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Analog Devices Inc. LTC3853IUJ#TRPBF
- Part No.:
- LTC3853IUJ#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LTC3853IUJ#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 40QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,106
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Product details
Overview
LTC3853IUJ#TRPBF from Analog Devices (formerly Linear Technology) is a triple-output, multiphase synchronous step-down controller driving all-N-channel MOSFET stages for high-efficiency power conversion in server, telecom, and FPGA power systems. It delivers three independent outputs (up to 5.5V, 5.5V, and 13.5V), operates from 4.5V–24V input, supports 120° phase interleaving, and achieves ±0.75% output voltage accuracy at 0.8V reference.
For engineers reviewing the LTC3853IUJ#TRPBF datasheet, LTC3853IUJ#TRPBF pinout, LTC3853IUJ#TRPBF application, or LTC3853IUJ#TRPBF equivalent, key selection criteria include its 40-lead QFN package, phase-lockable 250kHz–750kHz switching frequency, independent soft-start/tracking via TK/SS pins, RSENSE/DCR current sensing, and dual PGOOD monitors with ±7.5% regulation window detection.
Technical Context
The LTC3853IUJ#TRPBF implements a constant-frequency current-mode control architecture across three independent channels, each with dedicated ITH error amplifier output, VFB feedback input, and SENSE± current sense interface. Its 120° phase interleaving reduces input ripple current and required bulk capacitance while enabling up to 92% peak efficiency.
It supports three configuration modes: triple 120° phased operation, dual-phase + single-phase (180° + 0°), or single 3-phase output. Channel 3 supports higher output voltages (up to 13.5V) and wider common-mode sense range (up to 13.5V), while MODE/PLLIN enables Burst Mode®, pulse-skipping, or forced continuous conduction-each with distinct light-load trade-offs in efficiency, noise, and ripple.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 24V (28V absolute max); supports 12V/24V intermediate bus and multi-cell battery inputs. |
| Output Voltage Range | Channels 1 & 2: 0.8V–5.5V; Channel 3: 0.8V–13.5V; enables mixed-rail systems (e.g., 5V/3.3V/1.2V or 12V/3.3V/1.8V). |
| Switching Frequency | 250kHz–750kHz, phase-lockable via FREQ/PLLFLTR and MODE/PLLIN; allows EMI optimization and inductor size reduction. |
| Feedback Accuracy | ±0.75% at 0.8V reference over –40°C to 125°C; ensures tight regulation under thermal stress and load transients. |
| Current Sensing | RSENSE or DCR sensing per channel; supports accurate cycle-by-cycle current limiting and foldback protection. |
| Power Good Monitoring | PGOOD12 (phases 1+2) and PGOOD3 (phase 3) open-drain outputs with ±7.5% window and 17µs mask timer. |
| Soft-Start & Tracking | Independent TK/SS1/2/3 pins with 1.3µA internal charge current; enables coincident or ratiometric ramping of multiple rails. |
Pinout & Package
Package: 40-lead 6mm × 6mm plastic QFN (UJ) with exposed PGND pad (Pin 41), rated for –40°C to 125°C operating junction temperature and θJA = 33°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TG1, TG2, TG3 (Pins 32, 26, 19) | Top gate driver outputs | Floating drivers for N-channel high-side MOSFETs; swing = INTVCC superimposed on SW node voltage. |
| BG1, BG2, BG3 (Pins 30, 28, 21) | Bottom gate driver outputs | Ground-referenced drivers for N-channel low-side MOSFETs; operate between PGND and INTVCC/DRVCC12. |
| SENSE1+/2+/3+, SENSE1−/2−/3− (Pins 3,5,7,4,6,8) | Current sense comparator inputs | Differential inputs supporting RSENSE or DCR sensing; SENSE3± supports up to 13.5V common-mode for high-VOUT channel. |
| VFB1, VFB2, VFB3 (Pins 9, 12, 14) | Error amplifier feedback inputs | Remote-sense inputs for closed-loop regulation; each compares divider output to 0.8V internal reference. |
| ITH1, ITH2, ITH3 (Pins 10, 13, 15) | Error amplifier output / current threshold | Controls peak inductor current per channel; voltage sets current limit threshold (e.g., 1.85V → 30mV max sense voltage). |
| TK/SS1, TK/SS2, TK/SS3 (Pins 40, 1, 2) | Soft-start and tracking control | Internal 1.3µA current charges external capacitor; voltage ramp controls output rise time or enables rail tracking. |
