My Inquiry
My Account
Analog Devices Inc. LTC3851IGN#PBF
- Part No.:
- LTC3851IGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3851IGN#PBF.pdf
- Description:
- IC REG CTRLR BUCK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:200
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LTC3851IGN#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 supports 4V–38V input, delivers 0.8V–5.5V output with ±1% accuracy, operates up to 750kHz, and features OPTI-LOOP® compensation and selectable light-load modes (Burst, Pulse-Skip, or Continuous). It is used in telecom power supplies requiring high efficiency and tight regulation under wide load transients.
For engineers reviewing the LTC3851IGN#PBF datasheet, LTC3851IGN#PBF pinout, LTC3851IGN#PBF application, or LTC3851IGN#PBF equivalent, key selection criteria include its RSENSE/DCR current sensing flexibility, phase-lockable oscillator, 99% duty cycle capability, integrated 5V INTVCC regulator, and thermal performance in –40°C to 125°C industrial environments.
Technical Context
The LTC3851IGN#PBF implements a constant-frequency current-mode control architecture with slope compensation, enabling stable operation across wide duty cycles and inductor values. Its transconductance error amplifier (gm = 2 mmho, GBW = 3 MHz) interfaces with OPTI-LOOP® compensation to optimize transient response for diverse output capacitor ESR and capacitance combinations.
It integrates dual gate drivers (TG/BG) with matched 25ns rise/fall times, anti-shoot-through logic, and programmable current limit via ILIM pin (30/50/75 mV thresholds). The MODE/PLLIN pin enables synchronization to external clocks up to 750 kHz while forcing continuous conduction mode, and the FREQ/PLLFLTR pin sets nominal frequency from 250 kHz to 750 kHz using an external resistor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide-input industrial and telecom DC distribution rails without pre-regulation. |
| Output Voltage Accuracy | ±1% at VFB - ensures precise regulation over temperature and line/load conditions for sensitive loads. |
| Switching Frequency | 250 kHz to 750 kHz - adjustable via FREQ/PLLFLTR resistor; higher frequencies reduce passive size, lower frequencies improve efficiency. |
| Reference Voltage | 0.800 V ±0.008 V - low-drift precision reference enabling accurate feedback scaling for 0.8V–5.5V outputs. |
| Quiescent Current | 1.2 mA typical in normal mode; 20 μA in shutdown - enables low-power standby in always-on systems. |
| Current Sense Threshold | Selectable 30/50/75 mV via ILIM pin - allows optimization of sense resistor power loss vs. noise immunity. |
| Duty Cycle Capability | Up to 99% - supports very low dropout operation (e.g., 12V→11.8V), critical for battery backup and hold-up applications. |
| Operating Temperature | –40°C to +125°C junction - qualified for extended-temperature industrial and automotive under-hood environments. |
Pinout & Package
Package: 16-lead plastic narrow SSOP (GN package), exposed pad not present; thermal resistance θJA = 110°C/W.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| MODE/PLLIN (1) | Mode selection & sync input | Configures Burst/Pulse-Skip/Continuous mode; accepts external clock up to 750 kHz for system-wide timing alignment. |
| FREQ/PLLFLTR (2) | Oscillator programming & PLL filter | Sets switching frequency via resistor-to-GND; when used with external clock, forms PLL loop filter with RC network. |
| RUN (3) | Enable control | Active-high enable with 1.25 V threshold and 130 mV hysteresis; internal 2 μA pull-up enables simple RC soft-start sequencing. |
| TK/SS (4) | Soft-start/tracking input | Internal 1 μA current charges external capacitor for controlled VOUT ramp; supports ratiometric or coincident tracking of master supply. |
| ITH (5) | Error amplifier output & current threshold | Directly sets peak inductor current; voltage range 0.4 V–1.6 V determines current limit and loop dynamics. |
| VFB (6) | Feedback input | Compares output divider voltage against 0.8 V reference; high-impedance input minimizes loading on feedback network. |
| SENSE– (7) | Current sense inverting input | Connects to low-side of sense resistor or DCR network; common-mode range 0 V–5.5 V supports high-side sensing topologies. |
| SENSE+ (8) | Current sense non-inverting input | Connects to high-side of sense resistor or DCR network; <1 μA bias current enables accurate low-value DCR sensing. |
| ILIM (9) | Current limit range select | Tri-level input (GND/FLOAT/INTVCC) selects 30/50/75 mV max sense threshold - balances accuracy, power loss, and noise rejection. |
