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Analog Devices Inc. LTC3851AMPMSE-1#PBF
- Part No.:
- LTC3851AMPMSE-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3851AMPMSE-1#PBF.pdf
- Description:
- IC REG CTRLR BUCK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,989
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Product details
Overview
LTC3851AMPMSE-1#PBF 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 delivers ±1% output voltage accuracy over –55°C to 150°C, supports 4V–38V input, 0.8V–5.5V adjustable output, and features phase-lockable 250kHz–750kHz switching with OPTI-LOOP® compensation. It is used in automotive power systems requiring extended temperature reliability and precise rail sequencing.
For engineers reviewing the LTC3851AMPMSE-1#PBF datasheet, LTC3851AMPMSE-1#PBF pinout, LTC3851AMPMSE-1#PBF application, or LTC3851AMPMSE-1#PBF equivalent, key selection criteria include MP-grade temperature range (–55°C to 150°C), PGOOD output replacing ILIM, RSENSE/DCR sensing flexibility, and Burst Mode®/pulse-skipping/continuous mode light-load control - all critical for ruggedized DC/DC designs in harsh environments.
Technical Context
The LTC3851AMPMSE-1#PBF implements a constant-frequency current-mode control architecture with a transconductance error amplifier (gm = 2 mmho, GBW = 3 MHz) and precision 0.8V reference (±1% over full temp range). Its OPTI-LOOP® compensation minimizes dependency on output capacitor ESR, enabling stable regulation across wide COUT values.
It integrates dual gate drivers (TG/BG) with matched 25ns rise/fall times, 30ns dead-time control, and 99% maximum duty cycle for ultra-low dropout operation. The improved PLL versus LTC3851-1 enables robust synchronization to external clocks up to 750kHz while maintaining forced continuous conduction during sync.
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% over –55°C to 150°C - ensures stable rail tolerance in automotive and industrial thermal extremes |
| Switching Frequency | 250kHz to 750kHz (phase-lockable) - balances efficiency vs. magnetics size; programmable via FREQ/PLLFLTR resistor |
| PGOOD Threshold | ±10% of 0.8V reference with 17µs mask - provides reliable power-good assertion after soft-start and fault recovery |
| Shutdown IQ | 20µA - enables low-power system standby without compromising fast wake-up capability |
| Current Sense Threshold | 35mV (MP-grade, min) to 70mV (MP-grade, max) - supports accurate current foldback limiting under short-circuit conditions |
| Operating Junction Temp | –55°C to 150°C - qualified for extended-temperature automotive and military applications |
Pinout & Package
Package: 16-lead plastic MSOP with exposed thermal pad (Pin 17 = GND), rated θJA = 40°C/W. Designed for high-density PCB layouts with enhanced thermal dissipation via soldered exposed pad.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| MODE/PLLIN (Pin 1) | Mode selection & external clock input | Selects Burst Mode®, pulse-skipping, or forced continuous operation; accepts 250–750kHz external sync clock |
| FREQ/PLLFLTR (Pin 2) | Oscillator frequency programming / PLL filter | Resistor-to-GND sets nominal frequency; RC network filters PLL loop when synchronized |
| RUN (Pin 3) | Enable/disable control | 1.22V threshold with 120mV hysteresis; internal 2µA pull-up enables simple RC soft-start enable |
| TK/SS (Pin 4) | Soft-start & tracking control | 1µA internal charge current ramps output voltage; supports ratiometric or coincident tracking of master supplies |
| ITH (Pin 5) | Error amplifier output & current limit setpoint | Voltage controls peak inductor current; also serves as compensation node for OPTI-LOOP® stability |
| VFB (Pin 6) | Feedback input | Compares output divider voltage to 0.8V reference; ±10% window triggers PGOOD assertion |
| SENSE– (Pin 7) | Current sense inverting input | Connected to output side of sense resistor or DCR network; enables accurate current foldback |
| SENSE+ (Pin 8) | Current sense non-inverting input | Connected to input side of sense resistor or DCR network; differential sensing rejects common-mode noise |
| PGOOD (Pin 9) | Open-drain power-good indicator | Pulled low during startup, shutdown, or VFB out-of-window; requires external pull-up to ≤6V |
| GND (Pin 10, Pin 17) | Analog & power ground | Pin 10 = signal ground; Pin 17 = exposed thermal pad = GND - must be soldered for thermal and electrical integrity |
