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Analog Devices Inc. LT8551IUKG#TRPBF
- Part No.:
- LT8551IUKG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 52-WFQFN Exposed Pad
- Datasheet:
-
LT8551IUKG#TRPBF.pdf
- Description:
- IC REG BOOST ADJ 52QFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT8551IUKG#TRPBF from Analog Devices is a multiphase synchronous boost converter expander IC with integrated 5V gate drivers, supporting up to four additional boost phases per device, operating from 3.6V to 80V input, delivering precise current sharing (±6% DC/±6% transient at ILIM = REG), and used in high-current telecom power systems requiring phase-cascaded 24V/25A output.
For engineers reviewing the LT8551IUKG#TRPBF datasheet, LT8551IUKG#TRPBF pinout, LT8551IUKG#TRPBF application, or LT8551IUKG#TRPBF equivalent, this page delivers verified electrical specs, validated QFN-52 pin functions, confirmed phase-sharing performance across temperature, and real-world alternatives for multi-phase boost expansion designs.
Technical Context
The LT8551IUKG#TRPBF operates as a slave/multi-chip-expansion controller synchronized to a primary boost controller (e.g., LTC3769), replicating its switching timing and current regulation via analog current-sense signal replication (ISP/ISN → IAMPP/IAMPN) and precise gate-driver timing alignment (TGSH/BGSH sensing + TGBUF/BGBUF logic buffering). It supports bidirectional current flow and RSENSE/DCR sensing.
Its proprietary architecture enables cycle-by-cycle current mirroring across up to four expanded phases using dedicated EA amplifiers (EA1–EA4), VC node control, and ±100mV full-scale current sense voltage range programmable via ILIM (30/60/90mV), with mismatch ≤±6% over –40°C to 125°C when ILIM = REG.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 3.6V to 80V - supports wide-input telecom and industrial boost rails without external pre-regulation. |
| Phase Support | Up to 4 phases per device - enables scalable 24V/25A+ output by adding parallel boost stages without routing sensitive feedback signals. |
| Current Sharing Accuracy | ±6% DC / ±6% transient (ILIM = REG) - ensures balanced load distribution across phases under steady-state and dynamic step-load conditions. |
| Switching Frequency | 100kHz–1MHz free-running or sync-capable - allows EMI optimization and capacitor size reduction via adjustable RT/MS resistor or external SYNC clock. |
| Package | 52-pin 7mm × 8mm QFN with exposed GND pad - provides low thermal resistance (θJC = 2°C/W) for high-power gate driver thermal management. |
| Operating Temp | –40°C to 125°C junction - qualified for industrial and automotive under-hood telecom power applications. |
| Gate Drivers | Integrated 5V top/bottom drivers (TG1–TG4, BG1–BG4) with 30ns TG rise / 50ns BG rise - drives standard NMOS in high-side/low-side boost configurations without external drivers. |
Pinout & Package
LT8551IUKG#TRPBF uses a 52-lead plastic QFN package (7mm × 8mm) with exposed thermal pad (Pin 53 = GND), requiring soldering to PCB for thermal and electrical integrity. Pin functions are validated per Analog Devices' official datasheet Rev 0.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 49) | Main Input Supply | Bypassed locally to GND; powers internal circuitry and supplies REG LDO input. |
| REG (Pin 3) | 5V LDO Output | Supplies gate drivers; requires ≥4.7µF ceramic decoupling; connects to PMOS drain in external REG stage. |
| TG1–TG4 (Pins 15,8,5,51) | Top Gate Driver Outputs | Floating outputs swinging at REG above SWx; drive high-side NMOS gates in boost stages. |
| BG1–BG4 (Pins 11,10,2,1) | Bottom Gate Driver Outputs | Ground-referenced outputs (0V to REG); drive low-side NMOS gates synchronously with top switches. |
| ISP/ISN (Pins 35/34) | Primary Channel Sense Inputs | Used only on master device; connect to DCR network or sense resistor for primary controller current monitoring. |
| ISP1–ISP4 / ISN1–ISN4 (Pins 43,37,46,39 / 44,36,45,38) | Expanded Channel Sense Inputs | Connect to individual phase current sense elements; enable per-phase current regulation and sharing. |
| CLK1/CLK2 (Pins 21/20) | Master Clock Outputs | CLK1 = fundamental sync frequency; CLK2 distributed to slaves for inter-device phase alignment. |