| GND (10) | Analog ground reference | Kelvin connection point for all small-signal components; decoupling caps must tie directly here to minimize noise coupling. |
| BG (11) | Bottom gate driver output | Drives low-side N-MOSFET gate between GND and INTVCC (5 V); 1.1 Ω pull-down ensures fast turn-off and shoot-through prevention. |
| INTVCC (12) | Internal 5 V regulator output | Supplies gate drivers and analog circuitry; requires ≥2.2 μF low-ESR ceramic/tantalum cap to GND for stability and ripple suppression. |
| VIN (13) | Main input supply | Accepts 4 V–38 V; powers INTVCC LDO and provides bootstrap energy; requires local bulk and high-frequency decoupling. |
| BOOST (14) | Bootstrap supply for top gate | Swings from ~4.3 V below INTVCC to VIN + INTVCC; connects to (+) terminal of bootstrap capacitor for floating TG drive. |
| TG (15) | Top gate driver output | Drives high-side N-MOSFET gate with swing equal to INTVCC superimposed on SW node; 2.6 Ω pull-up ensures robust turn-on. |
| SW (16) | Switch node | Connects to inductor and MOSFET sources; voltage swings from Schottky diode drop below GND to VIN; critical for layout EMI control. |
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. |
| Programmable Light-Load Operation | Selectable Burst Mode®, Pulse-Skipping, or Forced Continuous Conduction - enables >90% efficiency at 1 mA load while maintaining low noise. |
| DCR or RSENSE Current Sensing | Supports both methods without external op-amps - eliminates sense resistor losses in high-current designs and improves thermal performance. |
| Output Overvoltage Protection | Hardware comparator triggers immediate top-FET turn-off and bottom-FET turn-on if VFB exceeds 0.88 V - protects downstream ICs during transients. |
| 99% Maximum Duty Cycle | Enables ultra-low dropout operation (e.g., 12 V → 11.88 V) - essential for battery-backed systems and input-voltage hold-up applications. |
| Phase-Lockable Oscillator | Synchronizes to external clock up to 750 kHz via MODE/PLLIN - eliminates beat frequencies in multi-rail systems and simplifies EMI filtering. |
Applications
| Telecom Power Supply | Industrial PLC Power Module |
|---|---|
|
Use Scenario: 48 V telecom rectified input converted to isolated 3.3 V/15 A for baseband processor and FPGA. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating intermediate bus; manages dynamic load steps up to 10 A/μs. Use Value: OPTI-LOOP® compensation maintains stability with polymer tantalum output caps; 750 kHz operation shrinks magnetics for dense card layouts. |
Use Scenario: 24 V factory automation rail stepped down to 5 V/10 A for I/O modules and real-time controllers. IC Role / Device Role / Timing Role: High-reliability buck controller operating continuously at full load in –40°C to +85°C ambient. Use Value: 125°C junction rating and 110°C/W θJA ensure thermal margin; RSENSE/DCR flexibility accommodates legacy vs. new inductor sourcing. |
| Automotive Infotainment Head Unit | Distributed DC Power System |
|
Use Scenario: 12 V vehicle battery input regulated to 1.5 V/8 A for SoC core supply with strict EMI limits. IC Role / Device Role / Timing Role: Synchronous buck controller with Burst Mode® for low-quiescent audio subsystems. Use Value: 20 μA shutdown IQ extends battery life; phase-locking to system clock suppresses conducted emissions in CISPR-25 bands. |
Use Scenario: Central 36 V DC bus distributed to multiple point-of-load converters in datacom rack. IC Role / Device Role / Timing Role: High-efficiency intermediate converter feeding downstream POLs; supports 99% duty cycle for brownout resilience. Use Value: Adjustable current foldback prevents MOSFET thermal runaway during short-circuit events; 38 V max input handles load-dump 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 stage (4 A), 2.8 V–42 V input, 30 ns min on-time, Silent Switcher® architecture | Better EMI performance and smaller solution size; lacks tri-level ILIM and DCR sensing support | Preferred for space-constrained, low-EMI designs where integrated FETs meet current needs |
| MP2918 | Monolithic 12 A buck, 4.5 V–16 V input, 0.6 V reference, no PLL sync, lower temp grade (–40°C to 105°C) | Lower cost, simpler layout; missing OPTI-LOOP®, phase-lock, and wide VIN range | Cost-sensitive, mid-range industrial applications with limited input voltage variation |
Compared with LT8640S and MP2918, the LTC3851IGN#PBF offers superior flexibility in current sensing (RSENSE/DCR), wider input range (4 V–38 V), and system-level timing control via PLL sync - making it optimal for high-reliability, thermally demanding, or multi-rail synchronized power architectures.
