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Analog Devices Inc. LTC3850IUFD#PBF
- Part No.:
- LTC3850IUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3850IUFD#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,672
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Product details
Overview
LTC3850IUFD#PBF from Analog Devices is a dual, 2-phase synchronous step-down switching controller driving all-N-channel MOSFET stages. It delivers ±1% output voltage accuracy at 0.8V reference, supports 250kHz–780kHz phase-lockable frequency, and operates from 4V–24V input (30V max for I-grade) - enabling high-efficiency dual-rail power supplies for portable computing and battery-powered instrumentation.
For engineers reviewing the LTC3850IUFD#PBF datasheet, LTC3850IUFD#PBF pinout, LTC3850IUFD#PBF application, or LTC3850IUFD#PBF equivalent, key selection criteria include dual-phase current-mode control, independent soft-start/tracking (TK/SS), RSENSE/DCR sensing flexibility, OPTI-LOOP® compensation, and automotive-grade AEC-Q100 qualification (I-grade).
Technical Context
The LTC3850IUFD#PBF implements constant-frequency current-mode control with two 180° out-of-phase channels, minimizing input ripple and supply noise. Each channel features independent error amplifiers, current comparators with foldback limiting, and programmable ITH-based peak-current threshold control.
Its MODE/PLLIN pin selects among Burst Mode®, pulse-skipping, or forced continuous conduction, while FREQ/PLLFLTR enables DC-set frequency tuning or external clock synchronization. The IC integrates dual N-channel gate drivers (TG/BG), internal 5V INTVCC regulator, and open-drain PGOOD with ±7.5% window detection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Dual synchronous buck controller - drives external high-side and low-side N-MOSFETs per channel. |
| Input Voltage Range | 4V to 24V (30V absolute max for I-grade) - supports wide battery chemistries and intermediate bus rails. |
| Output Voltage Accuracy | ±1% at 0.8V reference - ensures tight regulation across temperature and load for core logic supplies. |
| Switching Frequency | 250kHz to 780kHz, phase-lockable - balances efficiency vs. inductor/capacitor size; adjustable via FREQ/PLLFLTR voltage. |
| Current Sensing | RSENSE or DCR - selectable via ILIM pin configuration (GND/FLOAT/INTVCC) to set 20/40/60mV max sense threshold. |
| Soft-Start & Tracking | Independent TK/SS1/TK/SS2 pins with 1.3µA internal charge current - enables controlled ramp-up or precise voltage sequencing. |
| Thermal Performance | θJA = 34°C/W (UFD package) - enables high-power density designs with minimal heatsinking. |
Pinout & Package
Package: 28-lead (4mm × 5mm) plastic QFN with exposed pad (Pin 29 = SGND/PGND). RoHS-compliant, lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2 | Channel enable control | Logic-high (>1.22V) enables respective channel; pull-low disables independently - supports staggered startup and power sequencing. |
| TK/SS1, TK/SS2 | Soft-start & tracking input | Internal 1.3µA current charges external capacitor; voltage ramp sets output VOUT rise rate or tracks master rail. |
| SENSE1+/SENSE1−, SENSE2+/SENSE2− | Differential current sense inputs | Accepts RSENSE or DCR network signals - enables accurate cycle-by-cycle current limiting and foldback protection. |
| VFB1, VFB2 | Error amplifier feedback input | Compares remote-sensed output voltage against 0.8V reference - determines regulation setpoint via external resistor divider. |
| ITH1, ITH2 | Error amplifier output / current threshold | Controls peak inductor current per channel; voltage directly sets current comparator trip point in current-mode loop. |
| TG1, TG2 / BG1, BG2 | Top/bottom gate driver outputs | Drive N-MOSFET gates with 2.6Ω/1.5Ω (TG) and 2.4Ω/1.1Ω (BG) on-resistance - supports fast switching with <30ns dead-time control. |
| SW1, SW2 | Switch node connection | Connects to inductor and MOSFET source/drain nodes - handles up to 28V swing (30V for I-grade) with body-diode clamping. |
| PGOOD | Power-good indicator | Open-drain output pulled low if either VOUT deviates >±7.5% from target after 17µs mask timer - enables system-level fault signaling. |
| MODE/PLLIN | Mode select & sync input | Selects Burst Mode® (float), pulse-skip (INTVCC), or forced CCM (SGND); accepts external clock for synchronization. |
| FREQ/PLLFLTR | Oscillator frequency control | DC voltage sets nominal frequency (250–780kHz); also serves as PLL loop filter node when synchronized externally. |
| VIN, INTVCC, PGND, SGND | Power and ground domains | VIN powers internal LDO; INTVCC supplies control circuitry; PGND carries high di/dt return paths; SGND isolates analog references. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® compensation | Enables stable loop response across wide range of output capacitance (10µF–1000µF) and ESR values without redesign. |
| Dual 180° phased operation | Reduces RMS input capacitor current by ~30% and lowers conducted EMI compared to single-phase or in-phase dual controllers. |
| Pre-biased output support | Allows safe startup into pre-charged output capacitors - prevents reverse current flow and avoids system reset during hot-swap events. |
| AEC-Q100 qualified (I-grade) | Rated for –40°C to +85°C ambient with full performance guarantee - suitable for automotive infotainment and ADAS subsystems. |
| Independent current foldback | Reduces MOSFET thermal stress during short-circuit by lowering peak current limit based on ILIM pin state - improves reliability under fault. |
Applications
| High-Efficiency Dual-Rail Notebook Supply | Portable Instrumentation Power Management |
|---|---|
|
Use Scenario: Generating tightly regulated 3.3V/2.5V rails from 12V battery or adapter input in ultra-thin notebooks. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing two independent output stages with interleaved switching. Use Value: Achieves up to 95% efficiency at 5A per rail while reducing input ripple and EMI - extends battery life and simplifies filtering. |
Use Scenario: Powering mixed-signal data acquisition systems requiring clean, sequenced 1.8V and 3.3V supplies. IC Role / Device Role / Timing Role: Dual-channel controller with independent TK/SS pins enabling precise voltage tracking and soft-start timing. Use Value: Eliminates sequencing ICs; ensures zero-crossing startup and avoids latch-up in ADC/DAC reference circuits. |
