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Analog Devices Inc. LT8551EUKG#TRPBF
- Part No.:
- LT8551EUKG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 52-WFQFN Exposed Pad
- Datasheet:
-
LT8551EUKG#TRPBF.pdf
- Description:
- IC REG BOOST ADJ 52QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,361
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Product details
Overview
LT8551EUKG#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 distributed power systems such as telecom 24V/25A step-up supplies.
For engineers reviewing the LT8551EUKG#TRPBF datasheet, LT8551EUKG#TRPBF pinout, LT8551EUKG#TRPBF application, or LT8551EUKG#TRPBF equivalent, key selection considerations include phase synchronization capability (125kHz–1MHz), RSENSE/DCR current sensing flexibility, bidirectional current support, and master/slave cascading for up to 18-phase systems.
Technical Context
The LT8551EUKG#TRPBF implements a proprietary cycle-by-cycle replication architecture that monitors primary controller gate timing and inductor current to drive expanded phases with matched switching edges and current regulation. It uses dedicated primary channel sensing (ISP/ISN, TGSH/TGSL/BGSH) and distributed current amplifiers (IAMPP/IAMPN) to achieve ±6% current matching over temperature when ILIM is tied to REG.
Its clock scheme supports hierarchical synchronization: CLK1 carries the fundamental frequency from the master, while CLK2 distributes phase-aligned timing to slaves; PHS1/PHS2/PHS3 and RT/MS jointly configure phase angles from 20° to 180° across up to four channels per device, enabling ripple cancellation and scalable current capacity.
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. |
| Switching Frequency | 125kHz to 1MHz - adjustable via RT/MS resistor or external SYNC signal for EMI optimization and component size trade-offs. |
| Current Sharing Accuracy | ±6% (DC & transient, ILIM = REG) - ensures balanced load distribution across phases under dynamic conditions. |
| Gate Driver Supply | Integrated 5V REG LDO (4.9V–5.3V, 250mA max) - powers all internal gate drivers without external bias supply. |
| Phase Support | Up to 4 phases per chip, 18 total with cascading - enables scalable high-current designs with reduced output ripple and smaller bulk capacitance. |
| Current Sense Range | ±30mV / ±60mV / ±90mV (ILIM-selectable) - accommodates diverse DCR/resistor values while maintaining accuracy across temperature. |
| Operating Temp | –40°C to +125°C junction - qualified for industrial and automotive under-hood environments. |
Pinout & Package
LT8551EUKG#TRPBF is housed in a 52-lead (7mm × 8mm) plastic QFN package with exposed thermal pad (Pin 53 = GND), requiring soldering to PCB for thermal and electrical integrity. θJA = 31°C/W, θJC = 2°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 49) | Main Power Input | Accepts 3.6V–80V input; requires local ceramic bypass to GND for stability and noise suppression. |
| REG (Pin 3) | 5V Gate Driver Supply Output | Provides regulated 5V (±0.2V) to drive all internal top/bottom MOSFET gates; decouple with ≥4.7µF low-ESR ceramic. |
| TG1–TG4 (Pins 15,8,5,51) | Top Gate Driver Outputs | Floating drivers with REG-referenced swing; connect to gate of high-side NMOS in each boost phase. |
| BG1–BG4 (Pins 11,10,2,1) | Bottom Gate Driver Outputs | GND-referenced drivers (0V to REG); control low-side NMOS switches synchronously with top FETs. |
| ISP/ISN (Pins 35/34) | Primary Channel Current Sense Inputs | Differential inputs for master's current sense amplifier; used only on master device for closed-loop replication. |
| IAMPP/IAMPN (Pins 33/32) | Current Amplifier Interface | Master outputs IAMPP; slaves share IAMPP bus to align current references across all devices. |
| RT/MS (Pin 26) | Timing & Master/Slave Select | Resistor-to-GND configures master mode; tie to REG for slave operation-enables multi-chip phase coordination. |
| CLK1/CLK2 (Pins 21/20) | Master Clock Distribution | CLK1 = fundamental sync source; CLK2 = daisy-chained phase alignment signal for slave devices. |
Key Features
| Feature | Design Value |
|---|---|
| Multiphase expansion without feedback routing | Eliminates need to route sensitive analog control signals between controllers-reduces layout complexity and noise coupling. |
| Programmable current limit thresholds | Three selectable full-scale sense voltages (30/60/90mV) via ILIM pin, enabling optimal SNR across diverse current-sense element values. |
| Stage shedding for light-load efficiency | Automatically disables underutilized phases (e.g., ch1/ch3 then ch4) when ISP–ISN falls below threshold-improves partial-load efficiency without firmware. |
| Bidirectional current support | Accurately senses and regulates reverse current flow, enabling regenerative or dual-directional power transfer applications. |
| Robust gate driver timing control | Non-overlap time (80–85ns) and minimum off-time (140ns) prevent shoot-through; rise/fall times <30ns ensure fast, clean switching transitions. |
Applications
| Telecom Power Systems | Data Center Intermediate Bus |
|---|---|
Use Scenario: 24V/25A step-up from 12V–48V battery or rectified AC input in 48V telecom shelf power. IC Role / Device Role / Timing Role: Multiphase boost expander synchronized to primary controller (e.g., LTC3769), managing four parallel phases with interleaved 90° offsets. Use Value: Reduces output ripple by >70% vs single-phase, cuts required bulk capacitance by 4×, and maintains ±6% current balance across temperature. | Use Scenario: High-efficiency 12V-to-48V intermediate bus conversion feeding multiple server VRMs in AI accelerator racks. IC Role / Device Role / Timing Role: Cascaded master-slave LT8551EUKG#TRPBF array (up to 18 phases) driving SiC MOSFETs with 200kHz–500kHz switching. Use Value: Enables >96% peak efficiency at 100A+ loads while meeting strict EMI Class B limits via programmable frequency and phase spacing. |
| Industrial Motor Drive Supplies | Automotive 48V Mild Hybrid Systems |
