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Analog Devices Inc. LTC3851AMPMSE#TRPBF
- Part No.:
- LTC3851AMPMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3851AMPMSE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,257
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Product details
Overview
LTC3851AMPMSE#TRPBF from Analog Devices (formerly Linear Technology) is a high-performance synchronous step-down switching regulator controller driving dual N-channel MOSFETs in a constant-frequency current-mode architecture. It operates from 4V to 38V input, delivers 0.8V–5.5V output with ±1% accuracy, supports phase-lockable 250–750kHz switching, and features OPTI-LOOP® compensation for wide output capacitance/ESR optimization - used in automotive power systems requiring extended temperature operation.
For engineers reviewing the LTC3851AMPMSE#TRPBF datasheet, LTC3851AMPMSE#TRPBF pinout, LTC3851AMPMSE#TRPBF application, or LTC3851AMPMSE#TRPBF equivalent, key selection criteria include its –55°C to 150°C MP-grade junction temperature range, RSENSE/DCR current sensing flexibility, adjustable light-load mode (Burst/Pulse-Skip/CCM), and integrated 5V INTVCC regulator with 50mA peak output.
Technical Context
The LTC3851AMPMSE#TRPBF implements a constant-frequency current-mode control loop where peak inductor current is set by the ITH voltage, and output regulation is maintained via error amplifier comparison of VFB against a precision 0.8V reference. Its OPTI-LOOP® architecture dynamically adjusts compensation based on output capacitor ESR and capacitance, enabling stable operation across diverse ceramic/polymer/tantalum configurations.
It integrates dual gate drivers (TG/BG) with matched 25ns transition times, anti-shoot-through logic, and dropout detection that forces periodic top-FET off-time to recharge the bootstrap capacitor during low-VIN operation. The MODE/PLLIN pin enables selectable light-load behavior and external clock synchronization up to 750kHz, while FREQ/PLLFLTR sets oscillator frequency via resistor-to-ground.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide industrial and automotive battery-fed rails without pre-regulation. |
| Output Voltage Accuracy | ±1% over –55°C to 150°C - ensures precise regulation across full MP-grade temperature envelope. |
| Switching Frequency | 250kHz to 750kHz, phase-lockable - enables EMI control and optimal trade-off between efficiency and magnetics size. |
| Current Sensing | RSENSE or DCR - allows cost-optimized (DCR) or high-accuracy (shunt) current limit implementation. |
| Light-Load Modes | Burst Mode®, Pulse-Skipping, or Forced CCM - selectable via MODE/PLLIN pin for efficiency vs. noise optimization. |
| INTVCC Regulator | 5V ±2%, 50mA peak - powers internal circuitry and gate drivers; eliminates need for external bias supply. |
| Duty Cycle Max | 99% - enables very low dropout operation, critical for high-VIN to low-VOUT conversion (e.g., 36V→3.3V). |
Pinout & Package
Package: 16-Lead Plastic MSOP (MSE) with exposed thermal pad (Pin 17 = GND), rated for –55°C to 150°C operating junction temperature and θJA = 40°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| MODE/PLLIN (Pin 15) | Mode selection & external sync input | Selects Burst/Pulse-Skip/CCM modes or synchronizes oscillator to external clock up to 750kHz. |
| FREQ/PLLFLTR (Pin 16) | Oscillator frequency programming / PLL filter | Sets nominal frequency (250–750kHz) via resistor-to-GND; serves as PLL loop filter when synchronized. |
| RUN (Pin 1) | Enable/disable control | Active-high enable with 1.22V threshold; 2µA internal pull-up enables simple RC soft-start or logic control. |
| TK/SS (Pin 2) | Soft-start & tracking input | 1µA internal current charges external capacitor for controlled VOUT ramp; supports ratiometric or coincident tracking. |
| ITH (Pin 3) | Error amplifier output & current threshold | Directly sets peak inductor current; also serves as compensation node for OPTI-LOOP® network. |
| VFB (Pin 4) | Feedback input | Compares remote-sensed output voltage against 0.8V reference; supports resistive divider for any VOUT ≥ 0.8V. |
| SENSE+ / SENSE– (Pins 5–6) | Current sense differential inputs | Accepts DCR network or shunt resistor; rejects common-mode noise for accurate current limiting. |
| ILIM (Pin 7) | Current limit threshold select | Tri-level input (GND/FLOAT/INTVCC) sets max sense threshold to 30mV/50mV/75mV for flexible overcurrent protection. |
| GND (Pin 8 + Exposed Pad 17) | Signal & power ground | Kelvin connection point for all small-signal references and compensation components; exposed pad must be soldered for thermal performance. |
| BG (Pin 9) | Bottom gate driver output | Drives low-side N-MOSFET gate from GND to INTVCC; 1.1Ω pull-down ensures fast turn-off. |