| Battery-Operated Digital Test Equipment | DC Power Distribution System |
|
Use Scenario: Providing isolated, high-current 5V and 1.2V rails from Li-ion pack (8–16V) in handheld oscilloscopes and logic analyzers. IC Role / Device Role / Timing Role: Dual-phase controller with RSENSE/DCR sensing and Burst Mode® for ultra-low quiescent current (<50µA shutdown). Use Value: Extends runtime in standby mode; maintains regulation during deep discharge (down to 4V VIN) without brownout. |
Use Scenario: Centralized 24V-to-12V/5V conversion in industrial rack-mounted equipment with redundant inputs. IC Role / Device Role / Timing Role: High-voltage input controller supporting wide VIN range and robust fault handling (PGOOD, UVLO, OVLO). Use Value: Enables single-board multi-rail generation with AEC-Q100 reliability margin - reduces BOM count and board space. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-phase synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers only (no external FET drive); fixed 500kHz frequency; no PLL sync. | Targeted at cost-sensitive consumer power supplies; lacks independent TK/SS, RSENSE/DCR flexibility, and AEC-Q100 rating. | Choose MP2918GL-Z only for non-automotive, space-constrained designs where integrated FETs suffice and frequency agility is unnecessary. |
| LTC3833EUFD#PBF | Single-channel, 2-phase controller (not dual independent); supports up to 60V VIN; no independent RUN/TK/SS per channel. | Designed for high-input-voltage telecom and industrial converters; lacks dual-rail flexibility and tracking capability. | Choose LTC3833EUFD#PBF only for single-output, high-VIN applications requiring 2-phase interleaving - not for dual independent rails. |
Compared with MP2918GL-Z and LTC3833EUFD#PBF, the LTC3850IUFD#PBF uniquely provides true dual independent channels with per-channel soft-start, tracking, and current limit control - essential for complex multi-rail sequencing and automotive-grade reliability.
Availability
LTC3850IUFD#PBF is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, and battery-operated digital devices requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for LTC3850IUFD#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. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors - serving precision instrumentation, communications, automotive, and industrial markets.
The LTC3850IUFD#PBF belongs to Analog Devices' Power by Linear™ controller family, engineered for high-efficiency, low-noise, multi-rail DC/DC conversion in space- and thermal-constrained portable and automotive systems.
FAQ
What is the maximum input voltage rating for LTC3850IUFD#PBF?
The LTC3850IUFD#PBF has an absolute maximum input voltage (VIN) rating of 30V, with continuous operation specified from 4V to 24V. This 30V rating applies specifically to the I-grade version (denoted by "I" in LTC3850I), which matches the LTC3850IUFD#PBF part number. Exceeding 30V risks permanent damage per Absolute Maximum Ratings.
Does LTC3850IUFD#PBF support pre-biased output startup?
Yes, the LTC3850IUFD#PBF explicitly supports pre-biased output startup. Its current-mode architecture and control logic prevent reverse current flow during startup into pre-charged capacitors - confirmed in the Applications section and Functional Diagram. This avoids system resets and protects downstream loads during hot-swap or backup power transitions.
How does the ILIM pin configure current sense thresholds on LTC3850IUFD#PBF?
On the LTC3850IUFD#PBF, the ILIM pin sets the maximum current sense threshold for both channels: tying ILIM to SGND selects 20mV, floating selects 40mV, and connecting to INTVCC selects 60mV. These values are verified in the Electrical Characteristics table (VSENSE(MAX)) and apply identically to SENSE1 and SENSE2 inputs.
What package type and thermal characteristics does LTC3850IUFD#PBF use?
The LTC3850IUFD#PBF uses a 28-lead 4mm × 5mm plastic QFN package (UFD) with exposed thermal pad (Pin 29 = GND). Its thermal resistance is θJA = 34°C/W and θJC = 2.6°C/W - enabling higher power density than the smaller 4mm × 4mm UFD variant (θJA = 37°C/W) and SSOP package (θJA = 95°C/W).
Can LTC3850IUFD#PBF synchronize to an external clock, and how is it configured?
Yes, the LTC3850IUFD#PBF can synchronize to an external clock via the MODE/PLLIN pin. When an external clock signal is applied to MODE/PLLIN, the internal oscillator locks to it - forcing continuous conduction mode and eliminating beat frequencies. The FREQ/PLLFLTR pin simultaneously serves as the PLL loop filter node, requiring appropriate RC network design per the datasheet.
LTC3850IUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 30V
- Frequency - Switching:
- 250kHz ~ 780kHz
- Duty Cycle (Max):
- 97.2%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3850IUFD#PBF FAQ
1.How can I place an order for LTC3850IUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3850IUFD#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 LTC3850IUFD#PBF reliable?
The price and inventory of LTC3850IUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3850IUFD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3850IUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3850IUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3850IUFD#PBF?
LTC3850IUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3850IUFD#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 LTC3850IUFD#PBF?
For technical support, including LTC3850IUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3850IUFD#PBF requirements.
6.How does Aetrix verify that LTC3850IUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3850IUFD#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 LTC3850IUFD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3850IUFD#PBF?
All LTC3850IUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3850IUFD#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 LTC3850IUFD#PBF part is unused and in its original packaging.
Return procedure for LTC3850IUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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