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Analog Devices Inc. LTC3854EMSE#PBF
- Part No.:
- LTC3854EMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 12-TSSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3854EMSE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 12MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,506
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Product details
Overview
LTC3854EMSE#PBF 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 integrated 5V LDO for gate drive - enabling high-efficiency, high-current (>10A) power supplies in telecom and industrial systems.
For engineers reviewing the LTC3854EMSE#PBF datasheet, LTC3854EMSE#PBF pinout, LTC3854EMSE#PBF application, or LTC3854EMSE#PBF equivalent, key selection criteria include its wide VIN range, RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation for broad capacitor/ESR compatibility, output overvoltage protection, and thermally enhanced MSOP-12 package with exposed ground pad.
Technical Context
The LTC3854EMSE#PBF implements a fixed-frequency (400kHz), peak-current-mode control architecture with dual N-channel MOSFET drivers, internal 5V LDO (INTVCC), and programmable soft-start via RUN/SS pin. Its error amplifier output (ITH) directly sets the current comparator threshold, while FB maintains ±1% 0.8V reference accuracy over temperature.
It supports both resistor-based and DCR-based current sensing, includes slope compensation to prevent subharmonic oscillation, and features active current foldback limiting (disabled during soft-start) plus output overvoltage lockout at 0.86–0.90V at FB. The 97% maximum duty cycle enables operation in dropout with minimal voltage headroom.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide-input industrial, telecom, and automotive battery-supplied systems without pre-regulation. |
| Output Voltage Range | 0.8V to 5.5V - covers core logic, FPGA I/O, and intermediate bus voltages with ±1% reference accuracy. |
| Switching Frequency | 400kHz (±10%) - balances size (inductor/capacitor), efficiency, and EMI; fixed-frequency simplifies filtering. |
| Minimum On-Time | 75ns - enables high step-down ratios (e.g., 36V→3.3V) without pulse-skipping or instability. |
| Current Sensing | RSENSE or DCR - selectable method: precision resistive sensing or lossless inductor DCR sensing for higher efficiency. |
| Gate Drivers | Dual N-channel drivers (TG/BG): 2.1–2.5Ω RDS(ON), 25ns tr/tf - drives high-power external MOSFETs up to 20A output. |
| INTVCC Regulator | 5.0V ±4%, 40mA peak - powers internal circuitry and gate drivers; requires ≥2.2µF low-ESR ceramic bypass. |
| Shutdown IQ | 15µA - enables ultra-low-power standby in battery-backed or always-on systems. |
Pinout & Package
Tiny thermally enhanced 12-lead plastic MSOP package (3mm × 3mm footprint, 0.85mm height) with exposed ground pad (Pin 13) requiring PCB soldering for thermal and electrical performance (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (1) | Error amplifier feedback input | Connects to resistor divider across VOUT; regulates output to precise 0.8V reference with ±1% accuracy. |
| ITH (2) | Error amplifier output / compensation node | Controls peak inductor current threshold; used for loop compensation (OPTI-LOOP®) and transient optimization. |
| RUN/SS (3) | Enable + soft-start control | Pull <0.4V for shutdown; internal 1.25µA current charges external capacitor for controlled VOUT ramp (1.2V→2V). |
| BOOST (4) | Bootstrap supply for top-side driver | Connected via capacitor to SW; provides floating 5V gate drive for high-side N-MOSFET. |
| TG (5) | Top-gate driver output | Drives gate of high-side N-MOSFET with rail-to-rail swing referenced to SW node. |
| SW (6) | Switch node connection | Connects to inductor and bootstrap capacitor; voltage swings from GND to VIN during operation. |
| GND (7) | Signal and power ground | Kelvin-connected internal ground; high-current return path for gate drivers and sense circuitry. |
| BG (8) | Bottom-gate driver output | Drives gate of synchronous low-side N-MOSFET with 0V to 5V swing referenced to GND. |
| INTVCC (9) | Internal 5V LDO output | Powers control logic and drivers; must be decoupled with ≥2.2µF X5R/X7R ceramic capacitor. |
