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onsemi ML6554CU
- Part No.:
- ML6554CU
- Manufacturer:
- onsemi
- Package:
- 16-SOIC (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
ML6554CU.pdf
- Description:
- IC REG BUCK 3A DL 16PSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,735
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Product details
Overview
ML6554CU 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 without heatsink, delivers ±3% VTT regulation at full load, supports SSTL-2, GTL+, DDR SDRAM, and HSTL interfaces, and operates across 0°C to +70°C.
For engineers reviewing the ML6554CU datasheet, pinout, applications, or equivalent options, this page provides verified technical context, real-world termination use cases, validated alternatives, thermal performance data, and PSOP-16 package implementation guidance.
Technical Context
The ML6554CU integrates dual power MOSFETs in a synchronous buck topology capable of bidirectional current flow (source/sink) up to 3A. Its output voltage is programmable either via internal 50% VCCQ divider (default mode) or externally forced VREFIN input (0.7V to VDD–0.7V range).
It features separate analog (AVCC), digital (VDD), and power transistor (PVDD1/PVDD2) supply rails, buffered VREFOUT (3mA drive), thermal shutdown (~130°C), and shutdown control (active-low CMOS). Switching frequency is fixed at 650 kHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VOUT Accuracy | ±3% at ±3A load - ensures stable VTT within JEDEC SSTL-2 tolerance (±3%) under full bus current stress |
| Output Current | ±3A continuous - supports termination of multi-drop DDR/SSTL buses with up to 3A total sink/source demand |
| Switching Frequency | 650 kHz - enables compact external LC filter design (e.g., 3.3µH inductor + 330µF/0.1µF caps) |
| VREFOUT Drive | 3 mA - sufficient to drive multiple downstream VREF inputs (e.g., DDR SDRAM modules, buffers) |
| Thermal Shutdown | ≈130°C - protects device during sustained overload or poor PCB thermal layout |
| Operating Temp | 0°C to +70°C - qualified for commercial PC motherboard and graphics card applications |
| Supply Range | PVDD: 2.0–4.0 V - compatible with 2.5V/3.3V system rails; VCCQ: 1.4–4.0 V - supports wide reference input flexibility |
Pinout & Package
The ML6554CU is housed in a 16-pin PSOP (Power Small Outline Package) with integrated GND-connected heat slug for direct PCB thermal conduction. The package measures 9.90 × 3.90 mm with 1.27 mm pitch and requires soldering the backside slug to AGND/PGND copper planes per Fairchild's land pattern recommendation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD (Pins 1, 9) | Digital supply rail | Provides 3.3V ±10% power to logic control circuitry; dual pins reduce IR drop |
| PVDD1/PVDD2 (Pins 2, 7) | Power MOSFET supply | Independent 2.0–4.0 V inputs for high-side/low-side switch drivers; decoupling critical for EMI control |
| VL1/VL2 (Pins 3, 6) | Regulated output terminals | Parallel-connected outputs deliver combined ±3A termination current to bus lines via external inductors |
| PGND1/PGND2 (Pins 4, 5) | Power ground return | Dedicated low-inductance paths for power transistor switching currents; must be tied to heat slug/GND plane |
| VREFIN (Pin 11) | External reference input | Enables user-defined VTT (e.g., 1.5V for GTL+) by applying precise voltage; ZIN = 100 kΩ |
| VREFOUT (Pin 14) | Buffered reference output | Provides stable, low-noise VREF (e.g., 1.25V @ VCCQ=2.5V) to multiple memory devices |
| SHDN (Pin 12) | Active-low enable | CMOS-compatible shutdown signal; pulls VTT to high-Z during suspend/standby to eliminate leakage |
| VCCQ (Pin 15) | Internal divider reference | Sets default VTT = 0.5 × VCCQ; e.g., 2.5V input → 1.25V output for SSTL-2 compliance |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional 3A regulation | Eliminates need for discrete source/sink pairs - single IC handles dynamic bus line charging/discharging |
| Integrated heat slug (PSOP) | Enables 3A operation at ≤55°C case temp with 1 oz copper plane - no airflow or external heatsink required |
| VREFOUT buffer (3 mA) | Drives multiple DDR/SSTL memory modules' VREF inputs without external op-amp or divider loading error |
| Dual-mode VTT programming | Supports both standard (VCCQ-based) and custom (VREFIN-forced) termination voltages - one part covers SSTL, GTL+, HSTL, LV-TTL |
| Separate AVCC/VDD/PVDD | Prevents digital noise coupling into analog feedback path - maintains <±20 mV VTT–VREFOUT offset under load |
Applications
| PC Main Memory Termination | Graphics Memory Bus (AGP) |
|---|---|
Use Scenario: Termination of 168/184-pin DIMM address/data/control lines on desktop motherboard northbridge interface. IC Role / Device Role / Timing Role: ML6554CU generates VTT and VREF for SSTL-2 compliant DDR SDRAM modules while sourcing/sinking transient bus currents. Use Value: Maintains ±20 mV VTT stability across 1–3A loads - meets JEDEC JESD8-15A timing margin requirements for 200+ MHz DDR operation. | Use Scenario: Active termination of AGP graphics card SGRAM clock/address bus routed over 4-layer PCB with 50 Ω impedance control. IC Role / Device Role / Timing Role: ML6554CU supplies matched VTT/VREF to 3D graphics chip and SO-DIMM modules, enabling clean edge transitions on 333 MHz AGP 4× bus. Use Value: Dual VL1/VL2 outputs deliver low-impedance termination to parallel bus segments - reduces signal reflections and jitter below 15 ps RMS. |
| GTL+ Backplane Termination | HSTL Interface for FPGA I/O |
