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Analog Devices Inc. LTC3851EMSE#TRPBF
- Part No.:
- LTC3851EMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3851EMSE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,356
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Product details
Overview
LTC3851EMSE#TRPBF from Analog Devices (formerly Linear Technology) is a high-performance synchronous step-down switching regulator controller driving dual N-channel MOSFETs in constant-frequency current-mode topology. It operates from 4V to 38V input, delivers 0.8V–5.5V output with ±1% accuracy, supports phase-lockable 250kHz–750kHz switching, and enables Burst Mode™, pulse-skipping, or forced continuous conduction for optimized light-load efficiency in telecom power supplies.
For engineers reviewing the LTC3851EMSE#TRPBF datasheet, LTC3851EMSE#TRPBF pinout, LTC3851EMSE#TRPBF application, or LTC3851EMSE#TRPBF equivalent, this page provides verified package mapping (16-lead MSOP), validated pin functions, confirmed current-sense threshold options (30/50/75 mV), OPTI-LOOP® compensation behavior, and real-world soft-start/tracking implementation details - all critical for stable high-current DC/DC design.
Technical Context
The LTC3851EMSE#TRPBF implements a voltage-mode-compensated current-loop architecture with transconductance error amplifier (gm = 2 mmho, GBW = 3 MHz) and precision 0.8V reference (±1% over temperature). Its ITH pin directly controls peak inductor current via an external voltage, while FB pin regulates output by servoing VFB to match the reference or TK/SS ramp.
It integrates dual gate drivers (TG/BG) with matched 25ns rise/fall times, anti-shoot-through logic, dropout detection with forced off-time for bootstrap capacitor recharge, and output overvoltage protection triggered at 0.86–0.90V on VFB. The MODE/PLLIN pin selects operating mode and accepts external synchronization up to 750kHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide industrial and telecom input rails without pre-regulation. |
| Output Voltage Accuracy | ±1% over temperature - ensures tight regulation for sensitive digital loads like FPGAs and ASICs. |
| Switching Frequency | 250kHz to 750kHz, phase-lockable - balances efficiency vs. size; enables EMI reduction via synchronization. |
| Current Sense Threshold | Selectable 30/50/75 mV via ILIM pin - allows precise current limiting with RSENSE or DCR sensing networks. |
| Soft-Start Control | 1μA internal TK/SS charge current - enables linear output ramp and ratiometric tracking with master supplies. |
| Shutdown Quiescent Current | 20μA - minimizes system standby power in battery-backed or always-on applications. |
| Internal Regulator | 5V ±2% INTVCC with 50mA drive - powers gate drivers and analog circuitry independently of VIN. |
Pinout & Package
Package: 16-lead plastic MSOP (MSE), thermally enhanced with exposed pad (Pin 17 = GND), θJA = 40°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| MODE/PLLIN (Pin 15) | Mode selection & sync input | Configures Burst Mode™, pulse-skip, or forced CCM; accepts external clock up to 750kHz for EMI control. |
| FREQ/PLLFLTR (Pin 16) | Oscillator frequency set / PLL filter | Resistor-to-GND sets nominal frequency; RC network enables PLL lock when synchronized. |
| RUN (Pin 1) | Enable/disable control | 1.10–1.35V threshold with 130mV hysteresis; 2μA internal pull-up enables simple logic-level control. |
| TK/SS (Pin 2) | Soft-start & tracking input | 1μA internal current charges external capacitor for controlled VOUT ramp or master-supply tracking. |
| ITH (Pin 3) | Error amplifier output & current threshold | Directly sets peak inductor current; voltage range determines load transient response and loop stability. |
| FB (Pin 4) | Feedback input | Compares output divider voltage to 0.8V reference; supports remote sensing for improved regulation accuracy. |
| SENSE+ / SENSE− (Pins 5–6) | Current sense differential inputs | High-impedance inputs (±1μA bias) enable accurate DCR or low-R sensing with minimal power loss. |
| ILIM (Pin 7) | Current limit select | Tri-level logic (GND/FLOAT/INTVCC) sets max sense threshold to 30/50/75 mV for flexible overcurrent protection. |
| GND (Pin 8) | Analog ground reference | Kelvin connection point for compensation, CVCC, and CIN - critical for noise immunity and stability. |
| BG (Pin 9) | Bottom gate driver output | Drives low-side N-MOSFET gate between GND and INTVCC; 1.1Ω pull-down ensures fast turn-off. |
| INTVCC (Pin 10) | Internal 5V regulator output | Powers internal circuitry; requires ≥2.2μF low-ESR ceramic/tantalum decoupling to GND. |
