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onsemi ML6554IU
- Part No.:
- ML6554IU
- Manufacturer:
- onsemi
- Package:
- 16-SOIC (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
ML6554IU.pdf
- Description:
- IC REG BUCK 3A DL 16PSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,487
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Product details
Overview
ML6554IU from Fairchild Semiconductor is a 3A bus termination regulator designed for active voltage termination in 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, GTL+, HSTL, and DDR SDRAM termination, and features integrated power MOSFETs in a thermally enhanced PSOP-16 package.
For engineers reviewing the ML6554IU datasheet, pinout, applications, or equivalent options, key selection criteria include its dual-sourcing/sinking capability, VREFIN/VCCQ-based output programming, thermal shutdown at ≈130°C, and compatibility with -40°C to +85°C industrial temperature operation.
Technical Context
The ML6554IU implements a synchronous buck-boost capable switching regulator architecture with dual output terminals (VL1/VL2) enabling bidirectional current flow. Its internal error amplifier compares VFB against buffered VREFOUT or externally forced VREFIN, while the oscillator runs at 650 kHz to drive integrated N-channel MOSFETs.
It uses separate supply domains-PVDD1/PVDD2 for power transistors, AVCC for analog circuitry, and VDD/DGND for digital logic-with dedicated AGND, PGND1, and PGND2 pins to isolate noise paths. The PSOP-16 package integrates a GND-connected heat slug soldered directly to PCB ground planes for thermal management without external heatsinks.
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 derating. |
| Output Voltage Accuracy | ±3% at 3A load ensures stable VTT compliance across SSTL-2 (1.25V ±3%), GTL+ (1.5V ±10%), and HSTL standards. |
| Switching Frequency | 650 kHz allows compact external LC filter design using standard 3.3 µH inductors and low-ESR capacitors. |
| VREFIN Input Impedance | 100 kΩ enables direct connection to precision resistor dividers for user-defined VTT without loading errors. |
| Thermal Shutdown | ≈130°C threshold with automatic recovery protects against sustained overload or poor PCB thermal design. |
| Operating Temperature | -40°C to +85°C range qualifies ML6554IU for industrial and embedded systems where ambient extremes exceed commercial grade. |
| Supply Voltage Range | PVDD: 2.0–4.0 V supports direct connection to DDR VDDQ rails (2.5V/3.3V) without intermediate regulators. |
Pinout & Package
The ML6554IU is housed in a 16-pin PSOP (Power Small Outline Package) with integrated GND-connected heat slug on the backside, requiring soldering to a large AGND/PGND copper plane for optimal thermal performance (θJC = 2°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD (Pins 1, 9) | Digital supply input | Provides 3.3V ±10% power to internal logic; dual pins reduce IR drop and noise coupling. |
| PVDD1/PVDD2 (Pins 2, 7) | Power transistor supply | Independent inputs for high-side/low-side MOSFET drivers; decoupling required per pin for EMI control. |
| VL1/VL2 (Pins 3, 6) | Regulated output terminals | Connect directly to bus lines via series inductors; support simultaneous sourcing and sinking for dynamic termination. |
| PGND1/PGND2 (Pins 4, 5) | Power ground returns | Separate low-impedance paths for each power switch leg minimize ground bounce during fast current transitions. |
| VFB (Pin 10) | Feedback input | Accepts resistive divider from VL1/VL2 to set precise output voltage; enables closed-loop compensation. |
| VREFIN (Pin 11) | External reference input | Overrides internal VCCQ-based divider; accepts 0.7V–(VDD−0.7V) to program custom VTT. |
| SHDN (Pin 12) | Active-low shutdown | CMOS-compatible input pulls internal bias off; reduces quiescent current to <1 µA in suspend mode. |
| AGND (Pin 13) | Analog ground reference | Isolated return for internal reference divider; must tie to quiet analog ground plane, not power ground. |
| VREFOUT (Pin 14) | Buffered reference output | Drives up to 3 mA; supplies VREF to multiple SDRAM chips without external buffer. |
| VCCQ (Pin 15) | Internal divider reference | Sets default VTT = 0.5 × VCCQ; range 1.4–4.0 V supports SSTL-2 (2.5V → 1.25V) and LV-TTL (3.3V → 1.65V). |
| AVCC (Pin 16) | Analog supply input | Stable 3.3V ±10% source for error amp and reference circuitry; bypass capacitor mandatory. |
Key Features
| Feature | Design Value |
|---|---|
| No external heatsink required | PSOP-16 thermal design with soldered heat slug achieves <55°C case rise at 3A under natural convection. |
| Integrated power MOSFETs | Eliminates discrete high-side/low-side FETs and gate drivers, reducing BOM count and layout complexity. |
| VREFOUT buffering | On-chip buffer drives multiple DDR SDRAM VREF pins simultaneously, removing need for external op-amps. |
| VCCQ/VREFIN dual-mode programming | Supports both fixed-ratio (SSTL-2) and arbitrary (GTL+/PECL) termination voltages from single IC. |
| Separate VCCQ and PVDD | Enables independent optimization of reference accuracy (VCCQ) and power efficiency (PVDD) in mixed-rail systems. |
Applications
| DDR SDRAM Memory Bus Termination | SSTL-2 Graphics Memory Interface |
|---|---|
Use Scenario: Termination of 168/184-pin DIMM address/control lines on PC motherboards with 2.5V VDDQ. IC Role / Device Role / Timing Role: Generates precise 1.25V VTT and buffered 1.25V VREF for parallel SSTL-2 signaling. Use Value: Maintains ±20 mV VTT stability across 1A–3A load steps, ensuring signal integrity at >400 MHz data rates. | Use Scenario: Active termination of AGP graphics card SGRAM clock and data buses operating at 3.3V VDDQ. IC Role / Device Role / Timing Role: Provides 1.65V VTT (VCCQ = 3.3V) and clean VREF to suppress reflections on high-fanout clock nets. Use Value: Dual VL1/VL2 outputs drive separate clock and data groups, eliminating crosstalk between timing-critical paths. |
| GTL+ Processor Bus Termination | HSTL Backplane Interconnect |
