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Analog Devices Inc. LTC3851AIMSE-1#TRPBF
- Part No.:
- LTC3851AIMSE-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3851AIMSE-1#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,962
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Product details
Overview
LTC3851AIMSE-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 integrates PGOOD monitoring and OPTI-LOOP® compensation for wide output capacitor/ESR optimization. It is used in telecom intermediate bus converters requiring stable 3.3V/15A rails.
For engineers reviewing the LTC3851AIMSE-1#TRPBF datasheet, LTC3851AIMSE-1#TRPBF pinout, LTC3851AIMSE-1#TRPBF application, or LTC3851AIMSE-1#TRPBF equivalent, key selection criteria include its 99% duty cycle capability for low-dropout operation, selectable light-load modes (Burst/Pulse-Skip/Continuous), RSENSE or DCR current sensing flexibility, and automotive-grade –40°C to 125°C junction temperature range in thermally enhanced MSOP package.
Technical Context
The LTC3851AIMSE-1#TRPBF implements a constant-frequency current-mode control architecture with transconductance error amplifier (gm = 2 mmho, GBW = 3 MHz) and slope compensation. Its ITH pin serves as both error amplifier output and current threshold control point, enabling precise peak-current regulation across load and line variations.
It integrates a 5V INTVCC LDO (4.8V–5.2V, ±0.5% load regulation), dual gate drivers (TG/BG pull-up/down resistances: 2.2Ω/1.2Ω and 2.1Ω/1.1Ω), and a dedicated PLL circuit with external RC filter on FREQ/PLLFLTR for synchronization to external clocks up to 750 kHz. The improved PLL over LTC3851-1 enables tighter frequency lock and reduced jitter.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports 12V/24V/36V battery and intermediate bus systems without pre-regulation. |
| Output Voltage Accuracy | ±1% at 0.8V reference - ensures tight regulation for sensitive digital loads like FPGAs and ASICs. |
| Switching Frequency Range | 250kHz to 750kHz - adjustable via resistor on FREQ/PLLFLTR; enables trade-off between efficiency and magnetics size. |
| Light-Load Operation Modes | Burst Mode®, Pulse-Skipping, Continuous Conduction - selectable via MODE/PLLIN; Burst Mode achieves >85% efficiency at 1mA load. |
| Power Good Threshold | ±10% of VFB (i.e., ±80mV around 0.8V) - provides reliable rail validation with 17µs power-bad mask timing. |
| Shutdown Quiescent Current | 20µA - enables ultra-low-power system standby without compromising fast wake-up response. |
| Duty Cycle Capability | Up to 99% - supports near-input-output voltage operation (e.g., 12V→11.5V) with minimal dropout loss. |
Pinout & Package
Package: 16-lead plastic MSOP (MSE) with exposed thermal pad (Pin 17 = GND), rated for –40°C to 125°C junction temperature (θJA = 35–40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN (Pin 3) | Enable control input | 1.22V rising threshold with 120mV hysteresis; internal 2µA pull-up enables simple push-button start-up. |
| TK/SS (Pin 4) | Soft-start/tracking control | 1µA internal charge current ramps external capacitor; enables programmable VOUT ramp or ratiometric tracking of master supply. |
| ITH (Pin 5) | Error amplifier output & current limit setpoint | Directly sets peak inductor current threshold; gm = 2 mmho enables stable loop compensation across wide COUT/ESR. |
| FB (Pin 6) | Feedback input | Compares remote-sensed output voltage against 0.8V reference; ±10nA input bias minimizes divider error. |
| SENSE+ / SENSE– (Pins 7,8) | Current sense differential inputs | Accepts either RSENSE or DCR network; max sense threshold = 70mV (H/MP grade) with ±2µA input offset. |
| PGOOD (Pin 9) | Open-drain power-good indicator | Pulls low when VFB deviates >±10% or during soft-start/shutdown; compatible with 3.3V/5V logic pull-ups. |
| GND (Pin 10 + Exposed Pad 17) | Signal & thermal ground | Exposed pad must be soldered to PCB ground plane for thermal performance and noise immunity. |
| BG (Pin 11) | Bottom gate driver output | Drives N-MOSFET source-to-ground; 1.1Ω pull-down ensures fast turn-off and prevents shoot-through. |
| 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 | 4V–38V operating range; absolute max = 40V; decoupling capacitor required for EMI suppression. |
