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Analog Devices Inc. LTC3851AHMSE-1#TRPBF
- Part No.:
- LTC3851AHMSE-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3851AHMSE-1#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,299
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Product details
Overview
LTC3851AHMSE-1#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 operation. It supports 4V–38V input, delivers 0.8V–5.5V output with ±1% accuracy, features phase-lockable 250kHz–750kHz switching, and includes PGOOD monitoring and OPTI-LOOP® compensation. It is used in automotive power supplies requiring high-temperature reliability.
For engineers reviewing the LTC3851AHMSE-1#TRPBF datasheet, LTC3851AHMSE-1#TRPBF pinout, LTC3851AHMSE-1#TRPBF application, or LTC3851AHMSE-1#TRPBF equivalent, key selection criteria include H-grade (–40°C to 150°C) thermal rating, RSENSE/DCR current sensing flexibility, 99% duty cycle capability for low-dropout operation, and selectable light-load modes (Burst/Pulse-Skip/Continuous).
Technical Context
The LTC3851AHMSE-1#TRPBF implements a constant-frequency current-mode control architecture with transconductance error amplifier (gm = 2 mmho, GBW = 3 MHz), precision 0.8V reference (±1% over –40°C to 150°C), and integrated 5V INTVCC regulator (4.8V–5.2V, 50mA peak). Its OPTI-LOOP® compensation minimizes required output capacitance across wide ESR ranges.
It features dual gate drivers (TG/BG) with matched 25ns rise/fall times, 30ns dead-time control, and robust protection including output overvoltage detection (±10% trip), current foldback limiting, and undervoltage lockout (3.25V on INTVCC with 0.4V hysteresis). The MODE/PLLIN pin enables synchronization to external clocks up to 750kHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 38V - supports 12V/24V automotive batteries and intermediate bus rails without pre-regulation. |
| VOUT Accuracy | ±1% at –40°C to 150°C - ensures stable regulation under extended temperature stress in engine bay applications. |
| Switching Frequency | 250kHz to 750kHz (phase-lockable) - balances efficiency vs. magnetics size; PLL enables noise-sensitive system clock alignment. |
| Current Sensing | RSENSE or DCR - allows trade-off between sensing accuracy (RSENSE) and conduction loss (DCR) in high-current designs. |
| Thermal Rating | H-grade (–40°C to 150°C junction) - qualified for under-hood automotive environments with no derating up to 150°C TJ. |
| PGOOD Threshold | ±10% of 0.8V reference - provides fast, reliable power-good assertion with 17µs fault masking for transient immunity. |
| Shutdown IQ | 20µA - enables ultra-low-power system standby without external enable circuitry. |
Pinout & Package
Package: 16-lead plastic MSOP with exposed thermal pad (Pin 17 = GND), rated for θJA = 40°C/W and TJMAX = 125°C (derated per Note 3); H-grade variant validated to 150°C junction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| MODE/PLLIN (Pin 1) | Mode selection & external clock input | Selects Burst/Pulse-Skip/Continuous mode or synchronizes oscillator to external clock up to 750kHz; internal 100kΩ pull-up. |
| FREQ/PLLFLTR (Pin 2) | Oscillator frequency programming / PLL filter | Resistor-to-GND sets nominal frequency (250–750kHz); RC network serves as PLL loop filter when synchronized. |
| RUN (Pin 3) | Enable/disable control | 1.22V threshold with 120mV hysteresis; 2µA internal pull-up enables simple RC soft-start or logic-level control. |
| TK/SS (Pin 4) | Soft-start and tracking input | 1µA internal charge current ramps output voltage linearly; supports coincident or ratiometric tracking of master supply. |
| ITH (Pin 5) | Error amplifier output & current limit threshold | Controls peak inductor current; voltage directly scales current sense threshold (e.g., 1.2V → 53mV max VSENSE in H-grade). |
| VFB (Pin 6) | Feedback input | Compares resistive divider output to 0.8V reference; ±10nA input bias enables high-impedance dividers. |
| SENSE– (Pin 7) | Current sense comparator inverting input | Connected to low-side of sense resistor or DCR network; referenced to SW node for accurate differential sensing. |
| SENSE+ (Pin 8) | Current sense comparator non-inverting input | Connected to high-side of sense resistor or DCR network; supports Kelvin sensing for precision current measurement. |
| PGOOD (Pin 9) | Open-drain power-good indicator | Pulled low during startup, shutdown, or if VFB deviates >±10%; requires external pull-up to ≤6V. |
| GND (Pin 10 + Exposed Pad 17) | Signal & thermal ground reference | All small-signal grounds and capacitor negatives must Kelvin-connect here; exposed pad must be soldered for thermal performance. |
| BG (Pin 11) | Bottom gate driver output | Drives source of low-side N-MOSFET; 1.1Ω pull-down / 2.1Ω pull-up ensures fast turn-on/turn-off with minimal shoot-through risk. |