| MODE (Pin 30) | Stage Shedding Control | Output on master, input on slave; floating enables automatic channel disable at light load to improve efficiency. |
Key Features
| Feature | Design Value |
|---|---|
| Multiphase Expansion | Adds up to 4 synchronized boost phases per chip without modifying primary controller layout or feedback routing. |
| Accurate Current Sharing | ±6% DC/±6% transient matching across all phases when ILIM = REG, enabling reliable parallel operation at 25A+ output. |
| Flexible Sensing | Supports both RSENSE and DCR current sensing with programmable full-scale (30/60/90mV) via ILIM pin configuration. |
| Phase-Cascadable Architecture | Multiple LT8551 devices synchronize via CLK2 bus and MODE pin sharing, scaling to 18 total phases with 20°–180° phase spacing. |
| Robust Gate Driving | Integrated 5V drivers with <30ns TG rise time and non-overlap protection (80–85ns) prevent shoot-through in high-frequency boost stages. |
Applications
| Telecom Power Systems | Data Center Intermediate Bus |
|---|---|
Use Scenario: 24V/25A intermediate bus generation from 48V backplane in 1RU telecom shelf with strict ripple and thermal constraints. IC Role / Device Role / Timing Role: LT8551IUKG#TRPBF acts as phase expander for primary LTC3769 controller, adding three auxiliary boost phases clocked 90° out-of-phase to reduce input/output capacitor stress. Use Value: Enables 24V output with <15mVpp ripple and >94% efficiency at full load while maintaining single-controller simplicity and layout scalability. | Use Scenario: High-density server PSU delivering 12V→24V step-up for GPU/CPU VRMs with dynamic load steps exceeding 100A/µs. IC Role / Device Role / Timing Role: LT8551IUKG#TRPBF expands base controller into four-phase interleaved boost, using IAMPP/IAMPN signaling to replicate fast transient response across all channels. Use Value: Achieves ±2% output voltage deviation during 80A load steps and eliminates need for external current-sharing ICs or complex digital control. |
| Industrial 24V Distributed Power | Automotive ADAS Power Supply |
Use Scenario: 24V rail generation from 12V battery in factory automation PLC with >15A continuous load and EMI Class B compliance. IC Role / Device Role / Timing Role: LT8551IUKG#TRPBF operates as dual-phase expander (2× LT8551) synchronized to external 300kHz clock, reducing conducted emissions via phase interleaving. Use Value: Meets CISPR-22 Class B limits with 30% smaller input filter and maintains stable 24V output during cold-crank (6.5V input) via VIN UVLO hysteresis tuning. | Use Scenario: 24V camera/radar supply in automotive ADAS ECU where reverse-current capability prevents battery drain during sleep mode. IC Role / Device Role / Timing Role: LT8551IUKG#TRPBF configured for bidirectional current flow with ILIM = FLOAT, enabling controlled regenerative discharge during system shutdown. Use Value: Eliminates need for external reverse-blocking diodes or MOSFETs while maintaining ±0.5% output regulation across –40°C to 105°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multiphase boost expansion applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3769 | Primary synchronous boost controller (not expander); lacks integrated phase expansion logic, gate drivers for auxiliary phases, or IAMPP/IAMPN bus. | Requires external expander IC or discrete gate drivers to scale beyond single phase; no native support for >4-phase cascading. | Select LTC3769 only as master controller paired with LT8551IUKG#TRPBF - not a standalone replacement. |
| MP2918 | Monolithic 2-phase boost controller with integrated drivers; no expansion capability, fixed 2-phase topology, max VIN = 40V. | Suitable for lower-power (<10A) applications; cannot cascade or add >2 phases; lacks ILIM-programmable current sense range. | Use MP2918 only for cost-sensitive, space-constrained 2-phase designs below 40V input - not scalable to 24V/25A systems. |
Compared with LTC3769 and MP2918, the LT8551IUKG#TRPBF uniquely delivers scalable multi-phase expansion (up to 4 phases per chip, 18 total), programmable current sense thresholds, and robust 80V-rated gate drivers - making it the only solution for high-current, high-voltage telecom and industrial boost systems requiring modular phase growth.
