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Analog Devices Inc. LTC3854IDDB#TRMPBF
- Part No.:
- LTC3854IDDB#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LTC3854IDDB#TRMPBF.pdf
- Description:
- IC REG CTRLR BUCK 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,392
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Product details
Overview
LTC3854IDDB#TRMPBF from Analog Devices (formerly Linear Technology) is a high-performance synchronous step-down DC/DC controller driving all-N-channel MOSFETs. It operates from 4.5V to 38V input, regulates output from 0.8V to 5.5V, features 400kHz fixed-frequency current-mode control, 75ns minimum on-time, and delivers up to 20A output current in telecom power supplies.
For engineers reviewing the LTC3854IDDB#TRMPBF datasheet, LTC3854IDDB#TRMPBF pinout, LTC3854IDDB#TRMPBF application, or LTC3854IDDB#TRMPBF equivalent, key selection considerations include RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation for wide output capacitor/ESR ranges, 97% duty cycle dropout operation, pre-biased start-up capability, and integrated 5V LDO for gate drive.
Technical Context
The LTC3854IDDB#TRMPBF implements a constant-frequency peak-current-mode architecture with internal slope compensation that preserves maximum inductor peak current across all duty cycles. Its error amplifier outputs to the ITH pin, which directly sets the current comparator trip point and enables precise transient response tuning via OPTI-LOOP®.
It integrates dual N-channel MOSFET drivers with 2.1Ω–2.5Ω pull-down/pull-up resistances, 25ns transition times, and synchronized anti-shoot-through timing (30ns delays). The INTVCC 5V LDO powers internal circuitry and gate drivers, while the RUN/SS pin provides combined enable and soft-start control with 1.25µA internal charge current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide industrial and telecom input rails including 12V, 24V, and 36V systems. |
| Output Voltage Range | 0.8V to 5.5V - enables regulation of core voltages (e.g., 1.2V, 1.8V, 3.3V) and standard logic rails. |
| Switching Frequency | 400kHz ±10% - fixed frequency simplifies EMI filtering and enables compact magnetics design. |
| Reference Accuracy | ±1% at 0.8V over temperature - ensures tight output voltage regulation under thermal stress. |
| Minimum On-Time | 75ns - enables high step-down ratios (e.g., 36V→3.3V at 400kHz) without pulse-skipping instability. |
| Duty Cycle Limit | 97% - allows operation in dropout with minimal voltage headroom (e.g., VIN = 5.2V → VOUT = 5V). |
| Shutdown IQ | 15µA - minimizes system standby power in battery-backed or energy-sensitive applications. |
| Package | 12-pin 2mm × 3mm DFN with exposed GND pad - thermally enhanced for high-current operation up to 20A. |
Pinout & Package
Package: 12-lead (3mm × 2mm) plastic DFN with exposed thermal pad (Pin 13 = SGND), rated for –40°C to 85°C operating temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (1) | Error amplifier feedback input | Connects to resistor divider on VOUT; sets regulated output voltage with ±1% reference accuracy. |
| ITH (2) | Error amplifier output & compensation node | Controls current comparator threshold; used for OPTI-LOOP® compensation network placement. |
| RUN/SS (3) | Enable and soft-start control | Pulled low (<0.4V) for shutdown; internal 1.25µA current charges external capacitor for controlled VOUT ramp. |
| BOOST (4) | Bootstrap supply for top-side driver | Connected via capacitor to SW; generates floating bias for TG driver during high-side conduction. |
| TG (5) | Top N-channel MOSFET gate driver output | Drives high-side FET with 2.5Ω pull-up / 2.1Ω pull-down; supports fast switching with 25ns transitions. |
| SW (6) | Switch node connection | Connects to inductor and BOOST capacitor; swings from ground to VIN during operation. |
| GND (7) | Signal and power ground | Kelvin-connected internal ground; must be tied to PCB ground plane and exposed pad (Pin 13). |
| BG (8) | Bottom N-channel MOSFET gate driver output | Drives synchronous rectifier FET; rail-to-rail swing from 0V to INTVCC (5V). |
| INTVCC (9) | Internal 5V LDO output | Powers gate drivers and control circuitry; requires ≥2.2µF low-ESR ceramic bypass to GND. |