| INTVCC (Pin 10) | Internal 5V regulator output | Supplies internal circuitry and gate drivers; requires ≥2.2µF low-ESR capacitor to GND for stability. |
| VIN (Pin 11) | Main input supply | Primary power source for INTVCC LDO and high-side driver bootstrap; decoupled with bulk capacitor. |
| BOOST (Pin 12) | Bootstrap supply for top gate driver | Swings from ~INTVCC–0.7V to VIN+INTVCC; connects to (+) terminal of external bootstrap capacitor. |
| TG (Pin 13) | Top gate driver output | Floating driver referenced to SW node; provides INTVCC swing superimposed on switch-node voltage. |
| SW (Pin 14) | Switch node connection | Connects to inductor and MOSFET bridge midpoint; voltage swings from ~–0.3V to VIN. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Automatically adapts loop response to actual output capacitor ESR and capacitance, eliminating manual compensation redesign across capacitor types. |
| MP-Grade Temperature Range | –55°C to 150°C operating junction temperature - qualified for harsh automotive under-hood and industrial environments. |
| Adjustable Light-Load Operation | Three distinct modes (Burst/Pulse-Skip/CCM) selectable via single pin - enables design-specific optimization of efficiency, ripple, and EMI. |
| Output Overvoltage Protection | Dedicated comparator triggers immediate top-FET shutdown and bottom-FET activation if VOUT exceeds regulated value by >7.5% - prevents downstream component damage. |
| Current Foldback Limiting | Reduces MOSFET conduction time during short-circuit conditions, limiting power dissipation and enabling safe fault recovery. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module |
|---|---|
Use Scenario: Providing clean, regulated 1.5V/3.3V/5V rails from 12V/24V vehicle battery to microcontrollers, FPGAs, and ADCs in head units and telematics modules. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-current DC-DC conversion with tight transient response and low-noise operation. Use Value: MP-grade temperature rating ensures reliability at under-dash temperatures; Burst Mode extends battery life during standby; OPTI-LOOP® maintains stability with aging electrolytic output caps. | Use Scenario: Generating isolated or non-isolated auxiliary supplies for analog sensor interfaces, digital I/O drivers, and communication ICs in programmable logic controllers. IC Role / Device Role / Timing Role: High-efficiency step-down controller delivering stable 3.3V/5V from 24V industrial bus, supporting wide input transients and load steps. Use Value: 4V–38V input range tolerates brownouts and surges; RSENSE/DCR flexibility accommodates cost-sensitive or high-accuracy designs; 99% duty cycle enables 24V→3.3V conversion without pre-regulator. |
| Telecom Base Station Bias Supply | Distributed DC Power System |
Use Scenario: Generating intermediate 5V or 12V rails from –48V telecom rectified input (via intermediate boost stage) for RF amplifiers and signal processors. IC Role / Device Role / Timing Role: Secondary buck controller in multi-stage power architecture, optimized for high efficiency at partial load and low EMI. Use Value: Phase-lockable frequency allows synchronization to system clock to avoid beat frequencies; pulse-skipping mode reduces audible noise near sensitive RF sections. | Use Scenario: Local point-of-load regulation in server backplanes or data center racks, converting 12V or 48V distribution bus to processor/core voltages. IC Role / Device Role / Timing Role: High-current synchronous buck controller supporting dynamic voltage scaling and rapid load transients for CPU/GPU power domains. Use Value: Dual N-MOSFET drive capability enables high-efficiency, high-current delivery; adjustable soft-start prevents inrush current on hot-plug boards; INTVCC regulator simplifies auxiliary rail generation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3851AIMSE#TRPBF | I-grade (–40°C to 125°C); identical electrical specs and pinout. | Standard industrial temperature range; lower cost for non-extended environments. | Select when full MP-grade temperature range is not required and cost sensitivity is higher. |
| LTC3851AEMSE#TRPBF | E-grade (0°C to 70°C, guaranteed); same package and functional interface. | Commercial temperature range only; not qualified for automotive or extended industrial use. | Choose for cost-sensitive consumer or lab equipment where ambient temperature remains controlled. |
Compared with LTC3851AIMSE#TRPBF and LTC3851AEMSE#TRPBF, the LTC3851AMPMSE#TRPBF uniquely supports –55°C startup and continuous operation to 150°C junction temperature - essential for automotive under-hood, aerospace, and high-reliability industrial deployments where thermal margin is non-negotiable.
