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Analog Devices Inc. LTC3851IMSE-1#TRPBF
- Part No.:
- LTC3851IMSE-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3851IMSE-1#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,862
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Product details
Overview
LTC3851IMSE-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 topology. It operates from 4V to 38V input, delivers 0.8V–5.5V output with ±1% accuracy, supports phase-lockable 250kHz–750kHz switching, and features PGOOD monitoring and adjustable soft-start/tracking - used in telecom intermediate bus converters requiring tight regulation and thermal robustness.
For engineers reviewing the LTC3851IMSE-1#TRPBF datasheet, LTC3851IMSE-1#TRPBF pinout, LTC3851IMSE-1#TRPBF application, or LTC3851IMSE-1#TRPBF equivalent, key selection criteria include its 16-lead MSOP package with exposed GND pad, –40°C to 125°C industrial temperature grade, current-foldback short-circuit protection, OPTI-LOOP® compensation for wide-output-capacitance stability, and selectable light-load modes (Burst/Pulse-Skip/CCM).
Technical Context
The LTC3851IMSE-1#TRPBF implements a constant-frequency current-mode control architecture with dual gate drivers (TG/BG), precision 0.8V reference, and integrated 5V INTVCC LDO. Its ITH pin serves as both error amplifier output and current threshold control point, enabling dynamic peak-current adjustment across load transients.
It supports three light-load operating modes via MODE/PLLIN pin configuration: forced continuous conduction (CCM), pulse-skipping PWM, or high-efficiency Burst Mode® operation - each with distinct ripple, EMI, and efficiency trade-offs. Output overvoltage protection (±10% window) and power-good flag with 17μs mask timer provide system-level fault response.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports 5V, 12V, 24V, 36V battery and intermediate bus systems without external regulators. |
| Output Voltage Accuracy | ±1% at VFB - ensures stable 0.8V–5.5V regulation under line/load/temp variation for precision loads. |
| Switching Frequency | 250kHz to 750kHz - programmable via FREQ/PLLFLTR resistor; enables optimization of inductor size vs. MOSFET switching loss. |
| Light-Load Efficiency Mode | Selectable Burst Mode®, Pulse-Skip, or CCM - reduces quiescent current to 20μA in shutdown and maintains >85% efficiency at 10mA load in Burst Mode. |
| Current Sensing | RSENSE or DCR - supports low-loss inductor-based sensing or high-accuracy shunt resistor sensing with 40–65mV max threshold. |
| Thermal Rating | –40°C to 125°C junction - qualified for automotive under-hood and industrial control environments with θJA = 35–40°C/W (MSOP). |
| PGOOD Threshold | ±10% of 0.8V (0.72V–0.88V) - provides reliable power sequencing feedback with 17μs fault masking. |
Pinout & Package
Package: 16-lead plastic MSOP with exposed thermal pad (Pin 17 = GND), rated for –40°C to 125°C operation. Exposed pad must be soldered to PCB for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGOOD (Pin 9) | Open-drain power-good indicator | Pulls low when VFB is outside ±10% of 0.8V, during soft-start, or RUN=low - enables safe system enable sequencing. |
| RUN (Pin 3) | Enable/disable control input | Turns on IC when >1.25V; shuts down with <1.1V; internal 2μA pull-up allows simple RC delay startup. |
| TK/SS (Pin 4) | Soft-start and tracking control | Internal 1μA current charges external capacitor to ramp VOUT linearly; supports ratiometric or coincident tracking of master supply. |
| ITH (Pin 5) | Error amplifier output / current threshold | Directly sets peak inductor current; voltage range 0–2.2V determines current limit and loop dynamics. |
| VFB (Pin 6) | Feedback input | Compares resistive divider output against 0.8V reference; high-impedance input minimizes loading error. |
| SENSE+ / SENSE– (Pins 8/7) | Differential current sense inputs | Accept DCR or RSENSE signals; common-mode range 0–5.5V; ±1μA bias current enables accurate low-side sensing. |
| TG / BG (Pins 15/11) | Top/bottom N-MOSFET gate drivers | Drive external FETs with 2.6Ω/1.5Ω pull-up and 1.5Ω/1.1Ω pull-down; 25ns transition times support high-frequency operation. |
