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Analog Devices Inc. LTC3853EUJ#TRPBF
- Part No.:
- LTC3853EUJ#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LTC3853EUJ#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 40QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,613
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Product details
Overview
LTC3853EUJ#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/ASIC core logic supplies. It supports 4.5V–24V input, delivers up to 13.5V on Phase 3, operates at 250–750kHz with 120° phase shift, and achieves ±0.75% output voltage accuracy at 0.8V reference.
For engineers reviewing the LTC3853EUJ#TRPBF datasheet, LTC3853EUJ#TRPBF pinout, LTC3853EUJ#TRPBF application, or LTC3853EUJ#TRPBF equivalent, key selection criteria include independent soft-start/tracking per channel, RSENSE/DCR current sensing flexibility, foldback current limiting, pre-biased startup support, and dual PGOOD monitoring for multi-rail systems.
Technical Context
The LTC3853EUJ#TRPBF implements a constant-frequency current-mode control architecture with three independent PWM channels operating 120° out-of-phase to reduce input ripple and EMI. Each channel features a transconductance error amplifier (gm = 2.2 mmho), programmable current-sense threshold via ILIM pin (three levels: GND/FLOAT/INTVCC), and dedicated ITH/VFB/TK-SS pins for loop compensation, feedback, and soft-start/tracking.
It integrates independent RUN pins per channel for sequencing control, MODE/PLLIN for Burst Mode®/pulse-skipping/continuous operation selection or external clock synchronization, and FREQ/PLLFLTR for frequency programming or PLL loop filtering. The IC supports dropout recovery via forced top-FET off cycles and reverse-current prevention via IREV comparator.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 24V (28V absolute max); covers 5V/12V intermediate buses and Li-ion/LiPo battery stacks. |
| Output Voltage Range (Ch1–2) | 0.8V to 5.5V; supports DDR memory, CPU I/O, and low-voltage logic rails. |
| Output Voltage Range (Ch3) | 0.8V to 13.5V; enables higher-voltage auxiliary rails like analog front-ends or op-amp supplies. |
| Switching Frequency | 250kHz to 750kHz (phase-lockable); balances efficiency vs. inductor/capacitor size trade-offs. |
| Feedback Accuracy | ±0.75% at 0.8V over –40°C to 125°C; ensures tight regulation for sensitive digital loads. |
| Current Sensing | RSENSE or DCR; eliminates sense resistor losses and enables accurate current limiting across wide temperature range. |
| Phase Configuration | Triple 120° phased, dual 180° + single, or single 3-phase; reduces input capacitance and supply noise by interleaving. |
Pinout & Package
Package: 40-lead (6mm × 6mm) plastic QFN (UJ), exposed PGND pad (Pin 41) requiring PCB soldering for thermal and electrical integrity. θJA = 33°C/W, TJMAX = 150°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TK/SS1, TK/SS2, TK/SS3 (Pins 40, 1, 2) | Soft-start & tracking control inputs | Internal 1.3µA current charges external capacitor for linear VOUT ramp; enables ratiometric or coincident startup with master/slave configuration. |
| SENSE1+/–, SENSE2+/–, SENSE3+/– (Pins 3–8) | Differential current sense inputs | Supports RSENSE or DCR sensing; SENSE3 common-mode up to 13.5V allows high-VOUT Phase 3 operation. |
| VFB1, VFB2, VFB3 (Pins 9, 12, 14) | Feedback voltage inputs | Compare output voltage (via resistive divider) to 0.8V internal reference; enable remote sensing for load regulation. |
| ITH1, ITH2, ITH3 (Pins 10, 13, 15) | Error amplifier output & current threshold | Set peak inductor current via voltage; compensation node for loop stability tuning per channel. |
| PGOOD12, PGOOD3 (Pins 16, 17) | Open-drain power-good indicators | Assert low if any monitored VFB deviates >±7.5% from 0.8V after 17µs mask timer; separate outputs simplify multi-rail sequencing. |
| RUN1, RUN2, RUN3 (Pins 34–36) | Independent channel enable inputs | Turn on/off each controller individually; 1.2V threshold with 80mV hysteresis enables robust sequencing and fault isolation. |
| MODE/PLLIN (Pin 37) | Mode selection & external sync input | Select Burst Mode® (float), pulse-skip (INTVCC), or continuous (SGND); accept external clock for deterministic timing alignment. |
| FREQ/PLLFLTR (Pin 38) | Oscillator frequency control / PLL filter | DC voltage sets frequency (250–750kHz); RC network to SGND forms PLL low-pass filter when synchronized. |
| ILIM (Pin 39) | Current sense threshold select | Three-level programming (GND/FLOAT/INTVCC) sets max sense voltage from 21mV to 86mV for optimized MOSFET stress vs. accuracy. |