| VIN (Pin 11) | Main input supply | Accepts 4–38V; powers INTVCC LDO and provides bootstrap path via BOOST; needs local bulk capacitance. |
| BOOST (Pin 12) | Floating bootstrap supply | Connects to (+) terminal of bootstrap capacitor; swings from ~INTVCC–0.4V to VIN+INTVCC for high-side drive. |
| TG (Pin 13) | Top gate driver output | Floating driver with INTVCC swing referenced to SW node; 2.6Ω pull-up / 1.5Ω pull-down ensures fast switching. |
| SW (Pin 14) | Switch node | Connects to inductor and MOSFET sources; voltage swings from ~–0.4V (Schottky drop) to VIN. |
| Exposed Pad (Pin 17) | Thermal & electrical ground | Must be soldered to PCB copper pour - essential for thermal performance (θJA = 40°C/W) and noise reduction. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by enabling stable loop response across wide COUT/ESR ranges - reduces BOM cost and board area. |
| Dual N-Channel MOSFET Drive | Integrated high- and low-side drivers eliminate need for external level-shifters or gate-driver ICs - simplifies layout and improves timing control. |
| Adjustable Light-Load Operation | Three selectable modes (Burst, Pulse-Skip, Forced CCM) let designers optimize efficiency vs. ripple/noise trade-offs per application requirement. |
| Output Overvoltage Protection | Hardware comparator triggers immediate top-FET turn-off and bottom-FET turn-on if VFB exceeds 0.86–0.90V - protects downstream loads without software delay. |
| Very Low Dropout Operation | 99% duty cycle capability enables ultra-low ΔVIN operation (e.g., 3.3V out from 3.4V input) - extends usable input range in battery-powered systems. |
Applications
| Telecom Power Supply | Industrial PLC Power |
|---|---|
|
Use Scenario: 48V intermediate bus conversion to 3.3V/5V for baseband processors and FPGA I/O banks in 5G remote radio units. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing up to 15A load with tight transient response and EMI-controlled switching. Use Value: Phase-lockable 750kHz operation enables synchronization with system clock to suppress beat frequencies; ±1% VOUT accuracy ensures reliable logic-level compliance. |
Use Scenario: DIN-rail mounted programmable logic controller requiring robust 24V-to-5V/3.3V conversion tolerant of 40V surges and wide ambient temperatures. IC Role / Device Role / Timing Role: High-reliability step-down controller with undervoltage lockout (3.25V INTVCC), thermal shutdown, and output OVP for field-deployed equipment. Use Value: 4V–38V input range accommodates brownouts and transients; exposed-pad MSOP package ensures thermal stability at –40°C to +85°C. |
| Automotive Infotainment | Distributed DC Power System |
|
Use Scenario: Powering audio DSPs and display controllers from 12V battery rail in head-unit designs where low-noise and compact size are critical. IC Role / Device Role / Timing Role: Efficient buck controller operating in Burst Mode™ at light loads to minimize standby current while maintaining fast wake-up response. Use Value: 20μA shutdown IQ extends battery life; adjustable soft-start prevents inrush current during ignition-on sequencing. |
Use Scenario: Point-of-load regulation in server backplanes or data center racks converting 12V/48V intermediate bus to sub-1V core voltages for CPUs/GPUs. IC Role / Device Role / Timing Role: High-efficiency synchronous controller supporting DCR current sensing to eliminate power loss from discrete shunts. Use Value: Tri-level ILIM pin enables precise current limiting across multiple PoL rails; OPTI-LOOP® simplifies compensation for diverse output capacitors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8640S | Integrated 4A power stage (vs. external MOSFETs); 2.8V–42V input; 3.3V/5V fixed or adjustable output; Silent Switcher® architecture. | Better EMI performance and smaller solution size; lower max output current; no DCR sensing support. | Choose LT8640S for space-constrained, low-EMI designs needing ≤4A; retain LTC3851EMSE#TRPBF for >10A, DCR sensing, or custom MOSFET optimization. |
| TPS53689 | TI's 60A multiphase controller with PMBus interface; 4.5V–18V input; supports VR13/IMVP8 protocols; integrated MOSFET drivers only. | Designed for CPU/GPU VRMs with telemetry and dynamic voltage scaling; requires external power stages and complex loop tuning. | Choose TPS53689 for high-current, digitally managed VRMs; LTC3851EMSE#TRPBF remains optimal for analog-controlled, medium-power industrial/telecom converters. |
Compared with LT8640S and TPS53689, the LTC3851EMSE#TRPBF offers unmatched flexibility in external MOSFET selection, DCR sensing capability, and analog light-load mode control - making it ideal for cost-sensitive, thermally demanding, or high-reliability applications where integration is secondary to design sovereignty.
