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Analog Devices Inc. LTC3851EUD-1#TRPBF
- Part No.:
- LTC3851EUD-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LTC3851EUD-1#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,849
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Product details
Overview
LTC3851EUD-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 OPTI-LOOP® compensation, power-good monitoring (PGOOD), and operates up to 750kHz with phase-lock capability. It is used in telecom intermediate bus converters requiring precise voltage regulation and high efficiency across wide load ranges.
For engineers reviewing the LTC3851EUD-1#TRPBF datasheet, LTC3851EUD-1#TRPBF pinout, LTC3851EUD-1#TRPBF application, or LTC3851EUD-1#TRPBF equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative options, and supply-chain support for industrial and telecom power designs.
Technical Context
The LTC3851EUD-1#TRPBF implements a constant-frequency current-mode control architecture with an internal transconductance error amplifier (gm = 2 mmho, GBW = 3 MHz) and slope-compensated PWM. Its ITH pin serves as both error amplifier output and peak current threshold control point, enabling dynamic loop response tuning via external compensation.
It integrates dual gate drivers (TG/BG) with matched 25ns rise/fall times, 30ns dead-time control, and on-resistance values of 2.6Ω/1.5Ω (TG) and 2.4Ω/1.1Ω (BG). The PGOOD pin provides open-drain output with ±10% VFB window detection and 17μs power-bad mask timing - distinct from the LTC3851's ILIM pin, confirming functional differentiation per datasheet revision -1.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports 5V, 12V, 24V, and 36V battery/bus systems without external regulators. |
| Output Voltage Accuracy | ±1% at 0.8V reference - ensures tight regulation for sensitive digital loads like FPGAs and ASICs. |
| Switching Frequency | 250kHz to 750kHz - adjustable via resistor on FREQ/PLLFLTR; enables optimization of size vs. efficiency trade-offs. |
| Light-Load Operation Modes | Burst Mode®, pulse-skipping, or forced continuous conduction - selectable via MODE/PLLIN pin for >90% efficiency down to 1mA. |
| Current Sensing | RSENSE or DCR - supports low-loss inductor-based sensing for high-current (>15A) applications without added power loss. |
| Shutdown Quiescent Current | 20μA - enables ultra-low-power standby in always-on telecom or industrial systems. |
| Package | 16-lead 3mm × 3mm QFN (UD) with exposed thermal pad - provides θJA = 68°C/W for compact, thermally robust PCB layouts. |
Pinout & Package
Package: 16-lead (3mm × 3mm) plastic QFN (UD) with exposed GND pad (Pin 17), rated for –40°C to +85°C operating junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (RUN) | Enable control input | Active-high logic: ≥1.25V enables IC; ≤1.1V forces shutdown with 2μA internal pull-up. |
| Pin 2 (TK/SS) | Soft-start/tracking control | 1μA internal current charges external capacitor to ramp VOUT linearly; supports ratiometric or coincident tracking of master supplies. |
| Pin 3 (ITH) | Error amplifier output & current threshold | Directly sets peak inductor current; also serves as compensation node for loop stability tuning. |
| Pin 4 (FB) | Feedback input | Compares resistive divider output against 0.8V reference; ±1% accuracy maintained over temp and line. |
| Pin 5 (SENSE–) | Current sense inverting input | High-impedance (±1μA bias) node tied to output ground side for DCR or RSENSE sensing networks. |
| Pin 6 (SENSE+) | Current sense non-inverting input | Accepts common-mode voltages up to 5.5V; enables accurate sensing across full duty cycle range. |
| Pin 7 (PGOOD) | Open-drain power-good indicator | Pulls low when VFB deviates >±10% from 0.8V or during soft-start/shutdown; includes 17μs glitch filter. |
| Pin 8 (GND) | Analog/digital ground reference | Kelvin connection point for FB, SENSE, and compensation components; exposed pad must be soldered to PCB ground plane. |
| Pin 9 (BG) | Bottom gate driver output | Drives source of low-side N-MOSFET between GND and INTVCC; 1.1Ω pull-down ensures fast turn-off. |
| Pin 10 (INTVCC) | Internal 5V LDO output | Supplies gate drivers and control circuitry; requires ≥2.2μF ceramic decoupling to GND. |
| Pin 11 (VIN) | Main input supply | 4V–38V input rail; powers INTVCC LDO and high-side driver bootstrap circuit via BOOST pin. |