| BOOST1–3 (Pins 18, 25, 33) | Floating gate driver supplies | Connect to bootstrap capacitors; swing from diode drop below INTVCC to VIN + INTVCC for high-side N-MOSFET drive. |
| TG1–3, BG1–3 (Pins 19, 26, 32; 21, 28, 30) | Top/bottom gate drivers | Drive N-MOSFET gates with 2.6Ω pull-up / 1.5Ω pull-down (TG), 2.4Ω/1.1Ω (BG); <30ns transition times minimize switching loss. |
| VIN, INTVCC, EXTVCC (Pins 24, 22, 23) | Main input, internal 5V regulator, external bias | EXTVCC >4.7V disables INTVCC LDO and powers IC directly-improves efficiency when using regulated output as bias source. |
Key Features
| Feature | Design Value |
|---|---|
| Triple 120° interleaved control | Reduces RMS input current by ~58% vs. single-phase, cutting required bulk capacitance and conducted EMI. |
| Independent per-channel RUN and TK/SS | Enables precise power-up/down sequencing, staggered soft-start, and ratiometric tracking across mixed-voltage rails. |
| Programmable current limit via ILIM pin | Three discrete sense-threshold levels allow optimization of MOSFET SOA margin versus current-sense resolution. |
| Pre-biased output startup support | Allows safe turn-on into already-powered rails without reverse current flow-critical for hot-swap and redundant supply designs. |
| Output overvoltage protection | Hardware-based OVP triggers shutdown if VFB exceeds 0.84–0.89V (grade-dependent), protecting downstream loads from catastrophic failure. |
| Integrated dropout recovery | Forces periodic top-FET off time during dropout to recharge bootstrap capacitors-ensures reliable operation near VIN ≈ VOUT. |
Applications
| Server VRM Power Delivery | Telecom Line Card Supplies |
|---|---|
Use Scenario: Delivering tightly regulated 1.2V/5A, 3.3V/5A, and 5V/5A rails to multi-core CPUs, memory, and I/O interfaces in 1U rack servers. IC Role / Device Role / Timing Role: Triple-output controller managing three independent synchronous buck stages with interleaved timing to minimize input ripple and thermal stress. Use Value: 120° phase shift cuts input capacitor requirements by >50% and improves transient response via distributed current sourcing. | Use Scenario: Generating isolated 3.3V, 5V, and 12V auxiliary supplies for DSPs, PHYs, and management controllers on high-density line cards. IC Role / Device Role / Timing Role: Configured as dual-phase (3.3V+5V) plus single-phase (12V) to match load profiles while maintaining shared control logic and sequencing. Use Value: Independent RUN pins enable graceful shutdown of non-critical rails during brownout, preserving core functionality. |
| FPGA Core & I/O Voltage Sequencing | Industrial PLC Power Management |
Use Scenario: Powering Xilinx/Intel FPGAs requiring strict 0.85V core, 1.8V transceiver, and 3.3V I/O rail sequencing with monotonic ramp rates. IC Role / Device Role / Timing Role: Uses TK/SS1–3 pins with external RC networks to implement coincident or ratiometric tracking for guaranteed startup order. Use Value: ±0.75% VFB accuracy and 0.8V reference ensure FPGA core voltage stays within JEDEC specification limits across temperature. | Use Scenario: Providing robust, fault-tolerant 5V, 3.3V, and 12V rails in programmable logic controllers exposed to wide ambient temperatures (–40°C to 85°C). IC Role / Device Role / Timing Role: Leverages H-grade variant's 150°C junction rating and integrated OVP/UVLO to maintain reliability in unventilated enclosures. Use Value: Dual PGOOD outputs simplify system-level power health monitoring and enable automatic failover to backup supplies. |
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 shoot-through protection; supports higher VIN (up to 38V) and wider VOUT range (0.5V–5.5V on all channels). | Preferred for new designs needing higher input voltage tolerance and tighter 0.5% VFB accuracy; not drop-in due to different pinout and ILIM behavior. | Select LTC3855 when upgrading from LTC3853 for improved efficiency at light loads and extended input range-requires layout revision. |
| MP2950GQ-UT | Monolithic triple-output controller with integrated power stages; lower quiescent current (120µA vs. 42mA), but fixed 500kHz frequency and no phase-shift flexibility. | Suitable for cost-sensitive, space-constrained applications where full discrete design isn't required; lacks independent RUN/TK-SS per channel. | Choose MP2950 for simplified BOM and smaller footprint in mid-power embedded systems-sacrifices configurability for integration. |
Compared with LTC3855IUJ#TRPBF and MP2950GQ-UT, the LTC3853EUJ#TRPBF offers unmatched flexibility in phase configuration, independent per-channel control, and wide input/output voltage coverage-making it ideal for high-performance, thermally demanding, and highly sequenced multi-rail systems where discrete MOSFET selection and layout optimization are critical.