Availability
LTC3851EMSE#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial PLCs, and automotive infotainment systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3851EMSE#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 LTC3851EMSE#TRPBF belongs to Linear's high-efficiency synchronous controller product line, designed specifically for industrial, telecom, and automotive DC/DC conversion where reliability, wide input range, and flexible current sensing are critical.
FAQ
What is the maximum supported switching frequency for the LTC3851EMSE#TRPBF?
The LTC3851EMSE#TRPBF supports a phase-lockable switching frequency range of 250kHz to 750kHz. At RFREQ = 36kΩ, the typical frequency is 750kHz. This upper limit is confirmed in the Electrical Characteristics table and applies across the full –40°C to +85°C operating temperature range for the E-grade part.
Does the LTC3851EMSE#TRPBF support DCR current sensing?
Yes, the LTC3851EMSE#TRPBF explicitly supports DCR current sensing via its high-impedance SENSE+ and SENSE– pins, with common-mode range of 0V to 5.5V and input bias currents under ±1μA. The Applications Information section provides detailed guidance on RC filter design to match the L/DCR time constant for accurate sensing.
How does the ILIM pin configure current limit thresholds on the LTC3851EMSE#TRPBF?
The ILIM pin on the LTC3851EMSE#TRPBF is a tri-level logic input: tying it to GND sets the current sense threshold to 30mV, floating sets it to 50mV, and connecting it to INTVCC sets it to 75mV. These values are specified in the Electrical Characteristics table under "VSENSE(MAX)" and directly determine peak inductor current limiting.
What package type and thermal characteristics apply to the LTC3851EMSE#TRPBF?
The LTC3851EMSE#TRPBF uses a 16-lead plastic MSOP (MSE) package with exposed thermal pad (Pin 17 = GND). Its thermal resistance is θJA = 40°C/W, significantly lower than the SSOP version (110°C/W), due to the soldered exposed pad - a key advantage for high-power density designs.
Can the LTC3851EMSE#TRPBF operate with a pre-biased output during startup?
Yes, the LTC3851EMSE#TRPBF supports start-up into a pre-biased output. As shown in Figure G09 of the datasheet, the IC disables the bottom MOSFET until the feedback voltage rises above the internal reference, preventing reverse current flow and ensuring controlled ramp-up even when VOUT is initially non-zero.
LTC3851EMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (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):
- 4V ~ 38V
- Frequency - Switching:
- 250kHz ~ 750kHz
- Duty Cycle (Max):
- 99%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3851EMSE#TRPBF FAQ
1.How can I place an order for LTC3851EMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3851EMSE#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 LTC3851EMSE#TRPBF reliable?
The price and inventory of LTC3851EMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3851EMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3851EMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3851EMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3851EMSE#TRPBF?
LTC3851EMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3851EMSE#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 LTC3851EMSE#TRPBF?
For technical support, including LTC3851EMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3851EMSE#TRPBF requirements.
6.How does Aetrix verify that LTC3851EMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3851EMSE#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 LTC3851EMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3851EMSE#TRPBF?
All LTC3851EMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3851EMSE#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 LTC3851EMSE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3851EMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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