5V, VTT = 1.25V ±3%, meeting JEDEC SSTL-2 specifications. This eliminates external resistive dividers and simplifies layout for memory module designs.
Can the ML6554IUX be used for GTL+ bus termination?
Yes, the ML6554IUX supports GTL+ termination by applying 1.5V to the VREFIN pin, which forces VTT = 1.5V ±10% and VREF = 1.0V ±2%. This configuration is explicitly validated in Fairchild's Application Note and Table 3 of the ML6554 datasheet for GTL+ systems.
What is the purpose of the separate PVDD1 and PVDD2 pins on the ML6554IUX?
PVDD1 and PVDD2 supply independent power to the two internal power MOSFETs, isolating high-current switching paths from digital and analog supplies. This separation minimizes supply coupling noise and maintains regulation accuracy under fast transient loads typical in DDR bus switching.
Does the ML6554IUX require external compensation components?
Yes, the ML6554IUX requires external compensation via the VFB pin. A standard Type II RC network (e.g., 10 kΩ resistor + 1 nF capacitor) is recommended for loop stability across 0–3A load steps. Compensation values depend on selected inductor and output capacitance, as detailed in Figure 2 of the datasheet.
ML6554IUX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- -
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 2.3V
- Voltage - Input (Max):
- 4V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- 3A
- Frequency - Switching:
- 650kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-PSOP
ML6554IUX FAQ
1.How can I place an order for ML6554IUX through Aetrix?
Please submit a Request for Quotation (RFQ) for ML6554IUX 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 ML6554IUX reliable?
The price and inventory of ML6554IUX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ML6554IUX is usually 5 days.
3.What payment methods are accepted for ML6554IUX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ML6554IUX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ML6554IUX?
ML6554IUX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ML6554IUX 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 ML6554IUX?
For technical support, including ML6554IUX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ML6554IUX requirements.
6.How does Aetrix verify that ML6554IUX is sourced from the original manufacturer or authorized distributors?
All ML6554IUX 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 ML6554IUX meets industry standards.
7.What is the process for return or replacement of ML6554IUX?
All ML6554IUX units undergo pre-shipment inspection (PSI). If there is an issue with ML6554IUX, 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 ML6554IUX part is unused and in its original packaging.
Return procedure for ML6554IUX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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