| INTVCC (Pin 12) | Internal 5V regulator output | Supplies gate drivers and analog circuitry; requires ≥2.2µF low-ESR ceramic/tantalum decoupling to GND. |
| VIN (Pin 13) | Main input supply | Accepts 4V–38V; powers INTVCC regulator and high-side driver bootstrap circuit; requires local bulk decoupling. |
| BOOST (Pin 14) | Bootstrap supply for top gate driver | Swings from ~VIN to VIN+INTVCC; connects to (+) terminal of bootstrap capacitor; diode-fed from INTVCC. |
| TG (Pin 15) | Top gate driver output | Floating driver output referenced to SW node; 1.2Ω pull-down / 2.2Ω pull-up enables efficient high-side N-MOSFET drive. |
| SW (Pin 16) | Switch node connection | Connects to inductor and MOSFET sources; swings from ~–0.3V (Schottky drop) to VIN; critical for layout EMI control. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance and simplifies stability design across wide COUT/ESR variations without external compensation tuning. |
| 99% Maximum Duty Cycle | Enables ultra-low dropout operation (e.g., 5VOUT from 5.1VIN) - critical for post-regulator applications in battery-powered systems. |
| Output Overvoltage Protection | Active clamp via bottom MOSFET turn-on when VFB exceeds +10%, preventing damage to downstream 3.3V/1.8V loads during transients. |
| Programmable Light-Load Modes | Three selectable modes: Burst Mode (highest efficiency), Pulse-Skipping (low ripple/audio noise), or Forced Continuous (lowest ripple, fixed frequency). |
| DCR or RSENSE Sensing | Flexible current sensing eliminates need for power-wasting shunt resistors in high-current designs while retaining accuracy option via RSENSE. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial 24V DC-DC Distribution |
|---|---|
Use Scenario: Regulating 12V battery input to stable 3.3V/5V for microcontroller, CAN transceiver, and sensor interfaces in under-hood ECU modules. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-efficiency, high-reliability power conversion with thermal resilience up to 150°C junction. Use Value: H-grade qualification eliminates thermal derating, while PGOOD and OVP ensure functional safety compliance for ASIL-B subsystems. |
Use Scenario: Converting 24V industrial bus to isolated 5V/3.3V rails for PLC I/O modules operating in factory-floor enclosures with ambient temperatures up to 85°C. IC Role / Device Role / Timing Role: High-input-voltage step-down controller enabling compact, high-efficiency point-of-load regulation without pre-regulators. Use Value: 4V–38V input range accommodates brownout and surge conditions; adjustable soft-start prevents inrush current tripping upstream breakers. |
| Telecom Base Station Power | Distributed DC Power Systems |
Use Scenario: Generating 1.8V/2.5V core voltages for FPGAs and DSPs in remote radio units (RRUs) where airflow is limited and thermal management is constrained. IC Role / Device Role / Timing Role: Precision-controlled current-mode buck controller delivering tight output regulation with low noise and fast transient response. Use Value: ±1% output accuracy and 3MHz error amp bandwidth support dynamic load steps typical in digital signal processing workloads. |
Use Scenario: Building scalable, modular DC-DC converters for data center rack power distribution, supporting hot-swap and redundancy requirements. IC Role / Device Role / Timing Role: Synchronous controller enabling high-density, high-efficiency conversion with programmable tracking for multi-rail sequencing. Use Value: TK/SS pin supports ratiometric or coincident tracking of multiple outputs, ensuring safe power-up/down sequencing across distributed loads. |
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 |
|---|---|---|---|
| LTC3851AIMSE-1#TRPBF | I-grade (–40°C to 125°C), otherwise identical electrical specs and pinout. | Suitable for cabin electronics or industrial controls where ambient temperature stays below 85°C. | Select when full H-grade thermal margin is unnecessary; lower cost with same functionality in less demanding thermal environments. |
| LTC3851AEUD-1#TRPBF | QFN package (3mm × 3mm), E-grade (–40°C to 125°C), same electrical performance. | Better thermal resistance (θJC = 4.2°C/W) but lower max junction temp than H-grade MSOP. | Choose for space-constrained PCBs needing improved thermal transfer to heatsink, provided ambient and power dissipation allow 125°C TJ limit. |
Compared with LTC3851AIMSE-1#TRPBF, the LTC3851AHMSE-1#TRPBF adds 25°C higher junction temperature capability without sacrificing accuracy or feature set - essential for under-hood automotive use. Compared with LTC3851AEUD-1#TRPBF, it trades smaller footprint for superior high-temperature reliability in thermally harsh locations.