Use Scenario: Boosting 24V battery to 48V/60A for servo drive logic and gate drivers in factory automation PLCs. IC Role / Device Role / Timing Role: Four-phase LT8551EUKG#TRPBF expander paired with LTC7810 controller, using DCR current sensing for compact design. Use Value: Achieves stable current sharing despite board-level thermal gradients, with stage shedding extending standby runtime by 3×. | Use Scenario: Bidirectional 12V-to-48V boost/buck conversion in 48V mild hybrid vehicles during regenerative braking and engine start-stop. IC Role / Device Role / Timing Role: Dual LT8551EUKG#TRPBF master/slave pair supporting reverse current flow with identical forward/reverse current limit programming. Use Value: Maintains ±6% current matching in both directions, eliminating need for separate buck and boost controllers and reducing BOM count by 40%. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multiphase boost expander applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC7810 | Monolithic 4-phase synchronous boost controller (no external expander needed); integrates PWM controller, gate drivers, and current sensing-but lacks cascading capability beyond 4 phases. | Best for fixed 4-phase designs where no scalability beyond 4 phases is required; not suitable for >4-phase or multi-chip systems. | Select LTC7810 when system needs only up to 4 phases and prefers single-chip integration over modular expansion. |
| MPQ8633B | Single-channel 60V synchronous boost controller with integrated MOSFETs; no phase-expansion or multi-chip synchronization features. | Targeted at low-to-mid power (≤10A) applications; cannot replicate or synchronize with other controllers for current sharing. | Choose MPQ8633B only for cost-sensitive, low-current standalone boost stages-not as an LT8551EUKG#TRPBF alternative in multiphase systems. |
Compared with LTC7810 and MPQ8633B, the LT8551EUKG#TRPBF uniquely enables scalable, synchronized multiphase expansion beyond 4 phases with precise current matching-making it the only viable option for >100A telecom/datacom power systems requiring modularity and thermal distribution.
Availability
LT8551EUKG#TRPBF is available at Aetrix Electronics and suitable for telecom power systems, data center intermediate bus converters, industrial motor drive supplies, and automotive 48V mild hybrid systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT8551EUKG#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, communications, and automotive markets.
The LT8551EUKG#TRPBF belongs to ADI's Power by Linear™ multiphase DC/DC controller family, designed specifically for scalable, high-current, high-efficiency boost conversion in infrastructure-grade power systems where reliability, thermal management, and phase coordination are critical.
FAQ
What is the maximum number of phases supported by a single LT8551EUKG#TRPBF device?
A single LT8551EUKG#TRPBF supports up to four synchronous boost phases. Its eight integrated gate drivers (four top, four bottom) are configured to drive four independent boost stages. When cascaded with additional LT8551EUKG#TRPBF devices in master/slave topology, the system can scale to up to 18 distinct phases-enabling ultra-high-current solutions without redesigning the core controller architecture.
How does the LT8551EUKG#TRPBF achieve current sharing accuracy across phases?
The LT8551EUKG#TRPBF achieves ±6% DC and transient current sharing accuracy (at ILIM = REG) by continuously monitoring the primary controller's switch current via ISP/ISN differential inputs and replicating its timing and regulation behavior cycle-by-cycle. It uses dedicated current amplifiers (IAMPP/IAMPN) and synchronized gate drivers to match expanded phase currents to the master reference, with mismatch tolerance verified over –40°C to +125°C.
Can the LT8551EUKG#TRPBF operate in bidirectional current mode?
Yes, the LT8551EUKG#TRPBF supports bidirectional current flow. Its current sense architecture accepts both positive and negative differential voltages (±30mV/±60mV/±90mV) at ISP/ISN and expanded channel inputs, enabling accurate regulation during reverse current events-critical for regenerative braking in 48V automotive systems or energy recovery in industrial drives.
What is the role of the MODE pin on the LT8551EUKG#TRPBF?
The MODE pin on the LT8551EUKG#TRPBF controls stage shedding. When floating on the master device, it enables automatic deactivation of underutilized phases (e.g., ch1/ch3 then ch4) at light loads to improve efficiency. Driving MODE below 0.5V disables this feature. In multi-device systems, all MODE pins must be tied together and left floating to ensure coordinated shedding across the entire array.
Does the LT8551EUKG#TRPBF require an external oscillator or can it generate its own clock?
The LT8551EUKG#TRPBF includes an internal oscillator configurable from 125kHz to 1MHz via the RT/MS timing resistor. It also supports external synchronization through the SYNC pin (1.2V high / 0.8V low thresholds), allowing alignment to system clocks or spread-spectrum sources for EMI reduction-no external oscillator is required.
LT8551EUKG#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)
LT8551EUKG#TRPBF FAQ
1.How can I place an order for LT8551EUKG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8551EUKG#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 LT8551EUKG#TRPBF reliable?
The price and inventory of LT8551EUKG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8551EUKG#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8551EUKG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8551EUKG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8551EUKG#TRPBF?
LT8551EUKG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8551EUKG#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 LT8551EUKG#TRPBF?
For technical support, including LT8551EUKG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8551EUKG#TRPBF requirements.
6.How does Aetrix verify that LT8551EUKG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8551EUKG#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 LT8551EUKG#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8551EUKG#TRPBF?
All LT8551EUKG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8551EUKG#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 LT8551EUKG#TRPBF part is unused and in its original packaging.
Return procedure for LT8551EUKG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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