Availability
LTC3851AMPMSE#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLCs, telecom base station bias supplies, and distributed DC power systems requiring stable component supply across extreme temperature ranges.
Supply support for LTC3851AMPMSE#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 LTC3851A product line delivers high-efficiency, high-reliability synchronous buck controllers for demanding power conversion applications - designed specifically for automotive, industrial, and telecom systems requiring wide input range, precise regulation, and robust thermal performance.
FAQ
What is the operating temperature range of the LTC3851AMPMSE#TRPBF?
The LTC3851AMPMSE#TRPBF is rated for a junction temperature range of –55°C to 150°C, making it suitable for automotive under-hood, aerospace, and high-reliability industrial applications. This MP-grade specification is confirmed in the Absolute Maximum Ratings table and Electrical Characteristics section of the official datasheet, with thermal resistance θJA = 40°C/W for the MSOP package.
How does the ILIM pin configure current limiting on the LTC3851AMPMSE#TRPBF?
The ILIM pin on the LTC3851AMPMSE#TRPBF is a tri-level input that selects the maximum current sense threshold: 30mV when tied to GND, 50mV when floated, and 75mV when connected to INTVCC. This directly scales the peak inductor current limit without external components, enabling flexible overcurrent protection tailored to MOSFET RDS(on) and layout parasitics.
Can the LTC3851AMPMSE#TRPBF synchronize to an external clock, and what is the supported frequency range?
Yes, the LTC3851AMPMSE#TRPBF can synchronize its internal oscillator to an external clock applied to the MODE/PLLIN pin, operating in forced continuous mode. The supported synchronization frequency range is 250kHz to 750kHz, matching its native oscillator range and enabling EMI reduction through frequency alignment in multi-rail systems.
What is the purpose of the TK/SS pin on the LTC3851AMPMSE#TRPBF, and how is it used for soft-start?
The TK/SS pin on the LTC3851AMPMSE#TRPBF controls output voltage ramp rate during startup. An internal 1µA current charges an external capacitor from this pin to GND, generating a linear voltage ramp. As TK/SS rises from 0V toward 0.8V, the feedback reference tracks it - causing VOUT to rise smoothly, preventing inrush current and ensuring controlled power-up sequencing.
Does the LTC3851AMPMSE#TRPBF support both RSENSE and DCR current sensing, and how is the selection made?
Yes, the LTC3851AMPMSE#TRPBF supports both RSENSE (shunt resistor) and DCR (inductor winding resistance) current sensing via the SENSE+ and SENSE– pins. No configuration pins or registers are required - the choice is implemented entirely in the external circuit: a low-value resistor between SENSE+ and SENSE– for RSENSE, or a DCR network (RC filter) connecting those pins to the inductor.
LTC3851AMPMSE#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:
- 235kHz ~ 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:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3851AMPMSE#TRPBF FAQ
1.How can I place an order for LTC3851AMPMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3851AMPMSE#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 LTC3851AMPMSE#TRPBF reliable?
The price and inventory of LTC3851AMPMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3851AMPMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3851AMPMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3851AMPMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3851AMPMSE#TRPBF?
LTC3851AMPMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3851AMPMSE#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 LTC3851AMPMSE#TRPBF?
For technical support, including LTC3851AMPMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3851AMPMSE#TRPBF requirements.
6.How does Aetrix verify that LTC3851AMPMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3851AMPMSE#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 LTC3851AMPMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3851AMPMSE#TRPBF?
All LTC3851AMPMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3851AMPMSE#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 LTC3851AMPMSE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3851AMPMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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