| BOOST (Pin 14) | Floating bootstrap supply | Charges external bootstrap capacitor; swings from ~INTVCC–0.4V to VIN+INTVCC for top-FET drive. |
| TG (Pin 15) | Top gate driver output | Floating driver referenced to SW node; 2.2Ω pull-up enables fast top-FET turn-on under high dV/dt conditions. |
| SW (Pin 16) | Switch node connection | Connects to inductor and external Schottky diode cathode; handles full VIN swing and high di/dt. |
| MODE/PLLIN (Pin 1) | Mode selection & external clock sync | Selects Burst/Pulse-Skip/Continuous mode or accepts 250–750kHz external clock for synchronized multi-phase designs. |
| FREQ/PLLFLTR (Pin 2) | Oscillator programming & PLL filter | Resistor-to-GND sets nominal frequency; RC network filters PLL reference for low-jitter lock. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by adapting loop gain to actual COUT and ESR - reduces BOM cost and board area. |
| Programmable Output Tracking | TK/SS pin enables ratiometric or coincident startup with master supply - critical for multi-rail SoC sequencing (e.g., core/I/O voltage ramps). |
| Output Overvoltage Protection | Hardware-based OV comparator disables TG and enables BG if VFB exceeds +10%, preventing damage to downstream ICs. |
| Current Foldback Limiting | Reduces peak MOSFET current during short-circuit events - limits thermal stress and enables safe hiccup-mode recovery. |
| DCR or RSENSE Sensing | Flexible current sensing eliminates need for power-hungry shunt resistors in high-current designs while maintaining ±1% current limit accuracy. |
Applications
| Telecom Intermediate Bus Converter | Industrial PLC Power Supply |
|---|---|
Use Scenario: 48V backplane distributed to 12V/5V/3.3V rails in carrier-grade base station equipment. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating 3.3V/15A output from 36–57V input range. Use Value: 99% duty cycle enables direct 48V→3.3V conversion without pre-regulator stage, reducing component count and improving system efficiency by >3%. |
Use Scenario: DIN-rail mounted programmable logic controller requiring isolated 24V input converted to regulated 5V/3A for microcontroller and I/O buffers. IC Role / Device Role / Timing Role: High-reliability step-down controller with robust UVLO (3.25V) and thermal shutdown for harsh factory environments. Use Value: –40°C to 125°C operating range and 40°C/W θJA ensure stable operation inside sealed enclosures with ambient temperatures up to 70°C. |
| Automotive ADAS Camera Module | Network Switch PoE Midspan |
Use Scenario: Front-facing camera module powered from 12V vehicle battery with strict EMI and transient immunity requirements. IC Role / Device Role / Timing Role: Low-noise synchronous controller operating in forced continuous mode to suppress audible switching noise near image sensor. Use Value: Pulse-skipping mode disabled; fixed 500kHz operation with integrated slope compensation ensures clean 1.2V core rail for ISP with <10mV p-p ripple. |
Use Scenario: IEEE 802.3af/at midspan injector delivering 48V PoE plus local 3.3V/2A auxiliary rail for management MCU and PHY. IC Role / Device Role / Timing Role: Secondary buck controller deriving 3.3V from PoE-derived 54V intermediate bus with precise tracking to main 48V rail. Use Value: TK/SS pin configured for ratiometric tracking ensures 3.3V rail remains within ±2% of 48V bus during hot-swap events and load transients. |
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 power MOSFETs (42V IN, 4A); Silent Switcher® architecture; no external TG/BG drivers. | Lower solution size but limited to ≤4A; lacks PGOOD and tracking capability; not suitable for >10A discrete designs. | Choose LT8640S for compact, low-EMI 4A applications where integration outweighs flexibility. |
| TPS54560B | Single N-channel driver (external high-side only); 3.5V–60V input; no PLL sync or OPTI-LOOP; lower accuracy (±1.5% ref). | Cost-optimized for industrial DC/DC; lacks burst mode efficiency and precision tracking; higher IQ (145µA shutdown). | Choose TPS54560B for non-critical 5A applications where BOM cost is primary constraint. |
Compared with LT8640S and TPS54560B, the LTC3851AIMSE-1#TRPBF uniquely combines discrete MOSFET scalability (to 30A+), precision 0.8V reference (±1%), hardware OV protection, and flexible light-load mode selection - making it optimal for high-reliability, medium-to-high current telecom and automotive power systems.
