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Analog Devices Inc. LTC3854EDDB#TRPBF
- Part No.:
- LTC3854EDDB#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LTC3854EDDB#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,200
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Product details
Overview
LTC3854EDDB#TRPBF from Analog Devices (formerly Linear Technology) is a high-performance synchronous step-down DC/DC controller driving all-N-channel MOSFET stages. It operates from 4.5V to 38V input, regulates output from 0.8V to 5.5V, features 400kHz constant-frequency current-mode control, 75ns minimum on-time, and delivers up to 20A output current in telecom power supplies.
For engineers reviewing the LTC3854EDDB#TRPBF datasheet, LTC3854EDDB#TRPBF pinout, LTC3854EDDB#TRPBF application, or LTC3854EDDB#TRPBF equivalent, key selection considerations include RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation for wide output capacitance tolerance, output overvoltage protection, 97% duty cycle dropout operation, and thermal performance in the 3mm × 2mm DFN package.
Technical Context
The LTC3854EDDB#TRPBF implements a fixed 400kHz peak-current-mode control architecture with internal slope compensation that preserves maximum inductor peak current across all duty cycles. Its dual N-channel gate drivers deliver 2.1Ω–2.5Ω pull-down/pull-up resistance and 25ns transition times into 3300pF loads.
It integrates a 5V/40mA LDO (INTVCC) powered from VIN, supports startup into pre-biased outputs, and uses an internal 1.25µA RUN/SS charge current for adjustable soft-start. Current foldback limiting (40–65mV sense threshold) is disabled during soft-start, and output overvoltage lockout triggers at 0.86–0.90V at FB.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide-input industrial and telecom rails without external regulators |
| Output Voltage Range | 0.8V to 5.5V - enables direct regulation of core voltages (e.g., 1.2V, 1.8V, 3.3V, 5V) |
| Switching Frequency | 400kHz ±10% - balances size (inductor/capacitor), efficiency, and EMI in compact designs |
| Reference Accuracy | ±1% at 0.8V over temperature - ensures tight output voltage regulation under load and thermal variation |
| Min On-Time | 75ns - enables high step-down ratios (e.g., 24V→1.2V at 400kHz) without pulse-skipping |
| Duty Cycle Max | 97% - sustains regulation down to VIN ≈ VOUT + 0.5V, critical for low-dropout battery or backup systems |
| Shutdown IQ | 15µA - minimizes system standby power in always-on applications |
| Package | 12-pin 3mm × 2mm DFN with exposed GND pad - provides low θJA = 76°C/W for thermally constrained layouts |
Pinout & Package
Package: 12-lead (3mm × 2mm) plastic DFN with exposed thermal pad (Pin 13 = SGND), rated for –40°C to 85°C ambient operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (1) | Error amplifier feedback input | Connects to resistor divider for precise 0.8V reference regulation; ±5nA bias enables high-impedance sensing |
| ITH (2) | Error amplifier output & compensation node | Controls peak current limit; sets loop dynamics via external RC network for OPTI-LOOP® stability |
| RUN/SS (3) | Enable and soft-start control | Pulled low (<0.4V) for shutdown; internal 1.25µA current charges external capacitor for linear VOUT ramp |
| BOOST (4) | Bootstrap supply for top-side driver | Swings from INTVCC to (VIN + INTVCC); requires low-ESR cap between BOOST and SW for floating gate drive |
| TG (5) | Top N-MOSFET gate driver output | Drives high-side FET with 2.5Ω pull-up / 2.1Ω pull-down; supports logic-level FETs up to 38V VIN |
| SW (6) | Switch node connection | Connects to inductor and BOOST capacitor; voltage swings from ground to VIN (or below via Schottky) |
| GND (7) | Signal and power ground | Kelvin-connected internal ground; exposed pad (Pin 13) must be soldered for thermal and electrical integrity |
| BG (8) | Bottom N-MOSFET gate driver output | Drives synchronous rectifier with rail-to-rail swing (0V to INTVCC); enables >95% efficiency at 7A |
| INTVCC (9) | Internal 5V LDO output | Powers gate drivers and control circuitry; requires ≥2.2µF X5R ceramic bypass to GND |
| VIN (10) | Main input supply | Accepts 4.5V–38V; powers INTVCC LDO and provides UVLO detection at 3.0–3.5V falling threshold |