| MODE/PLLIN (Pin 37) | Mode selection & PLL sync input | Selects Burst Mode® (float), pulse-skip (INTVCC), or forced continuous (SGND); accepts external clock for synchronization. |
| PGOOD12, PGOOD3 (Pins 17, 16) | Power good status outputs | Open-drain indicators pulled low when any monitored VFB deviates >±7.5% from 0.8V or RUN pin <1.2V. |
Key Features
| Feature | Design Value |
|---|---|
| Triple 120° interleaved control | Reduces input RMS ripple current by ~58% vs. single-phase, lowering required input capacitance and supply-induced noise. |
| Configurable topology support | Enables dual-phase + single-phase (180° + 0°) or unified 3-phase mode-flexible for varying current demands per rail. |
| Independent channel enable/disable | RUN1/RUN2/RUN3 pins allow per-channel sequencing and dynamic rail shutdown without affecting other outputs. |
| Pre-biased output startup | Supports safe start-up into pre-charged outputs without reverse current flow, critical for hot-swap and multi-rail sequencing. |
| Output overvoltage protection | Hardware-based OVP triggers shutdown if VFB exceeds 0.86V (H-/MP-grade) or 0.84V (E/I-grade), protecting downstream loads. |
Applications
| Server CPU Core & I/O Power | Telecom Base Station RF Power |
|---|---|
Use Scenario: Providing tightly regulated 1.2V/5A core, 3.3V/5A I/O, and 5V/5A auxiliary rails from a 12V intermediate bus in a 1U rack server. IC Role / Device Role / Timing Role: Triple-output synchronous buck controller managing phase-interleaved switching, independent soft-start, and rail sequencing. Use Value: 120° phasing cuts input capacitor RMS current by >50%, reducing bulk capacitance count and board area while maintaining <±0.75% output accuracy. | Use Scenario: Generating 5V analog bias, 3.3V digital logic, and 12V PA bias rails in a 4G/LTE remote radio head with strict EMI limits. IC Role / Device Role / Timing Role: Multiphase controller with phase-lockable oscillator synchronized to system clock to suppress switching noise in sensitive RF bands. Use Value: PLL synchronization eliminates beat frequencies; Burst Mode® operation maintains >85% efficiency at 100mA load, extending thermal margin in sealed enclosures. |
| FPGA & ASIC Multi-Rail Power | Industrial PLC I/O Module Power |
Use Scenario: Delivering 0.85V/20A core, 1.8V/8A memory, and 3.3V/5A interface rails from a 24V DC input in an adaptive computing platform. IC Role / Device Role / Timing Role: Configured as dual-phase (core) + single-phase (memory/interface) with independent TK/SS tracking for controlled power-up sequence. Use Value: Coincident tracking ensures VCORE ramps before VMEM, preventing latch-up; DCR sensing eliminates current-sense resistor losses in high-current paths. | Use Scenario: Supplying isolated 5V sensor bias, 3.3V microcontroller, and 12V actuator drive rails in a DIN-rail mounted programmable logic controller. IC Role / Device Role / Timing Role: Triple-output controller with robust UVLO (3.35V INTVCC), wide -40°C to 125°C operation, and fault-tolerant PGOOD monitoring. Use Value: Dual PGOOD outputs enable independent power-good signaling to safety MCU; ±7.5% window tolerance accommodates industrial line variation without false trips. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3855IUJ#TRPBF | Includes integrated MOSFET drivers with enhanced gate drive strength (TG pull-up: 1.8Ω vs. 2.6Ω); adds PMBus interface and telemetry. | Targeted at systems requiring digital power management, telemetry, and tighter transient response; not pin-compatible. | Select LTC3855IUJ#TRPBF when digital control, voltage margining, or real-time current reporting is required. |
| TPS546D24ARVFT | Single-chip 30A triple-output buck converter (integrated MOSFETs); fixed 500kHz frequency; no phase interleaving or external MOSFET flexibility. | Suitable for space-constrained, lower-power applications (<15A per rail); lacks independent rail configuration and DCR sensing. | Choose TPS546D24ARVFT for simplified BOM and layout where integrated power stage suffices and phase control is unnecessary. |
Compared with LTC3853IUJ#TRPBF, LTC3855IUJ#TRPBF adds digital control but requires firmware integration, while TPS546D24ARVFT trades design flexibility for integration and reduced component count-making LTC3853IUJ#TRPBF optimal for high-current, thermally demanding, or highly configurable multi-rail systems.
