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Analog Devices Inc. LTC3850EUFD#TRPBF
- Part No.:
- LTC3850EUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3850EUFD#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,130
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Product details
Overview
LTC3850EUFD#TRPBF from Analog Devices is a dual, 2-phase synchronous step-down switching controller driving all-N-channel MOSFET stages. It delivers up to 95% efficiency, supports 250kHz–780kHz phase-lockable fixed-frequency operation, and features ±1% 0.8V reference accuracy. Used in high-density DC power distribution systems requiring tightly regulated dual outputs.
For engineers reviewing the LTC3850EUFD#TRPBF datasheet, LTC3850EUFD#TRPBF pinout, LTC3850EUFD#TRPBF application, or LTC3850EUFD#TRPBF equivalent, key selection criteria include dual-phase current-mode control, independent soft-start/tracking (TK/SS), RSENSE or DCR sensing, and automotive-grade AEC-Q100 qualification for LTC3850I variants.
Technical Context
The LTC3850EUFD#TRPBF implements constant-frequency current-mode control with two 180° out-of-phase channels, minimizing input capacitance requirements and supply-induced noise. Each channel uses an independent error amplifier with OPTI-LOOP® compensation, enabling stable loop response across wide output capacitance and ESR ranges.
It integrates dual N-channel MOSFET gate drivers (TG/BG), precision 0.8V reference, power-good monitoring, and selectable operating modes (Burst, pulse-skipping, continuous conduction) via MODE/PLLIN. The FREQ/PLLFLTR pin enables frequency programming or PLL synchronization, while ILIM pin configures current-sense threshold (20/40/60mV).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Dual synchronous buck controller - drives external high-side and low-side N-MOSFETs per channel. |
| Switching Frequency | 250kHz to 780kHz - adjustable via FREQ/PLLFLTR voltage; supports external clock sync on MODE/PLLIN. |
| Reference Voltage | 0.8V ±1% - enables precise output regulation; used directly by VFB1/VFB2 feedback comparators. |
| Input Voltage Range | 4V to 24V (30V max for LTC3850I) - covers common battery chemistries and intermediate bus rails. |
| Current Sensing | RSENSE or DCR - configurable via SENSE1±/SENSE2± pins; ILIM pin selects 20/40/60mV threshold. |
| Efficiency | Up to 95% - achieved via low-RDS(on) gate drive, optimized dead-time control, and phase interleaving. |
| Operating Temp | –40°C to +85°C - specified performance over full industrial temperature range. |
Pinout & Package
Package: 28-lead (4mm × 5mm) plastic QFN (UFD), exposed pad (Pin 29) soldered to PCB as SGND/PGND thermal and electrical connection. θJA = 34°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2 (Pins 27, 10) | Channel enable/disable control | Logic-high (>1.22V) enables channel; internal 0.5µA pull-up allows simple RC startup sequencing. |
| TK/SS1, TK/SS2 (Pins 2, 7) | Soft-start and tracking input | Internal 1.3µA current charges external capacitor to ramp VOUT linearly; supports master-slave voltage tracking. |
| ITH1, ITH2 (Pins 3, 6) | Error amplifier output / current limit threshold | Voltage sets peak inductor current; direct interface for loop compensation and current foldback control. |
| VFB1, VFB2 (Pins 4, 5) | Feedback input | Compares remote-sensed output voltage against 0.8V reference; supports resistor-divider-based regulation. |
| SENSE1+, SENSE1− / SENSE2+, SENSE2− (Pins 1, 8 / Pins 28, 9) | Current sense differential inputs | Accepts Kelvin-connected RSENSE or DCR network; rejects common-mode noise up to 5.5V. |
| TG1, TG2 / BG1, BG2 (Pins 23, 15 / Pins 21, 18) | Top/bottom gate drivers | Drive N-MOSFET gates with 2.6Ω pull-up / 1.5Ω pull-down; 25ns transition time into 3300pF load. |
| BOOST1, BOOST2 (Pins 22, 16) | Floating bootstrap supply | Connects to (+) terminal of bootstrap capacitors; swings from ~INTVCC–0.7V to VIN+INTVCC. |
| SW1, SW2 (Pins 24, 14) | Switch node connection | Direct connection to inductor; voltage swing from ~–0.7V to VIN; requires low-inductance layout. |
| MODE/PLLIN (Pin 25) | Mode selection & sync input | Configures Burst/PWM/pulse-skip mode; accepts external clock for phase locking (250kHz–780kHz). |
| FREQ/PLLFLTR (Pin 26) | Oscillator frequency control | DC voltage input (0–2.4V) sets nominal frequency; also serves as PLL loop filter node when synchronized. |
| PGOOD (Pin 13) | Power-good indicator | Open-drain output asserts low if either VOUT deviates >±7.5% from target after 17µs mask timer. |