| SENSE– (11) | Current sense comparator negative input | High-impedance input (±0.5µA bias); used with SENSE+ for RSENSE or DCR-based current monitoring |
| SENSE+ (12) | Current sense comparator positive input | Common-mode range 0V–5.5V; enables accurate DCR sensing with external RC filter matching L/DCR time constant |
Key Features
| Feature | Design Value |
|---|---|
| RSENSE or DCR current sensing | Supports both discrete shunt resistors (max 50mV threshold) and lossless inductor DCR sensing - reduces BOM cost and improves full-load efficiency |
| OPTI-LOOP® compensation | Allows stable loop response across wide ranges of output capacitance (e.g., 10µF–1000µF) and ESR (0.5mΩ–50mΩ) without redesign |
| Start-up into pre-biased output | Enables hot-swap and redundancy applications by preventing reverse current flow during VOUT presence at power-on |
| Output overvoltage protection | Hardware comparator disables TG and enables BG if FB exceeds 0.86V - protects downstream ICs during transient faults or feedback failure |
| 5V LDO for gate drive | Integrated PMOS LDO delivers 40mA peak current from VIN to INTVCC - eliminates need for external bias supply in most configurations |
| Adjustable soft-start | External capacitor on RUN/SS sets ramp time (tSS = 0.8·CSS/1.25µA); prevents inrush current and output overshoot during power-up |
Applications
| Telecom Power Supply | Industrial PLC I/O Module |
|---|---|
Use Scenario: Regulating 5V/7A from a 24V distributed DC bus in a 1U telecom shelf with strict thermal limits. IC Role / Device Role / Timing Role: Primary step-down controller managing synchronous MOSFET switching at 400kHz with DCR current sensing for minimal conduction loss. Use Value: 96% efficiency at 7A (VIN=24V) and 76°C/W thermal resistance enable operation without forced air in sealed enclosures. | Use Scenario: Generating isolated 3.3V/5A for microcontroller and interface ICs in a DIN-rail mounted programmable logic controller. IC Role / Device Role / Timing Role: High-reliability buck controller supporting wide input (18–36V DC) and maintaining regulation during brownouts via 97% duty cycle operation. Use Value: ±1% reference accuracy and current foldback limiting ensure stable MCU operation and prevent damage during short-circuit events on field wiring. |
| Automotive Infotainment Head Unit | Distributed Data Center PSU |
Use Scenario: Converting 12V battery rail to 1.2V/10A for SoC core power in a vehicle infotainment system with cold-crank immunity. IC Role / Device Role / Timing Role: Wide-VIN controller enabling start-stop operation; uses RSENSE sensing for precise current limiting during cranking (VIN dips to 6V). Use Value: 75ns min on-time allows 1.2V output from 6V input at 400kHz; RUN/SS pin supports controlled sequencing with main system processor. | Use Scenario: Intermediate 12V bus regulation feeding multiple point-of-load converters in a 48V server rack power architecture. IC Role / Device Role / Timing Role: High-current (20A capable) intermediate converter using dual-phase interleaving (with second LTC3854) to reduce input ripple and thermal stress. Use Value: Dual N-MOSFET drive strength and 400kHz frequency allow compact magnetics while maintaining >95% efficiency at 15A continuous load. |
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 |
|---|---|---|---|
| LTC3855EDDB#TRPBF | Includes phase-locking capability and dual-output tracking; same pinout, 400kHz base frequency but programmable via resistor | Required for multi-rail synchronized sequencing (e.g., DDR memory VDD/VTT) or parallel-phase operation | Select when precise timing coordination between multiple rails or current-sharing across phases is needed |
| MP2918GL-Z | 400kHz fixed frequency, 4.5–36V input, but uses internal compensation and lacks DCR sensing support; smaller 10-pin QFN | Suitable for cost-sensitive, space-constrained designs where RSENSE-only sensing and simplified layout are acceptable | Select when design simplicity and BOM reduction outweigh need for DCR sensing or OPTI-LOOP® flexibility |
Compared with LTC3854EDDB#TRPBF, LTC3855EDDB#TRPBF adds synchronization and tracking for complex multi-rail systems, while MP2918GL-Z trades configurability for integration and footprint - making LTC3854EDDB#TRPBF optimal for high-efficiency, thermally demanding, or DCR-sensing applications requiring proven loop stability.
