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Analog Devices Inc. LTC3851AEGN#TRPBF
- Part No.:
- LTC3851AEGN#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3851AEGN#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,961
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Product details
Overview
LTC3851AEGN#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 250kHz–750kHz switching, and enables Burst Mode™ for ultra-low-light-load efficiency. It is used in telecom power supplies requiring tight regulation and fast transient response under wide input and load variations.
For engineers reviewing the LTC3851AEGN#TRPBF datasheet, LTC3851AEGN#TRPBF pinout, LTC3851AEGN#TRPBF application, or LTC3851AEGN#TRPBF equivalent, key selection criteria include its RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation for broad capacitor/ESR compatibility, selectable light-load operating modes (Burst/Pulse-Skipping/Continuous), 99% duty cycle capability, and integrated 5V INTVCC regulator with 50mA peak drive.
Technical Context
The LTC3851AEGN#TRPBF implements a constant-frequency current-mode control loop with transconductance error amplifier (gm = 2 mmho, GBW = 3 MHz) and precision 0.8V reference (±1% over –40°C to 125°C). Its ITH pin serves as both error amplifier output and current threshold control, enabling dynamic current limit adjustment via ILIM pin tri-level programming (30/50/75 mV).
It integrates dual gate drivers (TG/BG) with matched 25ns rise/fall times, 30ns dead-time control, and robust protection features including output overvoltage lockout (>7.5% VFB), current foldback, and dropout detection with forced off-time for bootstrap capacitor recharge. The MODE/PLLIN pin supports external clock synchronization while selecting among three light-load modes without changing PCB layout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide industrial and telecom input rails, including 12V, 24V, and 36V systems. |
| Output Voltage Accuracy | ±1% at 0°C to 85°C - ensures stable regulation across temperature for precision analog and digital loads. |
| Switching Frequency | 250kHz to 750kHz (phase-lockable) - balances efficiency vs. size; higher frequencies allow smaller magnetics and capacitors. |
| Current Sense Threshold | 30mV / 50mV / 75mV (ILIM-selectable) - enables precise, scalable current limiting for diverse power stages. |
| INTVCC Regulator | 5.0V ±4%, 50mA peak - powers internal circuitry and gate drivers; eliminates need for external bias supply. |
| Shutdown Quiescent Current | 20µA - minimizes system standby power loss in battery-backed or always-on applications. |
| Duty Cycle Capability | Up to 99% - supports very low dropout operation, critical for high-VIN/low-VOUT conversion (e.g., 36V→3.3V). |
Pinout & Package
Package: 16-Lead Plastic SSOP (Narrow), exposed pad not present (GN package); thermal resistance θJA = 110°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| MODE/PLLIN (Pin 1) | Mode selection & external sync input | Selects Burst/Pulse-Skipping/Continuous mode or accepts external clock up to 750kHz for EMI control. |
| FREQ/PLLFLTR (Pin 2) | PLL filter / frequency set node | Connects RC network to program oscillator frequency or serve as PLL loop filter when synchronized. |
| RUN (Pin 3) | Enable/disable control | 1.22V threshold with 120mV hysteresis; internal 2µA pull-up enables simple RC soft-start or logic control. |
| TK/SS (Pin 4) | Soft-start & tracking input | 1µA internal charge current ramps external capacitor for controlled VOUT rise or ratiometric tracking of master supply. |
| ITH (Pin 5) | Error amp output & current threshold | Directly sets peak inductor current; also used for compensation network connection (OPTI-LOOP®). |
| VFB (Pin 6) | Feedback input | Compares remote-sensed output voltage against 0.8V reference; high-impedance (–50nA max) minimizes divider error. |
| SENSE– (Pin 7) | Current sense inverting input | Connects to output node for DCR sensing or low-side resistor return path; rejects common-mode noise. |
| SENSE+ (Pin 8) | Current sense non-inverting input | Connects to DCR network midpoint or high-side of sense resistor; enables accurate current measurement. |
| ILIM (Pin 9) | Current limit range select | Tie to GND/FLOAT/INTVCC to set max sense threshold to 30/50/75mV - scales current limit without resistor changes. |
| GND (Pin 10) | Analog & power ground | Kelvin connection point for feedback, compensation, and input/output caps; critical for noise immunity and stability. |