Use Scenario: Termination of processor-to-chipset GTL+ control bus on industrial backplane with >15 cm trace length. IC Role / Device Role / Timing Role: ML6554CU configured with VREFIN = 1.5 V provides precise 1.5 V ±10% VTT for open-drain GTL+ signaling. Use Value: Integrated power MOSFETs handle 3A peak sink current during bus arbitration - eliminates discrete FET + controller BOM overhead. | Use Scenario: Termination of high-speed FPGA I/O banks interfacing to HSTL-compliant memory controllers in telecom baseband processing. IC Role / Device Role / Timing Role: ML6554CU delivers 1.5 V VTT (via VREFIN) and buffered VREF to 8+ HSTL receivers, supporting 400 Mbps DDR I/O rates. Use Value: Thermal shutdown and ±3% regulation ensure reliable operation under FPGA I/O toggling bursts - prevents timing violations during burst-mode transfers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus termination regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ON Semiconductor NCP5662 | 3A sink-only (no sourcing); 1.2V–3.6V VOUT range; 1.2 MHz switching | Requires external sourcing path for bidirectional DDR termination; lacks VREFOUT buffer | Select when only sink termination is needed and VREF is generated elsewhere |
| Renesas ISL6522CRZ | 3A bidirectional; 600 kHz; includes remote sensing; no integrated heat slug | Higher thermal resistance (θJA ≈ 35°C/W vs. ML6554CU's 2°C/W θJC) - requires heatsink above 1.5A | Select when remote sense accuracy is critical and board space allows heatsink integration |
Compared with NCP5662 and ISL6522CRZ, the ML6554CU uniquely combines bidirectional 3A capability, integrated thermal slug, buffered VREFOUT, and dual-mode VTT programming - making it optimal for space-constrained, fanless DDR/SSTL termination where thermal headroom and BOM simplicity are primary constraints.
Availability
ML6554CU is available at Aetrix Electronics and suitable for PC motherboard design, graphics card development, and industrial backplane termination requiring stable component supply across commercial temperature range.
Supply support for ML6554CU 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 leading designer of high-performance analog and power ICs, acquired by ON Semiconductor in 2016. Its legacy products emphasize robustness, thermal efficiency, and application-specific integration.
The ML6554CU belongs to Fairchild's bus termination regulator product line, engineered specifically for DDR, SSTL, GTL+, and HSTL memory interface systems where precision VTT/VREF generation and high-current bidirectional regulation are essential.
FAQ
What is the maximum continuous output current rating for the ML6554CU?
The ML6554CU is rated for ±3A continuous output current in both sourcing and sinking directions. This is validated under natural convection with the PSOP-16 heat slug soldered to a 1 oz copper GND plane, achieving ≤55°C case temperature at full 3A load - no external heatsink or airflow required per Fairchild's thermal characterization.
How does the ML6554CU generate its output voltage in default mode?
In default mode, the ML6554CU sets VTT = 0.5 × VCCQ when the VREFIN pin is left floating. For example, applying 2.5V to VCCQ yields a nominal 1.25V VTT output - directly meeting SSTL-2 specification. This mode requires no external resistors and leverages the internal precision resistor divider.
Can the ML6554CU be used for GTL+ termination, and what configuration is required?
Yes, the ML6554CU supports GTL+ termination by applying 1.5V to the VREFIN pin, which forces VTT = 1.5V ±10%. The ML6554CU datasheet explicitly lists GTL+ in its supported standards and confirms 1.5V VTT compliance in Table 3. No additional components beyond the standard application circuit are needed.
What is the purpose of the separate PVDD1 and PVDD2 pins on the ML6554CU?
PVDD1 and PVDD2 supply independent power to the high-side and low-side internal power MOSFETs, respectively. This separation minimizes cross-coupling between switching nodes, improves efficiency under asymmetric load conditions, and allows optimization of gate drive strength per FET - critical for maintaining tight VTT regulation during fast current transients.
Does the ML6554CU include thermal protection, and at what junction temperature does it activate?
Yes, the ML6554CU incorporates thermal shutdown that activates at approximately 130°C junction temperature. This protection is confirmed in the Absolute Maximum Ratings table and functional description. Once triggered, the device halts switching and enters high-impedance state until junction temperature falls below the hysteresis threshold - safeguarding against permanent damage during overload or inadequate PCB cooling.
ML6554CU 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-PSOP
ML6554CU FAQ
1.How can I place an order for ML6554CU through Aetrix?
Please submit a Request for Quotation (RFQ) for ML6554CU 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 ML6554CU reliable?
The price and inventory of ML6554CU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ML6554CU is usually 5 days.
3.What payment methods are accepted for ML6554CU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ML6554CU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ML6554CU?
ML6554CU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ML6554CU 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 ML6554CU?
For technical support, including ML6554CU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ML6554CU requirements.
6.How does Aetrix verify that ML6554CU is sourced from the original manufacturer or authorized distributors?
All ML6554CU 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 ML6554CU meets industry standards.
7.What is the process for return or replacement of ML6554CU?
All ML6554CU units undergo pre-shipment inspection (PSI). If there is an issue with ML6554CU, 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 ML6554CU part is unused and in its original packaging.
Return procedure for ML6554CU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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