| Pin 12 (BOOST) | Floating bootstrap supply | Connects to (+) terminal of external bootstrap capacitor; swings from ~INTVCC–0.4V to VIN+INTVCC. |
| Pin 13 (TG) | Top gate driver output | Floating driver output referenced to SW node; 2.6Ω pull-up ensures robust high-side MOSFET turn-on. |
| Pin 14 (SW) | Switch node connection | Connects to inductor and external Schottky diode cathode; voltage swings from ~–0.4V to VIN. |
| Pin 15 (MODE/PLLIN) | Mode selection & sync input | Selects Burst/Pulse-skip/Continuous mode or accepts external clock (250–750kHz) for synchronization. |
| Pin 16 (FREQ/PLLFLTR) | Oscillator programming & PLL filter | Resistor-to-GND sets frequency; with external clock, forms RC loop filter for PLL lock stability. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® compensation | Minimizes required output capacitance by enabling stable loop response across wide COUT/ESR variations - reduces BOM cost and board area. |
| 99% duty cycle capability | Enables ultra-low dropout operation (e.g., 5V→4.95V), critical for post-regulation in distributed power architectures. |
| Output overvoltage protection (OVP) | Hardware-level OV comparator disables top MOSFET and activates bottom MOSFET within microseconds if VFB exceeds 0.88V. |
| Current foldback limiting | Reduces MOSFET stress during short-circuit by lowering peak current threshold as VFB drops - prevents thermal runaway. |
| DCR current sensing support | Eliminates power loss and cost of discrete sense resistors in high-current (>10A) applications while maintaining accuracy. |
Applications
| Telecom Intermediate Bus Converter | Industrial PLC Power Supply |
|---|---|
Use Scenario: Converting 48V backplane to 3.3V/5V for FPGA, DSP, and interface ICs in carrier-grade base stations. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing all N-MOSFET switching, current sensing, and power-good sequencing. Use Value: 750kHz operation enables <1μH inductors; ±1% VOUT accuracy ensures reliable logic-level margin under dynamic load steps. |
Use Scenario: Generating isolated 5V and 3.3V rails from 24V DC field bus in programmable logic controllers with harsh EMI environments. IC Role / Device Role / Timing Role: High-efficiency, low-noise buck controller supporting Burst Mode® for standby and forced CCM for real-time I/O timing. Use Value: Pulse-skipping mode reduces audible noise vs. Burst Mode; PGOOD enables safe firmware boot sequencing before downstream loads power up. |
| Automotive ADAS Camera Module | Distributed DC Power System |
Use Scenario: Regulating 12V vehicle battery to 1.2V core and 1.8V I/O for image signal processors in surround-view camera ECUs. IC Role / Device Role / Timing Role: Synchronous buck controller with precise soft-start (TK/SS) and tracking to coordinate multi-rail power-up with SoC requirements. Use Value: Coincident tracking ensures 1.2V and 1.8V rails ramp simultaneously, preventing latch-up or undefined states during cold cranking (4.5V min VIN). |
Use Scenario: Point-of-load conversion in server rack power distribution, stepping 12V intermediate bus to 0.8V–3.3V for CPUs, memory, and accelerators. IC Role / Device Role / Timing Role: High-current (15A+) controller with DCR sensing and thermal-aware layout (exposed QFN pad) for dense, air-cooled modules. Use Value: 99% duty cycle allows direct 12V→11.8V pre-regulation; low IQ (20μA) extends uptime in battery-backed management subsystems. |
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 die, but in 16-lead MSOP package (θJA = 35–40°C/W); no exposed thermal pad. | Better suited for prototyping or lower-power (<8A) designs where thermal density is less critical. | Select when manual rework or legacy footprint compatibility is required; avoid for >10A continuous loads due to higher thermal resistance. |
| MP2918GL-Z | Monolithic 30V/12A buck converter (integrated MOSFETs); fixed 500kHz frequency; no PGOOD or tracking. | Targeted at space-constrained, medium-current apps where integration outweighs flexibility. | Choose only if system current ≤12A and design can accept fixed frequency, no output tracking, and no external MOSFET upgrade path. |
Compared with LTC3851EMSE-1#TRPBF, the LTC3851EUD-1#TRPBF offers superior thermal performance (68°C/W vs. 40°C/W) and smaller footprint, making it preferred for high-density, high-current telecom and industrial designs; versus MP2918GL-Z, it trades integration for design flexibility, external MOSFET scalability, and advanced features like PGOOD and ratiometric tracking.
