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Analog Devices Inc. LTC3854IDDB#TRPBF
- Part No.:
- LTC3854IDDB#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LTC3854IDDB#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,935
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Product details
Overview
LTC3854IDDB#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 LTC3854IDDB#TRPBF datasheet, LTC3854IDDB#TRPBF pinout, LTC3854IDDB#TRPBF application, or LTC3854IDDB#TRPBF equivalent, key selection considerations include RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation for wide output capacitance tolerance, 97% duty cycle dropout operation, ±1% reference accuracy over temperature, and thermal performance in the 3mm × 2mm DFN package with exposed GND pad.
Technical Context
The LTC3854IDDB#TRPBF implements a fixed 400kHz peak-current-mode 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 sub-30ns transition times, supporting high-efficiency synchronous rectification.
It integrates a 5V/40mA LDO (INTVCC) powered from VIN, a dedicated 1.25µA RUN/SS soft-start current source, and independent overvoltage protection that disables TG and enables BG until fault clearance. Current foldback limiting activates only after soft-start completion.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide industrial and telecom input rails including 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%) - balances EMI, inductor size, and efficiency in space-constrained designs. |
| Reference Accuracy | ±1% at 0.8V over –40°C to +85°C - ensures tight output regulation under thermal stress. |
| Minimum On-Time | 75ns - enables high step-down ratios (e.g., 24V→1.2V at 400kHz) without pulse-skipping. |
| Duty Cycle Limit | 97% - sustains regulation during deep dropout (e.g., VIN = 5.2V → VOUT = 5V). |
| Shutdown IQ | 15µA - minimizes standby power loss in battery-backed or always-on systems. |
Pinout & Package
Package: 12-lead (3mm × 2mm) plastic DFN with exposed thermal pad (Pin 13 = SGND), rated for –40°C to +85°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (1) | Error amplifier feedback input | Connects to resistor divider for precise output voltage sensing; 0.8V reference sets regulation point. |
| ITH (2) | Error amplifier output / compensation node | Controls peak current threshold; external compensation network sets loop stability and transient response. |
| RUN/SS (3) | Enable and soft-start control | Pulled below 0.4V for shutdown; internal 1.25µA current charges external capacitor for linear VOUT ramp. |
| BOOST (4) | Floating supply for top-gate driver | Connected via ceramic capacitor to SW; enables high-side N-MOSFET drive using bootstrap topology. |
| TG (5) | Top N-MOSFET gate driver output | Delivers 2.5Ω pull-up / 2.1Ω pull-down drive into 3300pF load; supports fast switching with <30ns transitions. |
| SW (6) | Switch node connection | Connects to inductor and BOOST capacitor; voltage swings from ground to VIN during operation. |
| GND (7) | Signal and power ground | Kelvin-connected internal ground reference; must be low-impedance PCB plane tied to exposed pad. |
| BG (8) | Bottom N-MOSFET gate driver output | Drives synchronous rectifier with rail-to-rail swing (0V to INTVCC); complements TG for continuous conduction mode. |
| INTVCC (9) | Internal 5V LDO output | Powers gate drivers and internal circuitry; requires ≥2.2µF X5R ceramic bypass to GND. |
| VIN (10) | Main input supply | Feeds INTVCC LDO and provides energy to power stage; bypass capacitor required near pin. |
| SENSE– (11) | Current sense comparator negative input | High-impedance input for differential current sensing; common-mode range 0V–5.5V supports DCR or RSENSE schemes. |
| SENSE+ (12) | Current sense comparator positive input | Paired with SENSE–; 50mV max threshold sets peak inductor current limit. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Allows stable loop design across wide range of output capacitor ESR and capacitance values without re-tuning. |
| RSENSE or DCR Current Sensing | Supports both discrete shunt resistors (for accuracy) and inductor DCR (for efficiency), with programmable filtering. |
| Start-Up Into Pre-Biased Output | Enables safe hot-swap insertion without output voltage overshoot or reverse current flow. |
| Output Overvoltage Protection | Dedicated comparator disables TG and asserts BG to clamp VOUT if FB exceeds 0.88V (10% above nominal). |
| Low Dropout Operation | 97% duty cycle allows regulation down to VIN − 0.3V (e.g., 5.2V→5V), critical for high-efficiency backup rails. |
Applications
| Telecom Power Supply | Industrial 24V Distribution |
|---|---|
Use Scenario: Regulating 48V or 24V intermediate bus to 3.3V/5V for base station FPGAs and DSPs. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-current, high-efficiency conversion with tight transient response. Use Value: 400kHz switching and 75ns min-on-time enable compact magnetics while maintaining >94% efficiency at 10A load. | Use Scenario: Converting 24V factory automation bus to 12V/5V for PLC I/O modules and sensors. IC Role / Device Role / Timing Role: Robust DC/DC controller tolerant of wide input transients (up to 38V) and operating over –40°C to +85°C. Use Value: ±1% reference accuracy and UVLO hysteresis ensure reliable startup and regulation despite brownouts or surges. |
| Automotive Infotainment | Distributed Data Center PSU |