Availability
LTC3854EDDB#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial PLC modules, and automotive infotainment systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3854EDDB#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 acquired Linear Technology in 2017 and maintains its high-performance analog and power management portfolio with rigorous qualification standards.
The LTC3854 belongs to Linear's high-efficiency synchronous controller product line, designed specifically for wide-input, high-current DC/DC conversion in space- and thermally-constrained infrastructure equipment.
FAQ
What is the absolute maximum input voltage rating for the LTC3854EDDB#TRPBF?
The LTC3854EDDB#TRPBF has an absolute maximum input voltage (VIN) rating of 40V, as specified in the Absolute Maximum Ratings table. Operation above this voltage risks permanent device damage. The recommended operating range remains 4.5V to 38V, with undervoltage lockout engaging at 3.0–3.5V (falling) to prevent erratic behavior during brownouts. This rating applies directly to the VIN pin and is independent of boost or switch node ratings.
Does the LTC3854EDDB#TRPBF support DCR current sensing, and what external components are required?
Yes, the LTC3854EDDB#TRPBF supports both RSENSE and DCR current sensing. For DCR sensing, an RC filter (R1, R2, C1) must be placed near the SENSE+ and SENSE– pins, with R1||R2•C1 matched to the inductor's L/DCR time constant. R2 scales the sensed voltage when DCR exceeds the target sense resistance. The LTC3854EDDB#TRPBF's high-impedance sense inputs and common-mode range (0V–5.5V) ensure accuracy, and no additional op-amps or amplifiers are needed.
How does the OPTI-LOOP® compensation in the LTC3854EDDB#TRPBF improve design flexibility?
OPTI-LOOP® compensation in the LTC3854EDDB#TRPBF allows stable closed-loop operation across a wide range of output capacitor values (e.g., 10µF to 1000µF) and ESR (0.5mΩ to 50mΩ) without changing the compensation network. This eliminates iterative loop tuning when optimizing for cost, size, or reliability - for example, enabling use of low-ESR polymer caps for high ripple current or bulk aluminum electrolytics for hold-up time, all while maintaining phase margin >45°.
Can the LTC3854EDDB#TRPBF start up into a pre-biased output, and how is this enabled?
Yes, the LTC3854EDDB#TRPBF supports start-up into a pre-biased output. This is enabled by default - no configuration is required. During startup, the controller monitors the FB pin and prevents reverse current flow by holding both TG and BG off until the internal error amplifier can take control. This avoids discharging the existing output voltage and protects downstream loads, making the LTC3854EDDB#TRPBF suitable for hot-swap and redundant power systems.
What thermal considerations apply to the LTC3854EDDB#TRPBF in its 3mm × 2mm DFN package?
The LTC3854EDDB#TRPBF in the 12-lead DFN package has θJA = 76°C/W and θJC = 10°C/W. To maintain TJ ≤ 125°C, the PCB must incorporate adequate copper area connected to the exposed pad (Pin 13 = SGND). At 20A output with 24V input, INTVCC current dominates dissipation; junction temperature is calculated as TJ = TA + (VIN × IINTVCC) × 76°C/W. For example, at 17mA INTVCC load and 70°C ambient, TJ ≈ 116.5°C - confirming need for thermal validation in high-power layouts.
LTC3854EDDB#TRPBF 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)
LTC3854EDDB#TRPBF FAQ
1.How can I place an order for LTC3854EDDB#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3854EDDB#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 LTC3854EDDB#TRPBF reliable?
The price and inventory of LTC3854EDDB#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3854EDDB#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3854EDDB#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3854EDDB#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3854EDDB#TRPBF?
LTC3854EDDB#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3854EDDB#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 LTC3854EDDB#TRPBF?
For technical support, including LTC3854EDDB#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3854EDDB#TRPBF requirements.
6.How does Aetrix verify that LTC3854EDDB#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3854EDDB#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 LTC3854EDDB#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3854EDDB#TRPBF?
All LTC3854EDDB#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3854EDDB#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 LTC3854EDDB#TRPBF part is unused and in its original packaging.
Return procedure for LTC3854EDDB#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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