Availability
LTC3851IGN#PBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial PLC modules, and automotive infotainment systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3851IGN#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC3851IGN#PBF belongs to Linear's high-efficiency synchronous controller product line, designed specifically for demanding DC/DC conversion in telecom, industrial, and automotive applications where precision, reliability, and thermal robustness are critical.
FAQ
What is the maximum input voltage rating for the LTC3851IGN#PBF?
The LTC3851IGN#PBF has an absolute maximum input voltage (VIN) rating of 40 V, with recommended operating range from 4 V to 38 V. Exceeding 40 V risks permanent damage per Absolute Maximum Ratings. The device sustains full functionality across its specified –40°C to +125°C junction temperature range within this input window.
How does the ILIM pin affect current limiting on the LTC3851IGN#PBF?
The ILIM pin on the LTC3851IGN#PBF selects one of three maximum current sense thresholds: 30 mV (ILIM = GND), 50 mV (ILIM = FLOAT), or 75 mV (ILIM = INTVCC). This directly sets the peak inductor current limit, allowing design trade-offs between sense resistor power loss, noise immunity, and accuracy without changing external components.
Can the LTC3851IGN#PBF synchronize to an external clock, and what are the requirements?
Yes, the LTC3851IGN#PBF can synchronize its internal oscillator to an external clock applied to the MODE/PLLIN pin, supporting frequencies from 250 kHz to 750 kHz. A series RC network must be connected between FREQ/PLLFLTR and GND to serve as the PLL loop filter; the external clock should be applied before enabling RUN to avoid startup instability.
What package type and thermal characteristics apply to the LTC3851IGN#PBF?
The LTC3851IGN#PBF uses a 16-lead narrow plastic SSOP (GN package) with θJA = 110°C/W. It is rated for operation from –40°C to +125°C junction temperature. Unlike MSOP or QFN variants, this SSOP version lacks an exposed thermal pad, so PCB copper area and airflow become critical for thermal management at full load.
Does the LTC3851IGN#PBF support DCR current sensing, and how is it implemented?
Yes, the LTC3851IGN#PBF supports DCR current sensing via the SENSE+ and SENSE– pins. A passive RC network matching the L/DCR time constant is placed across the inductor; the voltage across the capacitor scales the DCR voltage drop for accurate current measurement - eliminating sense resistor losses and improving efficiency in high-current designs.
LTC3851IGN#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- 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:
- 250kHz ~ 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
LTC3851IGN#PBF FAQ
1.How can I place an order for LTC3851IGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3851IGN#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 LTC3851IGN#PBF reliable?
The price and inventory of LTC3851IGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3851IGN#PBF is usually 5 days.
3.What payment methods are accepted for LTC3851IGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3851IGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3851IGN#PBF?
LTC3851IGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3851IGN#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 LTC3851IGN#PBF?
For technical support, including LTC3851IGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3851IGN#PBF requirements.
6.How does Aetrix verify that LTC3851IGN#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3851IGN#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 LTC3851IGN#PBF meets industry standards.
7.What is the process for return or replacement of LTC3851IGN#PBF?
All LTC3851IGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3851IGN#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 LTC3851IGN#PBF part is unused and in its original packaging.
Return procedure for LTC3851IGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTC3851IGN#PBF Tags
-
UCC28C45DR
Texas Instruments
-
UCC28C40DR
Texas Instruments
-
UCC28C43DR
Texas Instruments
-
ZXSC410E6TA
Diodes Incorporated
-
LM3524DMX/NOPB
Texas Instruments
-
LM3489MMX/NOPB
Texas Instruments
-
MIC2102YML-TR
Microchip Technology
-
LM5148RGYR
Texas Instruments
-
TL598CDR
Texas Instruments
-
LM5155DSSR
Texas Instruments
-
LM25085MYX/NOPB
Texas Instruments
-
UCC2813DTR-0
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