| BG (Pin 11) | Bottom gate driver output | Drives source-connected N-MOSFET gate; 1.1Ω pull-down / 2.1Ω pull-up ensures fast turn-off/turn-on |
| INTVCC (Pin 12) | Internal 5V LDO output | Supplies internal circuitry and gate drivers; requires ≥2.2µF low-ESR ceramic/tantalum decoupling |
| VIN (Pin 13) | Main input supply | 4V–38V input; powers INTVCC LDO and high-side driver bootstrap circuit via BOOST path |
| BOOST (Pin 14) | Floating bootstrap supply | Connects to (+) terminal of bootstrap capacitor; swings from ~VIN + 5V down to ~INTVCC − 0.7V |
| TG (Pin 15) | Top gate driver output | Floating driver 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 bridge midpoint; voltage swings from ~0V to VIN during operation |
Key Features
| Feature | Design Value |
|---|---|
| MP-grade temperature qualification | –55°C to 150°C operating junction range - validated for aerospace, defense, and under-hood automotive use |
| PGOOD instead of ILIM pin | Replaces current-limit disable function with open-drain power-good monitoring - simplifies system health reporting |
| OPTI-LOOP® compensation | Minimizes required output capacitance and relaxes ESR constraints - reduces BOM cost and footprint |
| Three selectable light-load modes | Burst Mode®, pulse-skipping, or forced continuous - enables optimization of efficiency, ripple, and EMI per application need |
| Output overvoltage protection | Active OV comparator disables top MOSFET and turns on bottom MOSFET - prevents downstream damage during transients |
| DCR or RSENSE current sensing | Flexible sensing architecture - eliminates sense resistor losses in high-current designs or improves accuracy with discrete resistors |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module |
|---|---|
Use Scenario: Regulating 12V battery input to stable 3.3V/5V rails for DSPs, FPGAs, and CAN transceivers in head units and ADAS ECUs. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing rail sequencing, soft-start, and PGOOD signaling to MCU boot logic. Use Value: MP-grade temp range ensures operation at –40°C cold crank and 150°C under-hood ambient; PGOOD enables safe firmware initialization. |
Use Scenario: Generating isolated 5V and 3.3V outputs from 24V DC field bus for analog input conditioning and digital logic in modular controllers. IC Role / Device Role / Timing Role: High-efficiency step-down controller with adjustable soft-start and tracking for coordinated multi-rail power-up. Use Value: OPTI-LOOP® allows use of low-ESR polymer caps; Burst Mode® extends standby battery life in remote I/O nodes. |
| Telecom Base Station Bias Supply | Aerospace Avionics DC/DC Converter |
Use Scenario: Providing tightly regulated 1.8V/2.5V core voltages for RF transceivers and ADCs in 4G/5G macrocells with strict ripple requirements. IC Role / Device Role / Timing Role: Constant-frequency current-mode controller synchronized to system clock via MODE/PLLIN for EMI reduction. Use Value: Phase-lockable 750kHz operation enables deterministic switching harmonics; ±1% accuracy maintains signal integrity at RF frequencies. |
Use Scenario: Converting 28V aircraft bus to 5V/3.3V for flight control computers and sensor interfaces where radiation tolerance and long-term reliability are mandatory. IC Role / Device Role / Timing Role: Ruggedized buck controller with extended temp qualification and output overvoltage protection for safety-critical subsystems. Use Value: –55°C to 150°C rating meets MIL-STD-810H thermal shock requirements; OV protection prevents latch-up in single-event upset scenarios. |
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#PBF | Same functionality but I-grade (–40°C to 125°C); lacks MP-grade extended low-temp performance | Suitable for commercial/industrial environments without extreme cold requirements | Select when full –55°C operation is unnecessary and cost sensitivity favors standard grade |
| LTC3851AEUD-1#PBF | QFN package (3mm × 3mm), same electrical specs, different thermal profile (θJA = 68°C/W) | Better suited for space-constrained designs where MSOP footprint is prohibitive | Choose for high-density layouts needing smaller footprint and higher thermal resistance tolerance |
Compared with LTC3851AIMSE-1#PBF, the LTC3851AMPMSE-1#PBF adds guaranteed operation down to –55°C and tighter current-sense threshold stability at temperature extremes; versus LTC3851AEUD-1#PBF, it trades QFN miniaturization for MSOP manufacturability and lower thermal resistance in thermally demanding chassis-mount applications.