Availability
LTC3853IUJ#TRPBF is available at Aetrix Electronics and suitable for server power supplies, telecom base station power modules, and FPGA/ASIC power delivery systems requiring stable component supply, extended temperature operation, and precise multi-rail sequencing.
Supply support for LTC3853IUJ#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 and maintains its high-performance analog and power management portfolio with rigorous automotive, industrial, and aerospace qualification standards.
The LTC3853IUJ#TRPBF belongs to Linear's multiphase synchronous buck controller product line, designed specifically for high-efficiency, high-current, multi-rail power conversion in data center, communications infrastructure, and high-end computing applications.
FAQ
What is the maximum output voltage supported by LTC3853IUJ#TRPBF on its third channel?
The LTC3853IUJ#TRPBF supports up to 13.5V on Channel 3, enabled by extended common-mode voltage range (up to 13.5V) on SENSE3+ and SENSE3− pins. This allows direct generation of higher-voltage rails like 12V analog bias or industrial I/O supplies without post-regulation, unlike Channels 1 and 2 which are limited to 5.5V maximum output.
Does LTC3853IUJ#TRPBF support pre-biased output startup?
Yes, LTC3853IUJ#TRPBF supports pre-biased output startup. Its current-mode architecture and reverse-current comparator (IREV) prevent negative inductor current during start-up, allowing safe ramp-up into pre-charged outputs. This avoids damaging reverse current flow-a critical requirement in hot-swap and multi-rail systems where rails may be powered independently.
How does the MODE/PLLIN pin configure operating modes on LTC3853IUJ#TRPBF?
The MODE/PLLIN pin on LTC3853IUJ#TRPBF selects light-load behavior: floating enables Burst Mode® (highest efficiency, discontinuous conduction), connection to INTVCC enables pulse-skipping mode (lower ripple, moderate efficiency), and grounding forces continuous conduction mode (lowest ripple, lowest light-load efficiency). It also accepts external clocks for phase synchronization when used as PLLIN.
What is the purpose of the ILIM pin on LTC3853IUJ#TRPBF?
The ILIM pin on LTC3853IUJ#TRPBF sets the full-scale current sense threshold level for all three channels. Connecting ILIM to SGND, FLOAT, or INTVCC selects low (22mV), medium (42mV), or high (65mV) maximum sense voltage thresholds respectively-allowing optimization of current-sense resistor value and short-circuit protection sensitivity without changing external components.
Can LTC3853IUJ#TRPBF be configured for dual-phase + single-phase operation?
Yes, LTC3853IUJ#TRPBF can be configured as a dual-phase controller plus a single-phase controller. This is achieved by connecting VFB2 to VIN through a 200kΩ resistor and shorting ITH1/ITH2 and TK/SS1/TK/SS2 externally. The dual-phase section (Ch1+Ch2) operates 180° out-of-phase, while Ch3 runs independently-ideal for asymmetric rail requirements like CPU core + I/O + auxiliary.
LTC3853IUJ#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 40-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:
- 3
- Output Phases:
- 3
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 24V
- Frequency - Switching:
- 250kHz ~ 750kHz
- Duty Cycle (Max):
- 98%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 40-QFN (6x6)
LTC3853IUJ#TRPBF FAQ
1.How can I place an order for LTC3853IUJ#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3853IUJ#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 LTC3853IUJ#TRPBF reliable?
The price and inventory of LTC3853IUJ#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3853IUJ#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3853IUJ#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3853IUJ#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3853IUJ#TRPBF?
LTC3853IUJ#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3853IUJ#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 LTC3853IUJ#TRPBF?
For technical support, including LTC3853IUJ#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3853IUJ#TRPBF requirements.
6.How does Aetrix verify that LTC3853IUJ#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3853IUJ#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 LTC3853IUJ#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3853IUJ#TRPBF?
All LTC3853IUJ#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3853IUJ#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 LTC3853IUJ#TRPBF part is unused and in its original packaging.
Return procedure for LTC3853IUJ#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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