| VIN (10) | Main input supply | Primary power source for INTVCC LDO and internal logic; bypassed to GND with local ceramic capacitor. |
| SENSE– (11) | Inverting input of current comparator | Used with SENSE+ for differential RSENSE or DCR current sensing; 0–5.5V common-mode range. |
| SENSE+ (12) | Non-inverting input of current comparator | Paired with SENSE–; enables accurate current limit setting up to 50mV threshold. |
Key Features
| Feature | Design Value |
|---|---|
| RSENSE or DCR current sensing | Supports both discrete shunt resistors (≤50mV threshold) and lossless inductor DCR sensing for >95% efficiency in high-current designs. |
| OPTI-LOOP® compensation | Allows stable loop response across wide variations in output capacitance (e.g., 10µF–1000µF) and ESR (0.5mΩ–50mΩ), reducing design iterations. |
| Start-up into pre-biased output | Enables safe hot-swap and rail sequencing in multi-rail systems without output voltage overshoot or reverse current flow. |
| Output overvoltage protection | Hardware-based OV comparator disables TG and enables BG if FB exceeds 0.88V, protecting downstream loads from transient overvoltage events. |
| Current foldback limiting | Reduces MOSFET dissipation during short-circuit by lowering peak current limit; automatically disabled during soft-start to prevent startup failure. |
Applications
| Telecom Power Supply | Industrial PLC Power |
|---|---|
Use Scenario: 48V backplane-fed intermediate bus converter delivering 5V/7A to baseband processing boards. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating intermediate bus voltage with 400kHz switching and DCR current sensing. Use Value: 96% efficiency at 24VIN/5VOUT/5A enables compact heatsink-free design in space-constrained 1RU chassis. | Use Scenario: DIN-rail mounted 24V system powering I/O modules, sensors, and communication interfaces. IC Role / Device Role / Timing Role: High-reliability step-down controller supporting wide input (18–36V) and maintaining regulation during brownout conditions. Use Value: 97% duty cycle operation sustains 5V output down to 5.2V input, ensuring uninterrupted operation during line sags. |
| Automotive Infotainment | Distributed DC Power System |
Use Scenario: 12V vehicle battery powering 3.3V/10A SoC domain controller with strict EMC requirements. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller enabling predictable EMI signature and robust load transient response. Use Value: 75ns minimum on-time supports 12V→3.3V conversion at 400kHz without subharmonic oscillation or pulse-skipping noise. | Use Scenario: Data center rack-level 48V-to-12V intermediate bus converter feeding multiple point-of-load regulators. IC Role / Device Role / Timing Role: High-efficiency, high-current controller with RSENSE sensing for precise current monitoring and telemetry. Use Value: ±1% reference accuracy and programmable soft-start ensure tight voltage tracking and inrush current control across parallel modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3855IDDB#TRMPBF | Includes phase-locking capability and adjustable switching frequency (200kHz–800kHz); otherwise identical pinout, features, and specs. | Suitable for multiphase or synchronized multi-converter systems requiring frequency coordination. | Select LTC3855IDDB#TRMPBF only when clock synchronization or variable frequency tuning is required; otherwise LTC3854IDDB#TRMPBF offers cost and layout simplicity. |
| MP2918GL-Z | 400kHz fixed frequency, 4.5–36V input, but uses external VREF and lacks OPTI-LOOP®; smaller 10-pin QFN package. | Better suited for cost-sensitive, lower-current (<12A) applications where loop optimization flexibility is not critical. | Choose MP2918GL-Z for simplified BOM and footprint reduction where full OPTI-LOOP® tuning and 38V absolute max input are not needed. |
Compared with LTC3855IDDB#TRMPBF, the LTC3854IDDB#TRMPBF omits phase-locking and frequency adjustability-reducing complexity and cost-while retaining identical control architecture, current sensing options, and thermal performance. Against MP2918GL-Z, it provides superior transient response tuning, higher input voltage margin, and integrated 5V LDO, making it preferable for demanding industrial and telecom power rails.