| SW (Pin 16) | Switch node connection | Connects to inductor; swings from ~–0.3V to VIN - requires careful layout to minimize ringing and EMI. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by adapting loop gain to actual COUT and ESR - eliminates need for iterative stability tuning across capacitor families. |
| Phase-Lockable Oscillator | Syncs internal 250–750kHz clock to external source via MODE/PLLIN - enables noise-sensitive systems to avoid beat frequencies and meet EMI compliance. |
| 99% Duty Cycle Operation | Supports ultra-low dropout (VIN–VOUT < 100mV) - critical for post-regulation in high-current 12V→1.2V or 5V→3.3V applications. |
| Current Foldback Limiting | Reduces MOSFET power dissipation during short-circuit by lowering peak current as VFB drops - prevents thermal runaway without external circuitry. |
| DCR or RSENSE Sensing | Eliminates power loss and cost of current-sense resistors while maintaining ±5% current limit accuracy - ideal for high-efficiency 10A+ designs. |
Applications
| Telecom Intermediate Bus Converter | Industrial PLC Power Supply |
|---|---|
Use Scenario: Converts 48V backplane to 12V/5V intermediate rails in carrier-grade routers with strict thermal and reliability requirements. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing up to 30A output with phase synchronization to system clock. Use Value: 750kHz operation enables compact 1.5μH inductors; PGOOD enables hot-swap controller interlock; –40°C to 125°C rating ensures uptime in uncooled chassis. |
Use Scenario: Powers FPGA, microcontroller, and I/O modules in factory automation controllers exposed to vibration and wide ambient temperature swings. IC Role / Device Role / Timing Role: Regulates 24V DC input to stable 3.3V/1.2V rails with precise sequencing and fault reporting. Use Value: Adjustable soft-start prevents inrush current tripping upstream breakers; current foldback protects against field-wiring shorts; exposed pad improves thermal margin in sealed enclosures. |
| Automotive ADAS Camera Module | Server VR13-Compatible POL |
Use Scenario: Supplies image sensor and ISP in rear-view camera with minimal EMI in proximity to RF receivers. IC Role / Device Role / Timing Role: Low-noise synchronous buck controller operating in Burst Mode® at standby to reduce idle power. Use Value: Pulse-skipping mode eliminates audible coil whine; 250kHz minimum frequency avoids AM band interference; ±1% accuracy maintains sensor ADC reference stability. |
Use Scenario: Provides tightly regulated 0.8V core voltage to Xeon-class CPUs with dynamic load steps exceeding 100A/μs. IC Role / Device Role / Timing Role: High-bandwidth current-mode controller supporting VR13-compatible transient response and telemetry via VFB/ITH interface. Use Value: OPTI-LOOP® compensates for polymer capacitor aging; 99% duty cycle sustains regulation during CPU turbo boost; DCR sensing eliminates shunt resistor losses at 100A+. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3851EMSE-1#TRPBF | Same silicon, but rated for –40°C to 85°C ambient - lower thermal derating and no high-temp qualification testing. | Suitable for commercial indoor equipment only; not validated for extended temperature cycling or under-hood use. | Select when cost sensitivity outweighs industrial temperature requirement and board-level thermal management is sufficient. |
| MP2918GL-Z | Monolithic 30V buck controller with integrated 5V LDO; lacks PLL sync, OPTI-LOOP®, and DCR sensing - fixed 500kHz, no frequency programming. | Targeted at cost-sensitive consumer power supplies; no PGOOD flag or tracking capability. | Choose for simplified BOM and layout where phase sync, precision soft-start, and wide temp range are unnecessary. |
Compared with LTC3851EMSE-1#TRPBF, the LTC3851IMSE-1#TRPBF offers guaranteed operation up to 125°C junction and full characterization across that range - essential for thermally constrained industrial designs. Versus MP2918GL-Z, it provides superior design flexibility via programmable frequency, multiple light-load modes, and advanced compensation, at the cost of external FETs and higher component count.