| ILIM (Pin 11) | Current sense threshold select | SGND/FLOAT/INTVCC sets max sense voltage to 20/40/60mV - defines short-circuit foldback level. |
| VIN (Pin 20) | Main input supply | 4V–24V input rail; powers INTVCC regulator unless EXTVCC >4.7V (not present on LTC3850, only LTC3850-1). |
| INTVCC (Pin 19) | Internal 5V regulator output | Supplies gate drivers and logic; requires 4.7µF low-ESR ceramic/tantalum decoupling to PGND. |
| PGND (Pin 17) | Power ground | High-current return path for bottom MOSFET sources, CIN(–), CVCC(–); must be star-connected to SGND at one point. |
| SGND (Pin 29, Exposed Pad) | Signal ground | Reference for all small-signal circuitry (error amps, comparators); must be soldered and tied to PGND under IC. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® compensation | Enables stable loop response across wide output capacitor values (10µF–1000µF) and ESR ranges without redesign. |
| Independent TK/SS control | Per-channel soft-start ramp or voltage tracking eliminates output overshoot and ensures controlled power-up sequencing. |
| Phase-interleaved dual output | 180° out-of-phase operation cuts input ripple current by ~70%, reducing required input capacitance and EMI. |
| Three light-load operating modes | Burst Mode (highest efficiency), pulse-skipping (low ripple/audio noise), or forced CCM (lowest output ripple). |
| Pre-biased output support | Starts up safely into pre-charged output capacitors without reverse current flow or latch-up risk. |
| AEC-Q100 qualified variant | LTC3850I versions meet automotive reliability standards - validated for –40°C to +85°C operation with extended life testing. |
Applications
| High-Density Server Power | Notebook CPU/GPU Core Rails |
|---|---|
|
Use Scenario: Dual 3.3V/2.5V or 1.8V/1.2V supplies for FPGA I/O banks and core logic in compact server blades. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent output voltages with interleaved switching. Use Value: Phase interleaving reduces input RMS current by ~70%, allowing smaller bulk capacitors and lower board area vs. single-phase solutions. |
Use Scenario: Sequenced core and I/O voltage rails for Intel/AMD mobile processors in ultrabooks and 2-in-1 devices. IC Role / Device Role / Timing Role: Dual-channel controller with independent TK/SS pins enabling precise voltage ramp tracking during boot. Use Value: Eliminates need for external sequencing ICs; soft-start prevents inrush current damage to sensitive SoC power domains. |
| Portable Test Equipment | Industrial DC Distribution |
|
Use Scenario: Battery-powered oscilloscopes and spectrum analyzers requiring clean, low-noise analog and digital supplies. IC Role / Device Role / Timing Role: Dual-output controller delivering isolated 3.3V (digital) and 5V/±15V (analog) rails from single Li-ion input. Use Value: Burst Mode operation extends battery runtime; OPTI-LOOP® maintains stability with diverse capacitor types used in mixed-signal designs. |
Use Scenario: DIN-rail mounted programmable logic controllers (PLCs) converting 24V industrial bus to 5V/3.3V system rails. IC Role / Device Role / Timing Role: Robust dual buck controller handling wide input transients (up to 34V for LTC3850I) and high ambient temperatures. Use Value: AEC-Q100 qualified variants ensure long-term reliability; current foldback protects MOSFETs during field wiring faults. |
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 (Monolithic Power) | Integrated dual buck controller + drivers in 32-pin QFN; no external MOSFET requirement; fixed 500kHz freq. | Lower BOM count but less flexible MOSFET selection; lacks phase-lock capability and OPTI-LOOP® adaptability. | Choose MP2918GL-Z for cost-sensitive, space-constrained designs where fixed frequency and integrated drivers suffice. |
| LTC3838EUFD#TRPBF | Single-channel version with identical pinout, package, and feature set; shares same 0.8V ref, TK/SS, and MODE/PLLIN behavior. | Used where only one regulated output is needed; cannot replace dual-channel functionality without redesign. | Choose LTC3838EUFD#TRPBF when system requires only one high-efficiency buck stage and footprint compatibility is critical. |
Compared with MP2918GL-Z, LTC3850EUFD#TRPBF offers superior design flexibility via external MOSFET selection, phase-lock synchronization, and adaptive loop compensation - essential for high-reliability or thermally demanding applications. Compared with LTC3838EUFD#TRPBF, it provides true dual-output capability with independent control, eliminating need for two separate controllers.