Availability
LTC3851EUD-1#TRPBF is available at Aetrix Electronics and suitable for telecom intermediate bus converters, industrial PLC power supplies, and automotive ADAS camera modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3851EUD-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 LTC3851-1 belongs to Linear's high-efficiency synchronous controller product line, designed specifically for demanding intermediate bus and point-of-load DC/DC conversion in telecom, industrial, and automotive systems where precision, reliability, and thermal efficiency are critical.
FAQ
What is the maximum input voltage rating for the LTC3851EUD-1#TRPBF?
The LTC3851EUD-1#TRPBF has an absolute maximum input voltage (VIN) rating of 40V, with recommended continuous operation from 4V to 38V. This range supports 24V and 36V industrial buses, 48V telecom systems (with appropriate front-end clamping), and wide-range automotive inputs including cold-crank conditions down to 4.5V.
Does the LTC3851EUD-1#TRPBF support output voltage tracking during startup?
Yes, the LTC3851EUD-1#TRPBF supports both coincident and ratiometric output voltage tracking via the TK/SS pin. An external resistor divider from a master supply to GND applied to TK/SS enables synchronized ramp-up of multiple rails - a key requirement for FPGAs and multi-core processors to prevent latch-up or I/O contention.
How does the PGOOD function differ between the LTC3851EUD-1#TRPBF and the standard LTC3851?
The LTC3851EUD-1#TRPBF replaces the ILIM pin of the base LTC3851 with a dedicated PGOOD output, providing hardware-level power-good signaling with ±10% VFB window detection and 17μs glitch filtering. This change simplifies system sequencing and eliminates the need for external comparators in safety-critical applications.
Can the LTC3851EUD-1#TRPBF operate in Burst Mode® at light loads?
Yes, the LTC3851EUD-1#TRPBF supports Burst Mode® operation for high light-load efficiency. When MODE/PLLIN is biased to INTVCC through a 50k–250kΩ resistor, the controller enters sleep mode below ~1mA load, reducing quiescent current to 20μA while maintaining regulated output voltage via output capacitor discharge.
What thermal considerations apply to the LTC3851EUD-1#TRPBF's QFN package?
The LTC3851EUD-1#TRPBF uses a 3mm × 3mm QFN with exposed GND pad (Pin 17), delivering θJA = 68°C/W. To achieve rated performance, the exposed pad must be soldered to a minimum 100mm² copper thermal pad with ≥4 thermal vias to inner ground planes - essential for sustained 15A operation in telecom and industrial environments.
LTC3851EUD-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN 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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LTC3851EUD-1#TRPBF FAQ
1.How can I place an order for LTC3851EUD-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3851EUD-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 LTC3851EUD-1#TRPBF reliable?
The price and inventory of LTC3851EUD-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 LTC3851EUD-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3851EUD-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3851EUD-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3851EUD-1#TRPBF?
LTC3851EUD-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3851EUD-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 LTC3851EUD-1#TRPBF?
For technical support, including LTC3851EUD-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3851EUD-1#TRPBF requirements.
6.How does Aetrix verify that LTC3851EUD-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3851EUD-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 LTC3851EUD-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3851EUD-1#TRPBF?
All LTC3851EUD-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3851EUD-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 LTC3851EUD-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC3851EUD-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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