Use Scenario: Termination of Pentium III/IV front-side bus signals using GTL+ standard with 1.5V VTT. IC Role / Device Role / Timing Role: Configured with VREFIN = 1.5V to deliver regulated 1.5V VTT and 1.0V VREF (1.5V ±2%) for processor interface. Use Value: ±3% regulation holds VTT within JEDEC GTL+ spec across temperature, enabling reliable 533 MT/s operation. | Use Scenario: Distributed termination of VMEbus or CompactPCI backplane data lines requiring HSTL Class I (1.5V) levels. IC Role / Device Role / Timing Role: Sources/sinks bidirectional current on long traces to absorb line reflections without adding stub capacitance. Use Value: 3A peak current handles worst-case simultaneous switching noise (SSN) events on 16-bit wide backplane segments. |
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 | Lower 2A output rating; same PSOP-16 package and VCCQ/VREFIN programming interface. | Targeted at SSTL-2 and LV-TTL only; lacks extended voltage range for GTL+/PECL. | Select when system load never exceeds 2A and cost sensitivity outweighs future-proofing for multi-standard designs. |
| ISL6522CRZ | 3A rating with 1.2V–3.6V output range; uses QFN-24 package with higher thermal resistance (θJA = 35°C/W vs. ML6554IU's 25°C/W). | Requires external MOSFETs; supports VRM 8.5 compliance but no integrated VREFOUT buffer. | Choose for VRM-compliant CPU core regulation where VREFOUT buffering is handled elsewhere in the system. |
Compared with ML6554IU, ML6553CS offers lower cost and identical footprint but reduced current headroom, while ISL6522CRZ provides broader programmability at the expense of added external components and inferior thermal performance in high-density layouts.
Availability
ML6554IU is available at Aetrix Electronics and suitable for DDR SDRAM memory subsystems, AGP graphics interfaces, GTL+ processor buses, and HSTL backplane interconnects requiring stable component supply across industrial temperature ranges.
Supply support for ML6554IU 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, known for high-performance power management and interface solutions.
The ML6554IU belongs to Fairchild's bus termination regulator product line, engineered specifically for active termination of high-speed digital buses including DDR, SSTL, GTL+, and HSTL to replace discrete resistor networks and improve signal integrity.
FAQ
What is the maximum continuous output current supported by the ML6554IU?
The ML6554IU supports ±3A continuous sourcing and sinking current without external heatsink when mounted on a PCB with proper thermal land pattern per the datasheet. This rating is validated at -40°C to +85°C ambient with the integrated PSOP-16 heat slug soldered to a solid GND plane. Exceeding 3A requires derating based on actual board thermal resistance.
How does the ML6554IU generate its output voltage when VREFIN is left open?
When VREFIN is floating, the ML6554IU defaults to internal VCCQ-based regulation where VTT = 0.5 × VCCQ. For example, applying 2.5V to VCCQ yields a nominal 1.25V output, matching SSTL-2 requirements. This mode eliminates external components for standard memory interfaces and is confirmed in the Electrical Characteristics table for VCCQ = 2.5V.
Can the ML6554IU be used for Rambus DRAM termination?
Yes, the ML6554IU supports Rambus DRAM termination by configuring VREFIN to 2.0V, producing a corresponding 2.0V VTT output. Table 3 in the datasheet explicitly lists "RAMBUS" under supported bus types with VTT = 2.0V, and the VREFIN input range (0.7V to VDD−0.7V) fully accommodates this requirement at typical 3.3V VDD operation.
What is the purpose of the separate PGND1 and PGND2 pins on the ML6554IU?
The ML6554IU uses separate PGND1 and PGND2 pins to provide isolated return paths for the two internal power switches, minimizing ground loop interference and preventing switching noise from coupling into the feedback path. This separation is critical for maintaining ±3% output regulation under fast transient loads and is implemented per the recommended layout in Figures 6–8 of the ML6554IU datasheet.
Does the ML6554IU include built-in protection features beyond thermal shutdown?
Yes, the ML6554IU includes overcurrent protection via average switch current limiting (IAVG ≤ 3.0A), as specified in Absolute Maximum Ratings, and robust ESD tolerance per human-body model (HBM). While not explicitly labeled "overvoltage protection," the internal error amplifier clamps output during VFB overdrive, and the device enters shutdown if VDD or PVDD exceeds absolute max ratings (4.5V), preventing latch-up.
ML6554IU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width) Exposed Pad
- Packaging:
- Tube
- 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
ML6554IU FAQ
1.How can I place an order for ML6554IU through Aetrix?
Please submit a Request for Quotation (RFQ) for ML6554IU 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 ML6554IU reliable?
The price and inventory of ML6554IU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ML6554IU is usually 5 days.
3.What payment methods are accepted for ML6554IU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ML6554IU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ML6554IU?
ML6554IU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ML6554IU 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 ML6554IU?
For technical support, including ML6554IU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ML6554IU requirements.
6.How does Aetrix verify that ML6554IU is sourced from the original manufacturer or authorized distributors?
All ML6554IU 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 ML6554IU meets industry standards.
7.What is the process for return or replacement of ML6554IU?
All ML6554IU units undergo pre-shipment inspection (PSI). If there is an issue with ML6554IU, 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 ML6554IU part is unused and in its original packaging.
Return procedure for ML6554IU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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