Use Scenario: Generating 1.2V core voltage for automotive SoCs from 12V battery rail with cold-crank tolerance. IC Role / Device Role / Timing Role: High-step-down ratio controller leveraging 75ns min-on-time and 97% duty cycle for deep dropout support. Use Value: Starts into pre-biased output and withstands 40V abs-max input during load dump, eliminating need for upstream TVS. | Use Scenario: Point-of-load regulation in server racks where 12V or 48V backplane feeds ASICs and memory. IC Role / Device Role / Timing Role: High-current synchronous controller enabling 20A output with external MOSFETs optimized for low RDS(ON). Use Value: Dual N-MOSFET drive with <30ns dead-time control minimizes shoot-through losses and improves full-load efficiency. |
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#TRPBF | Includes dual-output capability and adjustable current limit; same pinout and package but adds second channel control logic. | Suitable for dual-rail systems (e.g., 1.2V + 3.3V) requiring coordinated sequencing; not drop-in for single-output use. | Select LTC3855IDDB#TRPBF only when dual-output coordination or programmable current limit is required. |
| MP2918GL-Z | 400kHz fixed frequency, 4.5V–36V input, but uses internal compensation and lacks DCR sensing support; 10-pin QFN vs 12-pin DFN. | Better suited for cost-sensitive, lower-complexity designs where OPTI-LOOP® tuning and DCR flexibility are unnecessary. | Choose MP2918GL-Z for simplified BOM and layout where advanced compensation and sensing options are not needed. |
Compared with LTC3854IDDB#TRPBF, LTC3855IDDB#TRPBF adds dual-output functionality at identical footprint and thermal performance, while MP2918GL-Z trades design flexibility (no DCR sensing, no OPTI-LOOP®) for integration and lower component count in less demanding applications.
Availability
LTC3854IDDB#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial 24V distribution systems, and automotive infotainment electronics requiring stable component supply and long-term production continuity.
Supply support for LTC3854IDDB#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC3854IDDB#TRPBF 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 environments.
FAQ
What is the absolute maximum input voltage rating for the LTC3854IDDB#TRPBF?
The LTC3854IDDB#TRPBF has an absolute maximum input voltage (VIN) rating of 40V, as specified in the Absolute Maximum Ratings table. Operation beyond this voltage risks permanent device damage. The recommended operating range remains 4.5V to 38V, ensuring full specification compliance across temperature and load conditions. Always observe the 40V limit during transient events such as load dump or hot-swap.
Does the LTC3854IDDB#TRPBF support DCR current sensing, and what external components are required?
Yes, the LTC3854IDDB#TRPBF supports both RSENSE and DCR current sensing. For DCR sensing, an RC filter (R1, R2, C1) must be placed between SENSE+ and SENSE–, with time constant R1||R2 × C1 matched to the inductor's L/DCR ratio. The LTC3854IDDB#TRPBF's high-impedance sense inputs and wide common-mode range (0V–5.5V) enable accurate DCR measurement without additional amplifiers.
What is the purpose of the OPTI-LOOP® compensation feature in the LTC3854IDDB#TRPBF?
The OPTI-LOOP® compensation in the LTC3854IDDB#TRPBF dynamically adjusts loop response to accommodate variations in output capacitor ESR and total capacitance. This eliminates the need for iterative compensation tuning when changing bulk capacitance or using polymer/ceramic hybrids, significantly reducing design cycle time while maintaining stability across manufacturing tolerances and temperature drift.
Can the LTC3854IDDB#TRPBF start up into a pre-biased output, and how does it behave during this condition?
Yes, the LTC3854IDDB#TRPBF supports start-up into a pre-biased output. During this condition, the bottom gate (BG) remains off until the feedback voltage (VFB) rises above the internal reference, preventing reverse current flow through the synchronous MOSFET body diode. This behavior ensures safe hot-swap operation and avoids output voltage overshoot or system reset caused by uncontrolled inrush.
What thermal considerations apply to the LTC3854IDDB#TRPBF in its 3mm × 2mm DFN package?
The LTC3854IDDB#TRPBF in the 12-lead DFN package has θJA = 76°C/W and θJC = 10°C/W. The exposed pad (Pin 13) must be soldered to a solid PCB ground plane for effective heat dissipation. Junction temperature must remain ≤125°C; for example, at 36V input and 17mA INTVCC current, TJ ≈ 116.5°C - underscoring the need for adequate copper area and airflow in high-power designs using the LTC3854IDDB#TRPBF.
LTC3854IDDB#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)
LTC3854IDDB#TRPBF FAQ
1.How can I place an order for LTC3854IDDB#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3854IDDB#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 LTC3854IDDB#TRPBF reliable?
The price and inventory of LTC3854IDDB#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3854IDDB#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3854IDDB#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3854IDDB#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3854IDDB#TRPBF?
LTC3854IDDB#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3854IDDB#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 LTC3854IDDB#TRPBF?
For technical support, including LTC3854IDDB#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3854IDDB#TRPBF requirements.
6.How does Aetrix verify that LTC3854IDDB#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3854IDDB#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 LTC3854IDDB#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3854IDDB#TRPBF?
All LTC3854IDDB#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3854IDDB#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 LTC3854IDDB#TRPBF part is unused and in its original packaging.
Return procedure for LTC3854IDDB#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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