Availability
LTC3851AHMSE-1#TRPBF is available at Aetrix Electronics and suitable for automotive power systems, industrial 24V distribution, telecom base station supplies, and distributed DC power architectures requiring stable component supply across extended temperature ranges.
Supply support for LTC3851AHMSE-1#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-1 product line delivers high-efficiency, high-reliability synchronous buck controllers optimized for automotive, industrial, and telecom applications demanding wide input range, precise regulation, and robust thermal performance.
FAQ
What is the maximum junction temperature rating for LTC3851AHMSE-1#TRPBF?
The LTC3851AHMSE-1#TRPBF is an H-grade device with a guaranteed operating junction temperature range of –40°C to 150°C. This rating is validated per manufacturer specifications and enables deployment in under-hood automotive environments without thermal derating up to 150°C TJ. The MSOP package's exposed pad must be soldered to PCB ground for effective heat dissipation.
How does the PGOOD function behave during startup and fault conditions in LTC3851AHMSE-1#TRPBF?
In the LTC3851AHMSE-1#TRPBF, the PGOOD pin remains low during soft-start, shutdown, or whenever VFB deviates more than ±10% from the 0.8V reference. It asserts high only after VFB stabilizes within that window and remains high until a fault occurs. An internal 17µs power-bad mask prevents false triggering during brief transients, ensuring reliable system power sequencing.
Can LTC3851AHMSE-1#TRPBF synchronize to an external clock, and what are the frequency limits?
Yes, the LTC3851AHMSE-1#TRPBF supports external synchronization via its MODE/PLLIN pin. When driven by an external clock, it locks the internal oscillator and operates in forced continuous conduction mode. The supported synchronization frequency range is 250kHz to 750kHz - matching its native switching range - and requires an RC loop filter on the FREQ/PLLFLTR pin for stable PLL operation.
What current sensing methods does LTC3851AHMSE-1#TRPBF support, and how do they differ in implementation?
The LTC3851AHMSE-1#TRPBF supports both RSENSE (shunt resistor) and DCR (inductor winding resistance) current sensing. RSENSE offers higher accuracy and simpler calibration but adds conduction loss and cost. DCR sensing eliminates the shunt resistor, reducing board area and power loss, but requires careful layout and compensation for temperature drift and parasitic effects in the inductor network.
Does LTC3851AHMSE-1#TRPBF provide output overvoltage protection, and how is it implemented?
Yes, the LTC3851AHMSE-1#TRPBF includes dedicated output overvoltage protection. An internal comparator monitors VFB and triggers immediate action if it exceeds +10% of the 0.8V reference. Upon detection, the top MOSFET is turned off and the bottom MOSFET is turned on to clamp the output, protecting downstream 3.3V/1.8V ICs from destructive overvoltage events caused by feedback loop failure or load disconnection.
LTC3851AHMSE-1#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:
- Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3851AHMSE-1#TRPBF FAQ
1.How can I place an order for LTC3851AHMSE-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3851AHMSE-1#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 LTC3851AHMSE-1#TRPBF reliable?
The price and inventory of LTC3851AHMSE-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3851AHMSE-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3851AHMSE-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3851AHMSE-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3851AHMSE-1#TRPBF?
LTC3851AHMSE-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3851AHMSE-1#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 LTC3851AHMSE-1#TRPBF?
For technical support, including LTC3851AHMSE-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3851AHMSE-1#TRPBF requirements.
6.How does Aetrix verify that LTC3851AHMSE-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3851AHMSE-1#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 LTC3851AHMSE-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3851AHMSE-1#TRPBF?
All LTC3851AHMSE-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3851AHMSE-1#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 LTC3851AHMSE-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC3851AHMSE-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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