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onsemi ML6554CUX
- Part No.:
- ML6554CUX
- Manufacturer:
- onsemi
- Package:
- 16-SOIC (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
ML6554CUX.pdf
- Description:
- IC REG BUCK 3A DL 16PSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,483
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Product details
Overview
ML6554CUX from Fairchild Semiconductor is a 3A dual-output bus termination regulator designed for active voltage termination in high-speed memory and logic buses. It sources/sinks up to 3A without heatsink, delivers ±3% VTT regulation at full load, and supports SSTL-2, GTL+, HSTL, and DDR SDRAM termination via configurable VREFIN/VCCQ inputs - deployed in PC motherboard and AGP graphics memory systems.
For engineers reviewing the ML6554CUX datasheet, pinout, applications, or equivalent options, key selection criteria include its dual-sourcing/sinking capability, PSOP-16 thermal performance (θJC = 2°C/W), VFB-based closed-loop compensation, and support for both floating-VREFIN (50% VCCQ) and externally forced reference modes.
Technical Context
The ML6554CUX integrates two synchronous power MOSFETs in a single PSOP-16 package with integrated GND heat slug, enabling bidirectional 3A current flow while maintaining tight output regulation. Its architecture uses an internal oscillator (650 kHz) and ramp-comparator control loop to regulate VL1/VL2 outputs based on either VCCQ (default 50% ratio) or externally applied VREFIN.
It features separate supply domains: PVDD1/PVDD2 for power transistors, AVCC for analog circuitry, VDD for digital logic, and AGND/PGND1/PGND2 isolation to minimize noise coupling. The buffered VREFOUT (±20 mV offset vs. VTT) drives external loads up to 3 mA while supporting system-wide reference distribution.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±3 A sourcing/sinking capability enables full-bus active termination without external heatsink. |
| Output Voltage Accuracy | ±3% VTT regulation at 3A load ensures compliance with SSTL-2 (1.25 V ±3%) and GTL+ (1.5 V ±10%) specs. |
| Switching Frequency | 650 kHz fixed-frequency operation allows compact 3.3 µH inductor and low-ESR capacitor selection. |
| VREFOUT Offset | ±20 mV max offset between VTT and VREFOUT guarantees precise tracking for multi-device reference distribution. |
| Thermal Resistance θJC | 2°C/W junction-to-case enables 55°C case temperature at 3A with 1 oz copper plane - no forced airflow required. |
| VREFIN Impedance | 100 kΩ input impedance permits stable biasing via high-value resistor dividers (e.g., 100 kΩ pairs). |
| Shutdown Threshold | CMOS-compatible SHDN pin (active-low) supports direct interface to chipset suspend signals for zero-quiescent standby. |
Pinout & Package
The ML6554CUX is housed in a 16-pin PSOP (Power Small Outline Package) with integrated GND-connected heat slug soldered to PCB ground planes for enhanced thermal conduction. Package dimensions: 9.90 × 3.90 mm, 1.27 mm pitch, JEDEC MS-012 AC compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 9 VDD | Digital supply input | Provides 3.3 V ±10% power to internal logic; dual pins reduce IR drop and noise coupling. |
| 2, 7 PVDD1/PVDD2 | Power MOSFET supply | Independent 2.0–4.0 V rails for high-side/low-side FET drivers - decouples switching noise from digital/analog domains. |
| 3, 6 VL1/VL2 | Regulated output terminals | Connect directly to memory bus lines via external inductors; support simultaneous sourcing/sinking of 3A total. |
| 4, 5 PGND1/PGND2 | Power ground returns | Dedicated low-inductance paths for power FETs; must be tied to heat slug and large GND copper area. |
| 8 DGND | Digital ground reference | Isolated return for VDD and logic circuits; separates digital noise from analog/power grounds. |
| 10 VFB | Closed-loop feedback input | Accepts resistive divider output from VL1/VL2 for precision regulation; enables custom compensation network. |
| 11 VREFIN | External reference input | When driven (0.7–VDD−0.7 V), forces VTT = VREFIN; floating defaults to 50% × VCCQ. |
| 12 SHDN | Active-low shutdown control | CMOS-level input; pulls internal regulators into ultra-low IQ (0.2–1.0 µA) during system suspend. |
| 13 AGND | Analog ground reference | Reference for internal VCCQ divider and error amplifier; requires low-noise connection to heat slug. |
| 14 VREFOUT | Buffered reference output | Drives multiple downstream devices (≤3 mA); tracks VTT within ±20 mV for system-level VREF distribution. |
| 15 VCCQ | Internal divider reference | 1.4–4.0 V input sets default VTT = 0.5 × VCCQ; used as bus voltage reference in DDR/SSTL applications. |
| 16 AVCC | Analog supply input | 3.3 V ±10% supply for error amp, oscillator, and reference buffer; bypassing critical for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Dual sourcing/sinking capability | 3A bidirectional current handling eliminates need for discrete complementary MOSFET pairs in active termination designs. |
| Integrated heat slug in PSOP-16 | Direct thermal path to PCB GND plane achieves 55°C case temp at 3A - no heatsink or airflow required. |
| Configurable VTT generation mode | Supports both default (VCCQ-derived) and user-defined (VREFIN-forced) termination voltages for multi-standard compatibility. |
| Buffered VREFOUT with low offset | ±20 mV tracking between VTT and VREFOUT enables reliable multi-chip reference sharing without additional level-shifting. |
| Separate AVCC/VDD/PVDD supplies | Domain isolation prevents switching noise from corrupting analog regulation or digital control logic. |
| Thermal shutdown at ≈130°C | Protects against sustained overload or poor layout; auto-recovery upon cooling avoids latch-up failure modes. |
Applications
| PC Main Memory Termination | AGP Graphics Memory Bus |
|---|---|
|
Use Scenario: Termination of 168/184/208-pin DIMM address/data/control lines on x86 motherboards. IC Role / Device Role / Timing Role: Generates VTT = 1.25 V (SSTL-2) and VREF for DDR SDRAM modules; interfaces with northbridge chipset. Use Value: Maintains ±3% VTT across 0–3A load steps, ensuring signal integrity at >200 MHz data rates without external heatsink. |
