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Analog Devices Inc. LTC3854EMSE#TRPBF
- Part No.:
- LTC3854EMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 12-TSSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3854EMSE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 12MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,759
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Product details
Overview
LTC3854EMSE#TRPBF from Analog Devices (formerly Linear Technology) is a high-performance, wide-input synchronous step-down DC/DC controller driving dual 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 optimized designs. It is used in telecom power supplies requiring high step-down ratio and pre-biased start-up.
For engineers reviewing the LTC3854EMSE#TRPBF datasheet, LTC3854EMSE#TRPBF pinout, LTC3854EMSE#TRPBF application, or LTC3854EMSE#TRPBF equivalent, key selection considerations include RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation for broad capacitor/ESR compatibility, 97% duty cycle dropout operation, ±1% 0.8V reference accuracy over temperature, and thermal performance in the 12-lead MSOP package.
Technical Context
The LTC3854EMSE#TRPBF implements a constant-frequency peak current-mode control architecture with internal slope compensation that preserves maximum inductor peak current across all duty cycles. Its transconductance error amplifier (gm = 2.0 mmho, GBW = 3 MHz) drives the ITH node to modulate peak switch current based on FB voltage deviation from 0.8V reference.
It integrates dual high-current gate drivers (TG/BG) with matched 2.1–2.5Ω on-resistances, 25ns rise/fall times, and programmable dead-time control via internal anti-shoot-through logic. The 5V INTVCC LDO (4.8–5.2V, 40mA peak) powers drivers and internal circuitry, while the RUN/SS pin provides combined enable and soft-start via internal 1.25µA current source charging an external capacitor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports 24V/36V industrial and telecom rails with 40V absolute max rating. |
| Output Voltage Range | 0.8V to 5.5V - enables core voltage regulation (e.g., 1.2V, 1.8V, 3.3V, 5V) with ±1% reference accuracy over –40°C to 85°C. |
| Switching Frequency | 400kHz (±10%) - fixed frequency simplifies EMI filtering; stable across input, load, and temperature. |
| Minimum On-Time | 75ns - enables high step-down ratios (e.g., 36V→3.3V at 400kHz) without pulse-skipping instability. |
| Duty Cycle Max | 97% - supports ultra-low dropout operation (e.g., 5.5V→5.0V), critical for battery backup and pre-biased start-up. |
| Current Sensing | RSENSE or DCR - selectable method: 50mV max sense threshold for resistor sensing; high-impedance SENSE± inputs support accurate DCR networks. |
| Quiescent Current | 2–3mA active, 15µA shutdown - enables low-power standby in always-on systems without compromising startup speed. |
Pinout & Package
Package: 12-Lead Plastic MSOP (3mm × 3mm footprint, 0.65mm pitch), exposed pad (Pin 13) tied to GND for thermal and electrical integrity. θJA = 40°C/W, suitable for compact, thermally constrained PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (1) | Error amplifier inverting input | Connects to resistor divider from VOUT; sets regulated output voltage with 0.8V internal reference. |
| ITH (2) | Error amplifier output / compensation node | Controls peak inductor current; interface for OPTI-LOOP® compensation network (type II/III). |
| RUN/SS (3) | Enable + soft-start control | Pulled below 0.4V for shutdown; internal 1.25µA current charges external capacitor for linear VOUT ramp (1.2V→2V). |
| BOOST (4) | Floating supply for top gate driver | Connected to SW via bootstrap capacitor; enables high-side N-MOSFET drive with voltage swing ≈ VIN + 5V. |
| TG (5) | Top N-MOSFET gate driver output | High-current floating driver (2.5Ω pull-up, 2.1Ω pull-down); drives gate with 25ns edges into 3300pF load. |
| 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; must be low-impedance plane; exposed pad (Pin 13) is SGND and requires soldering. |
| BG (8) | Bottom N-MOSFET gate driver output | Ground-referenced driver (2.5Ω pull-up, 1.2Ω pull-down); complements TG with 30ns interlock delay. |
| INTVCC (9) | Internal 5V LDO output | Powers gate drivers and internal circuits; requires ≥2.2µF X5R ceramic bypass to GND; 40mA peak capability. |
| VIN (10) | Main input supply | 4.5–38V input; powers INTVCC LDO and provides bias for UVLO (3.5V threshold) and current sensing circuitry. |
| SENSE– (11) | Current sense comparator negative input | High-impedance (±1µA bias) input for differential current sensing; common-mode range 0–5.5V. |
| SENSE+ (12) | Current sense comparator positive input | Paired with SENSE–; enables precise RSENSE or DCR-based peak current limiting up to 50mV threshold. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by enabling stable loop response across wide COUT/ESR ranges (e.g., polymer, ceramic, electrolytic). |
| Pre-Biased Output Start-Up | Allows safe startup into existing VOUT voltage without reverse current flow - essential for hot-swap and redundant power systems. |
| Output Overvoltage Protection (OVP) | Hardware comparator triggers immediate TG off / BG on if FB exceeds 0.88V - protects downstream loads from transient overshoot (>10%). |
| Current Foldback Limiting | Reduces MOSFET conduction during short-circuit to limit power dissipation; automatically disabled during soft-start to prevent false triggering. |
| 97% Duty Cycle Operation | Enables near-lossless dropout mode (e.g., 5.5V→5.0V), maintaining regulation even as input approaches output voltage. |
Applications
| Telecom Power Supply | Industrial 24V Distribution |
|---|---|
|
Use Scenario: Point-of-load regulation in 48V backplane systems converting to 3.3V/5V for FPGA, ASIC, or DSP cores. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-efficiency, high-current conversion with tight transient response. Use Value: 400kHz switching enables small magnetics; 75ns min on-time supports 48V→3.3V (6.5% duty) without frequency foldback. |
Use Scenario: DIN-rail mounted 24V-to-12V/5V converter powering PLC I/O modules and sensors in factory automation. IC Role / Device Role / Timing Role: Robust DC/DC controller tolerant of wide input variation (18–36V), brownouts, and EMI-rich environments. Use Value: ±1% 0.8V reference and UVLO hysteresis (350mV) ensure stable regulation despite line fluctuations and cold cranking dips. |