| VIN (10) | Main input supply | Primary power source (4.5–38V); supplies INTVCC LDO and enables UVLO (3.5V threshold). |
| SENSE– (11) | Current sense negative input | Differential input to current comparator; accepts common-mode voltage 0–5.5V for RSENSE or DCR sensing. |
| SENSE+ (12) | Current sense positive input | Paired with SENSE–; enables accurate peak-current detection with <1µA bias current. |
| SGND (13) | Exposed pad ground | Thermal and electrical ground; must be soldered to PCB copper for rated θJA and reliability. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by optimizing transient response across wide COUT/ESR ranges - reduces BOM cost and board area. |
| Start-Up Into Pre-Biased Output | Enables safe hot-swap or rail sequencing without reverse current flow - critical for redundant power systems. |
| Output Overvoltage Protection | Hardware-level OV lockout (0.86–0.90V at FB) disables TG and activates BG to clamp VOUT - prevents damage to downstream ICs. |
| Very Low Dropout Operation | 97% max duty cycle allows regulation down to VOUT ≈ VIN − (VF of body diode or Schottky), extending usable input range. |
| Adjustable Soft-Start | Capacitor-programmable tSS = 0.8·CSS/1.25µA ensures monotonic VOUT rise and avoids inrush current stress on input capacitors/MOSFETs. |
| Current Foldback Limiting | Reduces MOSFET conduction during short-circuit to limit power dissipation - protects external FETs without external circuitry. |
Applications
| Telecom Power Supply | Industrial PLC Power Rail |
|---|---|
Use Scenario: Generating stable 3.3V/5V rails from 24V or 48V backplane in base station power modules. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-current, high-efficiency conversion with tight load regulation. Use Value: 400kHz switching and 75ns min-on-time enable compact magnetics; 4.5–38V input accommodates wide-range telecom input transients. | Use Scenario: Providing isolated 5V/12V auxiliary power for I/O modules and microcontrollers in factory automation controllers. IC Role / Device Role / Timing Role: High-reliability DC/DC controller supporting long-life industrial operation with robust thermal design (MSOP-12 + exposed pad). Use Value: ±1% reference accuracy and OPTI-LOOP® ensure stable output under varying load/temperature; RSENSE/DCR flexibility simplifies design for diverse current levels. |
| Automotive Infotainment System | Distributed DC Power System |
Use Scenario: Converting 12V battery supply to 1.2V/1.8V for SoC cores and memory in head-unit applications. IC Role / Device Role / Timing Role: Step-down controller delivering low-noise, high-PSRR power with fast transient response to dynamic CPU loads. Use Value: Start-up into pre-biased output prevents backfeeding during cold-cranking; 97% duty cycle sustains regulation during cranking dips to ~6V. | Use Scenario: Local point-of-load regulation in server racks or datacom chassis where 12V/48V intermediate buses feed multiple loads. IC Role / Device Role / Timing Role: Scalable, high-efficiency buck controller supporting modular power architecture with flexible current sensing. Use Value: Dual current sensing (RSENSE/DCR) allows optimal trade-off between accuracy and efficiency; 15µA shutdown IQ minimizes standby losses across distributed nodes. |
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 |
|---|---|---|---|
| LTC3855EMSE#PBF | Includes PMBus interface and digital telemetry (VIN/VOUT/IOUT/temperature); same pinout, 400kHz, 4.5–38V input. | Required when system-level monitoring, fault logging, or dynamic VOUT adjustment is needed. | Select LTC3855EMSE#PBF only if digital control and telemetry justify added complexity and cost. |
| MP2918GL-Z | 4.5–32V input, 600kHz, integrated MOSFETs (30V/12A), no DCR sensing, smaller solution size but lower max current. | Suitable for space-constrained, medium-current (<12A) designs where integration outweighs flexibility. | Choose MP2918GL-Z for simplified layout and reduced component count in ≤12A applications without DCR sensing needs. |
Compared with LTC3854EMSE#PBF, LTC3855EMSE#PBF adds digital control at identical analog performance, while MP2918GL-Z trades external MOSFET flexibility and DCR support for monolithic simplicity and higher frequency - making LTC3854EMSE#PBF optimal for high-current, high-efficiency, and thermally demanding industrial/telecom designs.