Use Scenario: Active termination of graphics memory bus on AGP 4x/8x video cards with SGRAM modules. IC Role / Device Role / Timing Role: Supplies matched VTT/VREF for high-speed clock/address lines; replaces discrete op-amp + MOSFET solutions. Use Value: Delivers ±20 mV VTT–VREFOUT tracking to meet JEDEC SSTL-2 timing margins under dynamic GPU load conditions. |
| GTL+ Backplane Termination | HSTL/PECL Logic Interface |
|
Use Scenario: Termination of processor-to-chipset GTL+ buses in telecom and server backplanes. IC Role / Device Role / Timing Role: Generates 1.5 V ±10% VTT using VREFIN = 1.5 V; sinks/source current during bus arbitration transitions. Use Value: Supports >300 MHz GTL+ signaling with <100 ps edge-induced droop due to 3A peak current capability. |
Use Scenario: Level-matched termination for HSTL Class I/II and PECL differential receivers in FPGA I/O banks. IC Role / Device Role / Timing Role: Provides 1.5 V VTT (HSTL) or 2.0 V VTT (PECL) via VREFIN forcing; buffers reference to multiple I/O banks. Use Value: Enables single-chip termination for mixed-voltage FPGA designs with <±20 mV inter-bank VREF skew. |
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 (VL1 only), 3A sink-only; no VL2, no VREFOUT buffer, no VFB pin. | Suitable for simpler SSTL/LV-TTL termination where VREF distribution is handled externally. | Select ML6553CS only when dual-output and buffered reference are unnecessary - reduces BOM count by 20%. |
| ISL6522CRZ | 3A dual-output with integrated MOSFETs; supports 0.6–3.3 V VOUT via VID interface; no VREFIN pin. | Designed for VRM-compliant CPU core voltage regulation, not bus termination; lacks VREFOUT tracking. | Choose ISL6522CRZ only if system requires programmable VID control and can tolerate ±5% VTT tolerance. |
Compared with ML6554CUX, ML6553CS offers lower cost but sacrifices dual-output flexibility and system-level VREF distribution; ISL6522CRZ provides digital programmability but lacks the precise VTT–VREFOUT tracking needed for JEDEC-compliant memory termination.
Availability
ML6554CUX is available at Aetrix Electronics and suitable for PC motherboard design, AGP graphics card development, GTL+ backplane integration, and HSTL/PECL FPGA interface applications requiring stable component supply and long-term industrial availability.
Supply support for ML6554CUX 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 ML6554CUX belongs to Fairchild's bus termination regulator product line, engineered specifically for active termination of high-speed memory and logic buses including DDR, SSTL, GTL+, and HSTL standards.
FAQ
What is the maximum continuous output current rating for the ML6554CUX?
The ML6554CUX is rated for ±3 A continuous sourcing and sinking current per output (VL1/VL2) without external heatsink, verified under natural convection with 1 oz copper plane per Fairchild's thermal test board (1S2P). This rating applies across the full operating temperature range (0°C to +70°C for CU suffix).
How does the ML6554CUX generate its termination voltage when VREFIN is left unconnected?
When VREFIN is floating, the ML6554CUX operates in default mode and generates VTT = 0.5 × VCCQ. For example, with VCCQ = 2.5 V, VTT = 1.25 V - matching SSTL-2 specification. This mode eliminates external components for standard memory termination applications.
Can the ML6554CUX be used for Rambus DRAM termination?
Yes - the ML6554CUX supports Rambus termination by configuring VREFIN = 2.0 V to generate VTT = 2.0 V, as specified in Rambus signaling standards. Its ±3% regulation accuracy and 3A current capability meet RDRAM VTT supply requirements under dynamic bus loading.
What is the purpose of the separate PGND1 and PGND2 pins on the ML6554CUX?
PGND1 and PGND2 provide dedicated low-inductance return paths for the high-side and low-side internal power MOSFETs respectively. Separating these grounds minimizes switching noise coupling into the error amplifier and VFB loop, preserving regulation accuracy during fast current transients.
Does the ML6554CUX require external compensation components?
Yes - the ML6554CUX uses the VFB pin for external compensation. A standard Type II network (resistor + capacitor in series from VFB to AGND, plus capacitor from VFB to VL1/VL2) is required to stabilize the control loop; component values depend on inductor and output capacitance per Fairchild Application Note AN-6077.
ML6554CUX 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-PSOP
ML6554CUX FAQ
1.How can I place an order for ML6554CUX through Aetrix?
Please submit a Request for Quotation (RFQ) for ML6554CUX 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 ML6554CUX reliable?
The price and inventory of ML6554CUX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ML6554CUX is usually 5 days.
3.What payment methods are accepted for ML6554CUX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ML6554CUX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ML6554CUX?
ML6554CUX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ML6554CUX 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 ML6554CUX?
For technical support, including ML6554CUX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ML6554CUX requirements.
6.How does Aetrix verify that ML6554CUX is sourced from the original manufacturer or authorized distributors?
All ML6554CUX 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 ML6554CUX meets industry standards.
7.What is the process for return or replacement of ML6554CUX?
All ML6554CUX units undergo pre-shipment inspection (PSI). If there is an issue with ML6554CUX, 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 ML6554CUX part is unused and in its original packaging.
Return procedure for ML6554CUX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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