Availability
LTC3851IMSE-1#TRPBF is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and automotive ADAS systems requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for LTC3851IMSE-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 acquired Linear Technology in 2017 and maintains its high-reliability analog power portfolio. Linear's legacy emphasizes precision, ruggedness, and application-specific innovation in power management ICs.
The LTC3851-1 product line delivers high-performance synchronous buck controllers optimized for demanding intermediate bus conversion, with emphasis on thermal resilience, light-load efficiency, and system-level integration features like tracking and PGOOD.
FAQ
What is the maximum supported switching frequency for the LTC3851IMSE-1#TRPBF?
The LTC3851IMSE-1#TRPBF supports a phase-lockable switching frequency up to 750kHz, set by the resistor on the FREQ/PLLFLTR pin. At RFREQ = 36kΩ, typical operation reaches 750kHz with ±40kHz tolerance over temperature and supply. This enables compact magnetics while maintaining >90% efficiency at 12V→3.3V/15A.
How does the LTC3851IMSE-1#TRPBF implement output voltage tracking during startup?
The LTC3851IMSE-1#TRPBF uses the TK/SS pin to enable ratiometric or coincident tracking: an external resistor divider from a master supply to GND connects to TK/SS, causing VOUT to ramp proportionally. During startup, the internal 1μA current charges the TK/SS capacitor, forcing VFB to follow TK/SS voltage until it reaches 0.8V - ensuring controlled, sequenced rail activation in multi-voltage systems.
Does the LTC3851IMSE-1#TRPBF support DCR current sensing, and what external components are required?
Yes, the LTC3851IMSE-1#TRPBF supports DCR sensing via SENSE+ and SENSE– pins. A parallel RC network (R1||R2, C1) must match the L/DCR time constant; R2 scales the sensed voltage to target 40–65mV full-scale. Typical values: R1 = 10kΩ, R2 = 100kΩ, C1 = 10nF for 1μH/1mΩ inductor - enabling lossless, high-accuracy current limiting without shunt resistors.
What protection features are integrated into the LTC3851IMSE-1#TRPBF?
The LTC3851IMSE-1#TRPBF integrates output overvoltage protection (±10% trip), current foldback limiting during short circuits, undervoltage lockout on INTVCC (3.25V threshold), and reverse-current prevention via IREV comparator. Its PGOOD pin flags faults with 17μs masking, and thermal shutdown activates above 125°C junction - providing comprehensive fault coverage without external supervision circuitry.
Can the LTC3851IMSE-1#TRPBF be synchronized to an external clock, and how is this configured?
Yes, the LTC3851IMSE-1#TRPBF can be synchronized to an external clock applied to the MODE/PLLIN pin (Pin 1). When driven by a 250–750kHz square wave, the internal PLL locks and forces continuous conduction mode. An RC filter (e.g., 10kΩ + 1nF) must connect FREQ/PLLFLTR to GND to stabilize the PLL loop - enabling noise-sensitive systems to eliminate beat frequencies and meet CISPR-32 Class B EMI limits.
LTC3851IMSE-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:
- 250kHz ~ 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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3851IMSE-1#TRPBF FAQ
1.How can I place an order for LTC3851IMSE-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3851IMSE-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 LTC3851IMSE-1#TRPBF reliable?
The price and inventory of LTC3851IMSE-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 LTC3851IMSE-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3851IMSE-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3851IMSE-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3851IMSE-1#TRPBF?
LTC3851IMSE-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3851IMSE-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 LTC3851IMSE-1#TRPBF?
For technical support, including LTC3851IMSE-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3851IMSE-1#TRPBF requirements.
6.How does Aetrix verify that LTC3851IMSE-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3851IMSE-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 LTC3851IMSE-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3851IMSE-1#TRPBF?
All LTC3851IMSE-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3851IMSE-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 LTC3851IMSE-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC3851IMSE-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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