Availability
LTC3854EMSE#PBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial PLC power rails, and automotive infotainment systems requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LTC3854EMSE#PBF 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 power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC3854EMSE#PBF belongs to ADI's Power by Linear™ synchronous controller product line, designed specifically for high-efficiency, wide-input-voltage DC/DC conversion in demanding industrial, telecom, and automotive environments.
FAQ
What is the absolute maximum input voltage rating for the LTC3854EMSE#PBF?
The LTC3854EMSE#PBF has an absolute maximum input voltage (VIN) rating of 40V, as specified in the Absolute Maximum Ratings table. Operation above 38V nominal input is not recommended for sustained use, and exceeding 40V risks permanent device damage. The UVLO threshold is 3.5V (falling), ensuring reliable startup above 4.5V.
Does the LTC3854EMSE#PBF support DCR current sensing, and what external components are required?
Yes, the LTC3854EMSE#PBF supports both RSENSE and DCR current sensing. For DCR sensing, an RC network (R1, R2, C1) must be placed across the inductor to match the L/DCR time constant. Typical values depend on inductor specs - e.g., if DCR = 1.2mΩ and L = 2.2µH, then R1||R2•C1 ≈ 1.83µs. The LTC3854EMSE#PBF's high-impedance SENSE pins (±0.5µA bias) ensure accurate DCR voltage measurement.
What is the purpose of the exposed pad (Pin 13) on the LTC3854EMSE#PBF MSOP package?
The exposed pad (Pin 13, labeled SGND) on the LTC3854EMSE#PBF is electrically connected to ground and serves as the primary thermal path. It must be soldered to a PCB copper pour to achieve the specified θJA = 40°C/W and prevent junction temperature exceedance. Leaving it unconnected degrades thermal performance and may cause premature failure under load.
How does the RUN/SS pin control soft-start and enable functions in the LTC3854EMSE#PBF?
The RUN/SS pin on the LTC3854EMSE#PBF integrates enable and soft-start: pulling below 0.4V forces shutdown; releasing allows an internal 1.25µA current to charge an external capacitor, ramping RUN/SS from 1.2V to 2V. During this ramp, VOUT rises proportionally, ensuring controlled start-up. At RUN/SS > 2V, the LTC3854EMSE#PBF enters full forced continuous mode.
Can the LTC3854EMSE#PBF operate with an input voltage lower than 4.5V?
No - the LTC3854EMSE#PBF has a specified minimum operating input voltage of 4.5V. Below this, the internal UVLO circuit prevents startup, and the INTVCC LDO cannot regulate properly. While the absolute minimum for some bias circuits may be lower, functional operation (including gate drive, regulation, and protection features) is only guaranteed from 4.5V to 38V per the datasheet.
LTC3854EMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-TSSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- 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-MSOP-EP
LTC3854EMSE#PBF FAQ
1.How can I place an order for LTC3854EMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3854EMSE#PBF 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 LTC3854EMSE#PBF reliable?
The price and inventory of LTC3854EMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3854EMSE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3854EMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3854EMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3854EMSE#PBF?
LTC3854EMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3854EMSE#PBF 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 LTC3854EMSE#PBF?
For technical support, including LTC3854EMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3854EMSE#PBF requirements.
6.How does Aetrix verify that LTC3854EMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3854EMSE#PBF 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 LTC3854EMSE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3854EMSE#PBF?
All LTC3854EMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3854EMSE#PBF, 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 LTC3854EMSE#PBF part is unused and in its original packaging.
Return procedure for LTC3854EMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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