Availability
LTC3853EUJ#TRPBF is available at Aetrix Electronics and suitable for server VRMs, telecom line cards, FPGA power delivery, industrial PLCs, and high-reliability embedded computing applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3853EUJ#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 legacy of high-performance analog and power management ICs with rigorous qualification and long-term product support.
The LTC3853EUJ#TRPBF belongs to Linear's polyphase synchronous controller family, designed specifically for high-efficiency, low-noise, multi-rail DC/DC conversion in datacenter, communications, and industrial equipment where precision regulation and flexible sequencing are essential.
FAQ
What is the maximum output voltage supported by LTC3853EUJ#TRPBF on Channel 3?
The LTC3853EUJ#TRPBF supports an output voltage range of 0.8V to 13.5V on Channel 3, enabled by SENSE3+ and SENSE3– pins rated for up to 13.5V common-mode voltage. This allows the device to regulate higher auxiliary rails such as analog front-ends or op-amp supplies without external level-shifting circuitry.
Does LTC3853EUJ#TRPBF support pre-biased output startup?
Yes, the LTC3853EUJ#TRPBF supports pre-biased output startup. Its current-mode architecture and reverse-current comparator (IREV) prevent negative inductor current flow during turn-on, allowing safe operation when the output capacitor is already charged-essential for hot-swap and redundant power systems.
How does the ILIM pin affect current limiting on LTC3853EUJ#TRPBF?
The ILIM pin on LTC3853EUJ#TRPBF selects one of three maximum current-sense threshold levels: 21–39mV (ILIM = GND), 41–59mV (ILIM = FLOAT), or 64–86mV (ILIM = INTVCC), depending on grade. This adjusts the peak inductor current trip point to match MOSFET RDS(on) and thermal constraints without changing external sense components.
Can LTC3853EUJ#TRPBF be configured for dual-phase + single-phase operation?
Yes, the LTC3853EUJ#TRPBF can be configured as a dual-phase controller (Channels 1 & 2) plus a single-phase controller (Channel 3) by connecting VFB2 to VIN through a 200kΩ resistor and shorting ITH1/ITH2 externally. This mode maintains independent control of the third rail while interleaving the first two for reduced input ripple.
What thermal considerations apply to the exposed pad of LTC3853EUJ#TRPBF?
The exposed pad (Pin 41, PGND) of LTC3853EUJ#TRPBF must be soldered to a thermally robust PCB copper area to achieve θJA = 33°C/W. Inadequate thermal connection risks exceeding the 150°C maximum junction temperature, especially under full-load conditions at elevated ambient temperatures.
LTC3853EUJ#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)
LTC3853EUJ#TRPBF FAQ
1.How can I place an order for LTC3853EUJ#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3853EUJ#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 LTC3853EUJ#TRPBF reliable?
The price and inventory of LTC3853EUJ#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3853EUJ#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3853EUJ#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3853EUJ#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3853EUJ#TRPBF?
LTC3853EUJ#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3853EUJ#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 LTC3853EUJ#TRPBF?
For technical support, including LTC3853EUJ#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3853EUJ#TRPBF requirements.
6.How does Aetrix verify that LTC3853EUJ#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3853EUJ#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 LTC3853EUJ#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3853EUJ#TRPBF?
All LTC3853EUJ#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3853EUJ#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 LTC3853EUJ#TRPBF part is unused and in its original packaging.
Return procedure for LTC3853EUJ#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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