| BG (Pin 11) | Bottom gate driver output | Drives low-side N-MOSFET gate from GND to INTVCC; 1.1Ω pull-down ensures fast turn-off. |
| INTVCC (Pin 12) | Internal 5V regulator output | Supplies all internal circuitry and gate drivers; requires ≥2.2µF low-ESR ceramic/tantalum decoupling. |
| VIN (Pin 13) | Main input supply | Accepts 4V–38V input; connects to bulk input capacitor; feeds INTVCC LDO and high-side driver bootstrap path. |
| BOOST (Pin 14) | Bootstrap supply for top gate | Swings from ~INTVCC–0.7V to VIN+INTVCC; charges external bootstrap capacitor during BG on-time. |
| TG (Pin 15) | Top gate driver output | Floating driver referenced to SW node; swings INTVCC amplitude above SW to fully enhance high-side N-MOSFET. |
| SW (Pin 16) | Switch node connection | Connects to inductor and MOSFET bridge; experiences full VIN-to-GND swing with fast edges; requires careful layout. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by optimizing loop stability across wide COUT/ESR ranges - reduces BOM cost and board area. |
| Selectably Efficient Light-Load Operation | Three user-configurable modes (Burst/Pulse-Skipping/Continuous) enable >90% efficiency at 1mA load while maintaining low ripple in CCM. |
| Tri-Level Adjustable Current Limit | ILIM pin selects 30/50/75mV sense thresholds - simplifies design reuse across 5A–30A power stages without component changes. |
| 99% Maximum Duty Cycle | Supports ultra-low dropout conversion (e.g., 36V→3.3V) without external assist circuits - extends usable input range in aging or brownout conditions. |
| Integrated 5V INTVCC Regulator | Eliminates need for auxiliary bias supply; 50mA peak current drives gate drivers and internal logic - reduces system component count. |
Applications
| Telecom Power Supply | Industrial PLC Power Module |
|---|---|
Use Scenario: 48V backplane-to-3.3V/5V conversion in carrier-grade line cards with strict efficiency and thermal requirements. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-current, high-efficiency DC-DC stage with fast load transient response. Use Value: Phase-lockable 750kHz operation enables EMI filtering at fixed frequency; ±1% VOUT accuracy ensures reliable FPGA and ASIC core voltage compliance. | Use Scenario: DIN-rail mounted 24V input power module generating isolated 5V/12V rails for I/O and communication interfaces. IC Role / Device Role / Timing Role: Main non-isolated buck controller delivering regulated 5V at up to 15A with robust short-circuit foldback protection. Use Value: RSENSE/DCR sensing flexibility allows cost-optimized designs; 4V–38V input range accommodates wide industrial input tolerances and brownout conditions. |
| Automotive Infotainment System | Distributed Data Center PSU |
Use Scenario: 12V vehicle battery input converted to 1.2V/1.8V for SoC and memory in head-unit systems with stringent EMI limits. IC Role / Device Role / Timing Role: High-efficiency synchronous buck controller supporting Burst Mode™ for <100µA quiescent current during sleep states. Use Value: 20µA shutdown IQ and programmable soft-start meet automotive OEM low-power requirements; AEC-Q100 qualification available in I-grade variants. | Use Scenario: 48V intermediate bus converter supplying 12V to server VRMs in modular data center power architectures. IC Role / Device Role / Timing Role: High-current, high-efficiency buck controller operating at 500kHz with external clock synchronization to avoid beat frequencies. Use Value: MODE/PLLIN pin enables deterministic EMI reduction across multiple parallel converters; 99% duty cycle supports partial-load efficiency during server idle periods. |
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, 3V–42V input, 200kHz–3MHz sync-capable, lower IQ (2.5µA) | Higher integration reduces external MOSFET count but limits max current and thermal design flexibility | Choose LT8640S for compact, medium-current designs where board space is constrained and 4A is sufficient. |
| MP2918 | Monolithic 12A buck, 4.5V–18V input, 300kHz–2.2MHz, no external sync, lower cost | Limited input range and no PLL sync makes it unsuitable for telecom or wide-input industrial use | Choose MP2918 only for cost-sensitive, fixed-input consumer or computing applications below 18V. |
Compared with LT8640S and MP2918, the LTC3851AEGN#TRPBF offers superior input voltage range (4V–38V), external MOSFET scalability beyond 30A, and deterministic EMI control via PLL synchronization - making it optimal for high-reliability, wide-input, high-current industrial and telecom power systems.
