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Analog Devices Inc. LTC3854IMSE#PBF
- Part No.:
- LTC3854IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 12-TSSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3854IMSE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 12MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,973
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Product details
Overview
LTC3854IMSE#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 fixed-frequency current-mode control, 75ns minimum on-time, and delivers up to 20A output current in telecom power supplies.
For engineers reviewing the LTC3854IMSE#PBF datasheet, LTC3854IMSE#PBF pinout, LTC3854IMSE#PBF application, or LTC3854IMSE#PBF equivalent, key selection considerations include RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation for wide output capacitance tolerance, 97% dropout duty cycle, ±1% reference accuracy over temperature, and MSOP-12 thermal performance (θJA = 40°C/W).
Technical Context
The LTC3854IMSE#PBF implements constant-frequency peak current mode control with internal slope compensation that preserves maximum inductor peak current across all duty cycles. Its error amplifier drives the ITH node to set current comparator trip level, while FB compares 0.8V reference against resistor-divider feedback.
It integrates dual N-channel gate drivers (TG/BG) with 2.1–2.5Ω pull-down/pull-up resistance, 25ns transition times, and 30ns synchronous switch timing delays. The 5V INTVCC LDO powers internal circuitry and gate drivers, and the RUN/SS pin provides combined enable and soft-start via 1.25µA internal charge current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide-input industrial and telecom rails without pre-regulation |
| Output Voltage Range | 0.8V to 5.5V - enables direct regulation of core logic, DDR, and intermediate bus voltages |
| Switching Frequency | 400kHz (±10%) - balances efficiency, size, and EMI in compact board layouts |
| 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., 36V→3.3V at 400kHz) without pulse-skipping |
| Duty Cycle Max | 97% - sustains regulation during deep dropout (e.g., VIN ≈ VOUT + losses) |
| Shutdown IQ | 15µA - minimizes standby power in always-on systems |
| Package Thermal Resistance | θJA = 40°C/W (MSOP-12) - enables higher continuous output current vs DFN in same footprint |
Pinout & Package
12-lead plastic MSOP package with exposed pad (Pin 13 = SGND), optimized for thermal dissipation in space-constrained applications. Pin pitch: 0.5mm; body dimensions: 3mm × 4.9mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (1) | Error amplifier inverting input | Connects to resistor divider for precise 0.8V feedback regulation; high-impedance (±50nA bias) |
| ITH (2) | Error amplifier output / compensation node | Controls peak current limit; used for OPTI-LOOP® network to stabilize loop across COUT/ESR variation |
| RUN/SS (3) | Enable & soft-start control | Pulled low (<0.4V) for shutdown; internal 1.25µA current ramps external capacitor for controlled VOUT rise |
| BOOST (4) | Floating supply for top-gate driver | Connected via ceramic cap to SW; enables high-side N-MOSFET drive using bootstrap architecture |
| TG (5) | Top N-MOSFET gate driver output | Drives high-side switch with 2.5Ω pull-up / 2.1Ω pull-down; 25ns transitions into 3300pF load |
| SW (6) | Switch node connection | Connects to inductor and BOOST cap; voltage swings from ground to VIN during operation |
| GND (7) | Signal & 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; rail-to-rail swing (0V to 5V) with matched 25ns transitions |
| INTVCC (9) | Internal 5V LDO output | Powers gate drivers and analog circuitry; requires ≥2.2µF X5R ceramic bypass to GND |
| VIN (10) | Main input supply | Supplies INTVCC LDO and sets UVLO threshold (3.5V typ); bypass with low-ESR capacitor |
| SENSE– (11) | Current sense comparator negative input | High-Z differential input (bias <1µA); used with SENSE+ for RSENSE or DCR-based current sensing |
| SENSE+ (12) | Current sense comparator positive input | Common-mode range 0V–5.5V; enables accurate DCR sensing with external RC filter matching L/DCR |
Key Features
| Feature | Design Value |
|---|---|
| RSENSE or DCR current sensing | Supports both discrete shunt (50mV max threshold) and lossless inductor DCR sensing with programmable RC filter |
| OPTI-LOOP® compensation | Allows single-loop compensation network to maintain stability across wide ranges of output capacitance (10µF–1000µF) and ESR (1mΩ–100mΩ) |
| Output overvoltage protection | Hardware comparator triggers immediate TG off / BG on if FB exceeds 0.88V, preventing damage to downstream loads |
| Start-up into pre-biased output | Enables safe hot-swap or rail sequencing without reverse current flow into powered outputs |
| Current foldback limiting | Reduces MOSFET conduction during short-circuit by lowering ITH-set current limit; disabled during soft-start to prevent latch-up |
| 97% duty cycle operation | Maintains regulation when VIN drops near VOUT (e.g., 5.5V input → 5V output), critical for battery-backed systems |
Applications
| Telecom Intermediate Bus | Industrial 24V Distribution |
|---|---|
Use Scenario: Regulating 48V telecom rectified input down to 12V intermediate bus for downstream POL converters. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-current (15A), high-efficiency conversion with minimal thermal footprint. Use Value: 400kHz switching enables small magnetics; 97% duty cycle sustains regulation during brownout; DCR sensing eliminates shunt losses. | Use Scenario: Converting 24V factory automation rail to 5V/3.3V for PLC I/O modules and sensors. IC Role / Device Role / Timing Role: High-reliability step-down controller with ±1% reference accuracy and robust UVLO (3.5V) for noisy industrial environments. Use Value: Low shutdown IQ (15µA) extends backup battery life; MSOP thermal performance (θJA = 40°C/W) avoids derating at 70°C ambient. |