Availability
LTC3854IDDB#TRMPBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial PLC power, and automotive infotainment systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3854IDDB#TRMPBF 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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC3854IDDB#TRMPBF belongs to Linear's high-voltage synchronous controller product line, designed specifically for efficient, high-current DC/DC conversion in telecom, industrial, and automotive intermediate bus applications.
FAQ
What is the absolute maximum input voltage rating for the LTC3854IDDB#TRMPBF?
The LTC3854IDDB#TRMPBF has an absolute maximum input voltage (VIN) rating of 40V, as specified in the Absolute Maximum Ratings table. Operation above 38V is not recommended for continuous use, though the device tolerates brief transients up to 40V. Exceeding 40V risks permanent damage per Note 1 in the datasheet.
Does the LTC3854IDDB#TRMPBF support DCR current sensing, and what external components are required?
Yes, the LTC3854IDDB#TRMPBF supports both RSENSE and DCR current sensing. For DCR sensing, an RC filter (R1, R2, C1) must be placed between SENSE+ and SENSE–, sized so R1||R2 × C1 equals the inductor's L/DCR time constant. The LTC3854IDDB#TRMPBF's high-impedance sense inputs and wide common-mode range (0–5.5V) enable accurate DCR measurement without added power loss.
Can the LTC3854IDDB#TRMPBF start up into a pre-biased output, and how is this enabled?
Yes, the LTC3854IDDB#TRMPBF supports start-up into a pre-biased output. This behavior is inherent to its architecture and requires no external configuration. During startup, the bottom MOSFET (BG) remains off until the RUN/SS pin reaches 1.2V, preventing reverse current flow. The LTC3854IDDB#TRMPBF then regulates VOUT smoothly without overshoot, even when the output capacitor is initially charged.
What is the purpose of the OPTI-LOOP® compensation feature in the LTC3854IDDB#TRMPBF?
The OPTI-LOOP® compensation in the LTC3854IDDB#TRMPBF minimizes output capacitor dependency by allowing the control loop to remain stable across wide variations in output capacitance value and ESR. This eliminates the need for iterative compensation tuning when changing bulk capacitors or using polymer/ceramic hybrids, significantly accelerating design validation for the LTC3854IDDB#TRMPBF.
How does the LTC3854IDDB#TRMPBF handle overvoltage protection, and what triggers it?
The LTC3854IDDB#TRMPBF includes a dedicated hardware overvoltage (OV) comparator monitoring the FB pin. It triggers when FB exceeds 0.88V (typical), corresponding to ~10% overvoltage relative to the 0.8V reference. Upon detection, the LTC3854IDDB#TRMPBF immediately disables the top gate (TG) and enables the bottom gate (BG) to clamp the output, providing fast, autonomous protection independent of the main control loop.
LTC3854IDDB#TRMPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 38V
- Frequency - Switching:
- 400kHz
- Duty Cycle (Max):
- 98%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-DFN (3x2)
LTC3854IDDB#TRMPBF FAQ
1.How can I place an order for LTC3854IDDB#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3854IDDB#TRMPBF 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 LTC3854IDDB#TRMPBF reliable?
The price and inventory of LTC3854IDDB#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3854IDDB#TRMPBF is usually 5 days.
3.What payment methods are accepted for LTC3854IDDB#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3854IDDB#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3854IDDB#TRMPBF?
LTC3854IDDB#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3854IDDB#TRMPBF 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 LTC3854IDDB#TRMPBF?
For technical support, including LTC3854IDDB#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3854IDDB#TRMPBF requirements.
6.How does Aetrix verify that LTC3854IDDB#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LTC3854IDDB#TRMPBF 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 LTC3854IDDB#TRMPBF meets industry standards.
7.What is the process for return or replacement of LTC3854IDDB#TRMPBF?
All LTC3854IDDB#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3854IDDB#TRMPBF, 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 LTC3854IDDB#TRMPBF part is unused and in its original packaging.
Return procedure for LTC3854IDDB#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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