| Automotive Infotainment | Network Equipment |
|
Use Scenario: Powering display controllers and audio codecs from 12V battery rail with strict EMI and thermal constraints. IC Role / Device Role / Timing Role: High-efficiency synchronous controller supporting pre-biased start-up during engine restart sequences. Use Value: Ability to start into pre-biased output prevents bus collapse; 97% duty cycle maintains 5V output during cranking (down to ~6.5V input). |
Use Scenario: Midspan power sourcing in PoE++ switches delivering 57W to remote access points and cameras. IC Role / Device Role / Timing Role: Secondary-side synchronous buck controller regulating isolated 54V input down to 12V/5V system rails. Use Value: RSENSE/DCR flexibility allows optimal trade-off between sensing accuracy and conduction loss in high-current, space-constrained 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 |
|---|---|---|---|
| LT8640S | Monolithic 4A buck regulator (integrated MOSFETs); 2.8–42V input; 300kHz–3MHz sync frequency; no external sense resistor needed. | Better for lower-current (<5A), space-constrained designs where integration reduces BOM count and layout complexity. | Select LT8640S when board area and design simplicity outweigh need for >20A scalability and discrete MOSFET optimization. |
| MP2918 | Controller with PMBus interface, digital loop compensation, and telemetry; 4.5–36V input; 400kHz default; supports multiphase. | Suitable for systems requiring real-time monitoring (VIN/VOUT/IOUT/temp), dynamic voltage scaling, or multi-rail coordination. | Choose MP2918 when digital control, fault logging, or adaptive loop tuning is required - not for analog-only, cost-sensitive designs. |
Compared with LT8640S and MP2918, the LTC3854EMSE#TRPBF offers superior thermal management in MSOP via exposed pad, full analog control freedom for custom compensation, and proven high-current capability with discrete MOSFETs - making it optimal for 10–20A industrial and telecom converters where reliability and efficiency are prioritized over integration or digital features.
Availability
LTC3854EMSE#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial 24V distribution systems, and automotive infotainment modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3854EMSE#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision, industrial, automotive, and communications markets.
The LTC3854 belongs to Linear's high-voltage synchronous buck controller product line, designed specifically for demanding industrial and telecom applications requiring wide VIN range, high efficiency, robust protection, and flexible current sensing.
FAQ
What is the operating temperature range for the LTC3854EMSE#TRPBF?
The LTC3854EMSE#TRPBF is specified for operation from –40°C to +85°C ambient temperature. Its thermal resistance (θJA = 40°C/W) and internal thermal shutdown protect against junction overheating. The device is rated for maximum junction temperature of 125°C, and its electrical characteristics are guaranteed across this full industrial temperature range per datasheet Note 2.
Does the LTC3854EMSE#TRPBF support both resistor-based and DCR-based current sensing?
Yes, the LTC3854EMSE#TRPBF supports both methods. Its high-impedance SENSE+ and SENSE– inputs (bias < ±1µA) and 0–5.5V common-mode range enable accurate DCR sensing with RC filter networks. For resistor sensing, it uses a fixed 50mV current sense threshold. Designers select based on accuracy needs (RSENSE) versus efficiency goals (DCR), with no hardware change required.
How does the RUN/SS pin function in the LTC3854EMSE#TRPBF?
The RUN/SS pin on the LTC3854EMSE#TRPBF serves dual functions: pulling it below 0.4V places the IC in shutdown (IQ ≈ 15µA), while releasing it allows an internal 1.25µA current to charge an external capacitor, generating a linear voltage ramp from 1.2V to 2V. During this ramp, VOUT rises proportionally - enabling controlled soft-start. Above 2V, the controller enters full forced continuous mode.
What package type and thermal characteristics does the LTC3854EMSE#TRPBF use?
The LTC3854EMSE#TRPBF uses a 12-lead plastic MSOP package with an exposed thermal pad (Pin 13 = SGND). Its thermal performance is characterized by θJA = 40°C/W and θJC = 16°C/W. The exposed pad must be soldered to a solid copper thermal plane for reliable operation at full load, especially in high-ambient or high-VIN conditions.
Can the LTC3854EMSE#TRPBF start up into a pre-biased output voltage?
Yes, the LTC3854EMSE#TRPBF supports pre-biased start-up. Its synchronous architecture and controlled gate timing prevent reverse current flow during startup. When enabled, the bottom MOSFET (BG) is actively managed to avoid discharging the output capacitor, allowing safe ramp-up even when VOUT is initially non-zero - a critical feature for hot-swap and redundant power systems.
LTC3854EMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-TSSOP (0.118", 3.00mm Width) 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-MSOP-EP
LTC3854EMSE#TRPBF FAQ
1.How can I place an order for LTC3854EMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3854EMSE#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 LTC3854EMSE#TRPBF reliable?
The price and inventory of LTC3854EMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3854EMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3854EMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3854EMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3854EMSE#TRPBF?
LTC3854EMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3854EMSE#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 LTC3854EMSE#TRPBF?
For technical support, including LTC3854EMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3854EMSE#TRPBF requirements.
6.How does Aetrix verify that LTC3854EMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3854EMSE#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 LTC3854EMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3854EMSE#TRPBF?
All LTC3854EMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3854EMSE#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 LTC3854EMSE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3854EMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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