Availability
LTC3851AIMSE-1#TRPBF is available at Aetrix Electronics and suitable for telecom intermediate bus converters, industrial PLC power supplies, automotive ADAS camera modules, and PoE midspan injectors requiring stable component supply with guaranteed long-term availability.
Supply support for LTC3851AIMSE-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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving aerospace, industrial, automotive, and communications markets.
The LTC3851A-1 belongs to Linear's high-efficiency synchronous controller product line, designed specifically for demanding DC/DC conversion in space-constrained, thermally challenging, and reliability-critical applications such as telecom infrastructure and automotive electronics.
FAQ
What is the maximum input voltage rating for the LTC3851AIMSE-1#TRPBF?
The LTC3851AIMSE-1#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 bus systems and 12V automotive applications with load-dump tolerance. Exceeding 40V risks permanent damage per Absolute Maximum Ratings.
Does the LTC3851AIMSE-1#TRPBF support output voltage tracking during startup?
Yes, the LTC3851AIMSE-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 precise sequencing - for example, ramping the 3.3V rail in exact proportion to a 12V rail during cold start, ensuring safe FPGA or processor power-up.
How does the PGOOD function behave during soft-start on the LTC3851AIMSE-1#TRPBF?
The PGOOD pin on the LTC3851AIMSE-1#TRPBF remains low during soft-start until the FB voltage enters and remains within ±10% of 0.8V for longer than the internal 17µs power-bad mask timer. This ensures downstream circuits only enable after stable regulation is achieved - preventing premature logic initialization or latch-up in sensitive digital loads.
Can the LTC3851AIMSE-1#TRPBF synchronize to an external clock, and what is the supported frequency range?
Yes, the LTC3851AIMSE-1#TRPBF can synchronize its internal oscillator to an external clock applied to the MODE/PLLIN pin. It accepts input frequencies from 250kHz to 750kHz, forcing forced continuous conduction mode and eliminating beat frequencies in multi-phase or noise-sensitive systems such as audio amplifiers or RF front-ends.
What thermal considerations apply to the LTC3851AIMSE-1#TRPBF in MSOP package?
The LTC3851AIMSE-1#TRPBF in 16-lead MSOP (MSE) has a junction-to-ambient thermal resistance (θJA) of 35–40°C/W depending on PCB layout. To maintain ≤125°C junction temperature at full load, the exposed thermal pad (Pin 17) must be soldered to a minimum 100mm² copper pour with ≥4 thermal vias - failure to do so risks thermal shutdown or accelerated parametric drift.
LTC3851AIMSE-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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3851AIMSE-1#TRPBF FAQ
1.How can I place an order for LTC3851AIMSE-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3851AIMSE-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 LTC3851AIMSE-1#TRPBF reliable?
The price and inventory of LTC3851AIMSE-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 LTC3851AIMSE-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3851AIMSE-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3851AIMSE-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3851AIMSE-1#TRPBF?
LTC3851AIMSE-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3851AIMSE-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 LTC3851AIMSE-1#TRPBF?
For technical support, including LTC3851AIMSE-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3851AIMSE-1#TRPBF requirements.
6.How does Aetrix verify that LTC3851AIMSE-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3851AIMSE-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 LTC3851AIMSE-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3851AIMSE-1#TRPBF?
All LTC3851AIMSE-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3851AIMSE-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 LTC3851AIMSE-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC3851AIMSE-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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