Availability
LTC3851AEGN#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial PLC modules, automotive infotainment systems, and distributed data center PSUs requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across –40°C to 125°C.
Supply support for LTC3851AEGN#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. (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC3851AEGN#TRPBF belongs to ADI's high-efficiency power controller product line, designed specifically for demanding industrial, telecom, and automotive DC-DC conversion where wide input range, precision regulation, and flexible light-load efficiency are critical.
FAQ
What is the maximum input voltage rating for the LTC3851AEGN#TRPBF?
The LTC3851AEGN#TRPBF has an absolute maximum input voltage (VIN) rating of 40V. Its operational input range is specified from 4V to 38V, making it suitable for 24V and 36V industrial and telecom systems. Exceeding 40V may cause permanent damage per Absolute Maximum Ratings. The device includes undervoltage lockout (UVLO) on INTVCC (3.25V threshold) to prevent malfunction during brownout conditions.
How does the ILIM pin configure current limiting on the LTC3851AEGN#TRPBF?
The ILIM pin on the LTC3851AEGN#TRPBF provides tri-level current limit selection: tying ILIM to GND sets the maximum current sense threshold to 30mV, floating sets it to 50mV, and connecting to INTVCC sets it to 75mV. This directly scales the peak inductor current without changing external sense resistors or compensation, enabling rapid design iteration across different power levels while retaining the same LTC3851AEGN#TRPBF footprint and layout.
Can the LTC3851AEGN#TRPBF synchronize to an external clock, and what is the supported frequency range?
Yes, the LTC3851AEGN#TRPBF can synchronize to an external clock applied to the MODE/PLLIN pin. It supports external clock frequencies from 250kHz to 750kHz, matching its internal oscillator range. When synchronized, the device operates in forced continuous conduction mode and maintains tight phase alignment - essential for reducing beat frequencies and EMI in multi-converter systems. No additional components are required beyond the external clock source.
What package type and thermal characteristics apply to the LTC3851AEGN#TRPBF?
The LTC3851AEGN#TRPBF uses the 16-lead plastic narrow SSOP (GN) package with θJA = 110°C/W. It does not include an exposed thermal pad. For thermal design, junction temperature must be calculated as TJ = TA + (PD × 110°C/W). The device is rated for operation from –40°C to 125°C ambient, with internal thermal shutdown protecting against sustained overload conditions.
Does the LTC3851AEGN#TRPBF support both RSENSE and DCR current sensing methods?
Yes, the LTC3851AEGN#TRPBF supports both RSENSE (shunt resistor) and DCR (inductor winding resistance) current sensing. SENSE+ and SENSE– pins accept either configuration: RSENSE connects between SW and GND (with SENSE+ to resistor top), while DCR sensing uses a resistor-capacitor network across the inductor to provide a filtered voltage proportional to current. This dual-sensing capability gives designers flexibility to optimize for accuracy (RSENSE) or efficiency/cost (DCR) based on application requirements.
LTC3851AEGN#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- 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:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LTC3851AEGN#TRPBF FAQ
1.How can I place an order for LTC3851AEGN#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3851AEGN#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 LTC3851AEGN#TRPBF reliable?
The price and inventory of LTC3851AEGN#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3851AEGN#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3851AEGN#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3851AEGN#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3851AEGN#TRPBF?
LTC3851AEGN#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3851AEGN#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 LTC3851AEGN#TRPBF?
For technical support, including LTC3851AEGN#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3851AEGN#TRPBF requirements.
6.How does Aetrix verify that LTC3851AEGN#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3851AEGN#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 LTC3851AEGN#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3851AEGN#TRPBF?
All LTC3851AEGN#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3851AEGN#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 LTC3851AEGN#TRPBF part is unused and in its original packaging.
Return procedure for LTC3851AEGN#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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