Availability
LTC3851AMPMSE-1#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC modules, and aerospace avionics requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3851AMPMSE-1#PBF 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 for precision, industrial, automotive, and communications applications.
The LTC3851A-1 product line delivers high-efficiency, robust synchronous buck controllers optimized for demanding DC/DC conversion in harsh environments - emphasizing extended temperature operation, accurate current sensing, and flexible light-load efficiency modes.
FAQ
What is the operating temperature range of the LTC3851AMPMSE-1#PBF?
The LTC3851AMPMSE-1#PBF is qualified for operation from –55°C to 150°C junction temperature, making it suitable for under-hood automotive, aerospace, and industrial applications where extreme thermal conditions exist. This MP-grade specification exceeds standard industrial (–40°C to 125°C) and automotive AEC-Q100 Grade 1 (–40°C to 125°C) requirements, with full electrical characterization across the entire range.
How does the PGOOD pin on the LTC3851AMPMSE-1#PBF differ from the ILIM pin on earlier variants?
The LTC3851AMPMSE-1#PBF replaces the ILIM (current limit disable) pin with a dedicated PGOOD (power good) open-drain output. Unlike ILIM, which allowed external current limit adjustment, PGOOD asserts low when VFB deviates by more than ±10% from 0.8V, during soft-start, or when RUN is low - providing direct system-level power status feedback without requiring additional monitoring circuitry.
Can the LTC3851AMPMSE-1#PBF synchronize to an external clock, and what is the supported frequency range?
Yes, the LTC3851AMPMSE-1#PBF supports external synchronization via the MODE/PLLIN pin, accepting clock inputs from 250kHz to 750kHz. When synchronized, the device operates in forced continuous conduction mode and locks its internal oscillator phase to the external source - reducing EMI through deterministic harmonic placement and enabling coherent switching in multi-rail systems.
What current sensing methods does the LTC3851AMPMSE-1#PBF support, and how do they impact design?
The LTC3851AMPMSE-1#PBF supports both RSENSE (discrete shunt resistor) and DCR (inductor winding resistance) current sensing. RSENSE offers higher accuracy and simpler layout but adds power loss and cost; DCR eliminates sense resistor losses and improves efficiency in high-current designs, though it requires careful inductor selection and compensation for temperature drift. Both methods are fully supported in the LTC3851AMPMSE-1#PBF's current foldback and peak-current control architecture.
What is the purpose of the TK/SS pin on the LTC3851AMPMSE-1#PBF, and how is it used in practice?
The TK/SS (Track/Soft-Start) pin on the LTC3851AMPMSE-1#PBF controls output voltage ramp rate during startup and shutdown. An internal 1µA current charges an external capacitor to generate a linear voltage ramp, enabling smooth soft-start. It also supports ratiometric or coincident tracking of master supplies via external resistor dividers - allowing coordinated power-up of multiple rails in complex systems without additional sequencing ICs.
LTC3851AMPMSE-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- 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:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3851AMPMSE-1#PBF FAQ
1.How can I place an order for LTC3851AMPMSE-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3851AMPMSE-1#PBF 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 LTC3851AMPMSE-1#PBF reliable?
The price and inventory of LTC3851AMPMSE-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3851AMPMSE-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3851AMPMSE-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3851AMPMSE-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3851AMPMSE-1#PBF?
LTC3851AMPMSE-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3851AMPMSE-1#PBF 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 LTC3851AMPMSE-1#PBF?
For technical support, including LTC3851AMPMSE-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3851AMPMSE-1#PBF requirements.
6.How does Aetrix verify that LTC3851AMPMSE-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3851AMPMSE-1#PBF 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 LTC3851AMPMSE-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3851AMPMSE-1#PBF?
All LTC3851AMPMSE-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3851AMPMSE-1#PBF, 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 LTC3851AMPMSE-1#PBF part is unused and in its original packaging.
Return procedure for LTC3851AMPMSE-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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