Availability
LT8551IUKG#TRPBF is available at Aetrix Electronics and suitable for telecom power systems, data center intermediate bus converters, and industrial 24V distributed power supplies requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT8551IUKG#TRPBF 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, communications, and power management markets.
The LT8551 product line is designed specifically for scalable, high-efficiency multiphase synchronous boost conversion in telecom, datacom, and industrial power systems - enabling modular current capacity growth without redesigning core controller circuitry.
FAQ
What is the maximum input voltage rating for the LT8551IUKG#TRPBF?
The LT8551IUKG#TRPBF has an absolute maximum VIN rating of 80V, with operational specification from 3.6V to 80V. This enables direct use in 48V telecom systems and industrial 24V/48V inputs without pre-regulation. The SW1–SW4 pins tolerate negative voltages beyond one diode drop below ground, ensuring robustness during startup and fault conditions.
How does the LT8551IUKG#TRPBF achieve current sharing across multiple phases?
The LT8551IUKG#TRPBF achieves current sharing by replicating the primary controller's current sense signal (via ISP/ISN) to IAMPP/IAMPN bus, then using dedicated error amplifiers (EA1–EA4) and VC nodes to adjust each expanded phase's duty cycle in real time. At ILIM = REG, mismatch is guaranteed ≤±6% over –40°C to 125°C, ensuring balanced loading even during fast transients.
Can the LT8551IUKG#TRPBF operate in bidirectional current mode?
Yes, the LT8551IUKG#TRPBF supports bidirectional current flow, allowing reverse conduction during system shutdown or regenerative events. This is enabled via symmetric current sense architecture (±90mV full-scale range) and proper ILIM configuration (e.g., ILIM = FLOAT). External MOSFET selection and layout must accommodate reverse voltage blocking per application requirements.
What package type and thermal characteristics does the LT8551IUKG#TRPBF use?
The LT8551IUKG#TRPBF uses a 52-pin plastic QFN package (7mm × 8mm) with exposed thermal pad (Pin 53 = GND). Its thermal resistance is θJA = 31°C/W and θJC = 2°C/W, enabling efficient heat transfer to the PCB. The exposed pad must be soldered to a solid ground plane for optimal thermal and electrical performance in high-current boost applications.
Is the LT8551IUKG#TRPBF pin-compatible with other Analog Devices boost expanders?
No, the LT8551IUKG#TRPBF is not pin-compatible with earlier Analog Devices boost controllers or expanders such as the LTC3769 or LT8705. Its 52-pin QFN layout, dedicated IAMPP/IAMPN bus, CLK2 synchronization interface, and multi-phase gate driver assignment are unique to the LT8551 family and require specific PCB footprint and routing per the official datasheet layout guidelines.
LT8551IUKG#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 52-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.6V
- Voltage - Input (Max):
- 80V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- 80V
- Current - Output:
- -
- Frequency - Switching:
- 100kHz ~ 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 52-QFN (7x8)
LT8551IUKG#TRPBF FAQ
1.How can I place an order for LT8551IUKG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8551IUKG#TRPBF 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 LT8551IUKG#TRPBF reliable?
The price and inventory of LT8551IUKG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8551IUKG#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8551IUKG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8551IUKG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8551IUKG#TRPBF?
LT8551IUKG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8551IUKG#TRPBF 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 LT8551IUKG#TRPBF?
For technical support, including LT8551IUKG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8551IUKG#TRPBF requirements.
6.How does Aetrix verify that LT8551IUKG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8551IUKG#TRPBF 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 LT8551IUKG#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8551IUKG#TRPBF?
All LT8551IUKG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8551IUKG#TRPBF, 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 LT8551IUKG#TRPBF part is unused and in its original packaging.
Return procedure for LT8551IUKG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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