Availability
LTC3850EUFD#TRPBF is available at Aetrix Electronics and suitable for high-density server power, notebook CPU/GPU core rails, and industrial DC distribution systems requiring stable component supply and long lifecycle support.
Supply support for LTC3850EUFD#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 (now part of Analog Devices, Inc., following merger with Maxim Integrated) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC3850EUFD#TRPBF belongs to the LTC® high-efficiency power controller family, designed specifically for demanding multi-rail DC/DC conversion in computing, communications, and industrial equipment where efficiency, density, and reliability are critical.
FAQ
What is the maximum switching frequency supported by the LTC3850EUFD#TRPBF?
The LTC3850EUFD#TRPBF supports a phase-lockable fixed-frequency range from 250kHz to 780kHz. Frequency is set via a DC voltage on the FREQ/PLLFLTR pin (0V → 250kHz, 1.2V → 500kHz, ≥2.4V → 780kHz) or synchronized to an external clock applied to MODE/PLLIN. Operation beyond 780kHz is not guaranteed per datasheet specifications.
Does the LTC3850EUFD#TRPBF support pre-biased output startup?
Yes, the LTC3850EUFD#TRPBF supports safe startup into pre-charged outputs. Its current-mode architecture and reverse-current protection (via IREV comparator) prevent negative inductor current and output voltage collapse during initial turn-on, making it suitable for hot-swap and redundant power applications.
How does the ILIM pin affect current limiting on the LTC3850EUFD#TRPBF?
The ILIM pin on the LTC3850EUFD#TRPBF selects the maximum current-sense threshold for both channels: tying to SGND sets 20mV, floating sets 40mV, and tying to INTVCC sets 60mV. This directly determines the foldback current limit during short-circuit conditions and scales the current-sense gain without changing external components.
Can the LTC3850EUFD#TRPBF operate with only one channel enabled?
Yes, the LTC3850EUFD#TRPBF supports independent channel control. Pulling RUN1 low disables Channel 1 while Channel 2 remains fully operational, and vice versa. Both channels share the same INTVCC supply and oscillator, but maintain separate feedback (VFB1/VFB2), current sense (SENSE1±/SENSE2±), and soft-start (TK/SS1/TK/SS2) paths.
What is the purpose of the exposed pad (Pin 29) on the LTC3850EUFD#TRPBF UFD package?
The exposed pad (Pin 29) on the LTC3850EUFD#TRPBF is a signal ground (SGND) connection that must be soldered to the PCB. It provides low-impedance grounding for internal control circuitry and serves as the primary thermal path - contributing to the package's θJA of 34°C/W. It must be electrically tied to PGND at a single point beneath the IC.
LTC3850EUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-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:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 24V
- 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)
LTC3850EUFD#TRPBF FAQ
1.How can I place an order for LTC3850EUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3850EUFD#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 LTC3850EUFD#TRPBF reliable?
The price and inventory of LTC3850EUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3850EUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3850EUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3850EUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3850EUFD#TRPBF?
LTC3850EUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3850EUFD#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 LTC3850EUFD#TRPBF?
For technical support, including LTC3850EUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3850EUFD#TRPBF requirements.
6.How does Aetrix verify that LTC3850EUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3850EUFD#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 LTC3850EUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3850EUFD#TRPBF?
All LTC3850EUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3850EUFD#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 LTC3850EUFD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3850EUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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