| Automotive Infotainment Power | Distributed Data Center PSU |
Use Scenario: Generating stable 1.2V/1.8V core supplies for automotive SoCs from 9–16V battery input. IC Role / Device Role / Timing Role: Wide-VIN synchronous controller supporting cold-crank (6V) and load-dump (38V) transients. Use Value: 4.5V–38V input range covers full automotive transient profile; 75ns min on-time enables 12V→1.2V conversion at 400kHz. | Use Scenario: High-density 48V-to-12V conversion in server rack power shelves with strict thermal constraints. IC Role / Device Role / Timing Role: High-efficiency controller enabling >95% efficiency at 10A with external 3mΩ MOSFETs. Use Value: Dual N-MOSFET drive with 25ns transitions minimizes switching losses; INTVCC LDO (5V/40mA) supports large gate charges without external bias. |
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 |
|---|---|---|---|
| LTC3891EMSE#PBF | Includes integrated 5V/150mA bias supply for external circuits; wider VIN (4.5V–60V); same MSOP-12 package | Preferred where auxiliary 5V rail needed for gate drivers or monitoring ICs; supports higher input transients | Select LTC3891EMSE#PBF when system-level bias supply integration reduces BOM count and improves startup reliability |
| MP2918GL-Z | 400kHz fixed frequency; 4.5V–36V input; but uses external VREF (not internal 0.8V), lacks DCR sensing, and has no OPTI-LOOP® | Suitable for cost-sensitive industrial designs where loop tuning is done per board, not per part | Choose MP2918GL-Z only when simplified compensation and absence of DCR support align with design constraints |
Compared with LTC3854IMSE#PBF, LTC3891EMSE#PBF adds system-level integration at higher VIN range, while MP2918GL-Z trades advanced features for lower unit cost-neither offers identical OPTI-LOOP® adaptability or 75ns on-time capability.
Availability
LTC3854IMSE#PBF is available at Aetrix Electronics and suitable for telecom intermediate bus, industrial 24V distribution, and automotive infotainment power systems requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.
Supply support for LTC3854IMSE#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC3854IMSE#PBF 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 LTC3854IMSE#PBF?
The LTC3854IMSE#PBF 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 sustained use, and the device incorporates undervoltage lockout (UVLO) with a typical falling threshold of 3.5V to ensure reliable startup and shutdown behavior across its 4.5V–38V operating range.
Does the LTC3854IMSE#PBF support DCR current sensing, and what external components are required?
Yes, the LTC3854IMSE#PBF fully supports DCR current sensing via SENSE+ and SENSE– pins. It requires an external RC filter network (R1, R2, C1) placed close to the pins, sized so that R1||R2 × C1 matches the inductor's L/DCR time constant. This enables accurate, lossless current measurement without a discrete shunt resistor-critical for high-efficiency, high-current designs where copper loss must be minimized.
How does the OPTI-LOOP® compensation in the LTC3854IMSE#PBF simplify design compared to traditional Type II/III networks?
The OPTI-LOOP® compensation in the LTC3854IMSE#PBF allows a single-pole, single-zero network on the ITH pin to maintain loop stability across a wide range of output capacitors (10µF–1000µF) and ESR values (1mΩ–100mΩ). Unlike conventional compensation that requires re-tuning for each COUT/ESR combination, OPTI-LOOP® eliminates iterative loop analysis-reducing design time and validation risk for multi-platform power systems.
Can the LTC3854IMSE#PBF start up into a pre-biased output, and how is this behavior enabled?
Yes, the LTC3854IMSE#PBF 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 detects rising output voltage. This protects downstream loads and avoids inrush-induced voltage collapse in hot-swap or redundant power architectures.
What is the thermal performance difference between the MSOP and DFN packages for the LTC3854IMSE#PBF?
The LTC3854IMSE#PBF in the 12-lead MSOP package (LTC3854IMSE#PBF) has θJA = 40°C/W, significantly better than the DFN variant's θJA = 76°C/W. This 47% lower junction-to-ambient thermal resistance allows higher continuous output current (e.g., 15A vs 10A at 70°C ambient) without heatsinking-making the MSOP version preferred for thermally dense telecom and industrial applications where PCB real estate permits.
LTC3854IMSE#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
LTC3854IMSE#PBF FAQ
1.How can I place an order for LTC3854IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3854IMSE#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 LTC3854IMSE#PBF reliable?
The price and inventory of LTC3854IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3854IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3854IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3854IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3854IMSE#PBF?
LTC3854IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3854IMSE#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 LTC3854IMSE#PBF?
For technical support, including LTC3854IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3854IMSE#PBF requirements.
6.How does Aetrix verify that LTC3854IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3854IMSE#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 LTC3854IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3854IMSE#PBF?
All LTC3854IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3854IMSE#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 LTC3854IMSE#PBF part is unused and in its original packaging.
Return procedure for LTC3854IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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